Evaluation of Mycobacterial Recovery by Specimen Preparation and Inoculating Media

Jeong, Joseph; Chang, Chulhun L

Abstract

BACKGROUND: During the specimen preparation, neutralization after alkali processing is not necessary when inoculate into agar or broth media, but into 3% Ogawa media, the mostly used egg-based media in Korea. To simplify the specimen processing, the recovery of mycobacteria from 3% Ogawa media inoculating differently processed sputa, was evaluated. Futhermore, the recovery from the three different media was evaluated, too.
METHODS
209 sputa were included. Each specimen was divided into 3 bottles.(A) One was only decontaminated by 4% NaOH before inoculation.(B) Another was decontaminated, and concentrated without neutralization. These two specimens were inoculated into 3% Ogawa media.(C) The other was decontaminated, neutralized and concentrated, and innoculated into 3% Ogawa, Middlebrook 7H9 selective broth and 7H10 selective agar media. The isolates were identified by AccuProbe method.
RESULTS
M. tuberculosis were isolated from 43(20.5%) specimens. The recovery number and time from Ogawa media, inoculating specimens processed by A, B, and C method, were 29(13.9%), 35(16.7%), and 36(17.2%), and 23, 23, and 19 days, respectively. The recovery number and time from Ogawa, 7H10 agar and 7H9 broth media, inoculating specimens processed by C method, were 36(17.2%), 42(20.1%), and 41(19.6%), and 26, 24, and 22 days, respectively.
CONCLUSIONS
Neutralization of alkali-decontaminated specimens could be used to inoculate into 3% Ogawa media. Inoculation into homemade 7H10 agar and 7H9 broth media in addition to 3% Ogawa media improved the recovery rate and time of mycobacteria.