Evaluation of microscopic observation drug susceptibility assay for diagnosis of multidrug-resistant Tuberculosis in Viet Nam

BMC Infectious Diseases

Research Article

Vo Thi Ha¹  Nguyen Thi Nho¹  Nguyen Thi Ngoc Lan¹  Phan Thi Hoang Anh¹  To My Huong¹  Vuong Minh Bach¹  Nguyen Hong Duc¹  Nguyen Thi Phuong Thao¹  Nguyen Thi Bich Tuyen¹  Tran Van Quyet¹  Dai Viet Hoa¹  Nguyen Huy Dung¹  Dang Thi Minh Ha²  Maxine Caws³  Hoang Thi Thanh Hang³  Jeremy Farrar³  Vo sy Kiet³  Marcel Wolbers³ 

[1] Pham Ngoc Thach Hospital, 120 Hung Vuong, District 5, Ho Chi Minh City, Viet Nam;Pham Ngoc Thach Hospital, 120 Hung Vuong, District 5, Ho Chi Minh City, Viet Nam;Wellcome Trust Major Overseas Programme and Oxford University Clinical Research Unit, Hospital for Tropical Diseases, 190 Ben Ham Tu, District 5, Ho Chi Minh City, Viet Nam;Wellcome Trust Major Overseas Programme and Oxford University Clinical Research Unit, Hospital for Tropical Diseases, 190 Ben Ham Tu, District 5, Ho Chi Minh City, Viet Nam;

关键词: MDR-TB;    Tuberculosis;    MODS;    Diagnosis;   

DOI  :  10.1186/1471-2334-12-49

 received in 2011-07-20, accepted in 2012-03-01,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundEarly diagnosis of tuberculosis (TB) and multidrug resistant tuberculosis (MDR TB) is important for the elimination of TB. We evaluated the microscopic observation drug susceptibility (MODS) assay as a direct rapid drug susceptibility testing (DST) method for MDR-TB screening in sputum samplesMethodsAll adult TB suspects, who were newly presenting to Pham Ngoc Thach Hospital from August to November 2008 were enrolled into the study. Processed sputum samples were used for DST by MODS (DST-MODS) (Rifampicin (RIF) 1 μg/ml and Isoniazid (INH) 0.4 μg/ml), MGIT culture (Mycobacterial Growth Indicator Tube) and Lowenstein Jensen (LJ) culture. Cultures positive by either MGIT or LJ were used for proportional DST (DST-LJ) (RIF 40 μg/ml and INH 0.2 μg/ml). DST profiles on MODS and LJ were compared. Discrepant results were resolved by multiplex allele specific PCR (MAS-PCR).ResultsSeven hundred and nine TB suspects/samples were enrolled into the study, of which 300 samples with DST profiles available from both MODS and DST-LJ were analyzed. Cording in MODS was unable to correctly identify 3 Mycobacteria Other Than Tuberculosis (MOTT) isolates, resulting in 3 false positive TB diagnoses. None of these isolates were identified as MDR-TB by MODS. The sensitivity and specificity of MODS were 72.6% (95%CI: 59.8, 83.1) and 97.9% (95%CI: 95.2, 99.3), respectively for detection of INH resistant isolates, 72.7% (95%CI: 30.9, 93.7) and 99.7% (95%CI: 98.1, 99.9), respectively for detecting RIF resistant isolates and 77.8% (95%CI: 39.9, 97.1) and 99.7% (95%CI: 98.1, 99.9), respectively for detecting MDR isolates. The positive and negative predictive values (PPV and NPV) of DST-MODS were 87.5% (95%CI: 47.3, 99.6) and 99.3% (95%CI: 97.5, 99.9) for detection of MDR isolates; and the agreement between MODS and DST-LJ was 99.0% (kappa: 0.8, P < 0.001) for MDR diagnosis. The low sensitivity of MODS for drug resistance detection was probably due to low bacterial load samples and the high INH concentration (0.4 μg/ml). The low PPV of DST-MODS may be due to the low MDR-TB rate in the study population (3.8%). The turnaround time of DST-MODS was 9 days and 53 days for DST-LJ.ConclusionThe DST-MODS technique is rapid with low contamination rates. However, the sensitivity of DST-MODS for detection of INH and RIF resistance in this study was lower than reported from other settings.

【 授权许可】

CC BY   
© Minh Ha et al; licensee BioMed Central Ltd. 2012