10.3969/j.issn.2095-4344.2013.23.008

Objective To investigate status and risk factors of drug resistance of smear-positive pulmonary tuber-culosis (TB)patients in Hunan Province,and provide reference for the prevention and control of drug-resistant TB. Methods 1 935 Mycobacterium tuberculosis (MT)complex strains identified by 20 TB prevention and control insti-tutes in Hunan Province between 2012 and 2014 were collected and performed drug susceptibility testing,and influ-encing factors associated with drug resistance of TB were analyzed statistically.Results Of 1 935 MT complex strains,1 207 (62.38%)were sensitive to 6 kinds of antituberculosis drugs,728 were drug-resistant strains,overall drug resistance rate was 37.62%;467 (24.13%)were multidrug-resistant (MDR)strains,64 of which were exten-sively drug-resistant (XDR)strains,XDR rate was 3.31 %,resistance rates from high to low were as follows:isoniazid(INH)29.32%,rifampicin(RFP)25.84%,streptomycin(SM)20.73%,thambutol(EMB)9.00%,ofloxa-cin(OFX)7.83%,and kanamycin(KM)2.21 %.Multivariate logistic regression analysis showed that patients hav-ing a history of treatment,aged 20-39 and 40-60 years old were risk factors for drug resistance and MDR of pul-monary TB.Among patients who failed in retreatment,OR (95% CI )of resistance to INH,RFP,SM,EMB, OFX,KM,and MDR were 13.5(9.9-18.4),21 .2(15.2-29.5),5.3(3.9-7.2),11 .9(7.6-18.7),7.6(4.6-12.6),7.9(3.6-17.5),and 25.0(17.7-35.1 )respectively;among patients who had recurrence,OR(95% CI ) of resistance to INH,RFP,SM,EMB,OFX,and MDR were 7.4(5.5 -10.0),10.3 (7.4 -14.2),3.5 (2.5 -4.8),7.3(4.5 -11 .9),4.1 (2.5 -6.8),and 12.2(8.7 -17.1 )respectively;among patients who failed in initial treatment,OR (95% CI )of resistance to INH,RFP,SM,EMB,and MDR were 7.6 (4.7 - 12.3 ),9.8 (5.9 -16.0),4.1(2.5-6.8),12.1(6.5-22.7),and 11 .4(6.9-18.9)respectively.Among patients aged 20-39 years old,OR (95% CI )of resistance to INH,RFP,SM,and MDR were 2.5 (1 .8 -3.4),3.6(2.5 -5.2),2.9(2.0-4.1),and 4.1(2.8 -6.1 )respectively;among patients aged 40 -60 years old,the OR (95% CI )of resistance to INH,RFP,SM,and MDR were 2.2(1 .6-3.0),3.1(2.2-4.4),2.3(1 .6-3.2),and 3.3(2.3 -4.7)respectively. Conclusion Drug resistance of smear-positive pulmonary TB patients is serious in Hunan Province,patients receiv-ing anti-tuberculosis treatment and aged between 20-60 years old have high risk for drug resistance and MDR.

BACKGROUNDThe Xpert MTB/RIF showed high sensitivity and specificity in previous studies carried out in different epidemiological and geographical settings and patient populations in high-burden tuberculosis (TB) countries. However, there were little data obtained by validation or demonstration study of the assay in China. In this study, the performance of Xpert MTB/RIF was investigated in two county-level laboratories in Hunan Province, China.

METHODSConsecutive patients with suspected pulmonary tuberculosis (PTB) and suspicion for multidrug-resistant tuberculosis (MDR-TB) were enrolled. For each patient suspected to have PTB, three sputum specimens (one spot sputum, one night sputum, and one morning sputum) were collected and each sputum was tested with smear microscopy, Löwenstein-Jensen (LJ) culture, and Xpert MTB/RIF test. For comparison across subgroups and testing methods, 95% confidence intervals were calculated. All analyses were done with SPSS 16.0, and P < 0.05 was regarded as significant.

RESULTSFor case detection, the sensitivity of Xpert MTB/RIF was 100% for smear- and culture-positive TB and 88.6% for smear-negative and culture-positive TB; the overall sensitivity was 94.5% for all culture-positive patients. The specificity was 99.8%. The sensitivity of Xpert MTB/RIF assay was 22.0% in clinical TB patients and the specificity reached 100.0% in the group of patients who are infected with nontuberculous mycobacteria. For the detection of rifampin resistance, the sensitivity of MTB/RIF RIF-resistance detection was 92.9%, and the specificity was 98.7%. Of the 26 Xpert MTB/RIF-positive and RIF-resistant patients confirmed by LJ proportion tests, 20 (76.9%) patients were infected by MDR-TB.

CONCLUSIONSThe Xpert MTB/RIF assay is a highly sensitive and specific method for diagnosis of TB and RIF resistance, which will enable it to have the potential to be used in county-level laboratories and lead to the reduction of the infectious pool and improvements in TB control in China. Further evaluations in county-level laboratories for implementing the assay are still required.

Adult ; Antibiotics, Antitubercular ; therapeutic use ; China ; Female ; Humans ; Male ; Middle Aged ; Rifampin ; therapeutic use ; Tuberculosis ; diagnosis ; drug therapy ; Tuberculosis, Multidrug-Resistant ; Tuberculosis, Pulmonary ; diagnosis ; drug therapy ; Young Adult