QUANTITATION OF MYCOBACTERIA IN BLOOD SPECIMENS FROM PATIENTS WITH AIDS

Objective: To determine the effect of a delay in processing blood spec imens, that may occur by mailing them to a specialized laboratory, on the quantitation of the number of mycobacteria. Design: Simulated bloo d specimens in sodium polyanetholium sulfonate (SPS)-containing vacuta iners were spiked with Mycobacterium avium, and stored for 4 days afte r addition of clarithromycin or rifabutin, or remained drug-free. Dail y samples were lysed with sodium desoxycholate, and inoculated onto 7H 11 agar plates for the subsequent colony-forming units (CFU)/ml count. The isolation rates on two media, 7H11 agar and BACTEC 12B broth, wer e determined with 1212 specimens from AIDS patients. Results: The numb er of bacteria in blood specimens remained without substantial change during the period of storage, even in the presence of clarithromycin o r rifabutin, especially after refrigeration for 2 or 24 h before stora ge. 7H11 agar and 12B broth were equally sensitive for isolation of M. avium. Conclusions: A 4-day delay in processing blood specimens in SP S vacutainers does not affect the results of quantitation of the numbe r of mycobacteria. Combined use of 12B broth and 7H11 agar increased t he overall recovery along with an opportunity to quantitate the number of CFU/ml.