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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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MYCOBACTERIA CULTURE, SPUTUM

Item Value
Available Stat? No
Test code AFBR
Performed by? Microbiology (AFB)
Sendout? no
Price range $$$
In House Availability 7 days
Principle Respiratory specimens submitted for mycobacterial culture are almost always contaminated with normal host microbiota. Contaminated specimens require a digestion-decontamination step and concentration in order to maximize recovery of mycobacteria. An AFB smear is performed on the concentrated sediment. The sediment is inoculated into AFB culture media and incubated for up to 8 weeks. Negative cultures are finalized after 8 weeks. Positive cultures are reported as soon as AFB are recovered.
Patient Preparation The recommended specimen is an expectorated sputum specimen collected first thing in the morning. Inform the patient that sputum comes from deep in the chest not just from the mouth.
Container type sterile, screw-capped container
Amount to Collect 5 - 10 mL
Collection Instructions The mouth should be rinsed with clear water and the first morning specimen collected in sterile screw-capped containers. Three separate specimens should be obtained from different days, since mycobacteria are not uniformly present in sputa from patients with tuberculosis.
Sample type Sputum
Min. Volume 5 mL
Special instructions Specimens that contain food, vomitus, toothpaste, or consist entirely of saliva are not satisfactory for concentration and culture. Label specimens with date and time collected.
Stability Deliver to Microbiology Laboratory (2M33) immediately or hold at 4°C until delivery to avoid overgrowth of contaminating indigenous bacteria.
Causes for rejection Only one expectorated sputum specimen per day will be accepted and tested for each patient.

For ICU patients with endotracheal tubes, one tracheal aspirate per 8 hours will be accepted and tested.

Once three AFB smear positive sputum specimens have been tested for a patient, only one AFB smear positive sputum per week will be accepted for that patient.
References Kent, PT and GP Kubica. 1985. Public Health Mycobacteria: A Guide for the Level III Laboratory. U.S. Department of Health and Human Services. CDC. Atlanta GA.
CPT coding 87206
Last Updated 9/10/2009 4:01:25 PM
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