Gonococcal susceptibility to antimicrobials in Baltimore, 1988-1994. What was the impact of ciprofloxacin as first-line therapy for gonorrhea?

Abstract

Single-dose, oral quinolones have been a recommended treatment option for gonorrhea since 1989 and have since been used as first-line therapy for gonorrhea in Baltimore. The impact of this strategy on antimicobial susceptibility patterns in Neisseria gonorrhoeae was assessed utilizing data collected as part of the National Gonococcal Isolate Surveillance system. This system evaluates a systematically collected sample. Minimum inhibitory concentrations to penicillin, tetracycline, ceftriaxone, and ciprofloxacin were determined by agar dilution. Between January 1988 and September 1994, 1,846 gonococcal isolates were evaluated. The proportion of isolates with plasmid-mediated resistance (penicillinase-producing Neisseria gonorrhoeae or tetracycline-resistant Neisseria gonorrhoeae) increased from 22% in 1988 to 46% in 1992 and then dropped to 20% in 1994. In contrast, the prevalence of chromosomally mediated resistant isolates ranged between 3% and 10%. Between 1988 and 1994, the geometric mean penicillin and tetracycline minimum inhibitory concentrations decreased slightly (penicillin: from 0.509 microgram/ml to 0.369 microgram/ml; tetracycline: from 1.01 micrograms/ml to 0.767 microgram/ml). The mean ceftriaxone MIC increased from 0.005 microgram/ml in 1988 to 0.021 microgram/ml in 1992, and then abruptly decreased. Ciprofloxacin minimum inhibitory concentrations did not change substantially during the study period. Concurrent studies performed in this community suggest that quinolones were infrequently used for infections other than sexually transmitted ones during this time period. Single-dose quinolone therapy does not appear to foster development of resistant gonococcal isolates. However, resistance may develop as a result of complex ecological interactions with the community, underscoring the need for continued surveillance.