UAMS MICROBIOLOGY EXAM 4
QUESTIONS ANSWERS WITH
COMPLETE SOLUTIONS ALREADY
PASSED!!!
What is considered the optimal time for collecting a urine specimen for
microbiological culture?
✔✔ The first early morning specimen
(This specimen is the most concentrated and has had the longest incubation time in
the bladder, maximizing the likelihood of detecting low-level bacteriuria).
What is the optimal time for collecting blood cultures from a patient?
✔✔ During a fever spike (or just prior to the onset of chills/rigors)
(Microorganism concentration in the bloodstream typically peaks just before or
during clinical temperature spikes).
What are two critical parameters required for appropriate specimen
collection containers in microbiology?
✔✔ 1. Sterile (to prevent introduction of external microbial contaminants)
✔✔ 2. Sealed tightly / Leak-proof (to prevent specimen loss, environmental
contamination, and biohazard exposure)
What are the three primary purposes of using specimen transport media?
✔✔ 1. Prevent drying (desiccation) of the specimen.
✔✔ 2. Buffered to avoid pH changes that could harm fastidious organisms.
✔✔ 3. Non-nutritive (designed to maintain organism viability without allowing
overgrowth or multiplication during transit).
What are common components for transport media?
,-Thioglycollate (reducing substance)
-Small amount of agar (reduces spillage, reduces oxygenation)
-Charcoal may be added
-Special transport media for anaerobes and urine
Which culture specimen should not be refrigerated?
CSF
Culture specimens should be collected before the use of _______________.
Antibiotics
List some specimen types for culture that are routinely gram stained.
-Wounds
-Sputum
-Urethra (GC)
-Normally sterile body fluids
What do squamous epithelial cells indicate on a gram stain?
Contamination from the skin surface or that the specimen is saliva and not sputum
What indicates a good quality specimen on the gram stain?
,-All PMN's
-No squamous epi's
What indicates a poor quality specimen on the gram stain?
-No PMN's
-All squamous epi's
What objective should be used to enumerate WBC's and epi's on gram stain?
10x
What objective should be used to enumerate microorganisms on gram stain?
100x
What culture specimens are considered inappropriate for gram staining?
-Throat/rectal for GC
-Throat for GAS
-Stool for enteric pathogens (OK for Staph/Campy/PMN's)
-Urine
In a blood culture gram stain, what can you presumptively ID GPCs in chains as?
Probable streptococci
, In a blood culture gram stain, what can you presumptively ID GPCs in clusters as?
Probable staphylococci
In a blood culture gram stain, what can you presumptively ID GNDC as?
Probable Neisseria
What type of processing is done on normally sterile body fluids for culture?
-STAT
-Centrifuge is sufficient quantity (concentrates organism)
-Inoculate media with sediment, or directly if grossly purulent
What minimum media are used for sterile body fluid cultures?
-BAP
-CHOC
-Broth
-Others may be used depending on site
What type of smears can be made for sterile body fluids?
-Cytospin
-Gram stain
QUESTIONS ANSWERS WITH
COMPLETE SOLUTIONS ALREADY
PASSED!!!
What is considered the optimal time for collecting a urine specimen for
microbiological culture?
✔✔ The first early morning specimen
(This specimen is the most concentrated and has had the longest incubation time in
the bladder, maximizing the likelihood of detecting low-level bacteriuria).
What is the optimal time for collecting blood cultures from a patient?
✔✔ During a fever spike (or just prior to the onset of chills/rigors)
(Microorganism concentration in the bloodstream typically peaks just before or
during clinical temperature spikes).
What are two critical parameters required for appropriate specimen
collection containers in microbiology?
✔✔ 1. Sterile (to prevent introduction of external microbial contaminants)
✔✔ 2. Sealed tightly / Leak-proof (to prevent specimen loss, environmental
contamination, and biohazard exposure)
What are the three primary purposes of using specimen transport media?
✔✔ 1. Prevent drying (desiccation) of the specimen.
✔✔ 2. Buffered to avoid pH changes that could harm fastidious organisms.
✔✔ 3. Non-nutritive (designed to maintain organism viability without allowing
overgrowth or multiplication during transit).
What are common components for transport media?
,-Thioglycollate (reducing substance)
-Small amount of agar (reduces spillage, reduces oxygenation)
-Charcoal may be added
-Special transport media for anaerobes and urine
Which culture specimen should not be refrigerated?
CSF
Culture specimens should be collected before the use of _______________.
Antibiotics
List some specimen types for culture that are routinely gram stained.
-Wounds
-Sputum
-Urethra (GC)
-Normally sterile body fluids
What do squamous epithelial cells indicate on a gram stain?
Contamination from the skin surface or that the specimen is saliva and not sputum
What indicates a good quality specimen on the gram stain?
,-All PMN's
-No squamous epi's
What indicates a poor quality specimen on the gram stain?
-No PMN's
-All squamous epi's
What objective should be used to enumerate WBC's and epi's on gram stain?
10x
What objective should be used to enumerate microorganisms on gram stain?
100x
What culture specimens are considered inappropriate for gram staining?
-Throat/rectal for GC
-Throat for GAS
-Stool for enteric pathogens (OK for Staph/Campy/PMN's)
-Urine
In a blood culture gram stain, what can you presumptively ID GPCs in chains as?
Probable streptococci
, In a blood culture gram stain, what can you presumptively ID GPCs in clusters as?
Probable staphylococci
In a blood culture gram stain, what can you presumptively ID GNDC as?
Probable Neisseria
What type of processing is done on normally sterile body fluids for culture?
-STAT
-Centrifuge is sufficient quantity (concentrates organism)
-Inoculate media with sediment, or directly if grossly purulent
What minimum media are used for sterile body fluid cultures?
-BAP
-CHOC
-Broth
-Others may be used depending on site
What type of smears can be made for sterile body fluids?
-Cytospin
-Gram stain
