title: Evaluation of a novel biphasic culture medium for recovery of mycobacteria: a multi-center study.
abstract: BACKGROUND
  Mycobacterial culture and identification provide a definitive diagnosis of TB. Culture on Löwenstein-Jensen (L-J) medium is invariably delayed because of the slow growth of M. tuberculosis on L-J slants. Automated liquid culture systems are expensive. A low-cost culturing medium capable of rapidly indicating the presence of mycobacteria is needed. The aim of this study was to develop and evaluate a novel biphasic culture medium for the recovery of mycobacteria from clinical sputum specimens from suspected pulmonary tuberculosis patients.
  
  
  RESULTS
  The biphasic medium consisted of 7 ml units of L-J slant medium, 3 ml units of liquid culture medium, growth indicator and a mixture of antimicrobial agents. The decontamination sediments of sputum specimens were incubated in the biphasic culture medium at 37°C. Mycobacterial growth was determined based on the appearance of red granule sediments and the examination using acid-fast bacilli (AFB). The clinical sputum specimens were cultured in the biphasic medium, on L-J slants and in the Bactec MGIT 960 culture system. Among smear-positive specimens, the mycobacteria recovery rate of the biphasic medium was higher than that of the L-J slants (P<0.001) and similar to that of MGIT 960 (P>0.05). Among smear-negative specimens, the mycobacterial recovery rate of the biphasic medium was higher than that of L-J slants (P<0.001) and lower than that of MGIT 960 (P<0.05). The median times to detection of mycobacteria were 14 days, 20 days and 30 days for cultures grown in MGIT, in biphasic medium, on L-J slants for smear negative specimens, respectively (P<0.001).
  
  
  CONCLUSIONS
  The biphasic culture medium developed in this study is low-cost and suitable for mycobacterial recovery. It does not require any expensive detection instrumentation, decreases the time required for detection of M. tuberculosis complex, and increases the detection rate of M. tuberculosis complex.
authors.affiliation: Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Medical School, Tongji University, Shanghai, China.
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Cui
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Changtai
authors.initials: C
authors.lastname: Zhu
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Huang
authors.forename: Junmei
authors.initials: J
authors.lastname: Lu
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
authors.forename: Zhongnan
authors.initials: Z
authors.lastname: Chen
authors.forename: Junling
authors.initials: J
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Delin
authors.initials: D
authors.lastname: Gu
authors.forename: Lingjie
authors.initials: L
authors.lastname: Jing
authors.forename: Jin
authors.initials: J
authors.lastname: Chen
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Zheng
authors.forename: Lianhua
authors.initials: L
authors.lastname: Qin
authors.forename: Hua
authors.initials: H
authors.lastname: Yang
authors.forename: Ruiliang
authors.initials: R
authors.lastname: Jin
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Liu
authors.forename: Aixiao
authors.initials: A
authors.lastname: Bi
authors.forename: Jinming
authors.initials: J
authors.lastname: Liu
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Hu
mesh_terms: D003470:Culture Media / Q000737:chemistry*; D046508:Culture Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000254:growth & development* / Q000302:isolation & purification*; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000382:microbiology
chemical_list: D003470:Culture Media