Genetic Determinants of Drug-Resistant Tuberculosis among HIV-Infected Patients in Nigeria

Abstract

Total RIF resistance indicative of MDR-TB in treatment-naive patients was 5.52%, far exceeding the World Health Organization predictions (0 to 4.3%). RIF resistance was found in 6/213 (2.8%) cases, INH resistance was found in 3/215 (1.4%) cases, and MDR-TB was found in 8/223 (3.6%) cases. We found significantly different amounts of DR-TB by location (18.18% in the south of the country versus 3.91% in the north central region [P < 0.01]). Furthermore, RIF resistance was genetically distinct, suggesting possible location-specific strains are responsible for the transmission of drug resistance (P < 0.04). Finally, GenoType MTBDRplus correctly identified the drug-resistant samples compared to sequencing in 96.8% of cases. We found that total DR-TB in HIV-infection is high and that transmission of drug-resistant TB in HIV-infected patients in Nigeria is higher than predicted. Human immunodeficiency virus (HIV) greatly increases the risk for tuberculosis (TB), and the two epidemics continue to fuel one another (31). HIV-infected patients are significantly more likely to develop active TB diseases than non-HIV-infected people and are more likely to die from TB (13,27,28). In subSaharan Africa, 30% of HIV-infected patients who are diagnosed with TB die 12 months after the initiation of treatment (12,33). With an estimated national prevalence of HIV in Nigeria of 3.6% (7), the number of people living with HIV (3.3 million) represents the second largest burden of disease on the continent (32). Nigeria has the world's third largest TB burden, with the prevalence of 830,000 cases. The World Health Organization (WHO) estimates that 26% of patients with TB infection in Nigeria are HIV infected (37).Multidrug-resistant TB (MDR-TB), defined by resistance to isoniazid (INH) and rifampin (RIF), is a growing global health problem (5,19,22). While MDR-TB emerges as a consequence of poor adherence to anti-TB treatment (34,35), it can also be transmitted. MDR-TB results in significantly higher mortality rates in HIV-infected patients than drug-susceptible TB (18). The estimates based on modeling predict MDR-TB prevalence in Nigeria to range from 1.8% (0.0 to 4.3%) for new cases up to 7.7% (0.0 to 18.0%) for previously treated patients (36). Currently in Nigeria, streptomycin is the only treatment available for patients previously treated for TB or suspected of infection with MDR-TB. Furthermore, MDR-TB in HIV-infected individuals leads to higher mortality compared to mortality in non-HIV-infected patients or HIV-infected individuals with susceptible TB (18,24). These findings, combined with alarming evidence that MDR-TB can be transmitted, calls for close monitoring of the incidence of drug resistance, especially in HIV-infected populations (6).The conventional methods of drug resistance testing involve growth of Mycobacterium tuberculosis on liquid or solid culture medium (35). Culture methods are costly and time-consuming, thus limiting both utility for patient care and likelihood of timely treatment. Recently, several new commerci...

Molecular Detection of Mycobacterium tuberculosis (MTB) and Rifampicin Resistant Strain among Subjects Accessing Health Care at Federal Medical Centre, Yenegoa, Bayelsa State; Nigeria

“…In addition, studies from different geographic zones have showed varied prevalence of RIF resistance which all differ from the prevalence obtained from this present study as reported by Akaninyene and Dinic [23,24]. Also, comparatively a study done in Nnewi, South East Nigeria shared a similar view (prevalence of RIF's resistance of 2.7%) with this present study, although the general MDR-TB from their study was lesser (7.7%) than that obtained here (10.3%) Uzoewulu though, RIF resistance had the least prevalence when compared to isoniazid thus, it could be deduced that the non-resistant RIF strain might be isoniazid resistant strain and resistant to other TB drugs.…”

Rifampicin-resistance pattern of Mycobacterium tuberculosis and associated factors among presumptive tuberculosis patients referred to Debre Markos Referral Hospital, Ethiopia: a cross-sectional study

“…However, it was lower compared to reports in Nigeria (31.4%) [18] and Pakistan (37%) [19]. The lower proportion rate of confirmed M. tuberculosis in the present study compared to other studies is due to the fact that we included presumptive cases to identify M. tuberculosis while other studies included identified cases of M. tuberculosis to check gene Xpert technique.…”

Prevalence of Tuberculosis and Rifampicin Resistance Among Patients Seeking Medical Care in Nasarawa State, North Central Nigeria

“…Therefore Xpert® MTB/RIF assay was used in detecting Rifampicin resistance. Rifampicin resistance of 6.6% found in this study is very close to the 7.0% reported in samples collected from Jos and Lagos, Nigeria [11]. Another study in Calabar Nigeria reported a rifampicin resistance of 6%, although they did not find any patient with resistance to only rifampicin [12].…”