Surveillance of antituberculosis-drug resistance in Cuba, 2010-2011

Abstract

Introduction: Antituberculosis-drug resistance surveillance is very important to identify multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis isolates.

Objective: To determine the prevalence of resistance in M. tuberculosis strains isolated between 2010 and 2011, and to demonstrate the laboratory performance in the external quality control of drug susceptibility testing.

Materials and methods: A prospective longitudinal study was carried out to determine antituberculosis-drug resistance in 657 M. tuberculosis isolates obtained throughout the country. The nitrate reductase assay was used to detect resistance to isoniazid and rifampin. The proportion method was performed to confirm resistance to these drugs and to further investigate in multidrug-resistant isolates their susceptibility to streptomycin, ethambutol, ofloxacin, kanamycin and capreomycin. Additionally, as part of external quality control, susceptibility was evaluated in two M. tuberculosis strain panels.

Results: In 95.69% of the isolates recovered from new tuberculosis cases, and in 72.64% of isolates from previously treated patients we found susceptibility to isoniazid and rifampicin; multidrug resistance was 1,03 and 10.38%, respectively. We found two extensively resistant isolates. Except for ethambutol and capreomycin, the efficiency of all other drugs was 100% in the external quality control.

Conclusion: The study confirmed the low prevalence of M. tuberculosis multidrug-resistant isolates in Cuba. This result was confirmed by the external quality control of drug susceptibility testing.