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Frequent antibiotic treatment increases spread of resistant N. gonorrhoeae more than sexual behavior
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A recent modeling analysis suggested that increasing antibiotic treatment rates had a greater effect on the dissemination of resistant Neisseria gonorrhoeae than sexual behavior.
These higher treatment rates are the driving influence on resistance spread among men who have sex with men, a population estimated to proliferate antibiotic-resistant N. gonorrhoeae at a significantly greater rate than heterosexuals, according to Stephanie M. Fingerhuth, MSc, of the Institute of Integrative Biology, ETH Zurich, and colleagues.
“Although other antibiotics are being tested for their safety and efficacy for N. gonorrhoeae treatment, no new classes of antibiotics are currently available and management of antibiotics is urgently needed to preserve their efficacy,” they wrote. “Understanding the drivers of resistance spread and anticipating future resistance trends will provide rationales for antibiotic management and help to improve antibiotic treatment strategies.”
Future guidelines must balance prevention of resistance
Using data from the English Gonococcal Resistance to Antimicrobials Surveillance Program (GRASP) and the CDC’s Gonococcal Isolate Surveillance Project (GISP), Fingerhuth and colleagues constructed a mathematical model to estimate the spread of antibiotic-resistant gonorrhea among MSM and heterosexual men. The researchers used these findings, along with prevalence, incidence and sexual behavior data, in a dynamic transmission model to predict the spread of resistant disease among MSM and heterosexual men and women (HMW).
Fingerhuth and colleagues observed an initial spread of ciprofloxacin-resistant N. gonorrhoeae in the early 2000s and a marked increase in the proportion of resistance among MSM and heterosexual men after 2006. Resistance spread was consistently greater for MSM than heterosexual men (mean doubling time, 6 months vs. 16 months) regardless of antibiotic or data source.
Using the model, Fingerhuth and colleagues estimated that the proportion of antibiotic-resistant N. gonorrhoeae will increase faster among MSM than HMW (median doubling time, 3 months vs. 9 months). Their analysis of incidence and prevalence data revealed that this rate increase primarily stemmed from more frequent receipt of antibiotic therapy reported among MSM, as opposed to other factors such as the number of sexual partners.
This type of predictive modeling is subject to several limitations, including the assumption that resistant and susceptible strains have equal infectivity, according to the researchers. If accurate, however, these findings would imply a pressing need to continuously adapt new N. gonorrhoeae treatment guidelines with the potential spread of antibiotic resistance in mind.
“Our study challenges the currently prevailing notion that more screening and treatment will limit the spread of N. gonorrhoeae, as higher treatment rates will ultimately result in faster spread of antibiotic resistance,” they wrote. “Future treatment recommendations for N. gonorrhoeae should carefully balance prevention of N. gonorrhoeae infection and avoidance of the spread of resistance.”
CDC recommends azithromycin alternatives
Concerns of cephalosporin-resistant gonorrhea were reflected in the 2015 update to the CDC’s national STD treatment guidelines.
While 2010 guidance recommended dual therapy of cephalosporin plus either azithromycin or doxycycline, alternative treatments recommended for uncomplicated urogenital gonorrhea now consist of either combination treatment of oral gemifloxacin plus oral azithromycin, or dual treatment with single doses of intramuscular gentamicin plus oral azithromycin.
“[Gonorrhea] is very savvy at developing resistance to antibiotics,” Kimberly A. Workowski, MD, professor of medicine in the division of infectious diseases at Emory University, told Infectious Disease News in a previous interview. “It’s a really important addition to this version of the guidelines ... especially in people who have allergies to the only known remaining antimicrobial.” – by Dave Muoio
- References:
- Fingerhuth SM, et al. PLoS Pathog. 2016;doi:10.1371/journal.ppat.1005611.
- Workowski KA, et al. MMWR Morb Mortal Wkly Rep. 2015:64;1-137.
Disclosure: The researchers report no relevant financial disclosures.