VIENNA – A rising prevalence of ciprofloxacin resistance in gonorrhea linked with an increased rate of infections in the United States during 1991-2006, based on data from 17 U.S. cities.
An increase in the prevalence of ciprofloxacin-resistant gonorrhea isolates from none to 10% linked with a statistically significant 7% rise in the incidence of gonorrhea, reported Harrell W. Chesson, Ph.D., and his associates from the Centers for Disease Control and Prevention.
Courtesy Centers for Disease Control and Prevention
A rising prevalence of ciprofloxacin resistance in gonorrhea linked with an increased rate of infections in the United States during 1991-2006, based on data from 17 U.S. cities.
"To our knowledge, this is the first study to document an association between antimicrobial resistance and increased gonorrhea incidence rates at the population level," said Dr. Chesson, a health economist in the division of STD prevention of the CDC in Atlanta. The link between increased ciprofloxacin resistance and increased gonorrhea incidence occurred even though effective treatment options for gonorrhea other than ciprofloxacin existed at the time.
These findings can help anticipate the potential impact of cephalosporin resistance in circulating gonorrhea strains in the United States, Dr. Chesson and his associates said in a poster at the congress of the International Society for STD Research.
Cephalosporin resistance in gonorrhea isolates is a growing problem, and last year it prompted the CDC to eliminate cefixime as the first-line agent for treating gonorrhea (MMWR 2012;61:590-4). The CDC designated another cephalosporin, ceftriaxone, as the current first-line agent, but it also noted that emergence of gonococcal resistance to ceftriaxone was probably inevitable.
"Emerging cephalosporin resistance could have even more substantial health and economic consequences [than did ciprofloxacin resistance], particularly as the number of available treatment options decreases," Dr. Chesson and his associates said.
Although they cautioned that the evidence they found cannot establish ciprofloxacin resistance in gonorrhea as the cause of the increased incidence, their findings "offer evidence consistent with that of a causal association between resistance and increased incidence."
If 10% of circulating gonorrhea strains remained resistant to a widely used antibiotic, Dr. Chesson and his associates projected, the consequent rise in infection incidence would lead to 50,000 additional cases of pelvic inflammatory disease over a 10-year period and an additional 5,400 cases of epididymitis, compared with rates if resistance did not exist.
To perform the analysis, the researchers used data on gonorrhea resistance that were collected in the Gonococcal Isolate Surveillance Project of the CDC and coupled these data with incidence rates from routine surveillance done in 17 U.S. cities during 1991-2006. In their regression analysis they controlled for socio-demographic factors, city-specific factors, and national trends during the 16-year period.
Disease transmission models suggest that antimicrobial resistance may increase gonorrhea incidence by prolonging the average duration of a patient’s infection, but the authors cautioned that several other factors aside from antibiotic resistance also affect gonorrhea incidence rates.
Dr. Chesson had no disclosures.
On Twitter @mitchelzoler