Prevalence and Molecular Characterization of Pharyngeal Gonorrhea in Korean Men With Urethritis

Pharyngeal infection is more difficult to diagnose and treat than genital or rectal infection and can act as a reservoir for gonococcal infection. We determined the prevalence of pharyngeal gonorrhea in Korean men with urethritis and analyzed the molecular characteristics and antimicrobial susceptibility of the isolates.

Seventy-two male patients with symptoms of urethritis who visited a urology clinic in Wonju, Korea, between September 2016 and March 2018 were included. Urethral and pharyngeal gonococcal cultures, antimicrobial susceptibility testing, Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST), and multiplex real-time PCR (mRT-PCR) were performed.

Among the 72 patients, 59 tested positive for gonococcus by mRT-PCR. Of these 59 patients, 18 (30.5%) tested positive in both the pharynx and urethra, whereas 41 tested positive only in the urethra. NG-MAST was feasible in 16 out of 18 patients and revealed that 14 patients had the same sequence types in both urethral and pharyngeal specimens, whereas two patients exhibited different sequence types between the urethra and pharynx. Of the 72 patients, 33 tested culture-positive. All patients tested positive only in urethral specimens, except for one patient who tested positive in both. All culture-positive specimens also tested positive by mRT-PCR. All isolates were susceptible to azithromycin and spectinomycin, but resistance rates to ceftriaxone and cefixime were 2.9% and 14.7%, respectively.

The prevalence of pharyngeal gonorrhea in Korean men with gonococcal urethritis is as high as 30.5%, highlighting the need for pharyngeal screening in high-risk groups. Ceftriaxone is the recommended treatment for pharyngeal gonorrhea.