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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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Item Value
Available Stat? No
Test code THRC
Performed by? Microbiology (Bacteriology)
Sendout? no
Price range $$
In House Availability 7 days
Principle The organism sought must be indicated on the requisition so that proper selective media are set up. If this is not done, throats will be cultured for group A streptococci only.

Specimen is inoculated to media appropriate for the recovery of the specified organism and incubated for a minimum of 48 hours. All routine throat cultures are screened for group A streptococci as well as the specified request.
Interpretation Microorganisms that cause disease in the upper respiratory tract, the nasopharynx, and the pharynx must first come into contact with the mucosal epithelium, adhere to the epithelium, and multiply locally. Organisms such as N. meningitidis, C. diphtheriae, and many viruses are carried in with small droplets as aerosols. They may be present in secretions from colonized or infected persons and transmitted either by hands touching objects, or from person to person through aerosols in crowded conditions. Although a large number of different bacteria and fungi may be isolated from specimens taken from the upper respiratory tract, very few organisms have been shown to cause disease there.
Collection Instructions A single throat culture may be obtained before treatment of suspected bacterial pharyngitis, or a rapid test for group A streptococcal antigen may be done.

A Gram-stained scraping may be the fastest way to diagnose fuso-spirochaetal disease or thrush (caused by Candida). Request examination for these agents and send a smear.
Special instructions Throats are cultured for group A streptococci only, unless other specific organisms are requested. Indicate other organisms to be cultured, e.g., Haemophilus influenzae, Neisseria gonorrhoeae, Arcanobacterium (Corynebacterium) haemolyticum or Corynebacterium diphtheriae, by checking the "other" box and writing the name of the specific organism on the Microbiology requisition.
Synonyms Throat Culture;
Stability Keep transport medium at room temperature until the next messenger pick up. Blood, chocolate and Thayer Martin agars should be incubated in a candle jar immediately after inoculation.
Additional information Since group B strep rarely cause tonsillitis or pharyngitis, screening for group B strep will not be done on throat specimens.
References 1. Forbes BA, et al. Bailey and Scott's Diagnostic Microbiology, 11th Ed. Mosby, St. Louis MO, 2002.

2. Murray PR, et al. Manual of Clinical Microbiology, 9th Ed., ASM Press, Washington DC, 2007.

CPT coding 87070
Last Updated 8/19/2009 1:19:13 PM
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