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Objectives: To evaluate the efficacy of 1 g ceftriaxone in the treatment of urethritis, cervicitis and pharyngeal infection caused by Neisseria gonorrhoeae (N. gonorrhoeae) including the oral cephem-resistant strain with chimera penicillin-binding protein 2 (PBP-2) (cefozopran-resistant N. gonorrhoeae, CZRNG)., Methods: From September 2004 to November 2006, 67 patients (27 male and 40 female) who had genital infection and/or pharyngeal infection caused by N. gonorrhoeae were enrolled in this study at five participating centers in Japan. To detect the chimera PBP-2 gene, polymerase chain reaction (PCR) was performed using established primers against the altered penA of CZRNG isolates. All patients received a single 1 g dose of ceftriaxone. Efficacy was evaluated only in those who returned for examination and culture for N. gonorrhoeae between 3 and 14 days after the treatment., Results: CZRNG isolates detected by PCR accounted for 41.7% (20/48) of urogenital infections and 60.0% (15/25) of pharyngeal infections in the treatment efficacy evaluable cases. 37 of 39 CZRNG isolates (94.9%) were multi-drug resistant isolates that had simultaneous resistance to penicillin, tetracycline, and ciprofloxacin. Nineteen patients had N. gonorrhoeae isolates in the urogenital area and pharynx simultaneously. Ceftriaxone treatment eradicated all N. gonorrhoeae isolates from 48 patients with genitourinary infection and 25 patients with pharyngeal infection., Conclusions: We report for the first time that ceftriaxone is effective in patients with gonococcal urethritis, cervicitis, and pharyngeal infection caused by CZRNG that has chimera PBP-2.

The microbiological and clinical efficacies of a single-dose treatment of 2g spectinomycin administered by intramuscular injection were studied in 365 male patients with gonococcal urethritis. A total of 210 patients (57.5%) could be evaluated, in 28 (13.3%) of whom Chlamydia trachomatis was detected in addition to Neisseria gonorrhoeae. A single dose of spectinomycin eradicated N. gonorrhoeae in 203 (96.7%) of the 210 patients. Among patients in whom N. gonorrhoeae was eradicated, pyuria and clinical symptoms, respectively, disappeared in 92.6% (162/175) and 98.9% (173/175) of patients without concomitant C. trachomatis and in 78.6% (22/28) and 71.4% (20/28) with C. trachomatis. Minimal inhibitory concentrations (MICs) were determined for four of seven N. gonorrhoeae strains isolated after spectinomycin treatment. MICs to spectinomycin for three of the four isolates were 16 microg/mL (defined as susceptible) and the MIC of the other isolate was 128 microg/mL, indicating resistance. The resistant isolate was a multidrug-resistant strain with resistance to ciprofloxacin, tetracycline, penicillin and cephalosporins, except for ceftriaxone. The results of this study indicate that a single-dose treatment using 2g spectinomycin is effective in treating patients with urethritis caused by N. gonorrhoeae, even in the era of multidrug-resistant N. gonorrhoeae.

A single dose of cefodizime (CDZM), ceftriaxone (CTRX), or spectinomycin (SPCM) is recommended for the treatment of gonococcal urethritis or uterine cervicitis in the era of multidrug-resistant Neisseria gonorrhoeae; namely, cefozopran-resistant N. gonorrhoeae (CZRNG). N. gonorrhoeae pharyngeal infection is not so rare in Japan; however, the proper treatment regimen for this infection is not clear. We previously found that a single dose of CDZM completely eradicated multidrug-resistant N. gonorrhoeae in patients with urethritis and uterine cervicitis, so we tried a single 1.0-g dose of CDZM for the treatment of N. gonorrhoeae pharyngeal infection, including infections with CZRNG. The eradication rate of N. gonorrhoeae from the pharynx was 63.0% with a single 1.0-g dose of CDZM, while the rate for CZRNG with the same dose of CDZM was 38.5%. N. gonorrhoeae was completely eradicated from the pharynx when patients received one or two additional doses of CDZM. Therefore, we concluded that two to three doses of CDZM were necessary for the treatment of N. gonorrhoeae pharyngeal infection including infection with CZRNG.

Cefodizime (CDZM) has strong antimicrobial activity to Neisseria gonorrhoeae in vitro. However, multidrug-resistant N. gonorrhoea emerged and has been increasing in Japan. To know the effectiveness of CDZM on gonococcal urethritis and uterine cervicitis even in the era of multidrug-resistant N. gonorrhoeae, a clinical trial of single-dose therapy of CDZM for gonococcal urethritis and uterine cervicitis was conducted. N. gonorrhoeae was eradicated from 100% of patients with gonococcal urethritis and uterine cervicitis by a single dose of CDZM. In conclusion, CDZM is one of most suitable drugs for the treatment of gonococcal genital infection in the era of multidrug-resistant N. gonorrhoeae.

We have previously reported that the Neisseria gonorrhoeae isolates from clinical failure cases treated with cefdinir and aztreonam, beta-lactams exhibited high MICs. These resistant isolates were clearly separated from the isolates exhibiting a low level of resistance to beta-lactams as shown by the MIC distribution of cefozopran. Restriction fragment length polymorphism DNA typing revealed that the outbreak of cefozopran-resistant isolates in Kitakyushu, Japan, occurred as a result of clonal spread.

Regarding Neisseria gonorrhoeae, the National Committee for Clinical Laboratory Standards (NCCLS) has not defined the breakpoint minimum inhibitory concentration (MIC) for expanded spectrum cephems such as cefpodoxime and ceftizoxime, because of the absence of resistant strains to these antibiotics. To date, in gonococcal urethritis, after treatment with third generation cephems and aztreonam, clinical failures caused by resistant N. gonorrhoeae strains have not been reported. However, we experienced two clinical failures in patients with gonococcal urethritis treated with cefdinir and aztreonam. N. gonorrhoeae isolates from these two patients showed high-level MICs to these agents. The MIC of cefdinir was 1 microg/ml for both strains and that of aztreonam was 8 microg/ml for both strains, while the MICs of other beta-lactams were also higher than the NCCLS value, except for ceftriaxone, for which the MIC was 0.125 microg/ml for both strains. Moreover, the MICs of fluoroquinolones, tetracyclines, and erythromycin against these two isolates were higher than the NCCLS susceptibility value. These isolates were susceptible to spectinomycin. In N. gonorrhoeae, the emergence of these beta-lactam-resistant isolates is of serious concern. However, a more serious problem is that these isolates were already resistant to non-beta-lactam antimicrobials. In Japan, ceftriaxone has not been permitted for clinical use against gonococcal infections. Therefore, in Japan, patients with gonococcal urethritis caused by these resistant N. gonorrhoeae strains should be treated with cefodizime or spectinomycin.