Gonorrhoea treatment failure and ciprofloxacin resistance.

Ciprofloxacin-resistant strains of Neisseria gonorrhoeae have been on the increase over the past few years in Singapore and worldwide. The aim of this study is to correlate treatment failures with in vitro ciprofloxacin resistance of N. gonorrhoeae. A total of 694 patients attending the Department of STD Control (DSC) clinic in 1996 who were diagnosed to have gonococcal infection confirmed by culture were analysed. Treatment failure rates for ciprofloxacin were determined and the minimum inhibitory concentration (MIC) of ciprofloxacin were traced for all cases of treatment failure. The case notes of all patients who had strains with MICs of ciprofloxacin in the resistant (> or = 1 microg/ml) and less sensitive (0.125-0.5 microg/ml) range were also reviewed to determine the clinical outcome. Ciprofloxacin treatment failure rate was 1.7% (8/461) which was lower than the percentage of ciprofloxacin-resistant strains isolated in the laboratory. Of these 8 cases, 6 were resistant and 2 were less sensitive to ciprofloxacin. Cure rates with ciprofloxacin for resistant and less sensitive strains were 40% and 92% respectively. In conclusion, in vitro resistance to ciprofloxacin may not translate into clinical treatment failure. Clinical treatment failures, on the other hand, are also seen in less sensitive strains.