BOC Microbiology 6th Edition

The proper blood-to broth ratio for blood cultures to reduce the antibacterial effect of serum in adults is:
a. 1:2
b. 1:3
c. 1:10
d. 1:30

c

The most appropriate method for collecting a urine specimen from a patient with an indwelling catheter is:
a. remove the catheter, cut the tip and submit it for culture
b. disconnect the catheter from the bag, and aseptically collect urine from the terminal end of the catheter
c. asepticaly collect urine directly from the drainage bag
d. aspirate urine aseptically from the catheter bag

d

Which of the following groups of specimens would be acceptable for anaerobic culture?
a. vaginal swab, eye swab
b. intraoral surface swab, leg swab
c. pleural fluid, brain, brain abscess fluid
d. urine, sputum

c

Sodium polyanetholsulfonate (SPS) is used as an anticoagulant for blood cultures because it:
a. inactivates penicillin and cephalosporins
b. prevents clumping of red cells
c. inactivates neutrophils and components of serum complement
d. facilitates growth of anaerobes

c

The optimal collection of a wound specimen for culture of anaerobic organisms is a:
a. swab of lesion obtained before administration of antibiotics
b. swab of lesion obtained after administration of antibiotics
c. syringe filled with pus, obtained before administration of antibiotics
d. syringe filled with pus, obtained after administration of antibiotics

c

The MOST important variable in the recovery of organisms in adult patients with bacteremia (bacterial sepsis) is:
a. subculture of all bottles at day 5 of incubation
b. the recommended volume of blood cultured
c. collection of daily blood cultures set for 3 consecutive days
d. collection of multiple blood culture sets from a single venipuncture

b

Virus transport medium should contain agents that:
a. enable rapid viral growth during the transport time
b. inhibit bacterial and fungal growth
c. destroy nonpathogenic viruses
d. inhibit complement fixing antibodies

b

A bronchoscopy sample with the request for culture of Legionella is sent to the laboratory. The correct plating protocol is:
a. culture on thiosulfate citrate bile salt media
b. incubate the culture media anaerobically
c. reject the specimen and request a sputum sample
d. culture of buffered charcoal yeast extract agar with antibiotics

d

A community hospital microbiology laboratory is processing significant numbers of stool cultures because of an outbreak of diarrhea following heavy rains and flooding in the county. A media that should be incorporated in the plating protocol is:
a. colistin nalidixic acid for Listeria
b. MacConkey agar with sorbitol for Camplobacter
c. mannitol salt agar for Enterococcus species
d. thiosulfate citrate bile salts sucrose for Vibrio species

d

A male urethral discharge specimen submitted for culture should be innoculated to:
a. sheep blood and phenylethyl alcohol agars
b. eosin-methylene blue and sheep blood agars
c. thioglycollate broth and chocolate agar
d. chocolate and modified Thayer-Martin agars

d

The steam autoclave method of sterilization requires:
a. 15 lb of pressure for 15 minutes
b. dry heat for 20 minutes
c. a maximum temperature of 100 degrees C
d. a source of ethylene oxide

a

Which selective medium is used for the isolation of gram-positive microorganisms?
a Columbia CNA with 5% sheep blood
b trypticase soy agar with 5% sheep blood
c eosin methylene blue
d modified Thayer-Martin

a

Camplyobacter jejuni isolation requires the fecal specimen to be:
a. Inoculated onto selective plating media and incubated in reduced oxygen with added CO2 at 42 degrees C
b. stored in tryptic soy broth before plating to ensure growth of organism
c. inoculated onto selective plating media and incubated at both 35 degrees C and at room temperature
d. incubated at 35 degrees C for 2 hours in Cary-Blair media before inoculating onto selective plating media

a

Which of the following specimen requests is acceptable?
a. feces submitted for anaerobe culture
b. Foley catheter tip submitted for aerobic culture
c. rectal swab submitted for direct smear for gonococci
d. urine for culture of acid-fast bacilli

d

A CSF specimen containing only 2 drops of CSF was collected by lumbar puncture from a febrile 25-year old male and was submitted for a stat gram stain and culture. The direct specimen Gram stain was reported as many neutrophils and no microorganism seen. The remain drop of CSF should be inoculated to:
a. blood agar
b. CNA agar
c. chocolate agar
d. Thayer-Martin agar

c

A diabetic foot swab from an 82 year old woman with recurrent infections is submitted for culture. The gram stain reveals:
Many neutrophils, no squamous epithelial cells
Many Gram-negative bacilli
Many Gram-positive cocci in chains

The physician requests that all pathogens be worked up. In addition to the sheep blood, chocolate and MacConkey agar plates routinely used for wound cultures, the technologist might also process an:
a. anaerobic blood agar plate
b. BCYE agar plate
c. CNA agar plate
d. XLD agar plate

c

Which of the following is the most appropriate specimen source and primary media selection?
a. CSF Columbia CNA, MacConkey
b. endocervical chocolate, Martin Lewis
c. sputum sheep blood, Thayer-Martin, KV-laked blood
d. urine sheep blood, chocolate, Columbia CNA

b

Which of the following is the most appropriate organism and media combination?
a. Vibrio species - Skirrow
b. Enterohemorrhagic E coli - phenylethyl alcohol (PEA)
c. Campylobacter species - charcoal yeast extract
d. Yersinia enterocolitica - cefsulodin-irgasan-novobiocin

d

A Gram stain from a swab of a hand wound reveals:
moderate neutrophils
no squamous epithelial cells
moderate gram-positive cocci in chains moderate large gram-negative bacilli
Select the appropriate media that will selectively isolate each organism.
a KV-laked agar, Thayer-Martin
b sheep blood, MacConkey
c Columbia CNA, chocolate
d Columbia CNA, MacConkey

d

An organism that must be incubated in a microaerophilic environment for optimal recovery is:
a. Camplobacter jejuni
b. Escherichia coli
c. Pseudomonas aeruginosa
d. Proteus mirabilis

a

Vibrio parahaemolyticus is best isolated from feces on:
a. Eosin methylene blue (EMB) agar
b. Hektoen enteric (HE) agar
c. Salmonella Shigella (SS) agar
d. Thiosulfate citrate bile salts (TCBS) agar

d

Media used to support growth of Legionella pneumophila should contain which of the following additives?
A. X and V factors
B. hemin and Vitamin K
C. charcoal and yeast extract
D. dextrose and laked blood

c

The best medium for culture of Bordetella pertussis is:
a . phenylethyl alcohol agar
b. potassium tellurite blood agar
c. Regan-Lowe agar
d. Tinsdale agar

c

A medium that can be used to recover Francisella tularensis is:
a. Bordet-Gengou agar
b. Buffered charcoal yest extract agar
c. Loeffler agar
d. MacConkey agar

b

A 21-year old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be:
a. set up immediately
b. rejected as unacceptable
c. inoculated into thioglycollate broth
d. sent to a reference laboratory

b

The antibiotic used to suppress or kill contaminating fungi in media is:
a. amphotericin B penicillin
b. chloramphenicol
c. cycloheximide
d. streptomycin

c

A vaginal /rectal swab is collected from a pregnant patient to screen for group B Streptococcus colonization. The best medium to inoculate the specimen to is:
a. CNA agar
b. LIM broth
c. sheep blood agar
d. thioglycollate broth

b

When processing a patient specimen for Gram stain and culture, the proper use of a biological safety cabinet includes:
a. bringing into the cabinet all required media and equipment just prior to setting up each individual specimen
b. keeping the ultraviolet light on for the first 30 minutes of working in the cabinet
c. not using any heat generating equipment such as open flames or microburner/incinerators
d. not disrupting the air curtain barrier by keeping air flow and exhaust grills unobstructed

d

A wound specimen grew 2 colony types on sheep blood agar and a single, clear colony type on MacConkey gar. Sheep blood agar growth was documented as:
colony type #1 swarming over entire plate, Gram stain: Gram negative rod
colony type #2 white colony, Gram stain: Gram positive cocci in clusters
The best way to isolate colony type #2 from colony type #1 is to subculture:
a. colony #1 to sheep blood agar and chocolate agars
b. colony #1 to sheep blood agar and/or MacConkey agar
c. colony #2 to sheep blood agar and chocolate agar
d. colony #2 to CNA and/or PEA agar

d

A differential medium that can be used as a primary isolation agar producing predictable colored colonies that can be distinguished from other organism colony types describes:
a. buffered charcoal yeast extract agar
b. blood phenylethyl alcohol agar
c. campylobacter blood agar
d. chromagar

d

Anticoagulants acceptable for use with blood, bone marrow, and synovial fluid specimens that are to be cultured include:
a. EDTA and sodium citrate
b. heparin and sodium citrate
c. sodium polyanethol sulfonate (SPS) and heparin
d. sodium polyanethol sulfonate (SPS) and EDTA

c

Appropriate culture requirements for a specimen from a patient suspected of having tularemia include:
a a media with cysteine such as buffered charcoal yeast extract agar
b colistin nalidixic acid agar
c Mueller-Hinton agar with 5% sheep blood agar
d Regan-Lowe media

a

The primary isolation of Neisseria gonorrhoeae requires:
a. anaerobic conditions
b. starch media
c. carbon dioxide
d. blood agar

c

Acceptable specimens for culture of anaerobic bacteria that cause disease include:
a abscesses
b stool
c. clean catch urine
d. vaginal

a

In general, anaerobic infections differ from aerobic infections in which of the following ways?
a. they usually respond favorably to aminoglycoside therapy
b. they usually arise from exogenous sources
c. they are usually polymicrobic
d. Gram stains of specimens are less helpful in diagnosis

c

An expectorated sputum is sent to the laboratory for culture from a patient with respiratory distress. The Gram stain of the specimen shows many squamous epithelial cells (>25/lpf) and rare neutrophils. The microscopic appearance of the organisms present include:
moderate gram-positive cocci in chains and diplococci moderate gram-negative diplococci
moderate palisading gram-positive bacilli all in moderate amounts
This Gram stain is most indicative of:

a a pneumococcal pneumonia
b an anaerobic infection
c an Haemophilus pneumonia
d oropharyngeal flora

d

Upon review of a sputum Gram stain, the technician notes that all the neutrophil nucleiin the smear stained dark blue. The best explanation for this finding is the:
a. iodine was omitted from the staining procedure
b. slide was inadequately decolorized with acetone/alcohol
c. sputum smear was prepared too thin
d. cellular components have stained as expected

b

The principle difference between the Ziehl-Neelsen acid fast stain techniqueand the Kinyoun acid-fast stain technique is the:
a. type of dyes used
b. type of microscope used to interpret stained smears
c. strength of acid decolorizer
d. use of heat to allow the dye to penetrate organism

d

Relapsing fever in humans is caused by:
a. Borrelia recurrentis
b. Brucella abortus
c. Leptospira interoogans
d. Spirillum minus

a

Three sets of blood cultures were obtained from an adult patient with fever and suspected endocarditis. The aerobic bottle of one set had growth of Staphylococcus epidermidis at 5 days of incubation. This indicates that:
a there was low-grade bacteremia
b the organism is most likely a contaminant
c the patient has a line infection
d the blood culture bottles are defective

b

The Gram stain from a blood culture shows gram-positive cocci in chains. No growth occurs on blood agar plates incubated both aerobically and anaerobically. Additional testing should be done to detect the presence of:
a. Staphlococcus saprophyticus
b. Aerococcus urinae
c. Abiotrophia defectiva
d. Streptococcus pneumoniae

c

Gram stain examination from a blood culture bottle shows dark blue, spherical organisms in clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further tests should include:
a catalase production and coagulase test
b bacitracin susceptibility and serological typing
c oxidase and deoxyribonuclease reactions
d Voges-Proskauer and methyl red reactions

a

Gram-positive cocci in chains are seen on a Gram stain from a blood culture. The organism grows as a beta-hemolytic colony. Further tests that could be performed include:
a. PYR, bacitracin, and hippurate
b. catalase and agglutination test for Protein A
c. oxidase and mass spectrometry
d. Voges-Proskauer and methyl red

a

"Nutritionally variant" streptococci are:
a. enterococci
b. group D enterococci
c. beta hemolytic streptococci
d. in the genera Granulicatella and Abiotrophia

d

The most frequent cause of prosthetic heart valve infections occurring within 2-3 months after surger is:
a. Streptococcus pneumoniae
b. Streptococcus pyogenes
c. Staphlococcus aureus
d. Staphlococcus epidermidis

d

A Gram positive coccus isolated from a blood culture has the following characteristics:

Optochin susceptibility - negative
bacitracin susceptibility - negative
bile esculin hydrolysis - negative
hippurate hydrolysis - positive
catalase - negative
The organism is most likely:
a. Staphlococcus aureus
b. Streptococcus pneumoniae
c. Streptococcus pyogenes
d. Streptococcus agalactiae

d

During the previous month, Staphyloccus epidermis has been isolated from blood cultures at 2-3 times the rate from the previous year. The most logical explanation for the increase in these isolates is that:
a. the blood culture media are contaminated with this organism
b. the hospital ventilation system is contaminated with Staphylococcus epidermis
c. there has been a break in proper skin preparation before drawing blood for culture
d. a relatively virulent isolate is being spread from patient to patient

c

A 55 year-old man presents to the emergency room with chest pain and is found to have suffered a heart attack. He has a past history of hypertension, and a high cholesterol. The patient is admitted and scheduled for a triple bypass procedure. During recovery, he becomes septic, developing a high grade fever and pneumonia. Gram positive cocci in clusters, isolated from both his lungs via an induced sputum specimen and the surgical incision, produce beta hemolytic, catalase-positive colonies on sheep blood agar.

Identify the organism most likely isolated and the biochemical test performed to confirm the identification.
a. Staphylococcus aureus and latex agglutination
b. Streptococcus pyogenes and PYR
c. Streptococcus agalactiae and latex agglutination
d. Enterococcus faecium and PYR

a

A patient with a prosthetic heart valve visits the dentist for her yearly checkup. Two weeks later, she presents to her primary care physician with a high fever, chills, and shortness of breath and receives a diagnosis of subacute endocarditis. Multiple blood culture sets are drawn on the patient and sent to the lab. Twenty-four hours later the bottles are positive for bacterial growth. Which organism would you expect to grow?
a. Staphylococcus lugdenensis
b. Staphylococcus saprophyticus
c. Streptococcus viridans
d. Streptococcus agalactiae

c

A blood culture from a 64-year old male with lymphoma was positive blood culture at 18 hours incubation. The organism is a nonlactose fermenting Gram negative bacillus on MacConkey agar. Further testing gives the following reactions:
Oxidase - negative
TSI - alkaline/acid, no hydrogen sulfide
Motility - positive
Indole - positive
Citrate - positive
ornithine decarboxylase - negative
urea - positive
phenylalanine deaminase - positive
VP - negative
The genus is:
a. Morganella
b. Proteus
c. Providencia
d. Serratia

c

A blood culture bottle with macroscopic signs of growth is Gram stained and the technician notes small, curved Gram negative bacilli resembling "gull wings". It is subcultured to blood and chocolate agar, and incubated aerobically and anaerobically. After 24 hours, no growth is apparent. The next step should be to:
a. subculture the bottle, and incubate in microaerophilic conditions
b. assume the organism is nonviable, and ask for a repeat specimen
c. utilize the oxidase and indole test to detect Aeromonas
d. subculture the bottle to a medium containing X and V factors

a

Which of the following specimens is considered to be the most sensitive for the recovery of Brucella in cases of chronic infection?
a. blood
b. urine
c. bone marrow
d. lymph node

c

A college student attended a beach party where raw oysters and other shellfish were consumed. The next day, he had symptoms of septicemia. The blood cultures grew Gram-negative bacilli with the following characteristics:
oxidase - positive
MacConkey agar - pink colonies
O/129 - susceptible
The most likely organism is:
a. Aeromonas hydrophilia
b. Pseudomonas putida
c. Serratia marcescens
d. Vibrio vulnificus

d

The laboratory receives a blood culture from a veterinarian who has been ill for many weeks with fevers in the afternoon and evenings, arthritis and fatigue. The blood culture is positive after 5 days, and the organism has the following characteristics:

Gram stain- small, gram negative coccobacilli
sheep blood agar - growth after 48 hours with small, raised colonies.
What should the microbiologist do next?
a. consider the growth contamination and perform another gram stain
b. perform biochemical identification for HACEK organisms
c. perform identification and susceptibility using an automated system
d. take extra safety precautions for possible Brucella

d

Propionibacterium acnes is most often associated with:
a. food poisoning
b. post-antibiotic diarrhea
c. tooth decay
d. blood culture contamination

d

Which one of the following anaerobes is inhibited by sodium polyanethol sulfonate (SPS)?
a. Bacteroides fragilis
b. Propionibacterium acnes
c. Peptostreptococcus anaerobius
d. Veillonella parvula

c

A patient has a suspected diagnosis of subacute bacterial endocarditis. His blood cultures grow non spore forming pleomorphic Gram positive bacilli only in the anaerobic bottle. What tests will give a presumptive identification of the microorganism?
a. beta-hemolysis and oxidase
b. catalase and spot indole
c. esculin hydrolysis
d. hydrolysis of gelatin

b

Microorganisms resembling Mycoplasma pneumonia have been isolated from the blood of patients treated with antibiotics that:
a. complex with flagellar protein
b. interfere with cell membrane function
c. inhibit protein synthesis
d. interfere with cell was synthesis

d

Cerebrospinal fluid tests results that are most consistent with viral meningitis include:
a. decreased protein level
b. increased glucose level
c. increased lactate level
d. increased mononuclear leukocyte count

d

The organism most commonly associated with neonatal purulent meningitis is:
a. Neisseria meningitidis
b. Streptococcus pneumoniae
c. group B strepcocci
d. Haemophilus influenzae

c

A beta-hemolytic Gram-positive coccus was isolated from the cerebrospinal fluid of a 2-day old infant with signs of meningitis. The isolate grew on sheep blood agar under aerobic conditions and was resistant to a bacitracin disc. Which of the following should be performed for the identification of the organism?
a. oxidase production
b. catalase formation
c. latex antigen grouping
d. esculin hydrolysis

c

An 18-year old boy is admitted to the hospital with suspected meningitis. He is lethargic and presents with a rigid neck. He has not had most of the recommended vaccines from childhood to now. Gram stain of his spinal fluid shows many PMNS with intra and extra cellular Gram-negative diplococci. The suspected pathogen is:
a. Listeria monocytogenes
b. Haemophilus influenzae
c. Streptococcus agalactiae
d. Neisseria meningitidis

d

A 25-year old man who had recently worked as a steward on a transoceanic gran ship presented to the emergency room with high fever, diarrhea and prostration. Axillary lymph nodes were hemorrhagic and enlarged. A Wright-Giemsa stain of the aspirate showed bacilli that were bipolar, resembling safety pins. The most likely identification of this organsim is:
a. Brucella melitensis
b. Streptobacillus monoliliformis
c. Spirillum minus
d. Yersinia pestis

d

Anaerobic Gram-positive bacilli with subterminal pores were isolated fro a peritoneal abscess. The colony has a swarming appearance. The most likely identification of this organism is:
a. Bacillus cereus
b. Clostridium septicum
c. Eubacterium lentum
d. Bifidobacterium dentium

b

A gram stain of a peritoneal fluid showed large Gram-positive bacilli. There was 3+ growth on anaerobic media only, with colonies producing a double zone of hemoysis. To assist with the classic identification of the organism, the microbiologist could:
a. determine if the organism ferments glucose
b. perform the oxidase test
c. set up egg yolk agar plate
d. test for bile tolerance

c

An organism from a peritoneal abscess is isolated on kanamycin-vancomycin laked blood agar and grows black colonies on BBE agar. It is nonpigmented, catalase positive, and indole negative. The genus of this organism is:
a Acidominococcus
b Bacteroides
c Porphyromonas
d Prevotella

b

A thin, Gram negative bacillus with tapered ends isolated from a empyema specimen grey only on anaerobic sheep blood agar. It was found to be indole positive, lipase negative, and was inhibited by 20% bile. The most probable identification of this isolate would be:
a. Bacteroides distasonis
b. Prevotella melaninogenica
c. Fusobacterium nucleatum
d. Clostridium septicum

c

A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on sheep blood agar. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following the test results;
ONPG: POS
INDOLE: NEG
GLUCOSE: POS
OXIDASE: NEG
CITRATE: POS
VP: POS

The organism is most likely:
a. Edwardsiella tarda
b. Klebsiella pneumoniae
c. Escherichia coli
d. Proteus vulgaris

b

A patient with a nosocomial pneumoia has a sputum Gram stain that shows many neutrophils and numerous small Gram-negative coccobacilli. The organism grew in 24 hours as a mucoid, hemolytic colony on blood agar and a colorless colony on a MacConkey agar. The organism had the following characteristics:
OXIDASE: NEG
CATALASE: POS
NITRATE: NEG
ONPG: NEG
ORNITHINE DEC:NEG
LYSINE DEC: NEG

The organism is:
a. Stenotrophomonas maltophilia
b. Alcaligenes faecalis
c. Moraxella lacuata
d. Acinobacter baumannii

d

Serum samples collected from a patient with pneumonia demonstrate a rising antibody titer to Legionella. A bronchoalveolar lavage (BAL) specimen from this patient had a positive antigen test for Legionella but no organisms were recovered on buffered charcoal yeast extract medium after 2 days of incubation. The best explanation is that the:
a. antibody titer represents an earlier infection
b. positive antigen test is a false positive
c. specimen was cultured on the wrong media
d. culture was not incubated long enough

d

A 17-year old female with cystic fibrosis is diagnosed wit pneumonia. A sputum sample grew Gram negative bacilli with yellow, smooth colonies that have the following biochemical reactions:
OXIDASE: POS
TSI: alk/alk
GLUCOSE: OXIDIZED
FLOURENCENCE: NEG
LYSINE DEC: POS

a. Burkholderia cepacia
b. Klebsiella pneumoniae
c. Shewanella putefaciens
d. Stenotrophomonas maltophilia

a

A college student who recently studied a semester abroad in Southeast Asia is admitted to the hospital with a diagnosis of "glanders-like" infection (melioidosis). A sputum specimen grows a small, Gram negative rod that is positive for oxidase, reduces nitrate to gas, and oxidizes glucose, lactose and mannitol. What is the most likely organism?
a. Stenotrophomans maltophilia
b. Burkolderia pseudomallei
c. Pseudomonas aeruginosa
d. Acinobacter baumanni

b

An organism previously thought to be nonpathogenic, Moraxella catarrhalis, is now known to be associated with opportunistic respiratory infection and nosocomial transmission. Characteristici dentification criteria include:
a. beta-lactamase negative
b. butyrate esterase positive
c. gram-negative bacilli
d. oxidase negative

b

An organism recovered from a sputum has the following characteristics:
Culture: growth at 6 days on buffered charcoal yest extract (BYCE) agar, incubated under aerobic conditions with CO2 at 35 degrees C
Gram stain: delicate branching Gram positive bacilli
modified acid-fast stain: branching, filamentous, "partially" acid fast bacterium
a Nocardia
b Mycobacterium
c Actinomyces
d Streptomyces

a

The gram stain of drainage from a pulmonary sinus tract shows many WBCs and 3+ branching Gram-positive bacilli. Colonies grow only on anaerobic media after 3 days incubation. They are yellow-tan and have a molar tooth appearance. The most likely genus is:
a. Actinomyces
b. Bacteroides
c. Fusobacterium
d. Nocardia

a

A 1-2 mm translucent , nonpigmented colony, isolated from an anaerobic culture of a lung abscess after 72 hours, was found to flouresce brick-red under ultraviolet light. A Gram stain of the organism revealed a coccobacillus that had the following characteristics:
Growth in bile: inhibited
Vancomycin: resistant
Kanamycin: resistant
Colistin: susceptible
Catalase: negative
Esculin hydrolysis: negative
Indole: negative

The identification of this isolate is:
a. Bacteroides ovatus
b. Propionibacterium acnes
c. Prevotella melaninogenica
d. Porphyromonas asaccharolytica

c

Psittacosis is transmissible to man via contact with:
a. insects
b. birds
c. cattle
d. dogs

b

Which 2 diseases are usually preceded by infection with beta-hemolytic streptococci?
a rheumatic fever, undulant fever
b glomerulonephritis, rheumatic fever
c rheumatic fever, tularemia
d glomerulonephritis, undulant fever

b

A common cause of acute exudative pharyngitis is:
a. staphlococcus aureus
b. Streptococcus pneumoniae
c. Streptococcus agalactiae
d. Streptococcus pyogenes

d

a 6-year old male presents to his pediatrician with a severe case of tonsillitis. The physician collects a throat swab specimen and orders GAS (Group A streptococcus) probe test. The following day the probe comes back negative. A culture is requested. The following results are obtained:
Catalase: negative
Bacitracin disk: sensitive
Hippurate hydrolysis: negative
CAMP test: negative
Gram stain: Gram positive cocci in chains
Which of the following organism is most likely causing the tonsillitis?
a. group A beta hemolytic streptococci
b. group B beta hemolytic streptococci
c. group C beta hemolytic streptococci
d. group D beta hemolytic streptococci

c

A small, pleomorphic Gram-negative bacillus is isolated from an eye culture. It grows only on chocolate agar and is oxidase variable. The most likely organism is:
a. Acinetobacter Iwoffii
b. Haemophilus influenzae
c. Stenotrophomonas maltophilia
d. Pseudomonas aeruginosa

B

Haemophilus influenzae is most likely considered normal indigenous flora in the:
a. oropharynx
b. female genital tract
c. large intestine
d. small intestine

b

An isolate on chocolate agar from a patient with epiglottitis was suggestive of Haemophilus species. Additional testing showed that the isolate required NAD for growth and was nonhemolytic. The organism is most likely Haemophilus:
a. haemolyticus
b. ducreyi
c. influenae
d. parainfluenzae

a

A 3-year old unimmunized female presented in the ER with a severe cough, fever and flulike symptoms. The parents reported that the child had vomited a few times due to the severe coughing. A nasopharyngeal swab was used to collect the specimen and plated on a chocolate, Bordet-Gengous, and Regan Lowe media. After 5 days of incubation, colonies grew on all of the media with the growth of Bordet-Gengou described as "drops of mercury". The Gram stain showed minute coccobacilli that were catalase and oxidase positive. The most likely identification of the isolate is:
a. Bordatella parapertussis
b. Yersinia pestis
c. Francisella tularensis
d. Bordetella pertussis

d

A Gram stain performed on a sinus aspirate revealed Gram-negative diplococci within PMNs. Oxidase testing is positive and carbohydrate degradation tests are inert. The organism most likely is:
a. Neisseria lactamica
b. Moraxella catarrhalis
c. Neisseria meningitidis
c. Neisseria sicca

b

Establishing the pathogenicity of a microorganism isolated from a child's throat and identified as Corynebacterium diphtheria would depend on:
a. the morphological appearance as revealed by Gram stain
b. the type of hemolysis on blood agar
c. a positive toxigenicity test
d. the appearance of growth on Tinsdale tellurite agar

c

Chlamydia trachomitis infections have been implicated in:
a. LGV and conjuctivitis
b. gastroenteritis and urethritis
c. neonatal pneumonia and gastroenteritis
d. neonatal meningitis and conjunctivitis

a

A liquid fecal specimen from a three-month-old infant is submitted for culture. The stool culture should detect Salmonella, Shigella and:
a. Campylobacter spp
b. Clostridium botulinum
c. Entamoeba hartmanni
d. eterotoxigenic E. coli

a

MacConkey media for screening suspected cases of hemorrhagic E coli 0157:117 must contain:
a indole
b citrate
c sorbitol
d lactose

c

Which of the following organisms can grow in the small bowel and cause diarrhea in children, traveler's diarrhea, or a severe cholera-like syndrome through the production of enterotoxins?
a. Yersinia enterocolitica
b. E. coli
c. Salmonella typhi
d. Shigella dysenteriae

b

Shigella species characteristically are:
a. urease positive
b. nonmotile
c. oxidase positive
d. lactose fermenters

b

A gram-negative bacillus has been isolated from feces, and the confirmed biochemical reactions fit those of Shigella. The organism does not agglutinate in Shigella antisera. What should be done next?
a. test the organism with a new lot of antisera
b. test with Vi antigen
c. repeat the biochemical tests
d. boil the organism and retest with the antisera

d

Biochemical reactions of an organism are consistent with Shigella . A suspenion is tested in antisera without resulting agglutination. However, after 15 minutes of boiling, agglutination occurs in group-D antisera. The Shigella species is:
a. dysenteriae
b. flexneri
c. boydii
d. sonnei

d

When performing a stool culture, a colony type typical of an enteric pathogen is subcultured on a blood agar plate. The resulting pure culture is screened with several tests to obtain the following results:
TSI: acid butt/alkaline slant, no gas, no H2S
Phenylalanine deaminase: negative
Motility: positive
Serological testing: Shigella flexneri (Shigella subgroup B)
The serological typing is verified with new kit and controls. The best course of action would be to:
a. report the organism as Shigella flexneri without further testing
b. verify reactivity of motility medium with positive and negative controls
c. verify reactivity of the TSI slants with positive and negative controls for H2S production
d. verify reactivity of phenylalanine deaminase with positive and negative controls

a

An isolate from a stool culture gives the following growth characteristics and biochemical reactions:
MacConkey agar: colorless colonies
Hektoen agar: yellow-orange colonies
TSI: acid slant/acid butt, no gas, no H2S
Urea: Positive
a. Yersinia enterocolitica
b. Shigella sonnei
c. Vibrio parahaemolyticus
d. Camplobacter jejuni

a

An 8-year old girl was admitted to the hospital with a 3-day history of fever, abdominal pain, diarrhea, and vomitting. A stool culture grew many lactose-negative colonies that yielded the following test results:
Oxidase: negative
TSI: acid slant/acid butt
Indole: negative
Urease: Positive
Ornithinine decarboxylase: positive
Sucrose: positive
H2S: negative
motility at 25 degrees C: positive

a. E. coli
b. Providencia stuartii
c. Yersinia enterocolitica
d. Edwardsiella tarda

c

Biochemical reactions of an organism are consistent with Salmonella. A suspension is tested in polyvalent antiserum A through G and Vi antiserum. There is agglutination in the Vi antiserum only. What should be done next?
a. boil suspension of the organism for 10 minutes to inactivate the Vi antigen.
b. test organism with individual antisera for agglutination
c. report "no salmonella isolated"
d. repeat biochemical identification of the organism

a

The optimal incubator temperature for isolation of the Camplobacter jejuni/ coli group is:
a. 4 degrees C
b. 20 degrees C
c. 25 degrees C
d. 42 degrees C

d

A gastroenterologist submits a gastric biopsy from a patient with a peptic ulcer. To obtain presumptive evidence of H. pylori, a portion of the specimen should be added to which media?
a. urea broth
b. tetrathionate
c. selenite
d. tryptophan

a

A gram stain of a touch prep from a gastric biopsy shows Gram-negative bacilli that are slender and curved. The most likely pathogen is:
a. Burkholderia capacia
b. Corynebacterium urealyticum
c. H. pylori
d. Pasteurella multocida

c