Medical Laboratory Technician Clinical Microbiology 1 Flashcards
6 cards from real Medical Laboratory Technician Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Medical Laboratory Technician Clinical Microbiology 1 flashcards as text
A wound culture from a diabetic foot ulcer grows a Gram-positive coccus in clusters that tests positive for coagulase. The isolate is resistant to oxacillin. What is the most appropriate identification?
Answer: Methicillin-resistant Staphylococcus aureus (MRSA)
Coagulase-positive Gram-positive cocci in clusters are Staphylococcus aureus. Oxacillin resistance defines MRSA, which is clinically significant and requires contact precautions and specific antibiotic management.
A CSF specimen from a patient with meningitis is sent for fungal culture. After 5 days at 30°C, a mucoid, cream-colored colony appears. India ink preparation reveals encapsulated yeast cells. What is the most likely organism?
Answer: Cryptococcus neoformans
Cryptococcus neoformans produces a characteristic polysaccharide capsule visible as a clear halo around yeast cells with India ink stain. It is the leading cause of fungal meningitis, especially in immunocompromised patients.
A stool culture is plated on Hektoen enteric (HE) agar. After 24 hours, blue-green colonies with black centers are observed. Which organism is most likely responsible?
Answer: Salmonella typhimurium
Salmonella species produce blue-green colonies with black centers on HE agar due to hydrogen sulfide (H2S) production. Shigella produces green colonies without black centers; E. coli and Klebsiella are inhibited or produce salmon-colored colonies.
A sputum culture from an immunocompromised patient grows a mold with septate hyphae that branch at 45-degree angles. Conidiophores bear chains of conidia from a single point. What is the most likely identification?
Answer: Aspergillus fumigatus
Aspergillus fumigatus produces septate hyphae with characteristic 45-degree branching. Its conidiophores terminate in a flask-shaped vesicle bearing phialides that produce chains of conidia. Rhizopus and Mucor have non-septate (coenocytic) hyphae.
A throat swab from a patient with pharyngitis is plated on sheep blood agar. After 24 hours, a beta-hemolytic colony is observed. The isolate is catalase-negative, PYR-positive, and bacitracin-susceptible. What is the most likely organism?
Answer: Streptococcus pyogenes (Group A)
Streptococcus pyogenes (Group A Strep) is characteristically beta-hemolytic, catalase-negative, PYR-positive, and susceptible to bacitracin (A disc). Group B Strep is bacitracin-resistant, and Enterococcus is PYR-positive but not beta-hemolytic on sheep blood agar.
A technician receives a vaginal swab and must culture for Neisseria gonorrhoeae. Which combination of media and incubation conditions is most appropriate?
Answer: Thayer-Martin agar at 35-37°C in 5% CO2
Neisseria gonorrhoeae requires enriched, selective media. Thayer-Martin agar contains vancomycin, colistin, and nystatin to suppress normal flora while supporting gonococcal growth. Incubation at 35-37°C with 5% CO2 (capnophilic conditions) is essential for primary isolation.