Vol.66 No.2 March 2018
What antimicrobials should we select for non-gonococcal urethritis?
1)Department of Urology, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka, Japan
2)Department of Urology, Federation of National Public Services Affiliated Personal Mutual Aid Associations, Shin-Kokura Hospital
Abstract
Non-gonococcal urethritis (NGU) is a type of urethritis in which Neisseria gonorrhoeae is not detected from the patients' urine or urethral specimens and is caused by several microorganisms. Chlamydia trachomatis is detected from half of male patients with urethritis and is the most common organism. Mycoplasma genitalium is the second most common organism and is detected from 15%-25% of patients with urethritis. The antimicrobial therapies which are effective for C. trachomatis have been used for NGU in Japan. Macrolide, tetracycline or fluoroquinolone have good antimicrobial activities for C. trachomatis and these agents has been also used for NGU. However, the antimicrobial resistance of M. genitalium has increased remarkably worldwide and we have found that some patients with M. genitalium urethritis are hard to treat with any antimicrobials.
The three antimicrobials such as macrolide, tetracycline or fluoroquinolone were effective in the treatment of chlamydial urethritis in clinical trials. Some antimicrobial resistant C. trachomatis strains were reported, but had not spread. In contrast to this, the treatment for M. genitalium urethritis is becoming difficult according to a decrease in the antimicrobial susceptibility of M. genitalium. M. genitalium was originally sensitive to azithromycin (AZM) and clinical trials with AZM showed good microbiological efficacy for M. genitalium urethritis. However, treatment-failure cases by AZM in M. genitalium urethritis have been reported. The mechanisms of macrolide-resistance is point mutation on domain V of 23S rRNA which is the active site of macrolide. The mutation on 23S rRNA in M. genitalium genomes has been detected in many countries including Japan (the prevalence is over 40%). For macrolide-resistant M. genitalium, moxifloxacin (MFLX) or sitafloxacin (STFX) are effective. However, treatment-failure cases with MFLX have been reported and isolated MFLX-resistant M. genitalium strains have been isolated.
Considering the spread of macrolide-resistant M. genitalium, we cannot continue to use AZM as the first line treatment for NGU. The effectiveness of both doxycycline (DOXY) and AZM which are effective against C. trachomatis is not currently higher for M. genitalium urethritis. To maintain the AZM against pathogens for sexually transmitted infections, I recommend the tetracycline family such as DOXY 200 mg/day for 7 days or minocycline (MINO) 200 mg/day for 7 days as the first line treatment for NGU. The treatment-failure cases should be treated with STFX 200 mg/day for 7 days. However, we have to clarify some issues; the tests for detecting M. genitalium are not covered by the national health insurance; there is not so much evidence regarding the efficacy of MINO for M. genitalium infection; we have to consider the adverse effects of MINO; and effective therapies for macrolide and MFLX-resistant M. genitalium have not established.
Key word
non-gonococcal urethritis, C. trachomatis, M. genitalium, azithromycin, doxycycline, minocycyline, sitafloxacin
Received
October 10, 2017
Accepted
December 7, 2017
Jpn. J. Chemother. 66 (2): 173-184, 2018
