Correlation between In vitro susceptibility and treatment outcome with azithromycin in gonorrhoea: A prospective study

Purpose: This prospective study was carried out to determine the antimicrobial susceptibility of Neisseria gonorrhoeae isolates by disc diffusion method and minimum inhibitory concentration (MIC) by E -test with special reference to azithromycin. Also, the correlation between in vitro susceptibility and treatment outcome with single 2 g oral dose azithromycin was assessed. Methods: The study included 75 gonococcal isolates from males with urethritis, females with endocervicitis and their sexual contacts. All isolates were subjected to susceptibility testing for penicillin, ciprofloxacin, tetracycline, ceftriaxone, spectinomycin, cefixime and azithromycin. Males with gonococcal urethritis were randomised to receive a single dose of either azithromycin or ceftriaxone. Forty-two men with urethritis received 2 g single oral dose azithromycin, while all other patients were given 250 mg parentral ceftriaxone. All patients were called for follow-up to assess clinical and microbiological cure rates. Results: While all the isolates were susceptible to ceftriaxone, spectinomycin, cefixime and azithromycin; 74 (98.7%), 24 (32%) and 23 (30.7%) strains were resistant to ciprofloxacin, penicillin and tetracycline respectively, by both disc diffusion method and E -test. The MIC range, MIC 50 and MIC 90 of N. gonorrhoeae strains, to azithromycin were 0.016-0.25, 0.064 and 0.19 μg/mL, respectively. Follow-up attendance of the patients was 52.4 with 100% clinical and microbiological cure rates. Conclusions: Results of our study indicate that 2 g single oral dose azithromycin is safe and effective in the treatment of uncomplicated gonorrhoea