Issue: June 2017
May 09, 2017
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Researchers identify largest cluster of linked N. meningitidis urethritis cases

Issue: June 2017
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Researchers said a cluster of urethritis cases caused by Neisseria meningitidis in Columbus, Ohio, was the largest ever recorded in which all the isolates were linked.

Dozens of related cases occurred primarily in heterosexual black men and were identified incidentally through routine screening for urethral gonorrhea at an STD clinic in the city, according to a study in Clinical Infectious Diseases.

Jose A. Bazan, DO, assistant professor in the department of internal medicine at the Ohio State University College of Medicine and medical director of the sexual health clinic at Columbus Public Health, and colleagues studied 75 cases between Jan. 1 and Nov. 18, 2015, and discovered a distinct N. meningitidis clade among mostly young men who reported recent oral sex with a female partner, a risk factor for infection.

“The emergence of this cluster raises important questions about the ability of this [N. meningitidis] clade to cause urogenital disease and spread sexually similar to [N. gonorrhea],” Bazan and colleagues wrote.

Although N. meningitidis rarely infects the urogenital tract, men receiving fellatio from partners with nasopharyngeal colonization can be infected. Among the 75 patients in the study, 96% reported oral sex with a woman in the last 12 months, Bazan and colleagues said. The researchers reported being surprised by the apparent lack of involvement of MSM in the cluster given that nasopharyngeal N. meningitidis colonization is common among such patients and the MSM who attended the STD clinic in Columbus reported frequently engaging in fellatio.

N. meningitidis urethritis can be misidentified as gonorrhea, a more common STD, Bazan and colleagues said. Indeed, most patients in their study were presumed to have N. gonorrhea, and 95% were treated with a ceftriaxone-based regimen, which also appears to be effective against N. meningitidis.

Bazan and colleagues used biochemical and PCR testing to confirm cases of N. meningitidis urethritis and found that all the isolates were molecularly linked. The median age of the patients was 31 years, and they reported a median of two sex partners in the last 3 months. Approximately 81% of the patients were black, 99% were heterosexual, 91% had urethral discharge and 15% were coinfected with chlamydia.

The researchers said urethritis caused by N. meningitidis is historically rare and was not documented at the Columbus STD clinic in 2014, and that it was “theoretically possible” — although unlikely — that the 2015 cluster of urethritis cases was caused by an organism other than N. meningitidis.

As of December 2016, Bazan and colleagues had identified an additional 47 patients in what they described as an “ongoing” cluster. They said patients continued to receive treatment consistent with a diagnosis of gonorrhea.

“Additional research into this [N. meningitidis] clade should focus on the pathogenesis and prevalence of urogenital and extragenital infections, genotypic and phenotypic determinants that may enhance urogenital infection, and modes of sexual transmission in men and women,” the researchers wrote. – by Gerard Gallagher

Disclosure: The researchers report no relevant financial disclosures.