Preanalytical Procedures

Question 1

Specimens acceptable for anaerobic cultures

Answer 1

Bile, blood, body fluids, bone marrow, percutaneous lung aspirate/biopsy, suprapubic bladder aspirates, tissue, trans-tracheal aspirate, and deep wounds

Question 2

Specimens not acceptable for anaerobic cultures

Answer 2

Expectorated sputum, feces, gastric juice, swabs, voided or catheterized urine, and bronchial washings (unless obtained with a double-lumen plugged catheter)

Question 3

Throat/nasopharynx culture set up and interpretation

Answer 3

Plated on BAP and CHOC agar
Normal flora are alpha and gamma strep, commensal Neisseria, CNS, diphtheroids, S. pneumoniae, and Candida
Common pathogens are S. pyogenes (Group A beta strep)
Streak for isolation and stab BAP for the detection of streptolysin O

Question 4

Sputum, bronchial washings/aspirates, trans-tracheal aspirates culture set up and interpretation

Answer 4

Plated on BAP, CHOC, and MAC
Normal flora are CNS, non-beta hemolytic strep, diphtheroids, commensal Neisseria, Haemophilus, and yeast
Aspirates should not have any normal flora
Common pathogens are S. pneumoniae, H. influenzae, S. aureus, Enterobacteriaceae, Pseudomonas, M. catarrhalis, and C. albicans
Gram stain determines if specimen is “acceptable” or “spit” - should have >25 polys/LPF and <10 epis/LPF

Question 5

Urine culture set up and interpretation

Answer 5

Plated on BAP and MAC
Clean catch urine normal flora includes few skin flora
Catheterized or aspirated urines should have no normal flora
Common pathogens are E. coli, Klebsiella, Enterobacter, Proteus, Enterococcus, Pseudomonas, S. aureus, S. saprophyticus, CNS, and Group B beta strep
BAP is streaked for colony count using a 1 ul calibrated loop
MAC is streaked for isolation
Cultures should be worked up if there are >10 colonies and <3 colony types (>3 colony types indicates contamination and <10 colonies is insignificant)