Date Published: July 13, 2017
Publisher: Public Library of Science
Author(s): Cajetan C. Onyedum, Isaac Alobu, Kingsley Nnanna Ukwaja, Olivier Neyrolles.
Drug-resistant tuberculosis (TB) undermines control efforts and its burden is poorly understood in resource-limited settings. We performed a systematic review and meta-analysis to provide an up-to-date summary of the extent of drug-resistant TB in Nigeria.
We searched PubMed, Scopus, Embase, HINARI, AJOL, the Cochrane library, Web of Science, and Google Scholar for reports published before January 31 2017, that included any resistance, mono-resistance or multidrug resistance to anti-TB drugs in Nigeria. Summary estimates were calculated using random effects models.
We identified 34 anti-TB drug resistance surveys with 8002 adult TB patients consisting of 2982 new and 5020 previously-treated cases. The prevalence rate of any drug resistance among new TB cases was 32.0% (95% CI 24.0–40.0%; 734/2892) and among previously-treated cases, the rate was 53.0% (95% CI 35.0–71.0%; 1467/5020). Furthermore, multidrug resistance among new and previously-treated cases was 6.0% (95% CI 4.0–8.0%;161/2502)and 32.0% (95%CI 20.0–44.0; 357/949), respectively. There was significant heterogeneity between the studies (p<0.001, I2 tests). The prevalence of drug-resistant TB varied according to methods of drug susceptibility testing and geographic region of Nigeria. The burden of drug-resistant TB in Nigeria is high. We recommend that a national anti-TB drug resistance survey be carried out, and strategies for case detection and programmatic management of drug-resistant TB in Nigeria need to be strengthened.
According to the World Health Organisation (WHO) global report 2016, among 10.4 million incident TB cases worldwide, 3.9% are estimated to have had rifampicin- or multidrug-resistant tuberculosis (MDR/RR-TB) in 2015 . In addition, 21% of previously treated TB cases were estimated to have had MDR/RR-TB in the same year . MDR-TB is caused by strains of M. tuberculosis that is resistant to both isoniazid and rifampicin. Drug-resistant TB (DR-TB) patients require prolonged and expensive treatment using second-line medications that are less effective and more toxic . The acquisition or emergence M. tuberculosis resistance may occur from; previous exposures to quinolones , use of inferior regimens , poor adherence to anti-TB drug, previous TB treatment [4–5], and high human immunodeficiency virus (HIV) co-infection [6–7]. The diagnosis of drug-resistance require patients to be tested for susceptibility to anti-TB drugs, either by conventional (phenotypic) drug susceptibility testing (DST) or rapid molecular diagnostic (genotypic) methods . The WHO recommends all presumptive TB patients to undergo DST although many countries still lack laboratory capacity to achieve this . Therefore, in most low- and middle-income countries, there may be a high level of under-diagnosis and misdiagnosis of DR-TB. However, with the recent recommendation of rapid molecular diagnostic tests as a first-line TB screening test , there is progressive increase in reporting of DR-TB in resource-limited settings [8–9].
Our analyses showed that 32.0% of newly diagnosed cases and 53.0% of previously-treated TB patients from different settings in Nigeria were resistant to at least one anti-TB medication. Furthermore, we found that the burden of MDR-TB was high—occurring in 6.0% of new and 32.0% of previously-treated TB patients. In addition, we found that the pooled burden of DR-TB across new and previously-treated cases varied substantially across geographic regions of the country and the DST methods used.