Characteristics of Isolates of Mycobacterium Tuberculosis in Extrapulmonary Tuberculosis in Korle-Bu Teaching Hospital

Abstract

Tuberculosis (TB) is a worldwide disease. Annually, about nine million people contract tuberculosis and nearly two million are killed by the disease. The fatal synergy of human immuno deficiency virus (HIV) and tuberculosis, and the emergence of multi-drug resistant Mycobacterium tuberculosis have further contributed to the re-emergence of TB in many parts of the world. Extrapulmonary tuberculosis refers to the disease outside the lungs. Extrapulmonary tuberculosis can occur alone or occur in combination with pulmonary TB in a person. About twenty-five percent (25 %) of TB cases are extrapulmonary. In Ghana, studies on TB have focused more on pulmonary TB which is the most frequent form of the disease and no studies on extrapulmonary TB had been conducted. Therefore a study that aimed to understand the characteristics of extrapulmonary infections will enable the identification of risk factors contributing to the increase rate of extrapulmonary TB. Identifying these factors is also crucial for policy makers to appropriately strategize to control the disease in order to reduce the global burden of TB. This study sought to describe the characteristics of isolates of Mycobacterium tuberculosis in patients with extrapulmonary tuberculosis Methods: This study was a cross-sectional survey on extrapulmonary tuberculosis suspected patients and conducted between June 2013 and May 2014 at the Chest Clinic Laboratory of the Korle-Bu Teaching Hospital, Accra. All samples were analyzed bacteriologically using microscopy, culture and GeneXpert molecular technology. Drug susceptibility testing using MGIT 960 and Line Probe Assay and species identification were done on Mycobacterium tuberculosis complex isolates. Patient’s possible risk factors were also assessed. Results: One hundred and twenty-five (125) samples were analyzed in this study. Ninety one (72.8%) of the samples were pleural aspirates, 14 (11.2%) ascetic fluid, 8(6.4%)

cerebrospinal fluid, 5(4.0%) pericardial aspirate, 3(2.4%) urine, 2 (1.6%) lymph nodes, chestwall and sub-diaphram aspirates 1(0.8%) each. The mean age of the patients was 35.64 ± 21.12 years. There were 70 (56%) males with mean age of 36.74+20.94 and 55 (44%) females with mean age of 34 23+21.46. The culture positive prevalence rate of extrapulmonary tuberculosis was 6.4% (8 out of 125). Out of the 8 culture positive extrapulmonary tuberculosis detected, 5 were males and 3 females. HIV positive patients were 10 (8.0%) and only 1 out of the 10 had extrapulmonary tuberculosis. In this study there was no significant association between extrapulmonary tuberculosis and the socio-demographic characteristics such as HIV positive, alcohol use, age, smoking, previous treatment of TB and unemployment studied. Also MDR-TB was not found in extrapulmonary tuberculosis; however 4 isolates out of the 8 were resistant to isoniazid, with 3 found on the katG wild -type gene located on codon 315. Seven (87.5%) of the 8 Mycobacterium tuberculosis complex species were further confirmed as Mycobacterium tuberculosis and only 1(12.5%) confirmed as Mycobacterium africanum. Conclusion: The prevalence rate of extrapulmonary tuberculosis is 6.4% and pleural tuberculosis is the predominant form of extrapulmonary tuberculosis at Korle-Bu Teaching Hospital. Mycobacterium tuberculosis strains predominate in extrapulmonary tuberculosis. The occurrence of extrapulmonary tuberculosis is not determined by one’s sociodemographic risk factors and extrapulmonary tuberculosis is not associated with multi-drugs resistant tuberculosis at the Korle-Bu Teaching Hospital