Staphylococcus aureus surface contamination of mobile phones and presence of genetically identical strains on the hands of nursing personnel.

We investigated the genetic relatedness of Staphylococcus aureus isolates recovered from mobile phones and palms and fingers of users. Genetically identical isolates were detected from mobile phones and their user and multiple users, which is consistent with mobile phones serving as reservoirs of infection in the health care environment. These findings reinforce the need for hand hygiene prior to patient contact as the most effective intervention for preventing health care-associated infection.

[Evaluation of the BD Phoenix ID Yeast System for the Species Identification of Clinical Yeast-Like Organisms].

Most fungi isolated from patients with deep-seated mycosis are yeast-like organisms such as Candida and Cryptococcus. As their respective susceptibilities to antifungal agents can vary depending on the species, rapid identification is important for the administration of appropriate antifungal therapy. The aim of this study was to evaluate the performance of a new automated identification panel, Phoenix Yeast ID (Becton, Dickinson Diagnostics, USA) as well as the time required for identification. The identification results of 106 isolates generated by this system were then compared with those of the API 20C AUX system (SYSMEX bioMérieux Co., Ltd. Japan). Among the 106 isolates, the identification agreement between the two yeast panels was 97/106 (91.5%). Of the 9 (8.5%) discrepant identifications, 5 identification using the Phoenix Yeast ID system and 1 identification using the API 20C AUX system agreed with the genotypic identification. Genotypic identification did not agree with the Phoenix Yeast ID or API 20C AUX findings for the remaining 3 discrepant identifications. Approximately 60% of the C. albicans, C. tropicalis, and C. parapsilosis isolates were identified within 4 hours. In total, about 90% of the 4 major Candida sp. (C. albicans, C. tropicalis and C. glabrata) were identified within 8 hours. In conclusion, the Phoenix Yeast ID findings agreed well with the API 20C AUX findings. Genotypic identification of the discrepant identifications confirmed most of the Phoenix Yeast ID panel identifications. As approximately 80% of the major Candida sp. could be identified within 8 hours using the Phoenix Yeast ID identification system, our results suggest that this system is a clinically useful addition to commercially available yeast identification panels. The Phoenix Yeast ID system showed excellent concordance with genotypic identification for the classification of organisms with discrepant API 20C AUX findings.

[Bacteriological Properties of Meropenem-resistant Escherichia coli Isolated from Seven Patients within a Month].

From April to May 2014, a total of seven cases of meropenem (MEPM)-resistant Escherichia coli were isolated from the sputum specimens in 7 different patients in a community hospital. The MICs of MEPM for isolates were 8 to 32 µg/mL, whereas the MICs of imipenem (IPM) were 0.5 µg/mL or 1 µg/mL. All of the isolates possessed the metallo ß-lactamase (MBL) IMP-6 gene, and were CTX-M-2 type extended-spectrum ß-lactamase (ESBL)-producers. Pulsed-field gel electrophoresis (PFGE) patterns for the isolates were identical. At the time of specimen collection, one patient had been hospitalized for a long time and the other six patients had been comparatively recently admitted to the hospital. Of the six patients, two had been staying in the same nursing facility before admission, whereas the remaining 4 patients had no relationship with each other because they had been in separate locations. Thus, these cases were not considered to be nosocomially-acquired infection. Our findings suggest that MBL-producing E. coli has been spreading widely in the community such as in local nursing facilities.

[Decreasing Susceptibility of MRSA to Daptomycin During the Course of Treatment].

Methicillin-resistant Staphylococcus aureus (MRSA) with decreased susceptibility to daptomycin (DAP) were isolated from 4 patients receiving DAP from November 2013 to May 2014. These patients were treated with DAP for more than 7 days in all the cases. The pulsed-field gel electrophoresis (PFGE) patterns for MRSA isolates recovered from each patient pre- and post-DAP therapy were identical. Sequencing of mprF detected 2 amino acid substitutions (T345I or L826F) in 2 of the isolates. These results suggest that in vivo MRSA was resistant to DAP during DAP therapy. Furthermore, the MICs for DAP can vary by±1 dilution depending on the susceptibility test. When testing DAP susceptibility, there is a need to monitor reproducibility using different susceptibility tests, including the CLSI method.

High Prevalence of Azithromycin-Resistant Neisseria gonorrhoeae Isolates With a Multidrug Resistance Phenotype in Fukuoka, Japan.

BACKGROUND: The current guidelines recommend a combination of ceftriaxone and azithromycin as a first-line treatment of gonorrhea in the United States and Europe. Despite not being recommended as a first-line regimen in Japan, an oral 2-g dose of azithromycin did become available for gonococcal infections in 2009. Recently, the emergence of azithromycin-resistant Neisseria gonorrhoeae isolates has been reported in several countries, including Japan. METHODS: Antimicrobial susceptibility testing was performed on a total of 677 clinical isolates of N. gonorrhoeae obtained from January 2010 to December 2013 in Fukuoka, Japan. A molecular analysis by N. gonorrhoeae multiantigen sequence typing was conducted on the azithromycin-resistant isolates. RESULTS: The proportion of azithromycin-resistant isolates (minimum inhibitory concentration > 0.5 µg/mL) increased significantly from 1.8% in 2010 to 22.6% in 2013 (P < 0.001). Among 50 azithromycin-resistant isolates, 30 (60%) exhibited a resistant phenotype to multiple drugs including cefixime. The 2 predominant sequence types (STs) identified by N. gonorrhoeae multiantigen sequence typing were ST6798 (por allele 4033 and tbpB allele 110) and ST1407 (por allele 908 and tbpB allele 110) at 40.0% (20/50) and 12.0% (6/50), respectively. There was a statistically significant increase of the proportion of ST6798 from 0% (0/19) in 2010-2012 to 64.5% (20/31) in 2013 (P < 0.001). CONCLUSIONS: Over the previous 4 years, an increasing prevalence of azithromycin-resistant N. gonorrhoeae isolates with a multidrug-resistant phenotype was observed. Furthermore, the azithromycin-resistant isolates seemed to belong to 2 predominant STs. As a result, continued surveillance of gonococci resistant to antimicrobial agents, including azithromycin in Fukuoka, Japan, is necessary.

Distribution and antimicrobial susceptibility profile of extended-spectrum ß-lactamase-producing Proteus mirabilis strains recently isolated in Japan.

Here we report on the prevalence of extended-spectrum ß-lactamase (ESBL)-producing Proteus mirabilis from a nationwide antimicrobial resistance survey in different geographical regions of Japan. A total of 799 P. mirabilis isolates recovered between July 2009 and June 2010 from 314 healthcare facilities were characterised according to ESBL production, source, location and antimicrobial susceptibility pattern. ESBL production was found in 364 (45.6%) of the isolates, among which 354 (97.3%) produced CTX-M-2 group ß-lactamases. Of the 349 ESBL-producing isolates in which the inpatient or outpatient status of the source was known, 324 (92.8%) were from inpatients and 25 (7.2%) were from outpatients (P<0.05). Results of pulsed-field gel electrophoresis (PFGE) analysis performed on 66 of the ESBL-producers generated a distribution of PFGE patterns into 21 groups. Genetic relatedness was seen among isolates within a region, which is consistent with horizontal transmission. With respect to the frequency of ESBL-producers by specimen source, 12/14 (85.7%) central venous catheter specimens yielded ESBL-producing P. mirabilis compared with 159/405 (39.3%), 119/209 (56.9%), 42/77 (54.5%) and 20/49 (40.8%), respectively, for isolates from urine, sputum, decubitus ulcer and wound specimens. Among the ESBL-producers, non-susceptibility to ciprofloxacin was found in 74.2% of the ESBL-producing isolates compared with 17.7% of the ESBL-non-producing isolates. These results show that approximately one-half of the P. mirabilis isolates from clinical specimens in Japan are ESBL-producers and that the potential for concomitant fluoroquinolone resistance must also be considered.

The efficacy, safety, and pharmacokinetics of biapenem administered thrice daily for the treatment of pneumonia in the elderly.

Biapenem has been widely used to treat bacterial pneumonia; however, there is little information concerning its efficacy and safety in elderly patients. Based on pharmacokinetic-pharmacodynamic theory, administration of biapenem thrice rather than twice daily would be expected to be more effective because of longer time above the minimum inhibitory concentration. In this study, we aimed to evaluate the efficacy, safety, and pharmacokinetics of biapenem (300 mg) administered thrice daily in pneumonic patients aged 65 years or older. Biapenem was effective in 22 of 25 patients, as assessed by the improvement in clinical symptoms and/or the eradication of the causative organisms, and caused no serious adverse events. The pharmacokinetic profile was established based on simulations using a modeling program. Among 17 patients whose causative organisms were detected, time above the minimum inhibitory concentration was estimated to be 100% in 16 patients, all of whom showed clinical improvement. The results of this study confirmed the efficacy and safety of 300 mg of biapenem administered thrice daily for the treatment of pneumonia in elderly patients.

[Bactericidal activity of sitafloxacin and other new quinolones against antimicrobial resistant Streptococcus pneumoniae].

We conducted a study assess the bactericidal activity of sitafloxacin (STFX) against Streptococcus pneumoniae isolates recovered from respiratory infections including penicillin-resistant (PRSP) isolates, macrolide resistant isolates possessing mefA and ermB resistance genes and quinolone resistance isolates with mutations in gyrA or gyrA and parC. Each isolate tested was grown in hemosupplemented Mueller-Hinton broth and adjusted to approximately 10(5) CFU/ mL. Isolates were than exposed to a Cmax antimicrobial blood level that would be attained with routine antimicrobial administration and an antimicrobial level that would be expected 4 hours post-Cmax (Cmax 4hr). Bactericidal activity was measured for up to 8 hours. Excluding a subset of S. pneumoniae isolates with mutations in the quinolone resistance determining region (QRDR), all quinolones showed bactericidal activity at Cmax and Cmax 4 hr antimicrobial concentrations for up to 8 hours. Against S. pneumoniae isolates with either gyrA or gyrA and parC mutations, bactericidal activity of STFX was shown for up to 4 to 8 hours following Cmax based on a limit of detection of < 1.3 log CFU/mL. Garenoxacin (GRNX) did not showed bactericidal activity below the limit of detection for up to 8 hours with exposure to Cmax and no bactericidal activity was seen with levofloxacin. When all quinolones tested where adjusted to concentrations corresponding to their MICs, STFX showed the most rapid bactericidal activity against PRSP. This rapid bactericidal activity in PRSP is a key to the effectiveness of STFX. Our findings show that beyond inhibition of bacterial replication by blocking their DNA replication pathway and synthesis of proteins, STFX demonstrated characteristics contributing to greater bactericidal activity compared to GRNX. In conclusion, of the newer quinolones, STFX showed the strongest bactericidal activity against S. pneumoniae isolates with mutations in the QRDR which indicates that it may show the most effective clinical utility among the quinolones in respiratory infections.

[Examination of metallo-beta-lactamase-producing different types of Serratia marcescens detected in the same patient].

Metallo-beta-lactamase (MBL) producing Serratia marcescens isolate was recovered from a study patient in September, 2007 in whom MBL non-producing S. marcescens had been isolated 2 months previously. Two S. marcescens isolates recovered from the study patient showed the same pulsed-field gel electrophoresis (PFGE) pattern. Seven S. marcescens isolates were recovered from other patients in our hospital during August, 2007 and November, 2007. Five of the seven isolates produced MBL. All of the MBL-producing isolates showed the same PFGE pattern and harbored plasmids of the same size and bla(IMP) genes. The bla(IMP) genes were easily transferred to Escherichia coli DH5alpha by transformation of a plasmid purified from the MBL-producing isolate. Those transformation experiments suggested that bla(IMP) genes were encoded by the plasmid. From these observations, it was speculated that the MBL non-producing S. marcescens isolate recovered from the study patient had acquired the plasmid which encoded bla(IMP) genes and a monoclone of MBL-producing S. marcescens spread horizontally in our hospital.

In vitro activities of antimicrobial combinations against clinical isolates of Neisseria gonorrhoeae.

The Centers for Disease Control and Prevention (CDC) now recommend combination therapy with ceftriaxone 250 mg plus azithromycin (AZM) 1 g as a first-line regimen for gonorrhea because the increase of Neisseria gonorrhoeae resistant to multiple antimicrobial agents. However, reports on the in vitro activity of antimicrobial combinations against clinical isolates of N. gonorrhoeae are very rare. In the present study, a checkerboard method was utilized to examine the in vitro activity of ceftriaxone (CTRX), cefodizime (CDZM), spectinomycin (SPCM), or gentamicin (GM) in combination with AZM against 25 clinical isolates of N. gonorrhoeae. The SPCM + AZM combination demonstrated the lowest mean fractional inhibitory concentration index (FICI) of 0.69, followed by the CDZM + AZM combination (mean FICI, 0.75), the CTRX + AZM combination (mean FICI, 0.81), and the GM + AZM combination (mean FICI, 0.83). Additivity/indifference effect was detected for the SPCM + AZM combination, the CDZM + AZM combination, the CTRX + AZM combination, and the GM + AZM combination, against 96%, 72%, 92%, and 100% of the isolates, respectively. There was no antagonism for any of the antimicrobial combinations against the 25 N. gonorrhoeae isolates. These results suggest that the antimicrobial combinations may be worthy of clinical evaluation as an alternative regimen for gonococcal infections caused by antimicrobial-resistant strains.

[Antimicrobial susceptibility profile of Acinetobacter baumannii complex isolates in Japan].

The antimicrobial susceptibility of 93 Acinetobacter baumannii complex isolates from clinical specimens collected nationwide between May and October 2009 were measured by microdilution antimicrobial susceptibility testing based on CLSI M100-S20. Beta-lactamase genes, including classes B and D and ISAbal in meropenem nonsusceptible, including intermediate or resistant isolates, were detected using PCR. Rates of isolates nonsusceptible to meropenem were 18%, to ciprofloxacin 41% and to amikacin 14%. L7-L8: The rate of multidrug-resistant Acinetobacter (MDRA) isolates which were resistant to all 3 antimicrobial agents was 4.3%. MDRA isolates were classified into ST92 by multilocus sequence typing. No metallo-beta-lactamase producer was seen among the 17 meropenem nonsusceptible isolates. The blaoxa-51-like carbapenemase gene and ISAbal were detected in all 17 isolates. ISAba1 upstream presence of the blaOXA-51-like gene was observed in 7 of 17 isolates and the blaOXA-23 like gene in 5 of 17. Consistent with overseas reports, our results confirm the existence of MDRA isolates and isolates harboring OXA carbapenemase genes in Japan. While resistance rates were lower than reports elsewhere, it is clear that resistance trends must be carefully monitored.

Antibiotic-resistant phenotypes and genotypes of Neisseria gonorrhoeae isolates in Japan: identification of strain clusters with multidrug-resistant phenotypes.

OBJECTIVES: To determine the antibiotic susceptibility and the genotype distributions of N. gonorrhoeae isolates in Fukuoka, Japan, and to evaluate the specific associations between genotypes and antibiotic resistance. METHODS: Antibiotic susceptibility testing and N. gonorrhoeae multiantigen sequence typing (NG-MAST) were performed on 242 and 239 N. gonorrhoeae isolates, respectively, in Fukuoka, Japan in 2008. RESULTS: No isolates showed resistance to spectinomycin, ceftriaxone, or cefixime, although 34 (14.0%) and 149 (61.6%) isolates displayed decreased susceptibility to ceftriaxone (minimum inhibitory concentration range, 0.06-0.5 mg/L) and cefixime (minimum inhibitory concentration range, 0.06-0.5 mg/L), respectively. Furthermore, 171 (70.7%), 68 (28.1%), 39 (16.1%), and 1 (0.4%) isolates were resistant to ciprofloxacin, tetracycline, penicillin, and azithromycin, respectively. The 239 isolates were divided by NG-MAST into 67 sequence types (STs); the 4 most common STs were ST2958 (20.5%), ST4018 (7.5%), ST1407 (6.7%), and ST4487 (5.9%). ST2958 and ST1407 were characterized by a multidrug-resistant phenotype, whereas ST4018 and ST4487 presented a susceptible phenotype. Interestingly, ST1407, which is now common in Europe and Australia, was identified as a predominant ST in this study. CONCLUSIONS: This is the first report combining N. gonorrhoeae antibiotic susceptibility testing with molecular typing by using NG-MAST in Japan. Although a large diversity in NG-MAST was identified, based on comparisons with the international data, the ST1407 with a multidrug-resistant phenotype currently seems to be circulating worldwide.

[Nationwide antimicrobial susceptibility survey of Neisseria gonorrhoeae isolates in Japan].

In a nationwide antimicrobial susceptibility survey of 494 Nesseria gonorrhoeae isolates collected from February 2008 to December 2009 in 3 regions of Japan, 112 (22.7%) were collected from western Japan (Kinki, Chugoku, Shikoku, and Kyushu), 277 (56.1%) from mid-eastern Japan (Kanto), and 105 (21.1%) from eastern Japan (Tokai, Hokuriku, Koushinetsu, Tohoku, and Hokkaido). Resistance to ciprofloxacin (CPFX) was 72.8%, to penicillin G (PCG) 19.8%, and to tetracycline (TC) 18.2%. Intermediate resistance to CPFX was 1.8%, to PCG 73.7%, and to TC 43.7%. These results indicate that both types of resistance to the 3 agents were very high. Intermediate resistance to cefixime (CFIX) was 38.1% and to cefozidim (CDZM) 13.4%. Resistance to CFIX was only 0.4% and to CDZM 0%. Susceptibility to azithromycin was 96.6%, to ceftriaxone 99.8%, and to spectinomycin 100%. No significant difference in resistance was seen to different antimicrobial agent classes tested in the 3 regions, although intermediate resistance to CFIX in western Japan was significantly higher than in mid-eastern Japan.

Rapidly spreading CTX-M-type beta-lactamase-producing Proteus mirabilis in Japan.

In recent years, increased isolation of extended-spectrum beta-lactamase (ESBL)-producing Proteus mirabilis has been reported in Japan. We undertook an investigation to determine the prevalence of ESBL-producing P. mirabilis isolated in Japan and to characterise the genotype. Seventy-four P. mirabilis isolates recovered from specimens at 54 hospitals in Japan between March and October 2006 were included in the study. Of the 74 P. mirabilis isolates examined, 28 (37.8%) were ESBL-producers. The bla(CTX-M-2) gene was found in 27 isolates, whilst 1 isolate possessed bla(CTX-M-3). Amongst the 28 ESBL-producers, 25 (89.3%) were non-susceptible to ciprofloxacin, whilst 11 (23.9%) of 46 ESBL-non-producing isolates were non-susceptible to ciprofloxacin. Pulsed-field gel electrophoresis (PFGE) analysis of the 28 ESBL-producing isolates from 19 hospitals revealed 17 clusters. The same PFGE type was observed in two or more hospitals especially in the greater Tokyo area, suggesting possible clonal spread and the need for monitoring to determine whether emergence of a dominant clone occurs. Our results show that in Japan there is a high prevalence of CTX-M-type beta-lactamase-producing P. mirabilis. Moreover, these isolates are characterised by reduced susceptibility to fluoroquinolones.

[Evaluation of three selective enrichment media for detection of Group B Streptococcus in vaginal swabs].

As the most common cause of neonatal sepsis, Lancefield Group B Streptococcus (GBS) must be diagnosed as early as possible in pregnant women is prevent neonatal infection. A selective enrichment broth medium has been widely recommended to optimally recover GBS from genital and anorectal samples. To establish a culture suitable for screening vaginal swab specimens, we compared subcultures of three selective enrichment media to direct culture on agar medium. Vaginal swab samples were inoculated directly onto 5% sheep blood agar and into New Granada medium (Eiken), Lim broth (Becton, Dickinson, and Company), and Todd Hewitt broth with gentamicin and nalidixic acid (Becton, Dickinson, and Company, Todd). Of the 288 specimens tested, GBS was recovered from 43 samples (14.9%) on direct agar media, with 82 (28.5%), positive on New Granada medium subculture, 67 (23.3%) on Lim broth subculture, and 61 (21.2%) on Todd, subculture. These results demonstrates that selective enrichment broth media provides more superior sensitivity than direct agar media for detection of GBS colonization in vaginal specimens, underscoring the usefulness of selective enrichment broth media in GBS screening for vaginal swabs in pregnant woman.

[Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine samples of males and females by the strand displacement amplification (SDA) method].

Urine samples collected from 422 males and 53 females visiting a clinic in Kawasaki City who were suspected to have sexually transmitted infection were tested for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by BD ProbeTecET (SDA method). The detection rates of C. trachomatis by the SDA method and polymerase chain reaction (PCR) method (control) were as high as 98.1% for C. trachomatis, and as high as 99.4% for N. gonorrhoeae, and the concordance rate of detection of both bacterial species was high. The detection sensitivity and specificity of the SDA method were 90.6 and 99.3%, respectively for C. trachomatis and 98.7% and 100% for N. gonorrhoeae, when PCR was used as the standard method. There were no differences in these results between males and females. The number of patients showing a discrepancy of the results obtained between the SDA method and the PCR method was 9 for C. trachomatis and 1 for N. gonorrhoeae, but the results of redetermination by the SDA method tended to coincide with those of the PCR method. Urine samples tested by the SDA method were positive for N. gonorrhoeae even in patients in whom the culture of secretions from the male urethra was negative for N. gonorrhoeae. Based on these results, the BD ProbeTecET (SDA method) was confirmed to have the equivalent capability to the PCR method for the detection of C. trachomatis and N. gonorrhoeae in urine samples.

Antimicrobial resistance in clinical isolates of Neisseria subflava from the oral cavities of a Japanese population.

A recent study indicated that Neisseria subflava, one of the commensal Neisseria species, may play an important role in the emergence of Neisseria gonorrhoeae strains with chromosomally mediated resistance to penicillin or cephalosporin by the horizontal genetic exchange of penA genes encoding the target site for penicillin or cephalosporin. The present investigation examined the antimicrobial susceptibility of 45 isolates of N. subflava from the oral cavities of Japanese men and women to various agents used for the treatment of gonococcal infections. Of the 45 isolates, 40 (88.9%) and 4 (8.8%) were intermediately resistant and resistant to penicillin, respectively, with the minimal inhibitory concentration (MIC)(50) and MIC(90) of penicillin being 0.5 mg/l and 1 mg/l, respectively. Of the 45 isolates, 13 (28.9%) and 14 (31.1%) were resistant to tetracycline and ciprofloxacin, respectively, and 3 (6.7%) showed reduced susceptibility to cefixime (although the susceptibility category was not determined). These results indicate that several isolates of N. subflava have acquired resistance or intermediate resistance to various antimicrobial agents, including penicillin, cephalosporin, tetracycline, and ciprofloxacin. The present study may thus confirm that N. subflava may be involved in the emergence of N. gonorrhoeae strains with either intermediate or total resistance to penicillin or cephalosporin by the horizontal genetic exchange of the penA gene.

In vitro synergistic effects of double combinations of beta-lactams and azithromycin against clinical isolates of Neisseria gonorrhoeae.

In Japan, Neisseria gonorrhoeae, a sexually transmitted pathogen, has recently shown significant resistance to various antimicrobial agents. In this study, a checkerboard method was utilized to investigate the in vitro activities of cefixime (CFIX), cefteram (CFTM), or amoxicillin (AMPC) in combination with azithromycin (AZM) against 25 clinical isolates of N. gonorrhoeae. Synergy, defined as a fractional inhibitory concentration (FIC) index of less than or equal to 0.50, was observed in 32% of isolates with CFIX+AZM, 12% of isolates with CFTM+AZM, and 4% of isolates with AMPC+AZM. Moreover, partial synergy, defined as an FIC index of greater than 0.50 and less than 1, was observed in 44% of isolates with CFIX+AZM, 68% of isolates with CFTM+AZM, and 52% of isolates with AMPC+AZM. In particular, as a result of the combination of CFIX and AZM, for all isolates, significant reductions were observed in the median CFIX minimum inhibitory concentration (MIC; from 0.25 to 0.008 microg/ml; P < 0.0001) and the median AZM MIC (from 0.12 to 0.03 microg/ml; P < 0.0001). However, antagonism, defined as an FIC index of greater than 1, was observed in only 4% of the isolates with both CFIX+AZM and CFTM+AZM, while it was seen in 12% of the isolates with AMPC+AZM. To our knowledge, this is the first study to demonstrate that the in vitro activity of CFIX against N. gonorrhoeae can be significantly enhanced in combination with AZM.

Antibacterial activity of tosufloxacin against major organisms detected from patients with respiratory or otorhinological infections: comparison with the results obtained from organisms isolated about 10 years ago.

The minimum inhibitory concentrations (MICs) of tosufloxacin and other fluoroquinolone antimicrobials for Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella (Branhamella) catarrhalis, isolated, between January 2003 and July 2004, from patients suspected of having respiratory or otorhinological infections were determined. The results were compared with those for these organisms isolated in 1994, plus some H. influenzae strains isolated in 1998. Tosufloxacin was the most potent of all the antibiotics tested for antibacterial activity against S. pneumoniae (including penicillin-intermediate S. pneumoniae and penicillin-resistant S. pneumoniae). The MIC50 and MIC90 values did not differ from those obtained for the strains isolated in 1994. Fluoroquinolones exerted the most potent antibacterial activity against M. (B.) catarrhalis; the MICs for most of the strains were < or = 0.06 microg/ml; fluoroquinolones inhibited the growth of all the strains at 0.25 microg/ml or less. Fluoroquinolones showed the most potent antibacterial activity against H. influenzae strains isolated between 2003 and 2004, and in 1994, but, for one H. influenzae strain isolated, between 2003 and 2004, the MICs of fluoroquinolones were high. Some strains of S. pneumoniae and H. influenzae were resistant to fluoroquinolones. Genetic analysis showed that all of these strains had mutations in the quinolone resistance-determining region, but there were no differences according to the years of isolation. These results indicate that tosufloxacin has potent antibacterial activity against major organisms isolated from patients with respiratory or otorhinological infections; further, the results of the present study did not differ from those obtained about 10 years ago.

Analysis of mutations within multiple genes associated with resistance in a clinical isolate of Neisseria gonorrhoeae with reduced ceftriaxone susceptibility that shows a multidrug-resistant phenotype.

A Neisseria gonorrhoeae strain with a reduced susceptibility to ceftriaxone (minimum inhibitory concentration (MIC) = 0.5 microg/mL) was isolated among 398 clinical isolates obtained from 2000-2001 in Fukuoka City, Japan. The N. gonorrhoeae strain was negative for penicillinase production but it showed multidrug resistance against penicillin (MIC = 8 microg/mL), tetracycline (MIC = 4 microg/mL), azithromycin (MIC = 0.5 microg/mL) and ciprofloxacin (MIC = 16 microg/mL). The molecular mechanisms of the multidrug-resistant phenotype in this strain were analysed. Polymerase chain reaction and direct DNA sequencing were performed to identify mutations within the penA, ponA, mtrR, penB, gyrA and parC genes of the gonococcal strain, which thus explain the multidrug-resistant phenotype. The N. gonorrhoeae strain contained a significantly different sequence of the penA gene from that of the ceftriaxone-susceptible strains. Some regions of the transpeptidase domain within this penA gene were closely similar to those found in other Neisseria species such as Neisseria subflava, Neisseria flavescens or Neisseria perflava/sicca. This strain also included a ponA mutation that is associated with high-level resistance to penicillin, mtrR mutations that mediate overexpression of the MtrCDE efflux pump responsible for resistance to hydrophobic agents such as azithromycin, and penB mutations that reduce porin permeability to hydrophilic agents such as tetracycline. Moreover, this strain contained gyrA and parC mutations that confer high-level resistance to ciprofloxacin. These results indicate the emergence of a N. gonorrhoeae strain with reduced susceptibility to ceftriaxone, which also showed a multidrug-resistant phenotype that can be explained by the presence of multiple loci mutations associated with antibiotic resistance.