UAMS MICROBIOLOGY EXAM 4
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTION (GRADED A+)
Microbiology: Specimen Staining & CSF Subculture Protocols
Which clinical specimen sources and tests are considered clinically inappropriate
for Gram stain examination?
✔✔ Throat, vaginal, or rectal specimens for Neisseria gonorrhoeae (GC) (due to
normal flora cross-reactivity and low sensitivity/specificity compared to NAAT).
✔✔ Throat swabs for Group A Streptococcus (GAS) (Gram stain cannot
differentiate S. pyogenes from normal oral streptococcal flora).
✔✔ Routine stool specimens (Gram stains are generally not performed on routine
stool cultures; exceptions include staining specifically for fecal leukocytes,
Staphylococcus aureus, or Campylobacter morphology).
What is the mechanism and clinical application of the Acridine Orange (AO) stain?
✔✔ Mechanism: A fluorochrome dye that binds to nucleic acids (DNA and RNA)
of both living and dead cells.
✔✔ Target Organisms: Visualizes bacteria and yeast under UV/fluorescent
microscopy, especially in specimens with low microbial loads or high debris where
standard Gram stains are difficult to interpret (e.g., blood culture bottles, thick
fluids).
What plates do we subculture CSF?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC, Thio
,-37°C in CO2
What are common CSF pathogens? -ANSWER✔✔-H. influenzae
-S. pneumoniae
-N. meningitidis
-GBS
-Listeria
-CNS
What is CSF rhinorrhea? -ANSWER✔✔CSF leaking through nasal passage due to
blunt trauma, skull fracture or a tumor
What plates do we subculture abscess's and wound cultures?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC,
MAC/EMB, CNA/PEA
-anaerobic if requested
-37°C in CO2
***Pus is the best specimen***
What are common abscess and wound culture pathogens? -ANSWER✔✔-Staph
Aureus
-GAS
-Enterics
-Anaerobes
-PSAR
-Enterococci
, What plates do we subculture stool?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, MAC/EMB,
HE/SS/XLD, GN broth
-37°C in air
Special stool culture plates -ANSWER✔✔CampyBAP, CIN, TCBS, SMAC
What plates do we subculture genital specimens?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, MTM
-37°C in CO2
-Gram stain genital specimens and look for the following; clue cells, gram negative
diplococci, yeast
What plates do we subculture sinus specimens?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC, broth,
anaerobic media
-37°C in CO2
What are common sinus pathogens? -ANSWER✔✔-S. pneumoniae
-M. catarrhalis
-H. influenzae
What plates do we subculture otitis media specimens?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC, broth,
anaerobic media
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTION (GRADED A+)
Microbiology: Specimen Staining & CSF Subculture Protocols
Which clinical specimen sources and tests are considered clinically inappropriate
for Gram stain examination?
✔✔ Throat, vaginal, or rectal specimens for Neisseria gonorrhoeae (GC) (due to
normal flora cross-reactivity and low sensitivity/specificity compared to NAAT).
✔✔ Throat swabs for Group A Streptococcus (GAS) (Gram stain cannot
differentiate S. pyogenes from normal oral streptococcal flora).
✔✔ Routine stool specimens (Gram stains are generally not performed on routine
stool cultures; exceptions include staining specifically for fecal leukocytes,
Staphylococcus aureus, or Campylobacter morphology).
What is the mechanism and clinical application of the Acridine Orange (AO) stain?
✔✔ Mechanism: A fluorochrome dye that binds to nucleic acids (DNA and RNA)
of both living and dead cells.
✔✔ Target Organisms: Visualizes bacteria and yeast under UV/fluorescent
microscopy, especially in specimens with low microbial loads or high debris where
standard Gram stains are difficult to interpret (e.g., blood culture bottles, thick
fluids).
What plates do we subculture CSF?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC, Thio
,-37°C in CO2
What are common CSF pathogens? -ANSWER✔✔-H. influenzae
-S. pneumoniae
-N. meningitidis
-GBS
-Listeria
-CNS
What is CSF rhinorrhea? -ANSWER✔✔CSF leaking through nasal passage due to
blunt trauma, skull fracture or a tumor
What plates do we subculture abscess's and wound cultures?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC,
MAC/EMB, CNA/PEA
-anaerobic if requested
-37°C in CO2
***Pus is the best specimen***
What are common abscess and wound culture pathogens? -ANSWER✔✔-Staph
Aureus
-GAS
-Enterics
-Anaerobes
-PSAR
-Enterococci
, What plates do we subculture stool?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, MAC/EMB,
HE/SS/XLD, GN broth
-37°C in air
Special stool culture plates -ANSWER✔✔CampyBAP, CIN, TCBS, SMAC
What plates do we subculture genital specimens?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, MTM
-37°C in CO2
-Gram stain genital specimens and look for the following; clue cells, gram negative
diplococci, yeast
What plates do we subculture sinus specimens?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC, broth,
anaerobic media
-37°C in CO2
What are common sinus pathogens? -ANSWER✔✔-S. pneumoniae
-M. catarrhalis
-H. influenzae
What plates do we subculture otitis media specimens?
What temperature and atmosphere is needed? -ANSWER✔✔-BAP, CHOC, broth,
anaerobic media
