Microbiology BOC quiz with COMPLETE solutions

Microbiology BOC Proper media for culture of a urethral discharge from a man include: 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 ANSWERS d chocolate and modified Thayer-Martin agars d Chocolate agar and chocolate agar- based selective media should be used for recovery of Neisseria gonorrhoeae from urethral discharge. Chocolate agar provides the nutrients required by N gonorrhoeae and selective media contains antimicrobial agents that inhibits other organisms and permits recovery of pathogenic Neisseria. A sheep blood agar plate inoculated with 0.001mL of urine grows 70 colonies of Staphylococcus aureus. How many colony forming units per mL of urine be reported? a 70 b 700 c 7,000 d 70,000 ANSWERS d 70,000 d When 0.001 mL of urine is plated, the growth of one colony is equivalent to 1000 CFU/mL. Thus 70 colonies is 70,000 CFU/mL. The lowest concentration of antibiotic that inhibits growth of a test that inhibits growth of a test organism is the: a minimum inhibitory concentration b serum inhibitory concentration c minimum bactericidal titer d maximum inhibitory titer ANSWERS a minimum inhibitory concentration a The MIC is a basic laboratory measurement of the activity of an antibiotic against an organism. It is the lowest concentration of antibiotic that inhibits visible growth of the organism. It does not represent the concentration of antibiotic that is lethal to the organism. Which of the following clean catch urine culture colony counts indicates the patient likely has a urinary tract infection? a 10^1 CFU/mL b 10^3 CFU/mL c 10^5 CFU/mL d no growth ANSWERS b 10^3 CFU/mL b Patients with infection often have at least 100,000 bacteria/mL of urine in the bladder. However one third of young women with symptomatic cystitis have less than 100,000 bacteria/mL of urine. The Infectious Disease Society of America consensus definition of cystitis is greater than or equal to 1,000 CFU/mL of a uropathogen. The steam autoclave method of sterilization: a uses 15 lbs of pressure for 15 minutes