Clonal Diversity and Spatial Dissemination of Drug-resistant Mycobacterium tuberculosis Complex among HIV Seropositive Patients in Southwest Nigeria

Abstract

Mycobacterium tuberculosis complex display relatively static genomes and 99.9% nucleotide sequence identity. Studying the evolutionary history of such monomorphic bacteria is a difficult and challenging task. Therefore, this study was undertaken to investigate the clonal diversity and spatial dissemination of drug-resistant M. tuberculosis complex among HIV seropositive clients in Southwest Nigeria. A total of two-hundred and seventeen (217) consented HIV positive (case subjects) and fifty (50) non-HIV positive controls were recruited for this study. Two Sputum samples were collected from each participant in two consecutive days. The samples were divided into two parts: one part was decontaminated using NAOH-NALC method and aseptically cultured for Mycobacteria on Lowenstein-Jensen (LJ) medium with and without pyruvate. Mycobacterial isolates were characterized using conventional and molecular methods. Anti-TB drug sensitivity test was done using 1% proportion conventional method on LJ.  MTBC isolates were sequenced using Genetic Analyzer 3130xl sequencer. Genetic relatedness and clonal diversity (phylogenetic analysis) of MTBC isolates were done using Bio- Edit software and MEGA 6. Out of 217 HIV positive participants, 105(48.4%) were male, while 112(51.6%) were female. Twenty-six (26(52.0%)) of the control subjects were male, while 24(48.0%) were females. The overall prevalence of TB among PLHIV was found to be 19.1%. The prevalence of NTM among PLHIV was found to be 2.8% with M. intracellulare being the predominant organism isolated.  Participants’ age was found to be significantly associated with TB (P<0.05), however there was no significant association between TB and sex of the participants (P<0.05).  The prevalence of culture confirmed drug-resistant TB (DR-TB) among PLHIV was found to be 11.9%, with Rifampicin having the highest monoresistance rate of 5.5%. The overall prevalence of MDR-TB among PLHIV was found to be 9.2%. The phylogenetic analysis of M. tuberculosis strains revealed same clone of all isolates. All PLHIV should be screened for drug-resistant TB especially MDR-TB as the prevalence of primary MDR-TB is high among them. Further study like 3R gene-based studies of adaptation and evolution is needed to facilitate further epidemiological studies of these bacteria.