[A study of the bacteriophage-based assay for the detection of pyrazinamide resistance in Mycobacterium tuberculosis].
OBJECTIVE
To set up and evaluate the method of phage amplified biologically assay (PhaB) in rapid detection of pyrazinamide (PZA) resistance.


METHODS
The PhaB assay was developed and applied in detecting PZA resistance in 108 clinical isolates of Mycobacterium tuberculosis and the results were compared with those of the absolute concentration method. The minimum inhibitory concentration (MIC) was detected for all discrepancy isolates.


RESULTS
The results showed that the optimal detecting condition was pH 5.5, PZA 200 microg/ml and 48 h. Of the 108 strains of Mycobacterium tuberculosis, 28 strains were PZA-susceptible and 80 strains were PZA-resistant detected by PhaB; while 32 strains were PZA-susceptible and 76 strains were PZA-resistant by absolute concentration method. Twenty-eight of the 108 strains were PZA-susceptible and 71 were PZA-resistant by the two methods. The concordant isolates of determination of PZA resistance were 99 by the two methods and the concordance rates was 91.7%. There were 9 strains in discordant isolates, of which 7 were the same with MIC method and gene chip in drug susceptibility. If the results of absolute concentration method was the gold standard, the sensitivity, specificity, positive and negative predictive values, as well as accuracy of PhaB assay was 94.7%, 84.8%, 93.4%, 87.5% and 91.7% respectively.


CONCLUSIONS
The PhaB assay can be used as a rapid screening method for detection of drug susceptibility of PZA in clinical isolates of Mycobacterium tuberculosis.
Ao
Jun-ping
JP
The Tuberculosis Key Laboratory of Shanghai, The Pulmonary Hospital of Shanghai, Shanghai 200433, China.
Chen
Ji-wu
JW
Hu
Zhong-yi
ZY
Li
Jian-nong
JN
Wang
Jie
J
Wang
Qing
Q
Cui
Zhen-ling
ZL
Zhang
Wen-hong
WH
Wong
Xin-hua
XH
D000995:Antitubercular Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D008826:Microbial Sensitivity Tests; D009160:Mycobacteriophages; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification / Q000821:virology; D011718:Pyrazinamide / Q000494:pharmacology*
D000995:Antitubercular Agents; D011718:Pyrazinamide