14.pdf

169 MICROBIOLOGY SAMPLE QUESTIONS 1. A "rice water stool" is characteristic of patients 7. Loeffler's medium is used as a primary infected with...

169 MICROBIOLOGY SAMPLE QUESTIONS 1. A "rice water stool" is characteristic of patients 7. Loeffler's medium is used as a primary infected with isolation medium for A. Clostriclium botulinum. A. Bordetella pertussis. B. Salmonella typhi. B. Corynebacterium dipbtheriae. C. Shigeila dysenteriae. C. llfycohacterium tuberculosis. D. Vibrio cholerae. D. Streptococcus pyogc11es. 2. A sample of material from bluish purulent head 8. Autoclave sterilization of lab media requires lesions is submitted for analysis. A gram which of the following pressure, temperature negative, motile, non-sporeforming and time parameters? oxidase positive rod was isolated. This A. 15 lbs pressure, 115°C for 10 min organism is most likely B. 15 lbs pressure, 121 °C for 15 ruin A. Proteus mfrahilis. C. 20 lbs pressure, 100°C for 15 min B. Proteus vulgaris. D. 20 lbs pressure, 110°C for 10 min C. Pseudomonas aeruginosa. D. Stenotrophomonas maltophilia. 9. Clinical diagnosis of rabies in infected animals is dependent upon brain tissue 3. A gram stained smear from a genital soft observation of chancre demonstrated small gram negative A. Metachromatic granules. rods arranged in tangled chains. You would B. Multinucleatcd cells. suspect the cause of the chancroid to be C. Negri bodies. A. I-Iemophilus ducreyi. D. Vira] capsids. B. Herpes simplex II. C. Neisseria gonorrhoeae. 10. Which of the following results is typical of D. Treponema pallidmn. Campylobacter jejunf? A. Catalasc negative 4. Organisms of this genus are gram negative, B. Non-motile motile rods. A few are chromogenic and C. Optimal growth at 42°C produce a red non-water soluble pigment. D. Oxidase negative Some have been implicated in septicemia, pulmonary and urinary tract infections. One II. The use of penicillin/aminoglycoside to treat member of this genus is endocarditis due to Streptococci Group D A. Pseudomonas aeruginosa. represents a B. Sarcina lutea. A. Broad spectrum susceptibility. C. Serratia marcescens. B. Multi-drug resistance. D. Staphylococcus a ureus. C. "Shotgun" approach. D. Synergistic relationship. 5. Which characteristic is most useful in differentiating Citrobacter and Salmone/ld? 12. Characteristics indicating an appropriate A. H2S production sputum collection would be microscopic B. Indole production findings of C. Lysine decarboxylase A. > 25 epithelial cells,> 25 white cells. D. Urease production B. > 25 epithelial cells,< 25 white cells. C. 10-25 epithelial cells, 10-25 white cells. 6. A gram stain from a sputum specimen D. < 10 epithelial cells, 10-25 white cells. demonstrates many gram positive cocci in chains and pairs. Numerous small alpha 13. A clean catch urine specimen from a female streptococci are observed on the primary with a suspected UTI showed gram positive blood agar plate. To determine if these cocci that were catalase positive, coagulase organisms are Streptococcus pneumoniae negative and Staph latex negative. On the which of the following tests should be Microscan panel, growth in the novobiocin performed? well was noted. The most likely organism is A. Bacitracin susceptibility A. Staphylococcus aureus. B. Catalase B. Staphylococcus epidermi.dis. C. Esculin hydrolysis C. Staphylococcus saprophyticus. D. Optochin susceptibility D. Enterococcus fecalis. 170 14. The treatment of choice for methicillin 21. A scotochromogenic mycobacterium resistant Staphylococcus is showing hydrolysis of Tween 80 in 7 days is A. Cephalothin. probably B. Nafcillin. A. M. avium. C. Oxacillin. B. M. fortuitum. D. Vancomycin. C. M. gordonae. D. M. marinum. 15. The most likely cause of subacute bacterial endocarditis is 22. A gram negative rod, isolated from the urine of A. Staphylococcus aureus. a female with recurrent UTI, was oxidase B. Staphylococcus epidermidis. negative, urease positive showing NA with C. Streptococcus Group A. H2S on TSI and red/black on LIA is most likely D. Streptococcus viridans. A. Escherichia coli. B. Klebsiella pneumoniae. 16. The organism known for its "stormy C. Proteus mirabilis. fermentation" and double zone of beta D. Pseudomonas aerugi.nosa. hemolysis under anaerobic conditions causes A. Botulism. 23. An organism recovered from a diarrheal stool B. Gas gangrene. was K/A w ith no gas or H2S on TSI, lysine C. Pseudomembraneous colitis. negative, oxidase negative, urease negative D. Tetanus. and citrate negative. The most likely organism is 17. The bacteremic Waterhouse-Friderichsen A. Aeromonas hydrophila. syndrome is associated with B. Escherichia coli. A. Corynebacterium jeikeium. C. Proteus vulgaris. B. Listeria monocytogenes. D. Shigella sonnei. C. Mycopla.sma pneumoniae. D. Neisseria meningitidis. 24. A cause of acute infectious infantile diarrhea is A. Hantavirus. 18. The specimen of choice in a case of B. HIV. suspected epiglottitis is collected from the C. Rhabdovirus. A. Blood. D. Rotovirus. B. Spinal fluid. C. Sputum. 25. Specimens for viral culture should be D. Throat. transported in A. Anaerobic containers. 19. A specimen from a female complaining of B. Bovine albumin (22%). vaginitis emitted a "fishy" odor when mixed C. Nutrient medium with antihiotics. with 10% KOH. A wet prep showed some D. Sheep blood (5-10%). white cells and epithelial cells covered with small gram variable rods. The most likely organism is A. Chlamydia trachomatis. B. Gardm~rella vaginalis. C. Neisseria gonorrhoeae. D. Treponema pallidum. 20. A photochromogenic mycobacterium isolated at 30 C is most likely A. M. gordonae. B. M. marinum. C. M. ulceran s. D. M. xenopi.  171 ANSWERS AND RATIONALE 1. D 8. B Though options B and C may cause diarrhea, Autoclave sterilization requires 15 psi, at only V. cholera causes the characteristic "rice 121 °C for 15 min. water stool". Option A may cause infant botulism which is characterized by 2-3 days of 9. C constipation followed by flaccid paralysis. Demonstration of Negri bodies (cytoplasmic 2. C inclusion bodies) in brain tissue is the hallmark of rabies diagnosis. Option A is not seen in Pseudomonas aeruginosa is the only oxidase viruses. Option B is associated with measles positive organism listed. virus. Option D is seen in electron micrographs of many viruses and bacteria. 3. A 10. C Option B is a virus not visible on a gram stain. Option C are gram negative diplococci. Campylobacter jejuni is oxidase positive, Option D is a spirochete that causes a hard motile, catalase positive and grows optimally at chancre. 42 C. 4. C ll. D The only organism listed which produces a These drugs in combination enhance red pigment is Serratia. Options B and D are bactericidal activity. COCCI. 12. D 5. C Greater than 10 epithelial cells indicates the The classic biochemical reaction which specimen is heavily contaminated with oral flora. separates these two genera is lysine. The other biochemical reactions can he variable. 13. C 6. D S. saprophyticus is resistant to novobiocin and can cause urinary tract infections. Optochin susceptibility separates Streptococcus pneumoniae from the other 14. D Streptococci. Option A is a characteristic of Vancomycin is the drug of choice for Streptococcus pyogenes. Option B separates Staphylococcus (catalase positive) from methicillin resistant Staphylococci. Streptococcus (ca talase negative). Group D 15. D Streptococcus are positive with option C (esculin hydrolysis). Streptococcus viridans is most commonly associated with suhacute bacterial endocarditis. 7. B 16. B Microscopic morphology is best demonslraLed on Loeffler 's medium though cystine-tellurite Clostridium perfringens is the cause of gas agar is also used ( C. diphtl1eriae colonies gangrene and is noted for its stormy demonstrate a grey-to-black color on this media). fermentation and double zone of beta hemolysis. Option A is seen on Bordet-Gengou media. Option A is caused by C. hotulinum and is Option C is associated with Lowenstein Jensen diagnosed by demonstration of botulism toxin. media. Option D grows well on blood agar. Option C is caused by C. difficile which grows on CCFA agar. Option D is caused by C. tetani and is identified by its "racquet' or "drumstick" shaped terminal endospores. 172 17. D Overwhelming DIC (due to large amounts of endotoxin) with shock and destruction of adrenal glands is caused by N. meningitidis. 18. A Options B and C are not r elated to the diagnosis. Collecting a throat culture (op tion D) could cause the airway to close. 19. B Gard11erella is associated with the haractcristic "fishy" odor when vaginal discharge is mixed with KOH. Option A is diagnosed by EIA, DNA probes or FA. Option C are gram negative cocci. Option D is a spirochete seen with darkfield microscopy. 20. B Option A is a scotochromagen. Option C grows at 30°C but is a non-photochromagen. Option Dis a scotochr omagen and gr ows best at 37°C. 21. C Option A is a non-photochromogen and does not show hydrolysis of Tween 30. Option Bis a rapid grower and does not show hydr olysis of Tween 80. Option ID is a photochromogen which hydrolysis Tween 80 in less than 5 days. 22. C Options A and B are H2S negative and deaminase negative. Option D is K/K on TSI and oxidase positive 23. D Option A is oxidase positive. Option B is AJA on TSI and indole positive. Option C is H2S positive and urease positive 24. D Option A causes hemmorrhagic fever. Option B causes AIDS. Option C causes rabies. 25. C Media for transporting specimens for vir al culture are similar to bacterial transport media but must contain additional nutrients such as albumin or fetal calf serum and antibiotics ( to prevent bacterial growth).