Persistence of Neisseria gonorrhoeae DNA following treatment for pharyngeal and rectal gonorrhea is influenced by antibiotic susceptibility and reinfection.

BACKGROUND

To guide interpretation of gonorrhea tests of cure using nucleic acid amplification testing, this study examined the persistence of Neisseria gonorrhoeae DNA following treatment for pharyngeal and rectal gonorrhea.

METHODS

Men who had sex with men diagnosed with pharyngeal or rectal gonorrhea underwent swabbing from the pharynx or rectum 7 and 14 days following treatment. Repeat testing for N. gonorrhoeae was undertaken using real-time polymerase chain reaction (PCR) assays targeting the opa gene and porA pseudogene.

RESULTS

One hundred pharyngeal and 100 rectal gonorrhea infections in 190 men were included. For pharyngeal gonorrhea, positivity of N. gonorrhoeae DNA on both PCR assays was present at days 7 or 14 in 13% (95% confidence interval [CI], 6.4%-19.6%) and 8% (95% CI, 2.7%-13.3%), respectively. For rectal gonorrhea, DNA positivity was present in 6% (95% CI, 1.4%-10.7%) and 8% (95% CI, 2.7%-13.3%), respectively. Among 200 baseline pharyngeal and rectal isolates, there were 10 with ceftriaxone minimum inhibitory concentration (MIC) ≥0.06 mg/L and azithromycin MIC ≥0.5 mg/L, of which 3 (30%) had DNA detected at day 14; among the 190 isolates with lower ceftriaxone and azithromycin MICs, only 13 (7%) had persistent DNA (odds ratio, 5.8 [95% CI, 1.3-25.4]; P = .019). One man initially infected with N. gonorrhoeae multiantigen sequence type 2400 had type 4244 infection at day 14, indicating reinfection.

CONCLUSIONS

Pharyngeal and rectal gonorrhea DNA persisted in 8% of men 14 days after treatment. Persistence was associated with elevated ceftriaxone and azithromycin MICs. Persistence can also reflect reinfection.