Surveillance of Rifampicin Resistance With GeneXpert MTB/RIF in the National Reference Laboratory for Tuberculosis at the Institut Pasteur in Bangui, 2015-2017

Background. The Central African R epublic (CAR) has one of the heaviest burdens of tuberculosis (TB) in the world, with an incidence of 423 cases per 100 000 population. Surveillance of resistance to rifampicin with GeneXpert MTB/RIF was instituted in the National TB Reference Laboratory in 2015. The aim of this study was to evaluate, after 3 years, resistance to rifampicin, the most effective firstline drug against TB. Methods. The surveillance database on cases of rifampicin resistance was retrospectively analyzed. The populations targeted by the National TB Programme were failure, relapse, default, and contacts of multidrug-resistant TB (MDR-TB). Statistical analyses were performed with Stata software, version 14, using chi-square tests and odds ratios. Results. Six hundred seventeen cases were registered; 63.7% were male, 36.3% were female, and the mean age was 35.5 years (range from 2 to 81). GeneXpert MTB/RIF tests were positive in 79.1% (488/617), and resistance to rifampicin was positive in 42.2% (206/488), with 49.1% (56/114) in 2015, 34.7% (57/164) in 2016, and 44.3% (93/210) in 2017. Failure cases had the highest rate of resistance (70.4%), with a significant difference (P < .0001; odds ratio, 9.5; 95% confidence interval, 4.4-20.5). Resistance was observed in 40% of contacts of MDR-TB, 28.2% of the relapses and 20% of the defaults without significant difference. Conclusions. Resistance to rifampicin is still high in the CAR and is most strongly associated with treatment failure. The Ministry of Health must to deploy GeneXpert MTB/RIF tests in the provinces to evaluate resistance to TB drugs in the country.