Kyoko Hatazaki

Remarkable increase in fluoroquinolone-resistant Mycoplasma genitalium in Japan

OBJECTIVES We determined the prevalence of macrolide and fluoroquinolone resistance-associated mutations in Mycoplasma genitalium DNA specimens from men with non-gonococcal urethritis (NGU) and analysed their effects on antibiotic treatments of M. genitalium infections. METHODS In this retrospective study, we examined antibiotic resistance-associated mutations in the 23S rRNA, gyrA and parC genes of M. genitalium and the association of the mutations with microbiological outcomes of antibiotic treatments in men with M. genitalium-positive NGU. RESULTS No macrolide resistance-associated mutations in the 23S rRNA gene were observed in 27 M. genitalium DNA specimens in 2011 and in 24 in 2012. However, 5 of 17 in 2013 had 23S rRNA mutations. Three of 15 in 2011, 6 of 19 in 2012 and 8 of 17 in 2013 had fluoroquinolone resistance-associated alterations in ParC. Three in 2013 had both the antibiotic resistance-associated alterations coincidentally. In two men with M. genitalium harbouring 23S rRNA mutations, the mycoplasma persisted after treatment with a regimen of 2 g of extended-release azithromycin (AZM-SR) once daily for 1 day. All nine men with mycoplasma harbouring ParC alterations were microbiologically cured with a regimen of 100 mg of sitafloxacin twice daily for 7 days. CONCLUSIONS Macrolide- or fluoroquinolone-resistant M. genitalium appears to be increasing, and the increase in fluoroquinolone-resistant mycoplasmas is especially remarkable in Japan. Mycoplasmas harbouring 23S rRNA mutations would be resistant to the AZM-SR regimen, but those harbouring ParC alterations would still be susceptible to the sitafloxacin regimen.

Antimicrobial Susceptibility of neisseria gonorrhoeae in Japan from 2000 to 2015

Background Gonococcal infections are difficult to treat because of their multidrug antimicrobial resistance. The outbreak of antimicrobial-resistant Neisseria gonorrhoeae has begun in Asia and particularly in Japan. Therefore, it is very important that we understand the trend of antimicrobial resistance of N. gonorrhoeae in Asia including Japan. Our surveillance of the antimicrobial susceptibility of N. gonorrhoeae began in 2000 under the guidance of the Department of Urology, Gifu University. We report our surveillance data from 2000 to 2015. Methods We collected N. gonorrhoeae strains isolated from patients with gonococcal infections who visited our cooperating medical institutions in Japan from 2000 to 2015. MICs of penicillin G, cefixime, ceftriaxone, tetracycline, spectinomycin, azithromycin, and levofloxacin were determined by the agar dilution method approved by the Clinical and Laboratory Standards Institute. Results From 2000 to 2015, 2471 isolates of N. gonorrhoeae were collected in Japan. High rates of nonsusceptibility to penicillin, tetracycline, levofloxacin, cefixime, and azithromycin were shown. Around 5% to 10% of the strains isolated had a 0.25-mg/L MIC of ceftriaxone in each year, and 6 strains (0.24%) with a 0.5-mg/L MIC of ceftriaxone were isolated throughout the study period. Approximately 5% to 10% of the strains were resistant to each of ceftriaxone, azithromycin, and levofloxacin according to European Committee on Antimicrobial Susceptibility Testing breakpoints, and the rate has not increased significantly. Conclusions From this study and previous pharmacodynamic analyses, a single 1-g dose of ceftriaxone is recommended to treat gonorrhea. As strains with high-level ceftriaxone resistance continue to spread, higher doses of ceftriaxone in monotherapy or multiple doses of ceftriaxone should be considered.

Novel penA mutations identified in Neisseria gonorrhoeae with decreased susceptibility to ceftriaxone isolated between 2000 and 2014 in Japan

OBJECTIVES We examined four clinical strains of Neisseria gonorrhoeae (GU030113, GU110095, GU110332 and GU110362) isolated between 2000 and 2014 in Japan, exhibiting ceftriaxone MICs of 0.5 mg/L, for mutations of the genes associated with penicillin resistance. METHODS The penA, mtrR, porB1b (penB), ponA and pilQ genes of the strains were sequenced. PBP2s of the strains were aligned to the PBP2s associated with decreased susceptibility to oral cephalosporins, and PBP2s of previously reported strains with decreased susceptibility to ceftriaxone. RESULTS GU030113 had PBP2 pattern X with an additional substitution of A502T. GU110095 had PBP2 pattern XXVII. GU110332 had PBP2 pattern XXXIV with an additional substitution of P552S. GU110362 had PBP2 composed of pattern X (amino acid positions 1-291) and pattern V (amino acid positions 292-576). GU030113, GU110095 and GU110332 had deletion of A in the mtrR promoter, G120K and A121D or A121N in PorB1b and L421P in PBP1. GU110362 had A40D in the repressor of MtrR and L421P in PBP1. The strains did not have mutations of pilQ1 and pilQ2. CONCLUSIONS Addition of A502T to PBP2 pattern X in GU030113 and of P552S to PBP2 pattern XXXIV in GU110332 would possibly contribute to decreased susceptibility to ceftriaxone. In GU110095 and GU110362, it was suggested that, in addition to their altered PBP2s, the enhanced efflux pump, reduced permeability in the outer membrane, another altered target of β-lactams and/or other mechanisms not identified in the present study might contribute to decreased susceptibility.

Microbiological efficacy and tolerability of a single-dose regimen of 1 g of ceftriaxone in men with gonococcal urethritis

OBJECTIVES We treated men with gonococcal urethritis with a single-dose regimen of 1 g of ceftriaxone, which is recommended as the first-line treatment for gonorrhoea in Japan, to determine its microbiological outcomes and tolerability. METHODS We enrolled 255 men with gonococcal urethritis and treated them with a single-dose regimen of 1 g of ceftriaxone. We evaluated its microbiological outcomes and tolerability. We also determined ceftriaxone MICs for pretreatment isolates of Neisseria gonorrhoeae collected from the patients. RESULTS The microbiological efficacy of the ceftriaxone regimen, which was determined between 5 and 9 days after treatment in 111 men based on the Japanese guideline for clinical research on antimicrobial agents in urogenital infections, was 100%. In the 194 men who returned to the clinic between 2 and 41 days after treatment, 191 (98.5%; 95% CI 96.8%-100%) were negative for N. gonorrhoeae after treatment. Ceftriaxone MICs determined for 136 pretreatment isolates obtained from these 194 men ranged from 0.001 to 0.25 mg/L. One isolate persisting after treatment exhibited a ceftriaxone MIC of 0.008 mg/L. For two isolates persisting after treatment, ceftriaxone MICs were not determined. Seven adverse events were observed in 7 (3.2%) of the 220 men treated with the ceftriaxone regimen. Four men had diarrhoea classified as grade 1. Three had urticaria during ceftriaxone administration, with one event classified as grade 1 and two events classified as grade 3. CONCLUSIONS A single-dose regimen of 1 g of ceftriaxone was microbiologically effective against gonococcal urethritis and was safe and tolerable.

haemophilus influenzae : Its Pathogenic Roles, Responses to Antimicrobial Chemotherapies, and Antimicrobial Susceptibilities Isolated From Men With Acute Urethritis: Its Pathogenic Roles, Responses to Antimicrobial Chemotherapies, and Antimicrobial Susceptibilities

Background There have been few comprehensive studies on Haemophilus influenza–positive urethritis. Methods In this retrospective study, we enrolled 68 men with H. influenzae–positive urethritis, including coinfections with Neisseria gonorrhoeae, Chlamydia trachomatis, and/or genital mycoplasmas: 2, 3, 20, and 43 treated with ceftriaxone, levofloxacin, sitafloxacin, and extended-release azithromycin (azithromycin-SR), respectively. We assessed microbiological outcomes in 54 men and clinical outcomes in 46 with H. influenzae–positive monomicrobial nongonococcal urethritis. We determined minimum inhibitory concentrations (MICs) of 6 antimicrobial agents for 59 pretreatment isolates. Results H. influenzae was eradicated from the men treated with ceftriaxone, levofloxacin, or sitafloxacin. The eradication rate with azithromycin-SR was 85.3%. The disappearance or alleviation of urethritis symptoms and the decreases in leukocyte counts in first-voided urine were significantly associated with the eradication of H. influenzae after treatment. For the isolates, ceftriaxone, levofloxacin, sitafloxacin, azithromycin, tetracycline, and doxycycline MICs were ⩽0.008–0.25, 0.008–0.5, 0.001–0.008, 0.12–1, 0.25–16, and 0.25–2 &mgr;g/mL, respectively. The azithromycin MICs for 3 of 4 strains persisting after azithromycin-SR administration were 1 &mgr;g/mL. H. influenzae with an azithromycin MIC of 1 &mgr;g/mL increased chronologically. Conclusions H. influenzae showed good responses to the chemotherapies for urethritis. The significant associations of the clinical outcomes of the chemotherapies with their microbiological outcomes suggested that H. influenzae could play pathogenic roles in urethritis. All isolates, except for one with decreased susceptibility to tetracyclines, were susceptible to the examined agents. However, the increase in H. influenzae with an azithromycin MIC of 1 &mgr;g/mL might threaten efficacies of azithromycin regimens on H. influenzae–positive urethritis.