Urban density and HIV prevalence associated with increasing antibiotic resistance in gonorrhea

Urban density and HIV prevalence associated with increasing antibiotic resistance in gonorrhea

In a recently published study inThe Lancet Regional HealthResearchers identify key geographic and health factors that may predict the prevalence of antimicrobial-resistant (AMR) gonorrhea in the United States.

Monitoring the spread of resistant gonorrhea

Neisseria gonorrhoeaeis the bacterial pathogen responsible for gonorrhea, a sexually transmitted infection that affects the genitals, rectum and throat. This pathogen has developed resistance to all antibiotics used to treat the condition, leading to the development of Amr gonorrhea.

Significant differences in the prevalence of AMR gonorrhea have been observed in different geographic regions of the United States. To better understand the transmission of these strains, the Gonococcal Isolate Surveillance Project (GISP) was initiated to monitor antimicrobial susceptibility trends of gonococcal strains.

Despite these efforts, GISP only provides 25-35 monitoring sites in the United States each year. Therefore, it remains an urgent need to develop robust surveillance strategies that can provide information about the risk of Amr gonorrhea at population and county levels.

About the study

Identifying the population-level demographic, socioeconomic, and health factors associated with Amr gonorrhea burden could provide important insights needed to clarify the risk of Amr gonorrhea in the absence of local surveillance data. To this end, researchers in the current study examined the associations of several spatially and temporally varying predictors with the trends and prevalence of Amr gonorrhea between 2000 and 2019 in the United States

A mathematical model was developed and trained using data from the GISP. This model was then used to identify multiple population-level factors, including population density, unemployment rate, and prevalence of other sexually transmitted diseases (STDs), that are associated with the prevalence of resistance to ciprofloxacin, penicillin, and tetracycline between 2000 and 2019.

GISP isolates were obtained from the first 25 symptomatic men diagnosed with urethral gonorrhea each month who attended participating STD clinics in one of approximately 30 selected cities.

A total of 112,487 GISP isolates from 42 sentinel sites during the study period were included in the analysis. Isolates with resistance to ciprofloxacin, penicillin, and tetracycline were selected, while those with resistance to azithromycin, cefixime, and ceftriaxone were excluded from the analysis due to the low proportions of these isolates during the study period.

Regional and demographic trends in Amr gonorrhea

Among all isolates tested for antibiotic susceptibility, approximately 14%, 12%, and 20% showed resistance to ciprofloxacin, penicillin, and tetracycline.

A higher prevalence of ciprofloxacin- and penicillin-resistant gonorrhea has been observed in denser populations. Specifically, a greater prevalence of ciprofloxacin resistance has been reported in western regions of the United States, while a higher prevalence of ciprofloxacin and penicillin resistance has been observed in the Southeast.

Compared to the Midwest, the southeastern United States had a 6.7- and 7.6-fold greater prevalence of gonorrhea with ciprofloxacin and penicillin resistance, respectively. Western regions of the United States had a 14-fold higher prevalence of ciprofloxacin-resistant gonorrhea.

Among the health factors considered in the study, a positive association was observed between the prevalence of human immunodeficiency virus (HIV) infection and the prevalence of gonorrhea with ciprofloxacin and tetracycline resistance. Percentage of the Black American, American Indian, or Alaska Native population, unemployment rates, and at least a college degree were inversely associated with the prevalence of Amr gonorrhea.

Among selected antibiotics, a higher prevalence of tetracycline resistance was associated with an increased incidence of gonorrhea.

Study limitations

The model used in the current study may not be fully specified because other relevant factors, such as partner change rate, reinfection rate, or migration, were excluded from the analysis. All are known to be associated with bacterial resistance.

Due to the lack of county-level data on antibiotic use, researchers in the current study used state data as estimates of antibiotic use in catchment areas of GISP surveillance sites. However, this variable was excluded from the main model due to high geographic and ethnic variations.

Future direction

Amr gonorrhea is more likely to occur in cities in the western or southeastern regions of the United States, in cities with high population densities, or in cities with high prevalence of HIV. These observations provide important insight into specific factors that may increase the risk of AMR gonorrhea in cities that are not included in surveillance systems, allowing researchers to identify cities at higher risk of AMR gonorrhea.

Inconsistent associations were observed between population-level health insurance coverage and the prevalence of ciprofloxacin, penicillin, and tetracycline resistance. Therefore, future studies with more recent GISP data are needed to justify these inconsistencies across antibiotics.

The study results highlight the importance of continued surveillance efforts to ensure effective treatment of gonorrhea patients at higher risk of bacterial resistance. GISP may consider monitoring these cities more closely and revising treatment guidelines in response to an induction in the prevalence of bacterial resistance.

Sources: