Sitafloxacin showed MICs of less than or equal to 0.5 g/ml against 105 isolates of Helicobacter pylori, including 44 isolates with mutations in the gyrA gene. The highest MICs for garenoxacin and levofloxacin were 8 and 64 times, respectively, higher than the highest MICs observed for sitafloxacin.The guidelines for the management and treatment of Helicobacter pylori infections established by the European Helicobacter Study Group Third Masstricht Consensus Report recommend an eradication antimicrobial chemotherapy consisting of amoxicillin, clarithromycin, and a proton pump inhibitor alone or in combination with metronidazole and clarithromycin (10). On the other hand, a trend toward increased clarithromycin resistance in Japan has been reported (8); furthermore, high metronidazole resistance rates associated with H. pylori eradication failure have been seen in the United States, Europe, and Asia with the exception of Japan (11). In the search for alternative eradication treatment regimens, it has been recently reported in the United States and Europe that levofloxacin may be efficacious in H. pylori eradication therapy (7, 13). At the same time, the increased use of levofloxacin-based eradication regimens has led to increasing resistance to levofloxacin in H. pylori as a result of mutations in the quinolone resistance-determining region (QRDR) of the gyrA gene correlating with the decreased effectiveness of levofloxacin in eradication regimens (16). Sitafloxacin is a recently developed fluoroquinolone with wide-spectrum activity, ranging from gram-positive cocci to gram-negative bacilli (1, 15). We studied the effect of mutations in the gyrA gene and its impact on the antimicrobial activity of sitafloxacin in H. pylori.(This study was presented at the 48th Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, DC, 25 to 28 October 2008.)A total of 105 H. pylori isolates were recovered from the gastric mucosa of patients presenting with gastroduodenal diseases in health care facilities in Japan between 2004 and 2005. Of the 105 patients, 57 (54.3%) were males and 48 (45.7%) were females, and the average age was 57.9 years (range in age from 21 to 84). None of the patients had previously undergone eradication therapy. The spectrum of peptic ulcers included 39 (37.1%) cases of chronic gastritis, 21 (20.0%) gastric ulcers, 18 (17.1%) duodenal ulcers, 9 (8.6%) gastric cancers, 8 (7.6%) gastroduodenal ulcers, and 10 (9.5%) cases with other causes or an unspecified diagnosis. Only one isolate per patient was included among the 105 isolates.Susceptibilities to sitafloxacin (Daiichi Sankyo, Japan), garenoxacin [a novel des-fluoro(6)quinolone (Astellas, Japan) (6)], and levofloxacin (Daiichi Sankyo, Japan) were determined by agar dilution method according to CLSI guidelines by using drugs with known potency (4, 5). The agar dilution method was performed by serial twofold dilution on MuellerHinton agar (Becton Dickinson, MD) with 5% sheep blood using 1 to 3 l of a McFarland 2.0-adjusted inoculum and

␤-Lactamase-negative ampicillin-resistant (BLNAR) isolates of Haemophilus influenzae have been emerging in some countries, including Japan. The Clinical and Laboratory Standards Institute has only a susceptible MIC breakpoint (<1 g/ml) for piperacillin-tazobactam and a disclaimer comment that BLNAR H. influenzae should be considered resistant, which was adapted without presentation of data. In addition, fluoroquinoloneresistant H. influenzae isolates have recently been occasionally reported worldwide. To address these problems, we examined susceptibilities to ␤-lactams, including piperacillin-tazobactam, and ciprofloxacin by microdilution and disk diffusion (only for piperacillin-tazobactam) methods, against a total of 400 recent H. influenzae clinical isolates, including 100 ␤-lactamase-negative ampicillin-susceptible, ␤-lactamase-positive ampicillinresistant, BLNAR, and ␤-lactamase-positive amoxicillin-clavulanate-resistant (BLPACR) isolates each. BLNAR and BLPACR isolates were tested by PCR using primers that amplify specific regions of the ftsI gene. We also detected mutations in quinolone resistance-determining regions (QRDRs) by direct sequencing of the PCR products of DNA fragments. Among ␤-lactams, piperacillin-tazobactam exhibited potent activity against all isolates of H. influenzae, with all MICs at <0.5 g/ml (susceptible). A disk diffusion breakpoint for piperacillin-tazobactam of >21 mm is proposed. We confirmed that all BLNAR and BLPACR isolates had amino acid substitutions in the ftsI gene and that the major pattern was group III-like (87.5%). One ciprofloxacin-resistant isolate (MIC, 16 g/ml) and 31 ciprofloxacin-susceptible isolates (MICs, 0.06 to 0.5 g/ml) had amino acid changes in their QRDRs. Piperacillin-tazobactam was the most potent ␤-lactam tested against all classes of H. influenzae isolates. It is possible that fluoroquinolone-resistant H. influenzae will emerge since several clinical isolates carried mutations in their QRDRs.

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We evaluated the automated VITEK 2 system (bioMé rieux) for antimicrobial susceptibility testing of vancomycin-resistant Enterococcus (VRE). The results obtained with the VITEK 2 system were compared to those obtained using two NCCLS reference methods. The VITEK 2 system produced MICs for penicillin G, erythromycin and vancomycin that were very similar to those of the reference agar-dilution test with all results being within a twofold dilution. When MICs of teicoplanin for these isolates were measured by the agar-dilution method and VITEK 2 system, there was one 'very major' error and seven 'minor' errors. There were no 'major' errors for any of the antibiotics tested. When the results obtained by the micro broth-dilution method were compared with those obtained by the VITEK 2 system, there was one 'very major' error for teicoplanin by the VITEK 2 system, as was the case with the agar-dilution method. There were two 'minor' errors for erythromycin and seven 'minor' errors for teicoplanin. There were no 'major' errors for any of the antibiotics tested. The 35 VRE strains identified phenotypically by the VITEK 2 Advanced Expert System included nine of Enterococcus faecalis and 23 of Enterococcus faecium. Neither Enterococcus avium nor Enterococcus hirae were identified. A total of 32 phenotypes were classified into 22 VanA and 10 VanB strains. PCR genotyping demonstrated 23 vanA þ and nine vanB þ strains. There were differences between the VITEK 2 system results and those of PCR. Overall, 54 . 3 % of the test results were obtained within 7 h. All MIC values for the 35 VRE isolates were determined within 13 h of completing incubation. The VITEK 2 system is a simple method for accurately detecting vancomycinresistant strains of Enterococcus and can be used to rapidly determine MICs.