Modeling the Impact of Cephalosporin-Resistant Neisseria Gonorrhoeae

Background:  Neisseria gonorrhoeae has developed resistance against sulfonamides, penicillins, tetracyclines, and fluoroquinolones. Cephalosporin resistance may now be emerging.    Without new antimicrobials, cephalosporin-resistant N. gonorrhoeae could greatly complicate treatment.  Theoretically, the public health impact of screening programs may suffer as resistance increases, leading to increases in gonorrhea prevalence and sequelae, such as pelvic inflammatory disease (PID).    In this work we explore these potential impacts of resistance.

Methods:  We used an agent based model of sexual infection transmission that encompasses 1) sexual partnership formation and dissolution, 2) infection transmission and recovery, 3) screening, testing and treating for N. gonorrhoeae, and 4) resistance conversion of strains within people (either sensitive to resistant in the presence of antimicrobial treatment, or resistant to sensitive in the absence of treatment).  We explore the impact of resistance by comparing scenarios with and without resistant strains, and explore the performance of different screening scenarios compared to only testing and treating symptomatic women.

Results:  In one screening scenario and without resistance, testing and treating symptomatic women and men results in 42.8% lower infection prevalence and 39.0% lower annual PID compared to only testing/treating symptomatic women. With resistance, there is only 13.8% lower prevalence along with 450% higher resistance prevalence; this leads to 10.5% higher PID rates.   In another screening scenario, screening of asymptomatic women and ignoring symptomatic men results in more modest prevalence reductions both with and without resistance (6.2% and 8.7%), while still managing to decrease PID incidence (1.1%) with resistance because resistance only increases by 84%.

Conclusions:  In the presence of resistance, screening and treating men can increase the prevalence of resistant strains, thus ultimately increasing PID in women. This finding suggests that certain gonorrhea prevention strategies that are beneficial in the absence of resistance might be less effective or even detrimental in the presence of resistance.