Specimen Type/Requirements

Tests CANNOT be performed on mixed cultures. Only pure cultures of the organism being tested will yield valid results.

TYPE OF SUSCEPTIBILITY TESTING:
MIC (minimum inhibitory concentration): quantitative microdilution procedure or by E test agar dilution.

GENERAL GUIDELINES FOR WHEN SUSCEPTIBILITY TESTING IS DONE:

(1) Susceptibilities will be performed on potential pathogens.
(2) Susceptibilities will be performed on organisms isolated from a normally sterile body site.
(3) Susceptibilities will be performed on isolates from a urine if the colony count on that organism is greater than or equal to 100,000 col/mL.
(4) The physician may request susceptibilities on any organism isolated.

WHEN SUSCEPTIBILITY TESTING IS NOT DONE:
(1) No susceptibilities are performed on any beta hemolytic streptococcus isolated from a respiratory source, i.e., throat, sputum, etc.
(2) No susceptibilities will be performed on any organism considered to be normal flora of that particular area (skin, respiratory, oral, genital or GI).
(3) No susceptibilities will be performed when the physician requests a culture without susceptibilities.

Microbiology Specimen Collection Guidelines