Microbiologie médicale et diagnostic

Diagnosis of Pulmonary Tuberculosis Using Genotype MTBDRplus Assay in Three Local Government Primary Health Centres of Osun State, Nigeria- a Pilot Study

Abstract

Aderemi Oludiran Kehinde and Adetayo Emmanue Adetoye

Study background: Tuberculosis including multi-drug resistant form is not adequately diagnosed in spite of the fact that it constitutes a major public health challenge. This study was carried out to obtain data on laboratory diagnosis of pulmonary tuberculosis at the three local government areas in Osun state, Nigeria.

Methods: Six month pilot study was carried out at Iwo, Irewole and Ede North LGAs, all located in Osun state, Nigeria. Socio-demographic and clinical information of the subjects were obtained using a pre-tested questionnaire. Sputum samples were collected from symptomatic pulmonary tuberculosis patients, stained with Zeihl-Neelsen (ZN) reagents and cultured on egg-based Lowenstein-Jensen medium. The medium was incubated at 37°C for eight weeks. Acid Fast Bacilli was confirmed by repeat Z-N staining. Drug resistance testing of the isolates was done using Genotype MTBDRplus. Serum was screened for HIV test using recombinant ELISA. Those that were screened positive were retested using Capillus HIV 1 and 2.   Results: Of the 75 subjects studied, seven (9.3%) were over 60 years while the majority, 45 (76.0%) were aged 21-60 years. Thirty-four (45.3%) had their sputum positive for acid fast bacilli (AFB) while 24 (32.0%) were culture positive. Among the 24 isolates, 6 were identified to be non tuberculos mycobacteria (NTM) by molecular methods. The HIV prevalence rate was observed to be 18.6% among all the study participants. Six out of 34 AFB positive persons (17.6%) were also positive for HIV specific antibody, while eight (19.5%) of the AFB negative persons were positive for HIV. There is no significant difference in the incidence of TB between the HIV infected and uninfected groups (p>0.05).Among the 18 mycobacterial isolates (excluding NTM), one strain (5.5%) was found to be resistant to rifampicin and isoniazid (Multi-Drug Resistant-MDR) while three were resistant to isoniazid alone..   Conclusion: This pilot study reveals the existence of MDR-TB and warrants well designed studies to ascertain the magnitude of the problem.