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MP11-04: Meningococcal urethritis. A pitfall in the conventional diagnostic process based on the nucleic acid amplification test in men with suspected gonococcal urethritis

Friday, May 12
1:00 PM - 3:00 PM
Location: BCEC: Room 151

Presentation Authors: Munekado Kojima*, Yasufumi Yada, Kazuhiko Yosihida, Yosimasa Hayase, Nagoya, Japan

Introduction: Neisseria meningitidis is a Gram-negative diolococcus like Neisseria gonorrhoeae, and has been reportedly a pathogen of male urethritis. Unfortunately, in the current situation in which a nucleic acid amplification test (NAAT) is used exclusively for the diagnosis of N. gonorrhoeae, N. meningitidis is inevitably missed because the conventionally used diagnostic tests such as microscopic examination of urethral smear and NAAT are unable to distinguish these two microorganisms. The present study was conducted to reveal the prevalence of N. meningitidis as a pathogen of male urethritis using urine culture as a diagnostic test in relation to microscopic examination of urethral smear and NAAT for N. gonorrhoeae.

Methods: Between December 2013 and October 2016, a total of 480 male patients with suspected gonococcal urethritis based on symptoms and urethral discharge underwent microscopic examination of urethral smear stained with methylene blue. The presence of polymorphonuclear leucocytes containing dipolococci was judged to suggest gonococcal urethritis. In all patients, first-voided urine samples were tested for N. gonorrhoeae by NAAT and additionally also for culture of N. gonorrhoeae and N. meningitidis.

Results: As shown in the Table, among 480 patients 226 were positive for diplococci and 211 (93%) of them were also positive for N. gonorrhoeae by NAAT. Interestingly, in the remaining 15 patients with negative for N. gonorrhoeae by NAAT, 10 patients were positive for N. meningitidis as demonstrated by urine culture. Out of 254 patients with negative for diplococci, 251 (99%) were also negative for N. gonorrhoeae by NAAT. As a result, N. meningitidis was detected in 2.1% of patients with suspected gonoccocal urethritis, and 4.4% of patients with positive for diplococci by microscopic examination of urethral smear.

Conclusions: When diploccoci are positive on urethral smear but NAAT is negative for N. gonorrhoeae, N. meningitidis has to be considered as a possible pathogen of urethritis. It is to be stressed that N. meningitidis is not recognizable by conventionally used NAAT for N. gonorrhoeae, and meningococcal urethritis is a potential pitfall in the diagnosis and treatment of male urethritis.

Source Of Funding: none

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