Corrections

Previously: Lipase-mediated release of free fatty acids

Now: Lipase-mediated stimulation of follicular inflammation

Previously: Cutibacterium acnes, formerly Propionibacterium acnes, lives in the sebaceous follicle and secretes lipases that hydrolyze sebum triglycerides. The liberated free fatty acids are irritant and chemotactic, drawing neutrophils into the…

Now: Cutibacterium acnes, formerly Propionibacterium acnes, resides in the sebaceous follicle and produces a low-molecular-weight peptide that attracts leukocytes. The bacteria are phagocytized, and the release of bacterial hydrolytic enzymes,…

Previously: The organism secretes lipases that cleave sebum triglycerides into free fatty acids. These are proinflammatory and chemotactic for neutrophils, and together with cell wall components that signal through Toll-like receptor 2 they recruit…

Now: Bacteria residing in the sebaceous follicle produce a low-molecular-weight peptide that attracts leukocytes. The bacteria are phagocytized, and the release of bacterial hydrolytic enzymes — lipases, proteases, neuraminidase and…

Previously: produces lipases that split free fatty acids from skin lipids, contributing to tissue inflammation and acne formation

Now: releases hydrolytic enzymes, including lipases, that stimulate a localized inflammatory response contributing to acne formation

Previously: Cutibacterium acnes resides in sebaceous follicles and persists in the dermis after surgical antisepsis, so it is a frequent contaminant of blood, cerebrospinal fluid and operative specimens.

Now: Cutibacterium acnes is normal flora of the skin and is commonly isolated in blood cultures, where the finding usually represents contamination with bacteria on the skin at the site of the draw.

Previously: This organism does need 7 to 14 days of anaerobic incubation, which is why standard 5-day cultures are often reported as sterile and indolent prosthetic infections are missed.

Now: This organism grows slowly, and it may take 2 to 5 days for growth to appear, so a short incubation can be reported as sterile.

Previously: Cutibacterium acnes sits deep in sebaceous follicles where surface antisepsis does not reach, so it is among the commonest contaminants of blood and cerebrospinal fluid specimens.

Now: Cutibacterium acnes is normal flora of the skin, and it is commonly isolated in blood cultures, where the finding usually represents contamination with bacteria on the skin at the phlebotomy site.

Previously: it frequently contaminates blood/CSF cultures

Now: it frequently contaminates blood cultures

Previously: High-dose penicillin for 6-12 months

Now: High-dose penicillin for 4-12 months

Previously: Standard treatment is intravenous penicillin for 2 to 6 weeks followed by oral therapy to complete 6 to 12 months

Now: Treatment is high-dose intravenous penicillin, with oral penicillin or amoxicillin substituted after about 2 to 6 weeks, and it is prolonged: 4 to 12 months, until symptoms and signs have resolved

Previously: typically intravenous penicillin for 2 to 6 weeks, then oral penicillin or amoxicillin to complete 6 to 12 months

Now: typically intravenous penicillin at first, then oral penicillin or amoxicillin after about 2 to 6 weeks, for a prolonged course of 4 to 12 months

Previously: typically 6-12 months

Now: typically 4-12 months

Previously: Aeromonas hydrophila

Now: Aeromonas species

Previously: A gram-negative bacillus appearing within days of leech application, unresponsive to an aminopenicillin because the genus carries chromosomal β-lactamases, fits A hydrophila, the species classically implicated.

Now: A gram-negative bacillus appearing within days of leech application and unresponsive to an aminopenicillin fits Aeromonas, a genus resistant to the penicillins; the species that colonizes the leech gut is A veronii biovar sobria.

Previously: A hydrophila is the species classically reported, although A veronii biovar sobria is also recovered

Now: A veronii biovar sobria is the species that colonizes the gut of the medicinal leech

Previously: Cirrhosis or hematologic malignancy

Now: Cirrhosis or underlying malignancy

Previously: Invasive Aeromonas disease requires a compromised host, and two groups account for most cases. Cirrhosis brings portosystemic shunting, impaired Kupffer cell clearance and reduced opsonic activity, so gut-derived organisms reach the…

Now: Aeromonas causes systemic disease as an opportunist, in immunocompromised patients and particularly in those with hepatobiliary disease or an underlying malignancy, and sepsis with this organism is reported in the same patients. Cirrhosis…

Previously: Most species in the genus are unencapsulated. B anthracis alone produces a capsule, and chemical analysis shows it is composed entirely of poly-D-glutamic acid rather than of sugars.

Now: B anthracis produces a capsule, and chemical analysis shows it is composed entirely of poly-D-glutamic acid rather than of sugars.

Previously: B anthracis is the only Bacillus species with a capsule, and it is an unusual poly-D-glutamic acid polypeptide rather than the typical polysaccharide.

Now: B anthracis has an unusual poly-D-glutamic acid polypeptide capsule rather than the typical polysaccharide.

Previously: The answer given for treating Bacteroides fragilis infection was clindamycin.

Now: Metronidazole is the drug of choice, and clindamycin is less predictably active against B. fragilis. The question was rewritten and its answer is now metronidazole.

Previously: It is a far less frequent cause of jugular septic thrombophlebitis than F necrophorum, which, unlike it, is not a routine member of the healthy oral flora.

Now: Lemierre syndrome is attributed to F necrophorum, and both species belong to the normal oral flora.

Previously: Most Enterobacteriaceae produce beta-lactamases, chromosomal or plasmid-encoded, that hydrolyze the beta-lactam ring of ampicillin before it can acylate the penicillin-binding proteins.

Now: Ampicillin is penicillinase sensitive, and resistance to it in the Enterobacteriaceae, as in Salmonella, is mediated by beta-lactamase, which hydrolyzes the beta-lactam ring before the drug can acylate the penicillin-binding proteins.

Previously: The same mechanism explains why ampicillin alone cannot be relied on for most Enterobacteriaceae.

Now: The same mechanism explains why ampicillin alone cannot be relied on in the Enterobacteriaceae, where beta-lactamase mediates resistance to it.

Previously: nodes regress over two to four months

Now: nodes regress over 2 to 5 months

Previously: Pooled analyses do not support routine antibiotic therapy for uncomplicated disease, so analgesia, warm compresses and review are appropriate, with needle aspiration held in reserve for a painful fluctuant node.

Now: Antibiotic treatment is generally not given for localized infection in an immunocompetent patient, so local heat and analgesia are appropriate, with needle aspiration held in reserve for a painful fluctuant node.

Previously: A small randomized trial showed that azithromycin hastened shrinkage of node volume over the first month without altering the eventual outcome, so it is sometimes offered for bulky or painful adenopathy.

Now: Azithromycin may be given to reduce the duration of symptoms and adenopathy, so it is sometimes offered for bulky or painful lymphadenopathy.

Previously: Trimethoprim-sulfamethoxazole appears in older anecdotal series of cat-scratch disease alongside rifampin, gentamicin and the fluoroquinolones, but controlled evidence of benefit in uncomplicated adenitis is lacking.

Now: Trimethoprim-sulfamethoxazole is among the options for immunocompromised patients and systemic disease, with rifampin and the fluoroquinolones, but antibiotic treatment is not given for localized infection in an immunocompetent patient.

Previously: In the immunocompetent patient the regional lymphadenitis is self-limited over two to four months; several agents have anecdotal support, including azithromycin, trimethoprim-sulfamethoxazole, rifampin, gentamicin and ciprofloxacin, but…

Now: In the immunocompetent patient the lymphadenitis is self-limited and subsides within 2 to 5 months; azithromycin, doxycycline, rifampin, the fluoroquinolones and trimethoprim-sulfamethoxazole are the options when treatment is indicated,…

Previously: more recent analyses do not strongly support routine antibiotic use, despite anecdotal reports of several agents.

Now: antibiotic treatment is generally not given for localized infection in an immunocompetent patient.

Previously: carries an untreated mortality of up to 85%, which falls sharply with ciprofloxacin or chloramphenicol.

Now: carries an untreated case fatality rate that may exceed 50%, and ciprofloxacin with ceftriaxone for 14 days is the treatment of choice.

Previously: It is a vascular proliferative phase with little systemic disturbance and essentially no mortality, and it does not produce severe hemolysis.

Now: It is a vascular proliferative phase, which may be accompanied by pain and fever but not by the severe hemolysis of the acute stage.

Previously: Transient immunosuppression makes intercurrent salmonellosis and other infections common, and untreated mortality reaches 85%, which is why chloramphenicol was historically favored and ciprofloxacin is now standard.

Now: Superimposed bacteremia caused by Salmonella or other coliform organisms may occur, and untreated case fatality rates may exceed 50%, which is why ciprofloxacin with ceftriaxone for 14 days is the treatment of choice, with chloramphenicol…

Previously: Survivors may later develop verruga peruana, a benign angioproliferative nodular eruption treated with rifampin or azithromycin, with essentially no mortality.

Now: Survivors may later develop verruga peruana, an angioproliferative nodular eruption treated with azithromycin for 7 to 14 days, with rifampin or ciprofloxacin as alternatives.

Previously: with untreated mortality up to 85%

Now: with untreated case fatality rates that may exceed 50%

Previously: The recurrent 5-day fever of trench fever was explained by periodic release of the organism into the blood.

Now: Trench fever is marked by persistent bacteremia during the initial attack, during relapses and throughout the symptom-free intervals. The question was rewritten.

Previously: Next come the fastidious or intracellular organisms that routine bottles cannot recover: the HACEK group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella), Coxiella burnetii, Bartonella species, Brucella, Tropheryma…

Now: Next come the fastidious or intracellular organisms that routine bottles cannot recover: Coxiella burnetii, Bartonella species, Brucella, Tropheryma whipplei and Legionella, followed by fungi; the HACEK group (Haemophilus,…

Previously: The differential for culture-negative endocarditis always includes HACEK organisms, Coxiella burnetii (Q fever), Bartonella quintana, and Brucella — in homeless, malnourished, or body-louse-infested patients specifically, B. quintana…

Now: The differential for culture-negative endocarditis includes Coxiella burnetii (Q fever), Bartonella quintana, and Brucella — in homeless or body-louse-infested patients, B. quintana should be considered.

Previously: Fatty acids in cotton fibers are bactericidal for B pertussis, so the organism may be dead before the specimen reaches the laboratory, and degraded template lowers PCR yield as well. Calcium alginate swabs are also unacceptable because…

Now: Cotton-tipped and calcium alginate swabs are not acceptable for nucleic acid amplification, because residues present in these materials inhibit the assay, and cotton is not used for culture either. Polyester, rayon or nylon-flocked swabs,…

Previously: Swab material matters as much as swab position. Cotton and other natural-fiber swabs contain fatty acids that are toxic to B pertussis, so viable organisms are lost between bedside and bench. Calcium alginate swabs preserve the organism…

Now: Swab material matters as much as swab position. Specimens from the posterior nasopharynx are taken with polyester, rayon or nylon swabs rather than cotton, which is not used for culture. For nucleic acid amplification neither cotton nor…

Previously: Nasopharyngeal specimens for pertussis must use Dacron or rayon swabs only — calcium alginate swabs inhibit PCR, and cotton swabs actually kill the organism, both leading to false-negative results regardless of true infection status.

Now: Nasopharyngeal specimens for pertussis are taken with polyester, rayon or nylon swabs — cotton is not used, and residues in cotton and calcium alginate swabs inhibit the polymerase chain reaction, giving false-negative results.

Previously: Anti-pertussis toxin antibodies measured by enzyme immunoassay do not reliably rise until the third or fourth week of illness, so a negative result at day 5 reflects antibody kinetics rather than absence of infection. Nucleic acid…

Now: Serology is used 2 to 8 weeks after cough onset, when antibody titers are highest, so a negative result at day 5 reflects the timing of the test rather than absence of infection. Nucleic acid amplification on a nasopharyngeal specimen is…

Previously: Enzyme immunoassay for IgG against pertussis toxin does not become reliably positive until the third week of illness or later, and it peaks around weeks 4 to 8. A single high anti-pertussis toxin IgG titer is therefore most useful in the…

Now: Enzyme immunoassay for IgG against pertussis toxin is used 2 to 8 weeks after cough onset, when titers are highest. It is therefore the test for the patient presenting with a prolonged cough, in whom isolation of the organism is often…

Previously: Pertussis serology (IgA, IgG, IgM via eia) is not useful acutely, since antibodies do not rise until week 3 or later — though high-titer anti-pt IgG can be helpful specifically for diagnosing a prolonged cough lasting more than 4 weeks.

Now: Pertussis serology is not useful acutely: IgG against pertussis toxin is measured 2 to 8 weeks after cough onset, when titers are highest, which makes it the test for a patient presenting with a prolonged cough.

Previously: and that grow in ambient air

Now: and that were recovered on enriched medium incubated in 10% carbon dioxide

Previously: Growth in ambient air argues against B abortus, and soft cheese made from unpasteurized goat's milk is the classic vehicle.

Now: Soft cheese made from unpasteurized goat's milk is the classic vehicle.

Previously: Acquired from cattle, B abortus causes the mildest systemic illness of the group, producing noncaseating granulomas in liver and bone marrow rather than a fulminant febrile illness. It is also the one species that requires 5 to 10% carbon…

Now: Acquired from cattle, B abortus causes mild disease with suppurative complications rather than the severe, acute systemic illness of B melitensis. Some Brucella strains require supplemental carbon dioxide for growth, but no species is…

Previously: It grows in ambient air, so the culture atmosphere does not separate it, but the dairy vehicle and the acute severity do.

Now: The culture atmosphere does not separate the species, but the dairy vehicle and the acute severity do.

Previously: Like B abortus, it is also carbon dioxide-dependent in culture.

Now: No allowed culture property separates it from the species that infect humans.

Previously: B abortus comes from cattle, is mildest, produces noncaseating granulomas, and is the one species needing 5 to 10% carbon dioxide for primary isolation.

Now: B abortus comes from cattle and causes mild disease with suppurative complications; some Brucella strains require supplemental carbon dioxide for growth, but this does not distinguish the species.

Previously: The human placenta contains no erythritol, so that amplification does not occur.

Now: Human tissues are not rich in erythritol, so that amplification does not occur, although brucellosis in pregnancy still carries a risk of spontaneous abortion.

Previously: The human placenta lacks erythritol, so this amplification does not occur, and abortion is not a characteristic feature of human brucellosis, which instead presents as undulating febrile illness with osteoarticular, hepatosplenic and…

Now: Human tissues are not rich in erythritol, so this amplification does not occur, but brucellosis in pregnancy still carries a risk of spontaneous abortion, particularly in the first and second trimesters; the usual presentation is an…

Previously: but erythritol is absent from the human placenta, which is why abortion is not a feature of human brucellosis.

Now: but human tissues are not rich in erythritol, so the organism does not multiply in the placenta as it does in animals, although brucellosis in pregnancy still carries a risk of spontaneous abortion.

Previously: fever rises each afternoon and settles overnight with drenching sweats

Now: fever rises each evening and settles in the morning with profuse sweating

Previously: Weeks of wave-like fever with afternoon peaks and drenching night sweats, hepatosplenomegaly, sacroiliitis, and a normal-to-low leukocyte count with relative lymphocytosis, in a patient eating unpasteurized sheep's milk cheese, is the…

Now: Weeks of wave-like fever rising in the evening and subsiding with profuse sweating in the morning, with hepatosplenomegaly and sacroiliitis in a patient eating unpasteurized sheep's milk cheese, is the classic picture.

Previously: A temperature that climbs through the afternoon, falls overnight with profuse sweating, and recurs in waves separated by relatively well intervals is distinctive, and it is what earned brucellosis the historical names undulant fever,…

Now: A temperature that rises in the evening, subsides in the morning with profuse sweating, and recurs in waves separated by remissions is distinctive, and it is what earned brucellosis the historical names undulant fever, Malta fever,…

Previously: "Undulant fever" describes the classic brucellosis pattern where fever rises in the afternoon and falls at night with drenching sweats

Now: "Undulant fever" describes the classic brucellosis pattern where fever rises in the evening and falls in the morning with profuse sweating

Previously: The inhaled infectious dose of Francisella tularensis was given as 10 to 50 organisms.

Now: Inhalation of as few as 10 organisms can cause severe pneumonia. The question was withdrawn.

Previously: and is linked to rodents, hares, beavers and contaminated fresh water

Now: and is linked to rodents and to aquatic environments

Previously: Type B follows contact with rodents, hares, beavers and muskrats and with contaminated fresh water.

Now: Type B follows contact with rodents and with aquatic environments.

Previously: Type B (subspecies holarctica) occurs across Europe, Asia, and North America, causes milder disease, and is associated with rodents/hares/water

Now: Type B (subspecies holarctica) occurs across Europe, Asia, and North America, causes milder disease, and is associated with rodents/water

Previously: All begin abruptly after an incubation period of about 3 to 5 days

Now: All begin abruptly 1 to 10 days, usually 2 to 4 days, after exposure

Previously: Francisella is resistant to all beta-lactam antibiotics via beta-lactamase production, unlike Brucella, which has no established penicillin resistance

Now: Francisella produces a beta-lactamase that renders penicillins and cephalosporins ineffective, and penicillins and cephalosporins are ineffective or unpredictable against Brucella as well

Previously: with modern automated systems recovering the organism in most acute cases

Now: although its sensitivity is limited

Previously: Reinfection or relapse in a continuously exposed farmer typically produces a rising titer and a reappearance of IgM, because the antigenic re-exposure restimulates a primary-type response alongside the secondary one.

Now: Relapse is accompanied by transient rises in IgG and IgA but not IgM, and the titer would be rising rather than unchanged.

Previously: In brucellosis, IgM rises during week 1 and peaks around 3 months, while IgG rises later, at around 3 weeks, peaks at 6-8 weeks, and remains elevated in chronic disease

Now: In brucellosis, IgM predominates in acute infection and declines within weeks, while antibody can persist for many months or years, so a high titer with no IgM suggests long-standing infection

Previously: an infectious dose of fewer than 50 organisms

Now: an infectious dose as low as 10 organisms

Previously: BSL-2 practices are appropriate for the initial handling of clinical specimens before the organism has been identified, which is how this aspirate was correctly processed.

Now: BSL-2 practices do not meet what the sources require: specimens as well as cultures from a patient with suspected tularemia should be handled in a laboratory with a level 3 rating, so the open-bench processing of this aspirate was itself…

Previously: Francisella tularensis sits at BSL-3 for culture work because inhalation of fewer than 50 organisms can cause disease and it is one of the commonest causes of laboratory-acquired infection.

Now: Francisella tularensis sits at BSL-3 for culture work because inhalation of as few as 10 organisms can cause severe pneumonia and laboratory-acquired infections are disproportionately common.

Previously: initial handling of blood, tissue or aspirates from a suspected case is done under BSL-2 practices, whereas any work on a growing isolate, including subculture, suspension preparation and susceptibility testing, requires BSL-3

Now: specimens as well as cultures from a suspected case should be handled in a laboratory with a level 3 rating, and all processing and identification work is done inside a biohazard hood

Previously: Francisella tularensis is so highly infectious that all laboratory work on live cultures requires bsl iii containment, while handling of clinical specimens (before culture growth) only requires the lower bsl II level

Now: Francisella tularensis is so highly infectious that specimens as well as live cultures from a suspected case are handled at bsl iii, with all processing done in a biohazard hood

Previously: as few as 10 to 50 organisms

Now: as few as 10 organisms

Previously: whereas organism B requires a far larger inoculum to produce disease in the same model

Now: whereas organism B is also infectious by the aerosol route at a low inoculum

Previously: Two features identify it: an inhalational infectious dose of only 10 to 50 organisms, among the lowest of any bacterium, and an absolute requirement for cysteine

Now: Two features identify it: an inhalational infectious dose as low as 10 organisms and a requirement for cysteine

Previously: It grows on ordinary blood and chocolate agar without cysteine, needs a larger inoculum than Francisella in challenge models, and produces non-caseating granulomas with undulant fever rather than necrotizing lymphadenitis.

Now: It grows on ordinary blood agar without cysteine, may itself infect by aerosol at a low inoculum, and produces noncaseating granulomas with undulant fever rather than necrotizing lymphadenitis.

Previously: 10 to 50 organisms inhaled or inoculated intradermally suffice, which is why skinning one rabbit or opening a single culture plate on the open bench can transmit it

Now: inhalation of as few as 10 organisms can cause severe pneumonia, and the organism can penetrate apparently unbroken skin

Previously: Brucella is conventionally described as needing a larger inoculum, grows on standard media without cysteine, and produces an insidious undulant fever with non-caseating granulomas.

Now: Brucella may itself infect by the aerosol route at a low inoculum, grows on standard enriched media without cysteine, and produces an insidious undulant fever with noncaseating granulomas.

Previously: Francisella has an extraordinarily low infectious dose (as few as 10-50 organisms) compared with Brucella, which requires a much higher inoculum

Now: Francisella has an extraordinarily low infectious dose, as few as 10 organisms by inhalation, and Brucella may also infect by aerosol at a low inoculum

Previously: A standard tube agglutination titer above 1:80 against heat-killed phenolized smooth antigen indicates active brucellosis, and a fourfold rise between paired samples makes the interpretation secure.

Now: A standard tube agglutination titer of 1:160 or greater indicates active brucellosis, and a fourfold rise between paired samples makes the interpretation secure.

Previously: The accepted cutoff for the standard tube agglutination test is a titer greater than 1:80, and both of her results exceed it. Lower titers of 1:20 to 1:80 are the ones that need cautious interpretation

Now: The accepted threshold for the standard tube agglutination test is a titer of 1:160 or greater, which both of her results reach. Lower titers are the ones that need cautious interpretation

Previously: a titer greater than 1:80 indicates active infection, while lower titers are equivocal and must be read against the local background and the clinical picture

Now: a titer of 1:160 or greater indicates active infection, while lower titers are equivocal and must be read against the local background and the clinical picture

Previously: an IgG titer greater than 1:80 indicates active Brucella infection

Now: a total antibody titer of 1:160 or greater indicates active Brucella infection

Previously: Campylobacter is thermophilic for an enteric pathogen, growing best at 42°C and poorly at 37°C, with no growth at 25°C.

Now: Campylobacter is thermophilic for an enteric pathogen, growing best at 37 to 42°C, with no growth at 25°C.

Previously: Neuropathy develops later: local palatal and pharyngeal paralysis with nasal speech and nasal regurgitation around two to three weeks, then oculomotor involvement with blurred vision and diplopia, and finally a demyelinating…

Now: Neurological toxicity usually begins in the first week, with loss of ocular accommodation and bulbar palsy causing dysphagia and nasal regurgitation, and a peripheral neuropathy of the limbs appears in the third to sixth week.

Previously: A laboratory compares two obligate intracellular bacteria, Chlamydia trachomatis and Rickettsia prowazekii, in cultured human epithelial monolayers. Neither organism replicates on enriched cell-free agar. When the monolayer is treated…

Now: A laboratory studies Chlamydia trachomatis in cultured human epithelial monolayers. The organism does not replicate on enriched cell-free agar. When the monolayer is treated with an inhibitor of mitochondrial ATP synthase,

Previously: Rickettsia retains a tricarboxylic acid cycle and respiratory chain and generates its own ATP.

Now: Chlamydiae are grown in cell culture rather than on cell-free media, because the energy they use is the host cell's.

Previously: Rickettsia, Ehrlichia and Anaplasma are also obligate intracellular organisms, but they retain a tricarboxylic acid cycle and respiratory chain and can make their own ATP, using host transport systems as a supplement rather than a…

Now: Rickettsia and Coxiella are also obligate intracellular organisms that rely on host adenosine triphosphate; Rickettsia can in addition produce it through a tricarboxylic acid cycle.

Previously: different from Rickettsia and Ehrlichia/Anaplasma, which can synthesize their own ATP

Now: like the other obligate intracellular organisms Rickettsia and Coxiella, which also rely on host ATP

Previously: but it requires twice-daily application for about 6 weeks, stings, blurs vision and is adhered to poorly. Its effectiveness is lower than that of a single oral dose, and it is unworkable as the backbone of a community-wide program

Now: but it is applied twice daily for 5 consecutive days each month for 6 months and is recommended for individual or sporadic cases rather than as the backbone of a community-wide program

Previously: Single-dose azithromycin has displaced the former regimens of 6 weeks of topical tetracycline and prolonged oral erythromycin because one observed dose gives far better coverage, and it is preferred to doxycycline because tetracyclines…

Now: Single-dose azithromycin is the regimen used for mass administration, while topical tetracycline or erythromycin ointment, applied twice daily for 5 consecutive days each month for 6 months, is recommended for individual or sporadic…

Previously: which has replaced doxycycline/erythromycin — topical therapy is of little value

Now: with topical tetracycline or erythromycin ointment used for individual or sporadic cases

Previously: The delay while the organism sporulates and releases toxin gives the characteristic ten to twelve hour incubation, and the pore-forming action on enterocytes produces watery diarrhea and cramps without fever or vomiting

Now: The delay while the organism sporulates and releases toxin gives the characteristic eight to twelve hour incubation, and the toxin binds the brush-border membrane of the small intestine, altering permeability so that fluid is lost,…

Previously: That accounts for the intermediate incubation of ten to twelve hours — too long for a preformed toxin like staphylococcal enterotoxin or cereulide, too short for an invasive organism. The toxin inserts into the enterocyte membrane and…

Now: That accounts for the short incubation of eight to twelve hours — longer than that of a preformed toxin, shorter than that of an invasive organism. The toxin binds receptors on the brush-border membrane of the small intestinal epithelium,…

Previously: giving an incubation of ten to twelve hours and watery diarrhea without fever

Now: giving an incubation of eight to twelve hours and watery diarrhea without fever

Previously: AmpC is not inhibited by clavulanate or tazobactam, so for serious infection the reliable choices are cefepime, which is stable to the enzyme and a weak inducer, or a carbapenem.

Now: AmpC is not inhibited by clavulanate, tazobactam or sulbactam, and these strains often remain susceptible to carbapenems, which are the reliable choice in serious infection.

Previously: Salmonella Typhi, adapted to humans, needs a considerably lower dose than the non-typhoidal serovars.

Now: Salmonella Typhi has humans as its only reservoir and likewise requires a large inoculum, being inactivated by gastric acid.

Previously: It is taken up through M cells overlying colonic lymphoid follicles

Now: It is taken up through the M cells of the Peyer patches

Previously: They express the Vi capsule, survive within mononuclear phagocytes, require a comparatively small inoculum, and cause enteric fever

Now: They express the Vi capsule, are engulfed by macrophages, require a large inoculum, being acid-labile, and cause enteric fever

Previously: involvement of at least 20% of epithelial cells is an Amsel criterion

Now: involvement of more than 20% of epithelial cells is an Amsel criterion

Previously: at least 20% of epithelial cells must be involved

Now: more than 20% of epithelial cells must be involved

Previously: clue cells comprising at least 20% of epithelial cells on saline wet mount

Now: clue cells comprising more than 20% of epithelial cells on saline wet mount

Previously: clue cells ≥20% of epithelial cells on wet mount

Now: clue cells >20% of epithelial cells on wet mount

Previously: clue cells in at least 20% of epithelial cells

Now: clue cells in more than 20% of epithelial cells

Previously: twice weekly for four to six months

Now: twice weekly for more than 3 months

Previously: twice weekly for four to six months

Now: twice weekly for more than 3 months

Previously: yields pinpoint colonies with a fried-egg appearance

Now: yields colonies with a fried-egg appearance

Previously: It is urease-negative, grows within 2 to 5 days, and forms true fried-egg colonies.

Now: It is urease-negative, grows within 1 to 4 days, and forms true fried-egg colonies.

Previously: grows tiny colonies with a fried-egg appearance

Now: grows colonies with a fried-egg appearance

Previously: Mycoplasma hominis and Ureaplasma species grow on serum-enriched solid media within 2 to 5 days and can be identified by their substrate reactions, so culture remains a usable diagnostic tool for them.

Now: Mycoplasma hominis and Ureaplasma species grow on serum-enriched solid media within a few days and can be identified by their substrate reactions, so culture remains a usable diagnostic tool for them.

Previously: Mycoplasma genitalium causes acute and persistent nongonococcal urethritis in men, together with proctitis and epididymitis.

Now: Mycoplasma genitalium causes acute and persistent nongonococcal urethritis in men, together with proctitis.

Previously: Growth on plate C, which contains no serum, shows that removing an inhibitor cannot be the explanation.

Now: The inhibitors that gentle heating destroys in making chocolate agar are inhibitors of V factor, the NAD this organism requires.

Previously: A small pleomorphic gram-negative coccobacillus that grows on chocolate agar but not on sheep blood agar is dependent on hemin and NAD, which is diagnostic of this genus, and type b is the species' classic cause of meningitis between…

Now: A small pleomorphic gram-negative coccobacillus that grows on chocolate agar, which supplies hemin and NAD, but not on unheated sheep blood agar is the pattern of Haemophilus influenzae, and type b is its classic cause of meningitis in…

Previously: Invasive type b disease clusters between roughly 5 months and 5 years, the window after maternal IgG has waned and before natural anticapsular antibody develops

Now: Invasive type b disease occurs mostly between 6 months and 6 years, with a peak between 6 months and 1 year, the window after maternal IgG has declined and before the child can make sufficient antibody against the capsule

Previously: with Hib peaking at 5 months-5 years

Now: with Hib peaking between 6 months and 1 year

Previously: fulminating obstructive laryngotracheitis

Now: fulminant obstructive laryngitis (supraglottic cellulitis)

Previously: Resistance among Haemophilus isolates is now common and it is bacteriostatic against this organism, so it is not adequate for pyogenic meningitis.

Now: For invasive illness, including meningitis, cefotaxime or ceftriaxone is the recommended treatment.

Previously: and about half of patients develop tender inguinal nodes that suppurate into a fluctuant bubo requiring aspiration.

Now: and in fewer than half of patients the inguinal nodes are involved, forming a tender bubo that may become fluctuant and need needle aspiration or incision and drainage.

Previously: The organism is recovered on hemin-rich chocolate-based media incubated for several days at about 33°C in high humidity, and even then sensitivity is modest, so Gram stain of exudate from the undermined ulcer edge carries real weight.

Now: The organism is recovered on special enriched media incubated at 33°C for 7 days or more, and even then culture is insensitive; microscopic identification is confounded by the mixed flora of ulcers, so the diagnosis usually rests on the…

Previously: so recognizing it on morphology alone can justify treatment while cultures are pending.

Now: so it is diagnosed and treated on clinical grounds when suspected.

Previously: and become positive only on extended incubation, which is why HACEK traditionally appears on lists of culture-negative endocarditis

Now: and become positive only on extended incubation, although automated blood-culture systems usually detect them within a week

Previously: and were the classic cause of 'culture-negative' endocarditis; modern automated blood-culture systems usually recover them within 5 days, but they may still be reported negative at that routine endpoint and need prolonged incubation.

Now: in blood culture; automated blood-culture systems usually detect them within a week, although some cultures need longer incubation.

Previously: Type b disease peaks between about 5 months and 5 years

Now: Type b disease occurs mostly between 6 months and 6 years

Previously: Translocation into epithelial cells by type IV secretion

Now: Translocation into epithelial cells by type VI secretion

Previously: The cag pathogenicity island encodes a type IV secretion system, a pilus-like surface apparatus that delivers CagA straight through the epithelial membrane on contact.

Now: The cag pathogenicity island encodes a type VI secretion system, which acts like a syringe to inject CagA into the gastric epithelial cell on contact.

Previously: the cag island encodes a type IV apparatus evolved from conjugation machinery

Now: the cag island encodes a type VI secretion system

Previously: In Helicobacter pylori, the cag pathogenicity island encodes a type IV secretion system and its effector, CagA.

Now: In Helicobacter pylori, the cag pathogenicity island encodes a type VI secretion system and its effector, CagA.

Previously: via a type IV secretion system (T4SS)

Now: via a type VI secretion system

Previously: Proton pump inhibitors should be stopped about 2 weeks before urease-based testing.

Now: Proton pump inhibitors should be stopped at least 1 week before urease-based testing.

Previously: Testing is therefore performed after at least 2 weeks off a proton pump inhibitor and 4 weeks off antibiotics or bismuth.

Now: Testing is therefore performed after at least 1 week off a proton pump inhibitor and 4 weeks off antibiotics.

Previously: Proton pump inhibitors lower bacterial load and urease activity and can produce a negative breath test in an infected patient; a 2-week washout is required before testing.

Now: Proton pump inhibitors can produce a negative breath test in an infected patient, so testing is delayed at least 1 week after the drug is stopped.

Previously: They become negative once the organism is cleared, but they are suppressed by anything that reduces bacterial load, so acid suppression is withheld for about 2 weeks and antibiotics and bismuth for about 4 weeks before testing.

Now: They become negative once the organism is cleared, and testing is delayed at least 1 week after a proton pump inhibitor is stopped and 4 weeks after antibiotics.

Previously: 4 weeks after antibiotics and 2 weeks off omeprazole

Now: 4 weeks after antibiotics and 1 week off omeprazole

Previously: Waiting at least 4 weeks from the last antibiotic dose and stopping the proton pump inhibitor for at least 2 weeks satisfies both conditions.

Now: Waiting at least 4 weeks from the last antibiotic dose and stopping the proton pump inhibitor for at least 1 week satisfies both conditions.

Previously: Acid suppression must be stopped about 2 weeks beforehand, with an alternative such as an H2 blocker or antacid if symptoms demand it.

Now: Acid suppression must be stopped at least 1 week beforehand.

Previously: Proton pump inhibitors raise intragastric pH, reduce bacterial density and displace organisms from the antrum towards the body, so they are stopped at least 2 weeks before testing; an H2 blocker or antacid can cover symptoms in the…

Now: Proton pump inhibitors suppress the organism and raise intragastric pH, so they are stopped at least 1 week before testing.

Previously: Test of cure with ubt or stool antigen should wait at least 4 weeks after stopping antibiotics and 2 weeks after stopping ppi, to avoid false negatives from residual drug effects rather than true eradication.

Now: Test of cure with ubt or stool antigen should wait at least 4 weeks after stopping antibiotics and 1 week after stopping ppi, to avoid false negatives from residual drug effects rather than true eradication.

Previously: Eradication is then confirmed with a urea breath test or stool antigen test at least 4 weeks after treatment and 2 weeks off the proton pump inhibitor, and a regimen that has already failed is not repeated.

Now: Eradication is then confirmed with a urea breath test or stool antigen test at least 4 weeks after treatment and 1 week off the proton pump inhibitor.

Previously: Substituting 0.1% basic fuchsin for safranin was given as the way to show Legionella on Gram stain.

Now: Increasing the time of the safranin counterstain enhances visibility. The question was rewritten on the culture requirements of Legionella.

Previously: Legionella requires bcye agar (with L-cysteine, iron, and alpha-ketoglutarate)

Now: Legionella grows on buffered charcoal yeast extract agar, which supplies L-cysteine and iron

Previously: Entry of Legionella into macrophages was attributed to the Mip protein.

Now: Infection of macrophages is mediated by complement component C3b bound to an outer membrane porin and then by the CR3 complement receptor. The question was withdrawn.

Previously: Helicobacter pylori was said to deliver CagA through a type IV secretion system, the same apparatus as Legionella.

Now: The cag pathogenicity island of H. pylori encodes a type VI secretion system. The question was rewritten on how Legionella survives within macrophages.

Previously: Legionnaires' disease is a severe multilobar pneumonia, with mortality approaching 10% in treated hospitalized patients

Now: Legionnaires' disease is a severe pneumonia, with a case-fatality rate of about 10% overall and about 25% in healthcare-associated infections

Previously: Legionnaires' disease (severe pneumonia, up to 10% mortality, hyponatremia as a high-yield finding)

Now: Legionnaires' disease (severe pneumonia, case-fatality about 10% overall and about 25% in healthcare-associated infections, hyponatremia as a high-yield finding)

Previously: Antibody titers peak 4 to 8 weeks later

Now: Antibody rise needs convalescent serum weeks later

Previously: Specific antibody appears slowly in legionellosis, rising over weeks and peaking at about 4 to 8 weeks, which is why the acute sample was low and the convalescent sample 6 weeks later showed a diagnostic fourfold rise

Now: Specific antibody appears slowly in legionellosis, so the diagnosis requires a fourfold rise between acute serum and convalescent serum taken 3 to 6 weeks later, which is why the acute sample was low and the sample at 6 weeks was diagnostic

Previously: In legionellosis this delay is unusually long: titers rise slowly and peak at roughly 4 to 8 weeks, and a small proportion of patients never seroconvert

Now: In legionellosis the second sample comes late: CDC collects the acute serum within the first 2 weeks and the convalescent serum 3 to 6 weeks later, and Murray now calls serology insensitive and nonspecific

Previously: Serology's real role is retrospective confirmation and outbreak investigation, where paired sera establish how many people a common source infected

Now: Serology confirms the diagnosis only in retrospect, and CDC states that the delay makes it unsuitable for acute diagnosis and for active outbreak investigations

Previously: Legionella serology has a slow antibody rise, peaking 4-8 weeks after infection, making it mainly useful for retrospective diagnosis in outbreak investigations rather than acute clinical diagnosis

Now: Legionella serology needs paired sera, the second taken 3 to 6 weeks after the first, so it confirms the diagnosis only in retrospect and cannot guide acute management

Previously: Listeria expresses flagella at 20-28°C but represses flagellin synthesis at 37°C, producing tumbling motility at room temperature and apparent non-motility at body temperature

Now: Listeria is motile at room temperature, with characteristic end-over-end tumbling, and much less so at 37°C

Previously: Listeria monocytogenes expresses flagella maximally at 20-28°C and represses flagellin at 37°C, so wet mounts prepared from room-temperature broth show the characteristic end-over-end tumbling, while cultures at body temperature appear…

Now: Listeria monocytogenes is motile at room temperature, where wet mounts show the characteristic end-over-end tumbling, and much less motile at 37°C

Previously: Listeria shows characteristic end-over-end tumbling motility at 22-28°C but not at 37°C

Now: Listeria shows characteristic end-over-end tumbling motility at room temperature and much less at 37°C

Previously: This organism multiplies down to about 0-4°C, and also tolerates roughly 10% sodium chloride and a pH near 4.5

Now: This organism grows at 4°C, over a wide pH range and in the presence of salt

Previously: Listeria monocytogenes is psychrotolerant: it grows from about 0-4°C up to 45°C, tolerates around 10% sodium chloride and survives at a pH near 4.5

Now: Listeria monocytogenes grows at 4°C, over a wide pH range and in the presence of salt, so a lightly contaminated food can become heavily contaminated during refrigeration

Previously: Listeria grows even at refrigerator temperatures (4°C, "cold enrichment"), plus tolerates high salt and low pH, defeating the standard food-preservation barriers that control most other foodborne pathogens

Now: Listeria grows even at refrigerator temperatures (4°C, "cold enrichment"), and tolerates salt and a wide pH range, so lightly contaminated food can become heavily contaminated during refrigeration

Previously: Late-onset disease is acquired from the maternal genital tract during delivery and presents after about a week as meningitis, usually with serotype 4b

Now: Late-onset disease is acquired from the maternal genital tract during delivery and presents 2 to 3 weeks after birth as meningitis or meningoencephalitis

Previously: Listeria monocytogenes is intrinsically unresponsive to the cephalosporins, which is attributed to penicillin-binding proteins with low affinity for that class, and it is also a poor target for the fluoroquinolones

Now: Listeria monocytogenes is intrinsically unresponsive to the cephalosporins, which lack in vitro activity against it

Previously: Listeria is intrinsically resistant to cephalosporins and fluoroquinolones

Now: Listeria is intrinsically resistant to cephalosporins

Previously: abolished when the toxin is preincubated with free cholesterol. Electron microscopy of the treated membranes shows large ring-shaped oligomeric pores, and lytic activity is

Now: abolished when the toxin is exposed to oxygen, and lytic activity is

Previously: Streptolysin O and listeriolysin O are both cholesterol-dependent cytolysins. Each binds membrane cholesterol, oligomerizes into a large ring and forms an aqueous pore, which is why free cholesterol acts as a competitive inhibitor

Now: Streptolysin O is an oxygen-labile hemolysin, antigenically related to the oxygen-labile toxin of Listeria monocytogenes, and both form pores in the host membrane

Previously: The cholesterol-dependent cytolysins are a conserved family of secreted pore-forming toxins made by several Gram-positive genera. A monomer binds cholesterol in the target membrane, many monomers oligomerize into a ring, and the ring…

Now: Several gram-positive organisms secrete pore-forming hemolysins that are inactivated by oxidation. Listeria monocytogenes makes listeriolysin O, and Streptococcus pyogenes makes streptolysin O, which is antigenically related to the…

Previously: Members include listeriolysin O, streptolysin O of Streptococcus pyogenes, pneumolysin of Streptococcus pneumoniae and perfringolysin O of Clostridium perfringens. Listeriolysin O is distinctive in having an acidic pH optimum, which…

Now: Listeriolysin O is activated by the acid pH of the phagolysosome, where it and two phospholipase C enzymes release the organism into the cytosol

Previously: Listeriolysin O and Streptococcus pyogenes' streptolysin O belong to the same cholesterol-dependent cytolysin toxin family, but serve opposite purposes — one allows Listeria to persist within cells, the other allows group A streptococcus…

Now: Listeriolysin O and Streptococcus pyogenes' streptolysin O are antigenically related oxygen-labile toxins with opposite functions — one lets Listeria escape the phagosome into the cytoplasm, the other lyses host cells

Previously: Internalin A engages the extracellular domain of E-cadherin, and internalin B engages the receptor tyrosine kinase Met. Receptor clustering triggers clathrin-mediated, actin-dependent zipper uptake, so a non-phagocytic epithelial cell is…

Now: Internalin A on the bacterial surface binds glycoprotein receptors on the host cell, and that interaction makes a non-phagocytic epithelial cell internalize the bacterium

Previously: Listeria monocytogenes is the prototypical zipper invader. Internalin A, anchored in the cell wall, binds E-cadherin, while internalin B binds the Met receptor, and together they induce uptake into enterocytes, hepatocytes, endothelium…

Now: Listeria monocytogenes enters by this route. Internalin A on its surface binds glycoprotein receptors on the host cell, and that binding induces uptake into cells that do not normally phagocytose

Previously: The distribution of E-cadherin explains the organism's clinical behavior: it crosses the intestinal epithelium, then the blood-brain and placental barriers, accounting for meningitis, rhombencephalitis and fetal infection

Now: The organism goes on to cross the intestinal epithelium, the placenta and the meninges, which accounts for meningitis and fetal infection

Previously: Listeria surface internalins bind host E-cadherin to induce phagocytosis by normally non-phagocytic cells, the first step in its intracellular lifecycle

Now: Listeria surface internalin binds host cell-surface glycoprotein receptors to induce uptake by normally non-phagocytic cells, the first step in its intracellular lifecycle

Previously: In healthy adults, intact cell-mediated immunity contains the organism at the gut, producing a self-limited febrile gastroenteritis with a 6- to 48-hour incubation

Now: In healthy adults, intact cell-mediated immunity contains the organism at the gut, producing a self-limited febrile gastroenteritis about a day after the contaminated meal

Previously: producing a febrile gastroenteritis 6 to 48 hours after a contaminated meal that settles without antibiotics

Now: producing a febrile gastroenteritis about a day after a contaminated meal that settles without antibiotics

Previously: In healthy adults, Listeria typically causes only a mild, self-limited febrile gastroenteritis (6-48 hour incubation)

Now: In healthy adults, Listeria typically causes only a mild, self-limited febrile gastroenteritis beginning about a day after the meal

Previously: pleomorphic organisms 150 to 250 nm in diameter bounded by a triple-layered membrane with no cell wall

Now: pleomorphic organisms 0.2 to 0.3 µm in diameter bounded by a flexible cell membrane with no cell wall

Previously: Mycoplasmas are the smallest free-living, self-replicating organisms, 125 to 250 nm across, and they have no rigid cell wall

Now: Mycoplasmas are the smallest free-living, self-replicating organisms, with coccoid forms 0.2 to 0.3 µm across, and they have no rigid cell wall

Previously: The cell is therefore bounded only by a triple-layered unit membrane, with no rigid wall to hold a shape, which makes the organism highly pleomorphic and plastic. A cell 125 to 250 nm across that can also deform will pass through the…

Now: The cell is therefore bounded only by a flexible cell membrane, with no rigid wall to hold a shape, which makes the organism highly pleomorphic. Coccoid forms 0.2 to 0.3 µm across pass through the 0.45 µm filters used to sterilize fluids…

Previously: Mycoplasma has no rigid cell wall, bounded only by a triple-layered unit membrane, making it highly pleomorphic — the smallest free-living, self-replicating organisms (125-250 nm), small enough to pass through 450-nm filters like large…

Now: Mycoplasma has no rigid cell wall, bounded only by a flexible cell membrane, making it highly pleomorphic — the smallest free-living, self-replicating organisms (coccoid forms 0.2-0.3 µm), small enough to pass through 0.45 µm filters,…

Previously: because the organism may need up to 4 weeks on sterol-enriched medium

Now: because the organism may need 2 to 6 weeks on sterol-enriched medium

Previously: taking up to 4 weeks rather than the 2 to 4 days needed by Mycoplasma hominis or Ureaplasma urealyticum, which makes the result clinically useless

Now: taking 2 to 6 weeks rather than the 1 to 4 days needed by Mycoplasma hominis, which makes the result clinically useless

Previously: Mycoplasma hominis and Ureaplasma urealyticum are comparatively quick, producing colonies in 2 to 4 days, so genital-tract culture remains feasible

Now: Mycoplasma hominis is comparatively quick, producing its fried-egg colonies in 1 to 4 days, so genital-tract culture remains feasible

Previously: even on serum-enriched medium under optimal conditions it may take up to 4 weeks to form visible colonies

Now: even on serum-enriched medium it takes 2 to 6 weeks to form visible colonies

Previously: M. pneumoniae can take up to 4 weeks to grow in culture, slower than M. hominis or U. urealyticum (2-4 days)

Now: M. pneumoniae takes 2 to 6 weeks to grow in culture, far slower than M. hominis (1-4 days)

Previously: Hydrogen peroxide and superoxide release

Now: Hydrogen peroxide release at the cell surface

Previously: The organism adheres to sialylated glycoconjugates on the cell surface by its P1 tip adhesin and generates hydrogen peroxide and superoxide at that interface, while competing with the cell for nutrients

Now: The organism adheres by its P1 tip adhesin to sialated glycoprotein receptors at the base of the cilia and generates hydrogen peroxide at that interface

Previously: Three mechanisms operate at that interface: local release of hydrogen peroxide and superoxide, which oxidize the ciliated border and arrest ciliary beating; competition for nutrients and precursors the host cell needs; and recruitment of…

Now: Two mechanisms operate at that interface: local release of hydrogen peroxide, which damages the ciliated epithelium, and the host inflammatory response to an organism fixed to the mucosal surface

Previously: damage comes from H₂O₂/superoxide, immune-mediated cytolysis, and nutrient competition, not intracellular invasion

Now: damage comes from hydrogen peroxide and the host inflammatory response, not intracellular invasion

Previously: This organism is the leading cause of pneumonia between the ages of 5 and 20 years

Now: This organism is a leading cause of pneumonia in school-age children and young adults

Previously: Mycoplasma pneumoniae is the commonest cause of the atypical pattern and the leading cause of pneumonia overall in the 5 to 20 year age group

Now: Mycoplasma pneumoniae is the commonest cause of the atypical pattern and a leading cause of pneumonia in school-age children and young adults

Previously: M. pneumoniae is a leading cause of pneumonia in those 5-20 years old

Now: M. pneumoniae is a leading cause of pneumonia in school-age children and young adults

Previously: In mycoplasmal infection they arise by molecular mimicry: the mycoplasmal membrane glycolipid resembles the I antigen on the red cell surface, so the antibody response cross-reacts with the host cell

Now: In mycoplasmal infection they are directed at the I antigen on the red cell surface

Previously: Enzyme immunoassay serology was said to give the diagnosis from a single serum sample.

Now: Serologic tests need sera collected early in the illness and again after 3 to 4 weeks, and nucleic acid amplification tests are the preferred method. The question was rewritten.

Previously: the same molecular-mimicry-driven autoimmune hemolysis seen with EBV-associated cold agglutinins — different trigger, same anti-I antibody mechanism.

Now: the same cold-agglutinin autoimmune hemolysis seen with EBV-associated cold agglutinins — a different trigger, and an anti-i rather than an anti-I antibody.

Previously: It makes bacilli adhere end to end in serpentine cords, inhibits leukocyte migration, impairs phagosome-lysosome fusion, and drives tumor necrosis factor release and granuloma formation.

Now: It makes virulent bacilli grow in serpentine cords, activates macrophages to promote granuloma formation, and induces tumor necrosis factor release.

Previously: It is the most surface-exposed of these lipids and has three testable effects: it causes virulent bacilli to adhere in parallel, serpentine cords in liquid culture, it inhibits leukocyte chemotaxis and migration, and it arrests…

Now: It causes virulent bacilli to grow in parallel, serpentine cords in liquid culture, and it activates macrophages, promoting granuloma formation. It is also a potent inducer of tumor necrosis factor, which contributes to the fever, wasting…

Previously: Cord factor (trehalose dimycolate) causes virulent strains to grow in serpentine cords, inhibits leukocyte migration, and blocks phagosome-lysosome fusion — its presence correlates directly with virulence, since avirulent strains lack it.

Now: Cord factor (trehalose dimycolate) causes virulent strains to grow in serpentine cords, activates macrophages to promote granuloma formation, and induces tumor necrosis factor release; it correlates with virulence, and avirulent strains…

Previously: Mycobacteria produce no exotoxins and no classic endotoxin — the necrosis and cavitation of TB is driven entirely by the host's own cell-mediated immune response (activated macrophages and granulomatous/caseating reaction), not by any…

Now: Mycobacteria produce no well-recognized exotoxins and no endotoxin — the necrosis of TB is driven primarily by the host's own cell-mediated immune response (activated macrophages and the granulomatous, caseating reaction).

Previously: rise steadily for about 3 weeks

Now: rise steadily for about 3 to 6 weeks

Previously: letting the organism survive and multiply for roughly 3 weeks before any adaptive (Th1/IFN-γ) response develops to activate macrophage killing

Now: letting the organism survive and multiply for 3 to 6 weeks before any adaptive (Th1/IFN-γ) response develops to activate macrophage killing

Previously: 10 mm for recent immigrants, injection drug users, healthcare and congregate-setting residents;

Now: 10 mm for people born in high-burden countries, injection drug users, healthcare and congregate-setting residents;

Previously: Ten millimeters applies to intermediate risk, such as recent arrival from a high-prevalence country, injection drug use, healthcare work, and residence in prisons or shelters.

Now: Ten millimeters applies to intermediate risk, such as birth in a high-prevalence country, injection drug use, residence in prisons or shelters, and work in a mycobacteriology laboratory.

Previously: Tuberculin skin test positivity thresholds vary by risk category: ≥5mm for HIV+/immunosuppressed patients and close contacts of active TB; ≥10mm for recent immigrants, IV drug users, and shelter/prison residents; ≥15mm for the general…

Now: Tuberculin skin test positivity thresholds vary by risk category: ≥5mm for HIV+/immunosuppressed patients and close contacts of active TB; ≥10mm for people born in high-burden countries, IV drug users, and shelter/prison residents; ≥15mm…

Previously: 10 mm in recent arrivals from high-burden countries, healthcare workers, injection drug users, residents of congregate settings and children younger than 4 years

Now: 10 mm in people born in high-burden countries, healthcare workers, injection drug users, residents of congregate settings and children younger than 5 years

Previously: even liquid culture takes one to three weeks

Now: even liquid culture takes 2 to 3 weeks

Previously: far faster than traditional culture, which takes 6-8 weeks

Now: far faster than culture, which can take 2 to 6 weeks to grow

Previously: patient, is given by directly observed or self-administered therapy, and requires pyridoxine supplementation with isoniazid

Now: patient and is given by directly observed or self-administered therapy

Previously: Rifamycin monotherapy is not used for latent infection because single-drug rifamycin exposure risks selecting rpoB mutants and rifampin resistance.

Now: Rifapentine given alone is not among the latent-infection regimens that CDC recommends.

Previously: Untreated latent infection carries roughly a 5% to 10% lifetime risk of progression

Now: About 10% of people with latent infection progress to active disease

Previously: The lifetime risk of reactivation is roughly 5% to 10%, concentrated in the first 2 years after infection, and rises steeply

Now: About 10% of latently infected people progress to active disease, usually within the first 2 years, and the risk rises

Previously: Isoniazid requires pyridoxine supplementation to prevent peripheral neuropathy.

Now: Pyridoxine prevents isoniazid neuropathy in patients at risk, such as those with diabetes or alcohol use disorder.

Previously: groin and midline back, and the deep viscera, are correspondingly spared

Now: groin and midline back are correspondingly spared

Previously: Deep viscera are essentially never the site of disease, so hepatic or pulmonary involvement should prompt a search for another diagnosis.

Now: In lepromatous disease acid-fast bacilli are also found in internal organs, and the kidneys may be affected.

Previously: Opaque colonies were linked with symptomatic urethritis, and transparent colonies with asymptomatic endocervical carriage and pharyngeal colonization.

Now: Opaque colonies are recovered most commonly from localized disease, and transparent colonies are more commonly associated with pelvic inflammatory disease and disseminated infection. The question was rewritten.

Previously: leaving Fab fragments that block antigen without recruiting effector function

Now: creating immunologically inactive Fc and Fab fragments

Previously: releasing intact Fab fragments that still bind antigen but can no longer recruit Fc-dependent effector function

Now: creating immunologically inactive Fc and Fab fragments

Previously: The Fab fragments still coat the organism, but because Fc is gone they cannot agglutinate it, fix complement or engage Fc receptors; the bacterium is effectively coated with non-functional antibody.

Now: Both fragments are immunologically inactive, so the antibody no longer traps the organism in mucus or blocks its attachment to the mucosa.

Previously: Blood or synovial fluid cultures were said to be positive in only about 30% of disseminated gonococcal infections.

Now: Blood cultures are positive in about 30 to 40% of patients during the first week, and with gonococcal arthritis, joint-fluid cultures are usually positive. The question was rewritten.

Previously: Erythromycin was called the only licensed agent for newborn eye prophylaxis, and povidone-iodine was said to have been studied for it.

Now: Erythromycin is the only agent available in the United States, and povidone-iodine has not been studied adequately. The question was rewritten.

Previously: It also almost never causes a positive blood culture, since bacteremia in disseminated gonococcal infection is low-grade and the organism recovers poorly from blood culture media.

Now: It can be recovered from blood in disseminated infection, although blood cultures are positive in only about 30 to 40% of patients and supplements in blood culture media can be toxic to it.

Previously: The difficulty at that site reflects rising ceftriaxone and azithromycin minimum inhibitory concentrations rather than a tissue distribution problem.

Now: At that site the difficulty lies with ceftriaxone, whose concentrations in the pharynx tend to be more variable, which is one reason its dose was raised to 500 mg.

Previously: pure polysaccharide, poorly immunogenic under 18 months, no lasting immunity

Now: pure polysaccharide, with a serogroup C component poorly immunogenic under 24 months

Previously: predominantly susceptible, with most minimum inhibitory concentrations at or below 0.06 µg/mL

Now: predominantly susceptible to penicillin, although isolates with reduced susceptibility are increasing

Previously: Meningococci have not acquired the penicillinase plasmids that transformed their relatives, and most isolates remain fully susceptible with minimum inhibitory concentrations at or below 0.06 µg/mL.

Now: Penicillin G remains a drug of choice for meningococcal infection, although the incidence of isolates with reduced susceptibility to penicillin is increasing in many countries, including the United States.

Previously: N meningitidis has never acquired those plasmids; reduced susceptibility from altered penicillin-binding protein 2 exists in some regions but remains uncommon, so most isolates stay fully susceptible.

Now: Penicillin G is still a first choice for invasive meningococcal disease in many countries, but isolates with reduced susceptibility to penicillin are increasing in many others, including the United States.

Previously: N meningitidis is an extracellular pathogen of the nasopharyngeal mucosa and bloodstream, and relapse from a macrophage reservoir is not a feature of the disease.

Now: The second drug here is directed at the organism carried in the nasopharynx, which treatment of the invasive infection with penicillin does not eradicate.

Previously: CagA (injected via T4SS) + VacA = gastritis, ulcers, carcinoma risk.

Now: CagA (injected via a type VI secretion system) + VacA = gastritis, ulcers, carcinoma risk.

Previously: Legionella T4SS vs H. pylori T4SS

Now: Legionella T4SS vs H. pylori T6SS (H. pylori type VI secretion system)