Microbiology Techniques Flashcards
6 cards from real Laboratory Science practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Microbiology Techniques flashcards as text
Which culture medium is used for isolating Neisseria gonorrhoeae from clinical specimens?
Answer: Thayer-Martin (modified) agar
Thayer-Martin agar is a selective medium containing antibiotics (vancomycin, colistin, nystatin) that suppress normal flora while allowing N. gonorrhoeae to grow.
What is the significance of a 'satellite phenomenon' around Staphylococcus aureus on blood agar?
Answer: Suggests Haemophilus influenzae growth due to V-factor (NAD) provision
H. influenzae requires both X-factor (hemin) and V-factor (NAD); S. aureus provides V-factor, causing H. influenzae to grow as satellite colonies around the staph colonies.
Which rapid test is used for presumptive identification of group A streptococcal pharyngitis in the lab?
Answer: Lateral flow immunoassay antigen detection (rapid strep test)
Rapid strep tests use lateral flow immunoassay to detect Group A Strep carbohydrate antigen directly from throat swabs in minutes, guiding immediate treatment decisions.
What does a zone of inhibition in a Kirby-Bauer disk diffusion test represent?
Answer: Area where antibiotic has diffused and inhibited bacterial growth
In Kirby-Bauer testing, antibiotics diffuse outward from disks; the zone of inhibition (no growth) diameter is compared to CLSI breakpoints to determine susceptibility (S/I/R).
Which organism is identified by a positive urease test, H. pylori grows on what type of agar?
Answer: Skirrow or Columbia blood agar with antibiotics at microaerophilic conditions
H. pylori is microaerophilic and grows on Columbia blood agar or Skirrow's agar at 35–37°C in 5–10% CO₂ with reduced O₂ (microaerophilic atmosphere).
What is the triple sugar iron (TSI) agar test used for in bacteriology?
Answer: Determining Enterobacteriaceae sugar fermentation and H₂S production patterns
TSI agar detects fermentation of glucose, lactose, and sucrose (with acid/gas production) and H₂S production, generating patterns that help identify Enterobacteriaceae species.