Fluoroquinolone resistance in Mycobacterium tuberculosis strains isolated in Kenya

Abstract

Background: Fluoroquinolones are key second-line anti-tuberculosis drugs usually used in the treatment of patients with Multi-Drug Resistant Tuberculosis (MDR-TB). Anti-TB fluoroquinolones include ciprofloxacin, moxifloxacin, gatifloxacin (Gat), ofloxacin and levofloxacin. Resistance to one fluoroquinolone usually translates to resistance to the others in the group.

Objective: To determine whether there is fluoroquinolone resistance in Mycobacterium tuberculosis strains isolated in Kenya.

Design: A retrospective descriptive study involving archived strains from previous studies carried out at the Centre for Respiratory Diseases Research (CRDR), Kenya Medical Research Institute (KEMRI) between 2002 and 2007.

Setting: CRDR, KEMRI.

Methods: A total of 216 first-line Drug Susceptibility Testing (DST) pre-tested MTB strains were used including 78 resistant to one or more drugs, and randomly selected 138 susceptible to all four drugs. Of the 78 resistant strains, 25 were MDR-TB. The strains were subjected to drug susceptibility testing to Gat among other second-line drugs.

Results: Of the 216 strains tested, 32 [32/216 (14.8%)] showed resistance to second-line drugs. Of these seven [7/32 (21.9%)] were fully resistant to Gat of which six [6/7 (85.7%)] were mono-resistant strains and one [1/7 (14.3%)] with combined resistance strain to Ethionamide. Four [4/25 (16%)] MDR-TB strains showed mono-resistance to Gat.

Conclusion: Presence of Gat resistance especially in MDR-TB patients may significantly contribute to Extensively Drug Resistance TB, a more difficult to treat strain than MDR-TB. Therefore strict drug adherence among MDRTB patients and proper and appropriate use of flouroquinolones should be implemented in Kenya.

Keywords: Fluoroquinolones, MDR-TB, resistance