Success! In Clinical Laboratory Science – Bacteriology Practice Test

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• Using the rapid chromogenic cephalosporin method, a positive beta-lactamase result is indicated by which color change?
• Which of the following would not be appropriate as a positive control in the PYR test?
• Which finding in a peripheral blood smear is especially associated with tissue-invading helminths?
• Which agar is recommended by CLSI for routine susceptibility testing of nonfastidious bacteria?
• Which agar is recommended for the selective isolation of Vibrio spp.?
• Which organism requires both hemin (X factor) and NAD (V factor) for growth?
• The majority of the gram-positive, non-spore-forming, anaerobic bacilli isolated from clinical material are which organism?
• Which organism lacks a cyst stage?
• Haemophilus influenzae type b vaccine targets which serotype?
• Winterbottom's sign refers to lymphadenopathy at the base of the neck and is most closely associated with which disease?
• An anemic patient was transfused with packed red blood cells. Approximately one hour after the transfusion began, the patient developed fever and hypotension consistent with endotoxic shock. The red blood cells had been stored at 4°C for about 30 days before use. Which organism is most likely involved?
• Tellurite reduction is used for the presumptive identification of which organism?
• Which trophozoite shows two prominent nuclei and is identified as Giardia lamblia?
• Which agar medium is Regan-Lowe agar, used for Bordetella pertussis isolation?
• Hydatid cysts are most commonly found in which organ?
• Which statement is NOT true about Aeromonas hydrophila?
• Colonies that resemble a fried egg are characteristic of which organism?
• Which pair of helminths cannot be reliably differentiated by the appearance of their eggs?
• Listeria monocytogenes is a small, gram-positive bacillus that is actively motile at room temperature. Which option describes its motility temperature range?
• Swimmer's ear, a form of external otitis is commonly caused by which organism?
• Which is the cause of food poisoning with rapid onset after eating due to enterotoxin production?
• What does the MBC test specifically assess about a drug's activity?
• Which Clostridium species is most commonly recovered from gas gangrene?
• On TCBS agar, non-sucrose-fermenting Vibrio species typically produce which color colonies?
• In the VDRL test, which component serves as the antigen?
• Which statement about cultivation of Mycobacterium leprae is correct?
• Which Plasmodium species may readily be identified when crescent-shaped gametocytes are found in stained blood films?
• The majority of clinical isolates of Klebsiella are
• Which bacterium is part of the normal vaginal flora that helps resist the onset of bacterial vaginosis?
• Which organism produces bull's-eye colonies on CIN agar at about 48 hours, aiding its identification?
• Legionella pneumophila infections are most often acquired from which source?
• The flattened adjacent sides of the cellular appearance of which microorganism resemble kidney beans?
• Which organism is an occasional cause of respiratory tract infections and is rapidly urease positive?
• Which organism is associated with a blue-green pigment and is oxidase positive, commonly linked to burn wound infections?
• Which medium is used for the primary isolation of Corynebacterium diphtheriae and differentiates colonies by appearing as black colonies with a brown halo?
• Which nonfermenting gram-negative rod is rarely isolated in the United States?
• In a sputum sample showing gram-positive diplococci, which test should be performed to presumptively identify the organism?
• Escherichia coli O157:H7 produces a toxin similar to Shiga toxin produced by which organism?
• Which organism typically produces a green discoloration of the medium in which it is grown?
• Nocardia asteroides infections in humans characteristically produce which of the following clinical features?
• The K antigen of the Enterobacteriaceae is which of the following?
• Staphylococcus saprophyticus can be differentiated from other causes of cystitis by resistance to which antibiotic?
• Which organism is most likely to be isolated in cultures from the anterior nares of healthcare workers?
• A urine culture from a young female with catalase-positive gram-positive coccus (>100,000 CFU/mL) would most likely be which organism?
• Which test would be appropriate in the diagnosis of a mycobacterial infection?
• The clinical syndrome described as severe, tender erythema with epidermal peeling in an infant is most consistent with infection by which organism?
• Which statement is not associated with Staphylococcus aureus?
• Beta-lactamase-producing Haemophilus influenzae are resistant to which antibiotic?
• Eikenella corrodens is an opportunistic pathogen, but it is most noted for causing which type of infection?
• Actinomycosis pus characteristically shows which feature?
• Which feature is characteristic of Plasmodium vivax infection in red blood cells?
• Human infection with Coxiella burnetii is acquired by which route?
• For malarial blood smears prepared from venous blood, which anticoagulant is preferred?
• The paper strip test for hydrogen sulfide production is impregnated with which chemical?
• The latent form of typhus that may reactivate years after the initial infection is called what?
• Detection of antibody against cardiolipin is useful for diagnosing which disease?
• What is a common route of transmission for Escherichia coli O157:H7?
• For nonspecific staining of Rickettsia, the recommended stain is Gimenez stain. What is the correct stain for this purpose?
• What collection method is recommended for detecting Enterobius vermicularis eggs?
• Actinomyces israelii colony morphology on solid media resembles which description?
• Which test is most appropriate for the presumptive identification of Clostridium perfringens?
• Septicemia caused by which organism is generally associated with an underlying malignancy?
• A 3-year-old presented with fever, meningeal signs, and CSF; Gram stain shows gram-negative diplococci. The most likely etiologic agent is?
• A Giemsa-stained thick blood film showing many ring forms with double chromatin dots is most characteristic of which Plasmodium species?
• Indole production is characteristic of which organism?
• Which statement is not characteristic of Clostridium botulinum?
• Which statement correctly describes Shigella dysenteriae?
• The medium used to determine oxidative or fermentative metabolism is which?
• Which antibiotic can induce clindamycin resistance in vitro?
• Which of the following is not correct regarding spirochetes?
• Which stage of Trichuris trichiura is infective for humans?
• Small alpha-hemolytic colonies are seen on a sheep blood agar plate after 48 hours of incubation on a vaginal culture. This describes which organism?
• Which antibiotic is appropriate for chemoprophylaxis in close contacts of a patient with Neisseria meningitidis meningitis?
• Lack of motility is a characteristic of which genus among Enterobacteriaceae?
• What is the most important feature in differentiating cysts of Entamoeba histolytica from E. dispar?
• What is the most commonly used nonselective medium for isolation of Neisseria gonorrhoeae?
• In the MRVP test, which two reagents must be added to determine if the bacterium is VP positive?
• Which characteristic best identifies Staphylococcus aureus in routine testing?
• Which statement is not correct regarding blood cultures?
• The organism associated with a pseudomembrane in the throat and an exotoxin absorbed into the bloodstream causing a rapidly fatal hypertoxic disease is which?
• What is the optimal pH range for the Kirby-Bauer test agar?
• Exfoliatin produced by Staphylococcus aureus causes which syndrome?
• Which microorganism will grow only on culture media supplemented with either cysteine or cystine?
• Which statement best describes Clostridium tetani?
• Haemophilus influenzae requires which two growth factors?
• Which helminth produces an elongate, barrel-shaped egg with colorless polar plugs?
• For disk diffusion testing of Haemophilus influenzae, which medium is recommended?
• Which of the following statements is not true about blood cultures for recovering bacteria?
• A common member of the normal flora of the upper respiratory tract is which organism?
• Which anticoagulant is recommended when a body fluid that may clot is sent for microbiologic examination?
• Why are cultures for Gardnerella vaginalis not recommended?
• A negative citrate reaction is characteristic of which organism?
• Which intestinal parasite has acid-fast staining that is variable and produces spores about 1-3 micrometers in diameter?
• Which Mycobacterium produces an orange pigment and is most commonly recovered from water?
• On MacConkey agar, lactose-fermenting Enterobacteriaceae typically display which result?
• Which of the following is catalase negative?
• Which organism hydrolyzes sodium hippurate to glycine and benzoic acid?
• Kingella denitrificans can be differentiated from Neisseria gonorrhoeae because it is able to
• Which parasite lacks a cyst stage?
• Which organism is the causative agent of pinkeye (conjunctivitis)?
• In addition to inhalation, Coxiella burnetii infections can be acquired by ingestion of what?
• Which statement is not true of Haemophilus spp.?
• Which statement is not true about Clostridium tetani?
• Which acid-fast staining method requires heating?
• Which organism is the etiologic agent most commonly associated with septicemia and meningitis of newborns?
• An organism occasionally misidentified as an enteric pathogen because it produces a large amount of H2S is
• Which antibiotic combination specifically includes a beta-lactamase inhibitor to combat beta-lactamase-producing bacteria?
• The growth pattern known as satellitism is associated with which organism?
• A 7-year-old with bloody diarrhea who visited a petting zoo develops hemolytic uremic syndrome. The most likely etiologic agent is which organism?
• Cysts are the infective stage of which intestinal flagellate?
• Which statement about bacteremia is true?
• Which organism is associated with livestock and causes a zoonosis?
• Streptococcus pneumoniae is typically identified as what form on Gram stain and culture?
• Which statement about the acridine orange stain is not true?
• Oocysts of Toxoplasma gondii are most commonly found in which source?
• Elephantiasis is a complication commonly associated with which group of organisms?
• Exfoliative toxin produced by Staphylococcus aureus causes which clinical syndrome?
• Which genus among Enterobacteriaceae is nonmotile?
• Isospora belli oocysts are typically about 25 by 18 micrometers. Which organism is this description referring to?
• Which of the following is not characteristic of Mycobacterium kansasii?
• Buffered charcoal yeast extract medium is used to support the growth of which organism, in addition to its use for Legionella?
• Which test is used to screen for Mycoplasma pneumoniae isolates?
• Which Mycobacterium is commonly recovered from water stills and is often referred to as a tap water contaminant?
• The only species in the genus Hafnia is Hafnia alvei.
• Which organism is the etiologic agent of erysipelas?
• Which of the following is not true of the VDRL test?
• Cutaneous anthrax presents with which characteristic lesion?
• Which organism is a common contaminant in blood cultures due to skin colonization and is a coagulase-negative Staphylococcus?
• Which antimicrobial inhibits protein synthesis?
• What is the recommended medium for recovery of Mycoplasma pneumoniae from clinical specimens?
• Regan-Lowe medium is the recommended medium for isolation of which organism?
• Which organism is commonly associated with polymicrobial abscesses of the oral cavity and may produce pitting of the agar?
• Which of the following is not true of Shigella sonnei?
• Which organism is known for producing a violet pigment?
• Brucella species are best described as which morphological type?
• In the decontamination and digestion procedure for isolating mycobacteria from sputum samples, what is the role of NALC?
• If blood cultures fail to recover Brucella, which other culture site may yield the organism?
• Infant botulism is confirmed by detection of toxin in stool. How is the child most likely infected?
• Candle jars used to create capnophilic environments produce approximately what percent carbon dioxide?
• Which Schistosoma species has a large terminal spine?
• Which test is most appropriate for the presumptive identification of Peptostreptococcus anaerobius?
• A 21-year-old sexually active woman with urinary symptoms has a urine culture yielding more than 10^5 colony-forming units per milliliter of a lactose-fermenting gram-negative rod. Which organism is most likely responsible?
• The etiologic agent of Hansen disease (leprosy) is:
• Eikenella corrodens is commonly associated with which type of injuries?
• Neisseria lactamica can be differentiated from Neisseria meningitidis by its ability to metabolize which sugar?
• In the nitrate test, which reagents produce a red color indicating nitrite production?
• Naegleria fowleri is typically found in which environment?
• Which stage of Taenia saginata is infective for humans?
• Haemophilus aegyptius is characterized by which motility?
• Which Mycoplasmataceae has not been connected with human genital infections?
• Relapsing fever is caused by which genus of bacteria?
• What is the optimal growth temperature for Yersinia pseudotuberculosis?
• Which specimen is routinely decontaminated when trying to recover Mycobacterium spp.?
• During the first week of leptospirosis, the most reliable way to detect the causative agent is by direct culture of which specimen?
• Solubility in the presence of sodium desoxycholate is characteristic of which organism?
• The most common etiologic agent in keratitis associated with contaminated contact lens cleaning solutions is which organism?
• Which Vibrio species on TCBS agar does not ferment sucrose?
• Vancomycin exerts its antibacterial effect primarily by inhibiting which process?
• Plesiomonas was moved to which bacterial family?
• Vibrio vulnificus is most often associated with which clinical condition?
• Which Vibrio species is closely associated with rapidly progressing wound infections in patients with underlying liver disease?
• For in vitro susceptibility testing of Mycobacterium tuberculosis, which method is appropriate?
• Which statement about virulent strains of Vibrio cholerae is not true?
• The capsule of Haemophilus influenzae type b is composed of
• The symptom of diffuse, watery diarrhea with mucus flecks is most suggestive of infection with which organism?
• Nocardia can be differentiated from Actinomyces based on which characteristic?
• What is the best method to identify Bordetella pertussis?
• Which statement is NOT true about Pasteurella multocida?
• In capnophilic incubators, which CO2 concentration range is typically maintained?
• Which organism is known for double zone hemolysis on blood agar?
• The sexually acquired disease characterized by genital ulcers and tender inguinal lymphadenopathy, caused by a small, gram-negative bacillus, is known as
• The anaerobic, gram-negative curved, motile bacilli associated with bacterial vaginosis belong to which genus?
• Which staining technique is required to identify Mycobacteria due to high lipid content in their cell wall?
• Which is not a zoonotic disease?
• Which organism is described by a classic form with a large central body and peripheral nuclei, typically 6-40 μm in diameter?
• Colonies that resemble droplets of mercury are characteristic of which organism?
• Which medium would not be routinely used to culture Mycobacterium spp.?
• Which counterstain is recommended when Gram-staining Campylobacter jejuni due to poor uptake of safranin?
• Erythrogenic toxin is associated with which disease?
• Which statement about Neisseria gonorrhoeae is true?
• In Babesia infections, which parasite forms are typically observed on blood smears?
• A traveler presents with fever that recurs in cycles and anemia after visiting malaria-endemic regions. Which parasite is most likely responsible?
• Mycobacteria can be examined by which acid-fast stain that does not require heating?
• Which organism is isolated using 10B broth due to urease activity and alkaline pH?
• Outbreaks in hospital settings linked to faucet aerators and humidifiers are most commonly caused by which microorganism?
• The host in which the sexual reproductive stage of a parasite occurs is called the
• Which medium is not appropriate for the cultivation of Neisseria gonorrhoeae?
• A purulent aspirate of joint fluid from a young woman shows gram-negative diplococci within neutrophils on Gram stain. Which selective medium is most appropriate for primary isolation of the organism?
• Actinomyces israelii is part of the indigenous flora of which body site?
• Which method is described as the most accurate for detecting motility in nonfermentative bacteria?
• Blood cultures should be held for at least how long before being reported as negative?
• With a fecal specimen, which procedure is most dependable for the accurate diagnosis of an intestinal amebic infection?
• Which malaria parasite typically has ameboid trophozoites and Schuffner's dots in infected red blood cells?
• Which genus is frequently associated with hospital-acquired infections and antimicrobial-resistant strains causing severe infections like septicemia and meningitis?
• Aspiration of vomitus can lead to pneumonia. Which organism would NOT be a likely causative agent?
• Infection of the gastric mucosa leading to gastritis or peptic ulcers is most commonly associated with which organism?
• The presence of a soluble green pigment in culture from empyema is most consistent with which organism?
• Serious congenital infections are associated with which organism?
• The majority of laboratory-acquired infections are associated with what?
• What is the predominant indigenous flora of the human colon?
• Enterotoxin produced by Staphylococcus aureus is responsible for causing
• The description of "Medusa head" colonies on solid agar is most characteristic of which organism?
• Which statement about Acinetobacter baumannii is true?
• Production of hydrogen sulfide (H2S) is a distinguishing feature of which aerobic gram-positive bacillus?
• Streptomyces isolation can be distinguished by incubating the culture at what temperature?
• Which organism yields a negative PYR test?
• Blood cultures are the recommended method for recovering which organism?
• What killing percentage of the original inoculum defines the minimum bactericidal concentration (MBC)?
• Migration of larva through the skin can produce allergic reactions called larva migrans; this is associated with which parasite?
• Which other Mycobacterium species grows on MacConkey agar in 5 days?
• Which organism is an important cause of food poisoning?
• Color Plate 29 depicts a filamentous gram-positive rod recovered from a closed chest abscess that grows only under anaerobic conditions and is not acid-fast. What is the most likely presumptive identification?
• Which statement is correct regarding the collection and processing of stool specimens for parasite detection?
• The etiologic agent of the majority of adult joint infections is which organism?
• Which genus is vancomycin resistant and associated with septicemia in neonates?
• Which fermentative organism may infect reptiles and fish as well as humans when exposed to contaminated soil or water?
• A free-living ameba that causes primary amebic meningoencephalitis is which species?
• Haemophilus ducreyi is the causative agent of which sexually transmitted infection?
• Group B Streptococcus colonization of the vagina can be transmitted to the newborn during birth. Neonatal infection may present as which onset pattern?
• Which statement about Clostridium perfringens is true?
• Which statement about Chlamydophila pneumoniae is not true?
• An example of a halophilic microorganism is which species?
• Which Mycobacterium species is most commonly associated with contamination of hot water systems in large institutions?
• Penicillin is active against bacteria by which mechanism?
• A 36-year-old man with fever and a history suggesting typhoid fever; which laboratory test is most critical to establish or exclude the diagnosis?
• Streptococcus pyogenes is commonly associated with which of the following conditions?
• Reptiles kept as pets are sometimes associated with the transmission of which organism?
• Which feature aids isolation of staphylococci from clinical specimens?
• Rhodococcus equi is distinguished by pink pigmentation on culture media and was formerly classified in which genus?
• In an AIDS patient with chronic diarrhea, acid-fast oocysts about 4-6 micrometers are observed in stool. The most likely pathogen is?
• Susceptibility to thiophene-2-carboxylic acid hydrazide (T2H) is characteristic of which Mycobacterium?
• Pyocyanin is characteristically produced by which organism?
• Among the Burkholderia species, which is most commonly isolated from clinical specimens?
• Abiotrophia (nutritionally variant streptococci) require which nutrient for growth?
• Propionibacterium acnes is commonly a contaminant in blood cultures because it is part of the normal flora of which body surface?
• Which diagnostic method is commonly used for Legionella pneumophila detection?
• Enterobius vermicularis infection is usually diagnosed by detecting eggs in which sample?
• Mycetoma is most commonly caused by Streptomyces somaliensis.
• Chagas disease is found predominantly in which geographic region?
• Which statement about Mycobacterium leprae is true?
• Nocardia species are catalase-positive and aerobic.
• The classic form of Blastocystis hominis has which characteristic?
• Edwardsiella tarda is characterized by which flagellation pattern?
• Not appropriate when describing Streptococcus pneumoniae?
• Besides Pseudomonas aeruginosa, which organism is an important cause of lower respiratory tract infections in patients with cystic fibrosis?
• Which virulence factor is involved in Vibrio cholerae adherence to intestinal cells?
• What color indicates a positive citrate utilization test on Simmons citrate agar?
• A woman recently returned from vacation in Mexico presents with fever and flu-like symptoms after consuming cheese made from unpasteurized milk. The most likely etiologic agent is which organism?
• Campylobacter jejuni is isolated from stool using which culture condition?
• Which organism is the most common etiologic agent of infections associated with the surgical insertion of prosthetic devices such as artificial heart valves and cerebrospinal fluid shunts?
• Which genus is composed of anaerobic Gram-positive cocci commonly isolated in polymicrobial brain abscess?
• Which organism predominates in the fecal flora as part of the indigenous colon microbiota?
• Haemophilus spp. growth requirements are best described by which statement?
• The pulmonary form of anthrax is known as which of the following?
• Which organism is a gram-positive anaerobic coccus?
• The causative agent of malignant pustule is which organism?
• Which genus is most commonly described as having kidney bean-shaped Gram-negative diplococci?
• A 15-um pear-shaped flagellate with falling leaf motility is most consistent with which organism?
• Which statement about Brucella is NOT true?
• Which biochemical test result is characteristic of Yersinia enterocolitica?
• Which Gram-stain feature helps identify Fusobacterium nucleatum?
• The selective nature of Hektoen enteric agar is due to the inclusion of which component?
• A patient developed fever after eating raw oysters; the most likely etiologic agent is?
• Which organism among the following is not commonly associated with gas gangrene?
• Why is Mueller-Hinton agar commonly used for disk diffusion testing?
• Corneal scrapings are examined with direct fluorescent tests to detect inclusion bodies for the diagnosis of infection caused by
• Enterococcus faecium is typically PYR positive and usually nonhemolytic.
• In the CAMP test, a positive result indicates presumptive identification of which organism?
• Kanamycin-vancomycin laked blood agar (KVLB) is primarily used for the presumptive identification of which organisms?
• Which Fusobacterium species is described as much more virulent and commonly implicated in severe infections?
• Which organism is described as obligately anaerobic gram-positive cocci?
• Toxoplasma gondii undergoes sexual reproduction only in which host?
• Which Mycobacterium is most notably associated with patients with AIDS?
• In a 48-hour semisolid agar stab culture incubated at room temperature, lateral filamentous growth away from the stab near the top is most characteristic of which organism?
• Which bacterium is the most common indicator of bacterial vaginosis?
• Which parasite is associated with the Maltese cross pattern inside red blood cells?
• On Tinsdale agar, colonies of Corynebacterium diphtheriae are characterized by which appearance?
• Eggs or larvae recovered in the stool are not routinely used to diagnose infections caused by which helminth?
• Which is the largest intestinal protozoan to infect humans?
• Chlamydia trachomatis causes which of the following conditions?
• Traveler's diarrhea is commonly associated with which etiologic agent?
• Haemophilus influenzae biogroup aegyptius requires which growth factors, and what is its delta-aminolevulinic acid status?
• Which Bacillus species is nonmotile?
• Which organism shows a positive phenylalanine deaminase reaction?
• Which parasite's eggs can be ingested from fecally contaminated water leading to infection?
• Erythromycin eye drops in newborns are used to prevent conjunctivitis caused by which organism?
• How is the VDRL test read?
• What mechanism is responsible for the tolerance phenotype in bacteria against certain penicillins?
• Haemophilus influenzae biogroup aegyptius requires which growth factors, and what is its delta-aminolevulinic acid status?
• Which statement is not true about Coxiella burnetii?
• The phenomenon where bacterial growth is inhibited but not killed by a bactericidal antibiotic is known as what?
• An anaerobic, gram-negative bacillus isolated from a cervical mucosal abscess that is bile-resistant, produces a black pigment, is indole negative, and ferments glucose, sucrose, and lactose. Which is it?
• Which statement about Ascaris eggs in zinc sulfate flotation is true?
• Which organism produces pale pink colonies on culture media and is associated with disease in livestock?
• The most common photochromogenic Mycobacterium isolated in the United States is which species?
• Which organism is an intracellular parasite of red blood cells and can be cultured from blood in the acute stage?
• Which nematode parasite is acquired from eating inadequately cooked, infected pork?
• Which statement best describes Escherichia coli on sheep blood agar and related media?
• Cystine-tellurite blood agar plates are recommended for isolation of which organism?
• Which statement about Yersinia pestis is correct?
• New York City agar is selective due to the addition of which agents?
• Which statement about the Bacteroides fragilis group is true?
• Acinetobacter baumannii is characteristically
• Which statement about the rhabditiform larvae of Strongyloides stercoralis is correct?
• Which microorganism cannot be cultivated on artificial cell-free media?
• Mycobacterium haemophilum growth requirements include the need for which of the following?
• Which enzyme activity is NOT produced by Serratia species?
• Cefsulodin-irgasan-novobiocin (CIN) agar is primarily used for the recovery of which organism?
• Which of the following is a fluorescent stain for mycobacteria?
• In Enterobius vermicularis infection, specimens for detecting eggs are best collected at what time to maximize yield?
• In legionellosis, which statement is true?
• Which organism is associated with human infections often linked to deli meats and improperly pasteurized dairy products?
• To optimize recovery of the causative agent in blood cultures, cultures should be drawn before what event?
• Eco-Challenge participants contracting fever after exposure to water contaminated with animal urine are most likely infected with which organism?
• Chlamydophila pneumoniae is most commonly associated with which clinical presentation?
• Which disease is most likely to be acquired from a hot tub or whirlpool?
• Which Plasmodium species is characterized by Schiiffner's dots in infected erythrocytes?
• An acid-fast stain of a fecal smear reveals round structures 8-10 um in diameter. The most likely organism is?
• Which of the following reactions is typical for Escherichia coli?
• Which oxidation-reduction indicator is commonly used in anaerobic culture systems and turns from blue to white when reduced?
• The principal virulence factors of Bacillus cereus infections include which toxins?
• Which organism is most commonly associated with food poisoning following ingestion of reheated rice served at Asian restaurants?
• Colonies of Neisseria sp. turn color when a redox reagent is applied. The color change is indicative of the activity of the bacterial enzyme
• In which host does the sexual cycle of Toxoplasma gondii occur?
• In the catalase test, the formation of bubbles is due to which of the following?
• Which chemotherapeutic class inhibits bacterial folic acid synthesis by competitive inhibition with p-aminobenzoic acid?
• Which organism is the etiologic agent of epidemic cerebrospinal meningitis?
• Knowledge of nocturnal periodicity is especially important in diagnosing infections caused by which organism group?
• Which drug is not considered as primary antimycobacterial therapy?
• Hydatid cysts in humans arise after ingestion of a tapeworm stage normally found in canines. Which stage initiates this cyst formation?
• Which condition is most commonly associated with Acanthamoeba infections?
• In suspected brucellosis, which specimen is most sensitive for culture?
• Growth on buffered charcoal yeast extract (BCYE) agar for Legionella pneumophila may not be visible for how long?
• Campylobacter fetus subsp. fetus infection is most likely to occur as what in debilitated individuals?
• Chryseobacterium was formerly known by which genus name?
• Which test is most appropriate for the presumptive identification of Clostridium difficile?
• Which medium provides the best results for isolation of Bordetella pertussis?
• Streptococcus sanguis, a viridans streptococcus, is most commonly associated with which condition?
• Streptococcus pyogenes can be presumptively identified using which disk?
• Clavulanic acid belongs to which category?
• An identifying characteristic of Cardiobacterium hominis is
• Which microorganisms produce a positive phenylalanine deaminase reaction?
• Pasteurella multocida is commonly recovered in human infections following bites from which animal?
• An aerobic gram-positive rod known to cause bacteremia in hospitalized immunocompromised patients is which species?
• Vibrio vulnificus is typically transmitted via
• Which organism is a ciliate?
• Extended-spectrum beta-lactamases confer resistance to which antibiotic among the following?
• The enterotoxins of both Vibrio cholerae Ol and noninvasive (toxigenic) strains of Escherichia coli produce serious diarrhea by what mechanism?
• Cultures suspected to contain Campylobacter jejuni should be incubated at which temperature in which atmosphere for optimal recovery?
• Disseminated intravascular coagulation in fulminant meningococcemia is most closely associated with infection by
• Balantidium coli is primarily associated with which animal reservoir?
• Which statement about mycoplasmas is true?
• An example of an oxidase-positive, glucose nonfermenting organism is which of the following?
• Vibrio vulnificus is a halophilic organism that ferment lactose. Which statement best describes its ecology?
• The O antigens used to serogroup Shigella are also used to serogroup which other organism?
• Runyon group II Mycobacteria are slow-growing and form yellow-orange colonies that do not depend on exposure to light.
• In rapid beta-lactamase testing, what indicator is commonly used to detect penicilloic acid production?
• Which Clostridium species has a terminal spore that causes the cell to swell and appears drumstick-shaped on Gram stain?
• Which gram-negative, non-spore-forming anaerobic bacillus is frequently implicated in brain and lung abscesses?
• An amebic cyst 6-8 μm with four nuclei; name the species.
• Which statement best describes the antimicrobial resistance of the Bacteroides fragilis group?
• Which organism’s profile is lactose negative, citrate negative, urease negative, lysine decarboxylase negative, and nonmotile?
• Which organism produces dark colonies with a metallic sheen on eosin methylene blue agar?
• Egg yolk agar showing a precipitate around the colony indicates production of which enzyme?
• Beta-lactamase production by Haemophilus influenzae confers resistance to penicillin and which other antibiotic?
• Klebsiella pneumoniae is frequently mucoid on culture due to the presence of which feature?
• Which medium is both selective and differential?
• Which complication is most associated with chloramphenicol and limits its use?
• Which intestinal parasite infection can cause vitamin B12 deficiency?
• Which medium is used for primary isolation of Neisseria gonorrhoeae?
• The diagnosis of pseudomembranous colitis is most rapidly and accurately made by detecting what in stool?
• Which parasite is the only ciliate pathogenic for humans?
• What modification is made to MacConkey agar when used for Mycobacterium identification?
• The morphology known as the 'seagull wings' on Gram stain is most characteristic of which organism?
• Which enzyme is produced by Staphylococcus aureus and aids in its identification?
• Which of the following is not a standard weekly disk-diffusion quality-control organism?
• Which organism is a non-spore-forming, gram-positive anaerobic bacillus?
• A college student who repaired a marina outboard motor sustained several lacerations on his forearm. A biopsy of a lesion revealed a cutaneous granulomatous condition. Which microorganism would most likely be the etiologic agent?
• Pasteurella multocida grows on sheep blood agar but not on MacConkey agar.
• Which statement is not true of Mycobacterium leprae?
• Which Bacillus species is most commonly isolated in opportunistic infections such as bacteremia and endocarditis?
• Which test is commonly used for serologic confirmation of Lyme disease after an initial screening?
• Which enzyme differentiates Listeria monocytogenes from streptococci?
• Which of the following statements is not true of clostridia?
• Which Enterobacter species produces a yellow pigment?
• Which organism will turn a dark purple when tetramethyl-p-phenylenediamine hydrochloride is applied?
• Brucella spp. are
• Entamoeba coli cysts are distinguished from Entamoeba histolytica cysts by the number of nuclei in the cyst.
• Which genus may occasionally exhibit kidney bean-shaped diplococci morphology?
• Staphylococcus aureus, when present, could most likely be recovered from a stool sample if the primary plating medium included which selective agent?
• Fecal cultures are inoculated on thiosulfate-citrate-bile salts-sucrose agar specifically for the isolation of which genus?
• Continuous blood culture systems that detect changes in headspace pressure in bottles are referred to as which methods?
• Among the listed antibiotics, which is bactericidal?
• The axial fibrils of spirochetes most closely resemble which bacterial structure?
• Which growth factors are required by Haemophilus influenzae in culture?
• Streptococci are unable to synthesize which enzyme?
• Oocysts of Toxoplasma gondii are shed in cat feces and can contaminate soil. Which form is shed?
• Identify the Fusobacterium species considered the most frequent isolate recovered from clinical infections.
• Donovan bodies are diagnostic findings for granuloma inguinale; which description is correct?
• Purulent material from a cerebral abscess shows Gram-positive cocci in chains and gram-negative bacilli with pointed ends on Gram stain. Based on these smear findings, which combination of anaerobic organisms is most likely?
• Which organism produces alpha-toxin (lecithinase) and is associated with gas gangrene and food poisoning?
• Bullous impetigo is primarily caused by which organism?
• Rust-colored sputum in lobar pneumonia is most characteristic of which etiologic agent?
• Which biochemical description best matches Clostridium tetani?
• A fastidious gram-negative bacillus with gliding motility observed in darkfield is most likely which genus?
• An intestinal parasite seen in an iodine-stained fecal wet mount described as 25 μm in diameter with a central body and a ring of cytoplasm containing nuclei; best describes which organism?
• Hemolytic uremic syndrome is most commonly associated with infection by which organism?
• In Echinococcus granulosus infection, hydatid cysts are most often located in which organs?
• Which organism is rarely isolated from clinical specimens and is not a primary pathogen?
• Which of the following does not describe Acinetobacter sp.?
• Which organism is citrate-positive on citrate utilization testing?
• What is the optimal growth temperature for M. xenopi?
• Which statement is true about Taenia saginata infection?
• Endemic typhus is transmitted to humans by fleas infected with which organism?
• What is the optimal specimen type for recovering Bordetella pertussis?
• Milk has classically been the primary vehicle for transmission of which disease from cattle to humans?
• On Gram stain, Bacillus anthracis appears as a large, spore-forming gram-positive bacillus that characteristically grows in which arrangement?
• Which animal is a reservoir for Escherichia coli O157:H7 associated with outbreaks?
• Which test is most appropriate for the presumptive identification of Prevotella melaninogenica?
• Ethylhydrocupreine HC1 susceptibility is a presumptive test for the identification of which species?
• Shigella sonnei is differentiated from other Shigella species by which biochemical test?
• The species of Campylobacter noted to produce septicemia, septic arthritis, meningitis, jaundice with hepatomegaly, and thrombophlebitis in debilitated patients is which species?
• Salmonella Typhi exhibits a characteristic biochemical pattern; which of the following is not characteristic of S. Typhi?
• New York City agar was developed for the isolation of which organism?
• The etiologic agent of primary atypical pneumonia is which organism?
• A trophozoite about 12 μm in size with two nuclei and no cyst stage corresponds to which organism?
• The etiologic agent of epidemic relapsing fever is Borrelia recurrentis and is commonly transmitted by which vector?
• In antimicrobial synergy testing, what defines synergism?
• An important characteristic of Neisseria gonorrhoeae or the infection it produces is
• In a modified trichrome stain of a fecal smear, microsporidia appear as which of the following?
• In suspected brucellosis, the optimal specimen to be collected for the isolation of the etiologic agent is
• Severe disseminated intravascular coagulation often complicates cases of septicemia caused by
• Which name is given to the severe form of leptospirosis?
• Loeffler's serum medium is recommended for the cultivation of which organism?
• Which of the following is not urease positive?
• Propionibacterium spp. are best described as which of the following?
• A gram-negative bacillus recovered from a child's urine is oxidase negative, lactose negative, urease positive, and motile. The most likely identification is which species?
• In a genital culture using 10B broth, an alkaline reaction without turbidity indicates which organism?
• Which pairing correctly matches the agent Borrelia recurrentis with its vector?
• The Haemophilus influenzae vaccine protects against which serotype?
• Which statement about Giardia lamblia cysts is true?
• Which of the following describes Brucella species?
• Balantidium coli cysts range in size from approximately what micrometers?
• The growth phase during which Staphylococcus aureus produces enterotoxin in contaminated food?
• What is the general principle of rapid beta-lactamase tests in detecting enzyme activity?
• A patient with fatigue, eosinophilia, and periorbital edema has symptoms that mimic infectious mononucleosis. Which parasite should be considered in the differential?
• After 72 hours of anaerobic incubation, small olive-green to black colonies are seen. A Gram stain reveals Gram-positive cocci. What is the most likely identification?
• In manometric blood culture systems, what gas is produced by bacterial metabolism and detected in the headspace?
• Neisseria gonorrhoeae requires which growth condition for recovery?
• The porphyrin test determines an organism's requirement for which substance?
• An obligately anaerobic gram-negative bacillus isolated from an abdominal wound is resistant to penicillin and grows in the presence of bile. What is the most likely identification?
• Which Mycobacterium grows only at 35°C and is differentiated from other mycobacteria by its susceptibility to T2H?
• Which is the most potent bacterial exotoxin known?
• A yellow, nonfermentative gram-negative bacillus isolated from nebulizers in an environmental sampling study most likely belongs to which genus?
• A young woman develops fever, vomiting, diarrhea, and a diffuse rash; vaginal culture grows coagulase-positive Staphylococcus aureus. What diagnosis is most likely?
• Following incubation, if the organism is phenylalanine deaminase positive, a green color develops after adding which reagent?
• Which non-lactose fermenting organism does not produce fluorescein?
• A helicoidal, flexible organism observed in a blood smear corresponds most closely to which genus?
• Which medium is not appropriate for the primary isolation of Bordetella pertussis?
• For which disease is close contact with an infected human host the most important means of transmission?
• Which Neisseria species produces acid from glucose and maltose but not from sucrose or lactose?
• Staphylococcal enterocolitis results from ingestion of foods containing which toxin?
• Which mycobacteria has an optimal growth temperature of 30-32°C?
• Q fever is caused by which organism?
• Cardiobacterium hominis is most classically associated with which condition?
• The Moeller decarboxylase test is dependent upon which condition?
• Porphyrin test is most useful for the identification of which organism?
• Classic toxigenic strains of which Vibrio cholerae serogroup are implicated in epidemic infections of Vibrio cholerae?
• Which vector transmits Chagas disease?
• Arcanobacterium pyogenes was formerly considered a member of which genus?
• Which organism lacks a cell wall and is best visualized by darkfield or phase microscopy?
• Examination of stained blood films: Babesia spp. are likely to resemble which parasite?
• A middle-aged man with a history of smoking and heavy alcohol use develops atypical pneumonia. He works in the produce section where greens are misted. Which organism is the most likely etiologic agent?
• An adult presents with fever after travel to Africa. A peripheral blood smear reveals an extracellular, flagellated parasite. What is the most likely diagnosis?
• Chlamydia trachomatis is historically associated with which ocular condition?
• Which statement about the oxidase test is not appropriate?
• Chronic carriers are typically associated with dissemination of which organism?
• A catalase-negative gram-positive coccus isolated from a urine sample forms a black pigment on bile-esculin agar and ferments glucose in 6.5% NaCl. Which organism is most likely?
• Why should CAMP testing be incubated in ambient air?
• During the childbearing years, the normal flora of the vagina is predominantly which organism?
• Lack of motility is characteristic of which organism among Enterobacteriaceae?
• Which specimen provides the best yield for recovery of Legionella pneumophila?
• What is the reference method for detection of Chlamydia trachomatis in cases of sexually transmitted disease?
• Entamoeba hartmanni cysts are smaller than Entamoeba histolytica cysts. Which statement is true?
• What is the vector for Babesia species that infect humans?
• Campylobacter spp. are associated most frequently with cases of
• Serogrouping Shigella in the clinical laboratory is based on which antigen?
• Skin cultures for the recovery of Mycobacterium spp. should be incubated at which temperature?
• A gram-positive coccus that is catalase positive, nonmotile, lysostaphin resistant, and modified oxidase positive is best identified as a member of the genus
• Rocky Mountain spotted fever is transmitted by the bite of a tick infected with which species?
• Buffered charcoal yeast extract agar is the recommended medium for recovery of which organism?
• Mycobacterium marinum, associated with aquariums and aquatic environments, is typically found in which environment?
• Direct Gram stain of a tissue biopsy shows Gram-positive bacilli with central spores; after 24 hours incubation, no growth on sheep blood agar aerobically or on chocolate agar incubated in increased CO2. Which organism is most likely responsible?
• Colonies of Listeria monocytogenes on a sheep blood agar plate most closely resemble colonies of which organism?
• In OF medium, what modification helps reveal oxidative metabolism by reducing interference from peptone-derived alkaline products?
• Diphtheria toxin–mediated disease most commonly affects which age group?
• In an immunocompromised patient with a pulmonary abscess and brain abscess, aspirated material grew an aerobic, filamentous, branching gram-positive organism that stains weakly acid-fast. The most likely etiologic agent would be which?
• Chlamydophila psittaci infections in humans most commonly result after exposure to which?
• Edwardsiella tarda is occasionally isolated in stool and can be biochemically confused with which genus?
• The beta-hemolysis produced by group A Streptococcus on sheep blood agar is primarily the result of which streptolysin?
• Bacterial vaginosis can be diagnosed by detecting which cytologic finding?
• Bacillus anthracis can infect humans through which routes?
• Impetigo is most commonly caused by which organism?
• Metronidazole is most effective against which type of organisms?
• Which antimicrobial agent inhibits cell wall synthesis?
• Which organism is unable to grow on MacConkey agar?
• Which special disk is used to aid isolation of Abiotrophia?
• A culture from a decubitus ulcer shows a gram-negative facultative bacillus with acid slant and acid butt on TSI; Indole positive; Citrate negative; Urease negative; ONPG positive; Voges-Proskauer negative. Which organism is most likely?
• Which body site is not normally colonized by large numbers of normal flora?
• Which organism is the causative agent of melioidosis?
• Campylobacter jejuni is characterized by which attribute?
• In susceptibility testing, the suspension is standardized to match the turbidity of which McFarland standard?
• Posterior pharynx cultures are most commonly submitted to detect which organism?
• Entamoeba coli cysts are characterized by containing up to how many nuclei?
• Which Mycobacterium is niacin-positive?
• Which organism is most likely to produce hydrogen sulfide on triple sugar iron agar and test positive for lysine decarboxylation but negative for urease, differentiating it from Proteus species?
• What finding provides the best direct diagnosis of Echinococcus granulosus infection in humans?
• Which organism causes botulism from improperly canned foods?
• Which organism exhibits a curved appearance on a fresh Gram stain?
• Which statement about Eikenella corrodens is not characteristic?
• Which Neisseria species produces acid from glucose but not from maltose, lactose, or sucrose?
• Plesiomonas shigelloides is the only species in its genus. Which of the following is that organism?
• Which Plasmodium species is typically characterized by peripheral blood containing mainly ring forms and gametocytes, with other stages rarely seen unless the disease is severe?
• Which Mycobacterium appears as buff-colored colonies after exposure to light and is niacin positive?
• Lactobacillus species maintain an acidic vaginal environment by producing acids; what effect does this have on vaginal pH?
• What component is abundant in the cell wall of the mycobacteria that is lacking in other bacteria?
• Which species shows a band form trophozoite across the red blood cell in blood smears?
• In Clostridium perfringens food poisoning, the enterotoxin is produced as what form?
• Which organism is typically identified by a positive optochin sensitivity test?
• Spirochetes are visualized best using which method?
• Anthrax is transmitted to humans primarily through exposure to what?
• Which drug active against parasitic infections is important for treating infections caused by anaerobic bacteria?
• A semisolid medium containing resazurin appears pink. What does this indicate?
• Viridans group streptococci are normal inhabitants of which region?
• Which organism would not routinely undergo antimicrobial susceptibility testing?
• Which organism may yield a delayed positive PYR reaction?
• Chryseobacterium meningosepticum is associated with nosocomial outbreaks and contaminated respiratory therapy equipment. Which population is most at risk for infection by this organism?
• Borrelia burgdorferi is the etiologic agent of which disease?
• Which medium is used for isolation and identification of staphylococcal species due to high salt concentration and mannitol fermentation?
• Which organism is a common etiologic agent of community-acquired uncomplicated cystitis?
• For susceptibility testing of Streptococcus pneumoniae, which supplement is used with Mueller-Hinton broth?
• Why is a larger volume per blood culture important in adults?
• The Vi antigen of Salmonella Typhi is best described as which of the following?
• Streptococci obtain energy from fermentation of sugars to which acid?
• Haemophilus influenzae growth factors and culture media are best described by which statement?
• Which Plasmodium species can have exoerythrocytic stages capable of causing relapses months or years after initial infection?
• Which organism yields a positive CAMP test?
• Which statement about botulism is correct?
• A positive VDRL result in a patient with hepatitis prompts which next step?
• Double zone hemolysis on anaerobic blood agar is characteristic of which organism?
• The presence of a large glycogen mass in an immature amebic cyst can help identify which organism?
• The etiologic agent of 'swimming pool granuloma' is which Mycobacterium?
• Explosive watery diarrhea with severe abdominal pain after eating raw shellfish is most characteristic of infection caused by which organism?
• Which pair of organisms is suggested as quality control organisms for Simmons citrate agar slants?
• Which fixative containing mercury is commonly used to preserve parasites in stool specimens?
• An unheated suspension of Salmonella Typhi typically produces agglutination of Vi antisera. After heating the same suspension, agglutination will occur in which grouping sera?
• A slowly growing, orange-pigmented acid-fast bacillus isolated from a cervical lymph node in a child with cervical adenitis—most likely etiologic agent?
• Which cell line is commonly used to culture Chlamydia trachomatis from clinical samples?
• Eikenella corrodens often exhibits which characteristic on agar?
• Which of the following is not a characteristic of Klebsiella granulomatis?
• The immunodiffusion test used to detect toxigenic strains of Corynebacterium diphtheriae is called which test?
• The organism linked to peptic ulcers and gastritis is which bacterium?
• Which statement about Listeria monocytogenes is not correct?
• The MIDI identification system is based on which type of analysis?
• Which organism is part of the normal respiratory flora of laboratory animals and can cause kennel cough in dogs?
• To ensure anaerobic conditions are achieved in anaerobic jars or chambers, which indicator is employed?
• Which anaerobic gram-negative bacillus shows brick-red fluorescence under UV light and can produce a black pigment?
• An August case in New England with spirochetes seen on silver-stained skin biopsy has which diagnosis?
• In epidemiologic surveys for upper respiratory tract carriers of Neisseria meningitidis or Bordetella pertussis, what is the optimal specimen type for culture?
• Infection from undercooked meat typically involves tissue cysts containing which stage of Toxoplasma gondii?
• Which organism has a negative oxidase test?
• Isolation of Neisseria gonorrhoeae is best enhanced by which condition?
• Which animal is associated with the sylvatic form of typhus in the United States?
• Which organism is commonly found intracellularly in female genital tract smears and can be mistaken for normal flora?
• An anaerobic, gram-negative rod can be presumptively identified by its Gram stain morphology and inhibition by bile and a 1-µg kanamycin disk. Which organism is this?
• Which medium should be used for susceptibility testing of Streptococcus pneumoniae?
• A positive Voges-Proskauer reaction is characteristic of which organism among the following?
• A test for hydrolysis of esculin in the presence of bile is especially useful in identifying species of which genus?
• Which organism is commonly associated with recalls of disinfectants due to its ubiquity and resistance to many disinfectants, and is a hospital-associated opportunistic pathogen?
• What finding at surgery confirms infection with Echinococcus granulosus?
• Which of the following is typical in cysts of Lodamoeba biitschlii?
• Gram-positive rods were recovered from the chest fluid of a teenager with pneumonia; CAMP test positive and catalase negative. The most likely etiologic agent is?
• Which statement is correct regarding differentiating M. bovis from M. tuberculosis?
• Murine typhus is transmitted to humans by fleas infected with Rickettsia typhi. It is prevalent in which region?
• What is the purpose of adding NALC to the NaOH digestion when processing clinical specimens for tuberculosis?
• A stool culture yields a Gram-negative bacillus that is oxidase negative, citrate negative, indole negative, urease positive, and grows slowly; the most likely etiologic agent is?
• The finding of five to six acid-fast bacilli per field in a fuchsin smear should be reported as which grade?
• The novobiocin susceptibility test is used for the identification of which organism?
• Sulfur granules are characteristic of pus from infections with which organism?
• Which toxin types of Clostridium botulinum are associated with human botulism?
• Decontamination of drinking water, fruits, and vegetables would least affect which disease?
• On bile-esculin agar, what indicates a positive result for enterococci?
• Arabinose reaction is used to differentiate Serratia liquefaciens from Serratia marcescens.
• Which Legionella species is positive for hippurate hydrolysis?
• Which organism is actively motile at room temperature and is known to cause meningitis in newborns?
• A positive gelatin liquefaction is characteristic of which organism?
• Yersinia pseudotuberculosis commonly presents with which clinical condition?
• A positive DNase would be seen with which organism?
• Which statement about Giardia lamblia trophozoites is true?
• Listeria monocytogenes beta-hemolysis on blood agar may be mistaken for infection with which groups of streptococci?
• A Gram stain of cerebrospinal fluid from a 1-year-old girl with suspected meningitis shows many white blood cells. After 24 hours, small tan colonies grow on chocolate agar incubated in CO2, but there is no growth on sheep blood agar. Which organism is most likely?
• Which statement about laboratory diagnosis of pertussis is not true?
• Which characteristic differentiates Enterococcus faecalis from Group D streptococci?
• Which organism would yield a yellow slant and a yellow butt on TSI agar after 18 hours?
• Which statement about Campylobacter jejuni is true?
• Which statement describes Clostridium difficile infection?
• An ovum measuring about 70 by 38 μm with a thin shell is most consistent with which parasite?
• Pleomorphic gram-positive bacilli with a palisade arrangement resembling Chinese characters are most characteristic of which genus?
• Hematuria is a typical sign of human infection caused by which parasite?
• Which organism is most often associated with endocarditis?
• Which organism should rapid beta-lactamase testing be performed on before initiating antimicrobial therapy?
• Which organism is not gram-positive?
• Erysipelothrix infections in humans characteristically produce pathology at which site?
• Foodborne outbreaks of brucellosis are most commonly linked to eating which of the following foods?
• Legionella pneumophila is often difficult to visualize on Gram stain; which diagnostic method provides rapid positive identification?
• The causative agent of Oroya fever is which organism?
• Which virulence factor is important for Bacteroides fragilis?
• The etiologic agent of whooping cough is
• Which form of Toxoplasma gondii is produced in infected humans?
• Chagas disease is caused by which organism?
• A fermentative gram-negative bacillus that is oxidase positive, motile, and grows well on MacConkey agar is most consistent with which organism?
• Legionella pneumophila is the etiologic agent of Legionnaires disease and which other febrile illness?
• Malaria relapses months after primary infection are associated with exoerythrocytic liver stages in infections with which Plasmodium species?
• Enterococcus faecium is characteristically able to grow in the presence of high concentrations of salt.
• Which genera are known to produce a positive VP reaction in MRVP testing?
• What characteristic is key to identifying Staphylococcus saprophyticus among coagulase-negative Staphylococcus species?
• Serratia marcescens pigment production is enhanced by which condition?
• Staphylococcus saprophyticus is a recognized pathogen most commonly associated with which type of infection?