BOC Microbiology Practice Questions with Complete Solutions

BOC Microbiology Practice Questions with
Complete Solutions

In a nitrate reduction test, a positive result is indicated by a red color change. Which of the

following reagent(s) is (are) used in the reaction?


- Sulfanilic acid and alpha-naphthylamine


- Potassium hydroxide and alpha-naphthol


- o-Nitrophenyl-B-D-galactopyranoside


- Erlich's and Kovac's reagent Sulfanilic acid and alpha-naphthylamine




Which of the following would not be appropriate when collecting a urine for culture?


- The collected sample must be plated within 2 hours unless refrigerated


- The container must be sterile


- The sample may be held at 2C - 8C for up to 48 hours prior to plating


- The midstream void technique must be used The sample may be held at 2C - 8C for up

to 48 hours prior to plating

,A culture was ordered on pulmonary secretions from an 8-year-old cystic fibrosis patient who

had come down with pneumonia. Consider the following results from a pure culture of gram-

negative bacilli:


Oxidase = +, Motility = +, Glucose OF (open) = +, Gelatin hydrolysis = +, Growth at 42C = +,

Arginine dihydrolase = +, Pigment = red, non-fluorescent, Flagella = + with polar monotrichous


Which of the following organisms is most likely responsible for the pneumonia?


- Burkholderia (P.) pseudomallei


- Burkholderia (P.) cepacia


- Pseudomonas aeruginosa


- Pseudomonas stutzeri Pseudomonas aeruginosa




A vaginal swab was cultured using Thayer-Martin media. The colonies that grew stained as

gram-negative diplococci. Additional testing yielded the following results:


Catalase = +, Oxidase = +, Superoxol = -, Glucose = +, Lactose = +, Maltose = +, Sucrose = -,

Fructose = -


Which of the following is most likely present?


- No answer text provided


- Neisseria lactamica

,- Neisseria gonorrhoeae


- Neisseria sicca Neisseria lactamica




Blood cultures on a 5-day-old gave the following results:


Gram stain = gpc in chains, Beta hemolysis, CAMP test = +, Hippurate hydrolysis = -, Salt

tolerance = +, Bile solubility = -, Bile esculin = -, Bacitracin = resistant, PYR = -,

Trimethoprim/sulfamthoxazole = resistant


Which of the following is most likely present?


- Group B streptococci


- Group D streptococci


- Group A streptococci


- Nongroup A, nongroup B, nongroup D streptococci Group B streptococci




Which of the following is true regarding Streptococcus spp?


- Facultative anaerobe, oxidase-negative, catalase-negative


- Aerobic, oxidase-positive, and catalase-positive


- Facultative anaerobe, beta hemolytic, catalase-positive

, - May be alpha, beta, or gamma hemolytic, catalase-positive Facultative anaerobe,

oxidase-negative, catalase-negative




A swab from a diabetic ulcer is sent to the lab for culture and yields the following results:


Colony morph = creamy, pale yellow, B-hemolytic colonies on BAP, Catalase = +, Glucose OF =

open tube +, sealed tube -, Mannitol salt = - Slide coagulase = -


Which of the following is likely present?


- Micrococcus spp


- Staphylococcus epidermidis


- Staphylococcus aureus


- Streptococcus spp Micrococcus spp




An immunocompromised 55-year-old female patient undergoing chemotherapy treatment

received three units of packed RBCs. Three days later, the patient passed away and the results

from the autopsy listed septic shock as the cause of death. Cultures of the blood bags gave the

following results:


Growth on BAP and MAC = aerobic, gram-negative rods, Lactose = -, Sucrose = +, Citrate = -,

Indole = -, VP = -, H2S = -, Urease = +, Motility @ 22C = +, Motility @ 37C = -


Which of the following is most likely present?