Comparison of Antimicrobial Susceptibilities of Pharyngeal, Rectal, and Urethral Neisseria gonorrhoeae Isolates among Men Who Have Sex with Men

Abstract

N eisseria gonorrhoeae has developed resistance to multiple antimicrobials that were previously recommended for treatment, including penicillin, tetracycline, and ciprofloxacin (1). Currently, the only recommended treatment for gonorrhea in Europe and the United States is dual treatment with ceftriaxone and azithromycin (2, 3). However, decreases in susceptibilities to cephalosporins (4-7) and reports of cefixime and ceftriaxone treatment failures worldwide (8-10) indicate that the emergence of cephalosporin-resistant gonorrhea could be imminent. Because there are limited remaining effective therapeutic options for gonorrhea (11, 12), ceftriaxone resistance in N. gonorrhoeae would present significant challenges for individual case management and gonorrhea control in the community. As a result, surveillance of antimicrobial susceptibilities among N. gonorrhoeae strains will be increasingly critical to inform gonorrhea treatment recommendations.N. gonorrhoeae can infect the urogenital tract, rectum, and pharynx through sexual contact, and infection at extragenital sites may facilitate the acquisition or development of resistance mutations. Rectal infection and exposure to fecal lipids provide selective pressure for mutations such as those in the mtr locus, which confer resistance to hydrophobic molecules and drugs (13-16). Pharyngeal infection supplies the opportunity for genetic reassortment between N. gonorrhoeae and other Neisseria species that colonize the pharynx (17, 18). Specifically, the mosaic penA allele, a key genetic determinant associated with decreased cephalosporin susceptibility, appears to have evolved through recombination with penA genes from commensal Neisseria species (18)(19)(20). In addition, pharyngeal infections are more difficult to eradicate than urogenital or rectal infections (21,22) and are typically asymptomatic, which may provide an optimal setting for selection of resistance mutations. It is notable that the first identified N. gonorrhoeae strain with high-level resistance to ceftriaxone was isolated from the pharynx (8). Furthermore, high rates of resistance and elevated MICs are frequently observed among gay men, bisexual men, and other men who have sex with men (MSM) (7, 23), among whom extragenital infections are common (24-26).Globally, surveillance for N. gonorrhoeae antimicrobial susceptibilities is conducted mostly with urogenital isolates (5, 6, 27), and there are few published data comparing the susceptibilities of urogenital, rectal, and pharyngeal isolates. Although some reports

Susceptibility of Neisseria gonorrhoeae to Gentamicin—Gonococcal Isolate Surveillance Project, 2015–2016

“…Although some studies suggest that gonococcal antimicrobial susceptibility surveillance based on urethral isolates adequately reflects, at the population level, the susceptibilities of circulating N. gonorrhoeae strains, other studies suggest that disparities in susceptibility exist by anatomic site of infection and sex. 11,12 It may thus be prudent for future gentamicin susceptibility studies to include rectal, pharyngeal, and cervical isolates. Moreover, GISP participants do not comprise a nationally representative sample of all persons with gonorrhea; only men presenting at participating STD clinics with diagnosed urethral gonorrhea are included.…”

Neisseria gonorrhoeaeAntimicrobial Susceptibility Surveillance — The Gonococcal Isolate Surveillance Project, 27 Sites, United States, 2014

“…Antimicrobial susceptibility in isolates from MSW has been demonstrated to be a reliable proxy of antimicrobial susceptibility in isolates from women (13,14). In addition, population-level susceptibility of urethral isolates from MSM has been similar to that of population-level susceptibility of pharyngeal and rectal isolates from this population (15).…”

Epidemiological, behavioural, and clinical factors associated with antimicrobial-resistant gonorrhoea: a review

“…MSM can have gonococcal infection in the pharynx and rectum, resulting from oral and anal sexual intercourse, as well as the urethra 6 , 48 . Pharyngeal and rectal gonorrhoea are usually asymptomatic and can remain untreated if these anatomical sites are not sampled 49 . Anatomical site of infection is considered as a risk factor below.…”