Vol.59 No.1 January 2011
Susceptibility of male gonococcal urethritis-isolated Neisseria gonorrhoeae against antibacterial agents and penA gene analysis of strains with reduced cefixime susceptibility
1)Department of Infection Control, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, Japan
2)Department of Urology, Jikei University School of Medicine, Aoto Hospital
3)Department of Urology, JR Tokyo General Hospital
4)Kuden Clinic
5)Hosobe Clinic
6)Research Laboratories, Toyama Chemical Co., Ltd.
Abstract
From about 2000, male gonococcal urethritis-derived Neisseria gonorrhoeae strains tend to show reduced susceptibility to oral cephem agents such as cefixime(CFIX). Many reports find the base sequence of the structural gene penA of penicillin binding protein(PBP) 2 to be mosaic in these strains.
We measured the susceptibility of 2009 fresh clinical strains isolated in the Tokyo metropolitan area to antibacterial agents, using CLSI broth microdilution method, and comparing it to results for strains isolated in 1999, 2003, and 2006. We also analyzed the base penA gene sequence in 10 strains newly confirmed to show reduced CFIX susceptibility.
Results showed that 96.6% or more of strains isolated before 2006 were susceptible to CFIX, compared to only 47.4% of 2009 strains. Although 100% of strains were susceptible to cephem injection, such as ceftriaxone, the distribution of minimum inhibitory concentrations(MICs) of these agents indicated a trend toward reduced susceptibility. The susceptibility to spectinomycin was 100%. The susceptibility of isolates to levofloxacin in 2009 was 5.3%, suggesting further resistance (17.0%: isolates in 2006). For the penA gene of strains with reduced CFIX susceptibility, we analyzed mosaic-like penA gene changes. As a result, the mosaic-like penA gene similar to other Neisseria genus species, such as Neisseria perflava/sicca or Neisseria flavescens, were recognized as in past reports. These mosaics-like changes were divided into two patterns, with or without a mosaic variation after PenA, A549. This mosaic variation was almost the same as we reported. All agents recommended in guidelines by the Japanese Society for Sexually Transmitted Diseases showed susceptibility of 100%, but a trend toward reduced N. gonorrhoeae susceptibility to cephem antibiotics is continuing, suggesting the necessity for ongoing observation.
Key word
mosaic, penA, susceptibility, cefixime, Neisseria gonorrhoeae
Received
August 30, 2010
Accepted
September 17, 2010
Jpn. J. Chemother. 59 (1): 17-24, 2011
