Quick Review Cards for Medical Laboratory Science

Routine Culture Setup and Interpretation Clinical Microbiology Review 219

SPECIMEN MEDIA NORMAL FLORA COMMON PATHOGENS OTHER

Throat/nasopharynx

Sputum, bronchial
washings/aspirates,
transtracheal
aspirates

Urine

Stab streaking to detect beta

strep that only produce strep-

tolysin O. Direct antigen

tests for GAS. Negs should

be cultured.

Gram stain. Acceptable spu-

tum: <10 epithelial cells/LPF,

>25 polys/LPF. Note: Neu-

tropenic patients may not

produce polys.

Rapid screen for UTI: 1 or

more bacteria/OI field on

Gram stain of uncentrifuged

urine. Interpretive guidelines

vary. Low counts are signifi-

cant in catheterized urines &

aspirates. 3 or more organisms

with none predominant =

probable contamination.

Alpha & gamma strep,

commensal Neisseria,

CNS, diphtheroids,

S. pneumoniae,

Candida

CNS, non–beta-

hemolytic strep,

diphtheroids, com-

mensal Neisseria,

Haemophilus, yeast.

Aspirates: none

Clean catch: few skin

flora. Catheterized or

aspirate: none

SBA, CHOC.

Streptococcus-

selective agar

may be used

SBA, CHOC, MAC

SBA, MAC. Use

0.01-mL or 0.001-mL

calibrated loop

GAS (S. pyogenes)

S. pneumoniae, H. influenzae,

S. aureus, Enterobacteriaceae,

Pseudomonas, M. catarrhalis,

C. albicans

E. coli, Klebsiella, Enterobacter,

Proteus, Enterococcus,

Pseudomonas, S. aureus,

S. saprophyticus, CNS, GBS

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