Abstract
BackgroundsThe failure of current Standard Short-Course Chemotherapy (SCC) in new and previously treated cases with tuberculosis (TB) was mainly due to drug resistance development. But little is known on the characteristics of acquired drug resistant TB during SCC and its correlation with SCC failure. The objective of the study is to explore the traits of acquired drug resistant TB emergence and evaluate their impacts on treatment outcomes.MethodsA prospective observational study was performed on newly admitted smear positive pulmonary TB (PTB) cases without drug resistance pretreatment treated with SCC under China’s National TB Control Program (NTP) condition from 2008 to 2010. Enrolled cases were followed up through sputum smear, culture and drug susceptibility testing (DST) at the end of 1, 2, and 5 months after treatment initiation. The effect factors of early or late emergence of acquired drug resistant TB , such as acquired drug resistance patterns, the number of acquired resistant drugs and previous treatment history were investigated by multivariate logistic regression; and the impact of acquired drug resistant TB emergence on treatment failure were further evaluated.ResultsAmong 1671 enrolled new and previously treated cases with SCC, 62 (3.7 %) acquired different patterns of drug resistant TB at early period within 2 months or later around 3–5 months of treatment. Previously treated cases were more likely to develop acquired multi-drug resistant TB (MDR-TB) (OR, 3.8; 95 %CI, 1.4–10.4; P = 0.015). Additionally, acquired MDR-TB cases were more likely to emerge at later period around 3-5 months after treatment starting than that of non-MDR-TB mainly appeared within 2 months (OR, 8.3; 95 %CI, 1.7–39.9; P = 0.008). Treatment failure was associated with late acquired drug resistant TB emergence (OR, 25.7; 95 %CI, 4.3–153.4; P < 0.001) with the reference of early acquired drug resistant TB emergence.ConclusionsThis study demonstrates that later development of acquired drug resistant TB during SCC is liable to suffer treatment failure and acquired MDR-TB pattern may be one of the possible causes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12890-016-0187-3) contains supplementary material, which is available to authorized users.
Highlights
TB is a major global health problem with 8.6 million new cases and almost 1.3 million deaths attributed to the disease every year [1]
The sample size for new and previously treated cases of sputum smear-positive (SS+) TB was set at 1927 and 506 respectively which took into account a prevalence of overall resistance to first-line anti-TB drugs (H, R, E, S) of 18.6 % and 46.5 % respectively from a previous study [14], with desired precision of 1 %, a 95 % confidence level and a non-response rate of 10 %, assuming that 15 % of the culture samples would be lost due to failure to recover or due to growth of non-tuberculosis mycobacterium (NTM)
Patient enrollment and demographic characteristics During the study period, among 2142 confirmed pulmonary TB cases detected, 67 cases infected with NTM, 29 cases declined to participate the study, 321 cases with drug resistant TB and 54 cases with negative sputum culture results before treatment initiation
Summary
TB is a major global health problem with 8.6 million new cases and almost 1.3 million deaths attributed to the disease every year [1]. WHO recommended standardized first-line anti-TB drug regimen is a single 6month or 8-month regimen composed of isoniazid (H), rifampicin (R), ethambutol (E), and streptomycin (S) with pyrazinamide (Z) [2] This regimen is recommended for all new TB cases and previously treated cases in more than 90 countries. To address these issues, we conducted a prospective observational study tracing the emergence of acquired drug resistant TB at indicated time points among new and previously treated cases receiving first-line standard regimens to determine the characteristics and its effect on treatment failure
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