Evaluation of microscopic observation drug susceptibility assay for diagnosis of multidrug-resistant tuberculosis in Viet Nam.
BMC Infect Dis
; 12: 49, 2012 Mar 01.
Article
en En
| MEDLINE
| ID: mdl-22375832
ABSTRACT
BACKGROUND:
Early 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 samplesMETHODS:
All 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).RESULTS:
Seven 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.CONCLUSION:
The 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.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Tuberculosis Resistente a Múltiples Medicamentos
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Farmacorresistencia Bacteriana Múltiple
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Microscopía
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Mycobacterium tuberculosis
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Antituberculosos
Tipo de estudio:
Diagnostic_studies
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Evaluation_studies
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Prognostic_studies
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Screening_studies
Límite:
Adult
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Female
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Humans
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Male
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Middle aged
País como asunto:
Asia
Idioma:
En
Año:
2012
Tipo del documento:
Article