Comparison of Mycobacterium tuberculosis drug susceptibility using solid and liquid culture in Nigeria
1 Zankli Medical Centre, Plot 1021 Shehu YarAdua Way, Abuja, Nigeria
2 National Tuberculosis and Leprosy Control Programme, Abuja, Nigeria
3 Nnamdi Azikiwe Teaching Hospital, Nnewi, Nigeria
4 University College Hospital (UCH), Ibadan, Nigeria
5 Wuse General Hospital, Abuja, Nigeria
6 Mahidol-Oxford Tropical Medicine Research Unit, Angkor Hospital for Children, Siem Reap, Cambodia
7 School of Tropical Medicine, Liverpool, UK
BMC Research Notes 2013, 6:215 doi:10.1186/1756-0500-6-215Published: 30 May 2013
This study compares Mycobacterium tuberculosis culture isolation and drug sensitivity testing (DST) using solid (LJ) and liquid (BACTEC-MGIT-960) media in Nigeria.
This was a cross sectional survey of adults attending reference centres in Abuja, Ibadan and Nnewi with a new diagnosis of pulmonary tuberculosis (TB) or having failed the first-line TB treatment. Patients were requested to provide three sputum specimens for smear-microscopy and culture on LJ and BACTEC-MGIT-960. Positive cultures underwent DST for streptomycin, isoniazid, rifampicin and ethambutol.
527 specimens were cultured. 428 (81%) were positive with BACTEC-MGIT-960, 59 (11%) negative, 36 (7%) contaminated and 4 (1%) had non-tuberculosis mycobacteria (NTM). 411 (78%) LJ cultures were positive, 89 (17%) negative, 22 (4%) contaminated and 5 (1%) had NTM. The mean (SD) detection time was 11 (6) and 30 (11) days for BACTEC-MGIT-960 and LJ. DST patterns were compared in the 389 concordant positive BACTEC-MGIT-960 and LJ cultures. Rifampicin and isoniazid DST patterns were similar. Streptomycin resistance was detected more frequently with LJ than BACTEC-MGIT-960 and ethambutol resistance was detected more frequently with BACTEC-MGIT-960 than LJ, but differences were not statistically significant. MDR-TB was detected in 27 cases by LJ and 25 by BACTEC-MGIT-960 and using both methods detected 29 cases.
There was a substantial degree of agreement between the two methods. However using the two in tandem increased the number of culture-positive patients and those with MDR-TB. The choice of culture method should depend on local availability, cost and test performance characteristics.