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ABSTRACT: Forty-six Helicobacter cinaedi isolates from the same hospital were analyzed by multilocus sequence typing. Most H. cinaedi exhibited clonal complex 9 and were mainly isolated from immunocompromised patients in the same ward. Three H. fennelliae were isolated from the same ward and exhibited the same pulsed gel electrophoresis patterns. All isolates were resistant to clarithromycin and ciprofloxacin. H. cinaedi and H. fennelliae must be carefully monitored to prevent nosocomial infection.
Journal of clinical microbiology 05/2013; · 4.16 Impact Factor
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ABSTRACT: OBJECTIVES: Group B Streptococcus (GBS; Streptococcus agalactiae) has been regarded as uniformly susceptible to penicillins. However, we recently reported the existence of GBS with reduced penicillin susceptibility (PRGBS), with amino acid substitutions in penicillin-binding protein (PBP) 2X. Although most PRGBS show high MICs of ceftizoxime (4-64 mg/L) and cefotaxime (0.12-1 mg/L), those for strain B1 are exceptionally high (ceftizoxime MIC ≥256 mg/L and cefotaxime MIC 2 mg/L). We previously found an amino acid substitution (G539S) neighbouring the conserved K540TG motif in PBP1A in addition to the PRGBS-specific amino acid substitution Q557E in PBP2X of B1. The aim of this study was to reveal the effect of the amino acid substitutions in PBP1A and PBP2X of B1 on the high cephalosporin resistance. METHODS: A ceftizoxime competition assay was performed to reveal the PBPs that are the main targets of ceftizoxime. We generated two allelic exchange mutants from β-lactam-susceptible GBS BAA-611. BAA-611 (B1PBP2X) contained the PBP2X gene derived from B1 and BAA-611 (B1PBP2X, B1PBP1A) contained both the PBP2X and the PBP1A gene derived from B1. These allelic exchange mutants and strain B1 were subjected to susceptibility testing. RESULTS: The ceftizoxime competition assay revealed that PBP1A and PBP2X were the main targets of ceftizoxime. Although the MICs of ceftizoxime and cefotaxime for BAA-611 (B1PBP2X) were 64 and 0.5 mg/L, respectively, BAA-611 (B1PBP2X, B1PBP1A) showed high cephalosporin resistance (ceftizoxime MIC ≥256 mg/L and cefotaxime MIC 2 mg/L) comparable to B1. CONCLUSIONS: The high cephalosporin resistance of GBS was caused by amino acid substitutions in PBP1A and PBP2X.
Journal of Antimicrobial Chemotherapy 02/2013; · 5.07 Impact Factor
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Journal of Antimicrobial Chemotherapy 02/2013; · 5.07 Impact Factor
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Japanese journal of infectious diseases. 01/2013; 66(1):79-81.
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ABSTRACT: Helicobacter cinaedi colonizes the colons of human and animals and can cause colitis, cellulitis, and sepsis in humans, with infections in immunocompromised patients being increasingly recognized. However, methods for analyzing the molecular epidemiology of H. cinaedi are not yet established. A genotyping method involving multilocus sequence typing (MLST) was developed and used to analyze 50 H. cinaedi isolates from Japanese hospitals in addition to 6 reference strains. Pulsed-field gel electrophoresis (PFGE) results were also compared with the MLST results. Based on the genomic information from strain CCUG18818, 21 housekeeping genes were selected as candidates for MLST and were observed to have high homology (96.5 to 100%) between isolates. Following a comparison of the 21 housekeeping genes from 8 H. cinaedi isolates, 7 genes were chosen for MLST, revealing 14 sequence types (STs). The isolates from 3 hospitals belonged to the same STs, but the isolates from the other 4 hospitals belonged to different STs. Isolates belonging to ST6 were analyzed by PFGE and showed similar, but not identical, patterns between isolates. Isolates belonging to ST9, ST10, and ST11, which belonged to the same clonal complex, had the same pattern. All isolates were found to contain mutations in GyrA and the 23S rRNA gene that confer ciprofloxacin and clarithromycin resistance, respectively, in H. cinaedi. These results raise concerns about the increase in H. cinaedi isolates resistant to clarithromycin and ciprofloxacin in Japan.
Journal of clinical microbiology 05/2012; 50(8):2553-60. · 4.16 Impact Factor
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ABSTRACT: Mycoplasma pneumoniae strain 309, a type 2a (subtype 2 variant) strain of this bacterium, has variations in the P1 protein, which is responsible for attachment of the bacterium to host cells. Here, we report the complete genome sequence of M. pneumoniae strain 309 isolated from a pneumonia patient in Japan.
Journal of bacteriology 03/2012; 194(5):1253-4. · 3.94 Impact Factor
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ABSTRACT: In 2010, a three months survey of multidrug-resistant Enterobacteriaceae was conducted by Ministry of Health, Labour and Welfare of Japan. A total of 153 isolates were obtained through this survey and we performed PCR using the NDM-1 type, KPC type, IMP-1 type, IMP-2 type and VIM-2 type carbapenemase genes specific primers. Of 153 analyzed isolates, 72 (47.1%) were positive for IMP-1 type bla(IMP), and two isolates from two patients were positive for bla(NDM-1). None of those patients had traveled abroad. Two isolates from a single patient who had traveled and hospitalized in abroad were positive for bla(KPC). 77 (50.3%) isolates were all negative for those five carbapenemase genes. It was shown that IMP-1 type is the most predominant carbapenemase gene among Enterobacteriaceae in Japan.
Nippon rinsho. Japanese journal of clinical medicine 02/2012; 70(2):187-91.
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ABSTRACT: A carbapenem-resistant Serratia marcescens strain, 10mdr148, was identified in a Japanese hospital in 2010. The carbapenem resistance of this strain was attributed to the production of a novel metallo-β-lactamase (MBL), named SMB-1 (Serratia metallo-β-lactamase). SMB-1 possessed a zinc binding motif, H(Q)XHXDH (residues 116 to 121), H196, and H263 and was categorized as a member of subclass B3 MBL. SMB-1 has 75% amino acid identity with the most closely related MBL, AMO1, of uncultured bacterium, recently identified through the metagenomic analysis of apple orchard soil. The introduction of bla(SMB-1) into Escherichia coli conferred resistance to a variety of β-lactam antibiotics, penicillins, cephalosporins, and carbapenems, but not aztreonam, a resistance pattern consistent with those of other MBLs. SMB-1 demonstrated high k(cat) values of >500 s(-1) for carbapenems, resulting in the highest hydrolyzing efficiency (k(cat)/K(m)) among the agents tested. The hydrolyzing activity of SMB-1 was well inhibited by chelating agents. The bla(SMB-1) gene was located on the chromosome of S. marcescens strain 10mdr148 and at the 3' end of the ISCR1 element in complex with a typical class 1 integron carrying aac(6')-Ib and catB3 gene cassettes. Downstream of bla(SMB-1), the second copy of the 3'conserved segment and ISCR1 were found. To our knowledge, this is the first subclass B3 MBL gene associated with an ISCR1 element identified in an Enterobacteriaceae clinical isolate. A variety of antibiotic resistance genes embedded with ISCR1 have been widely spread among Enterobacteriaceae clinical isolates, thus the further dissemination of bla(SMB-1) mediated by ISCR1 transposition activity may become a future concern.
Antimicrobial Agents and Chemotherapy 08/2011; 55(11):5143-9. · 4.84 Impact Factor
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ABSTRACT: The complete sequence of the plasmid pNDM-1_Dok01 carrying New Delhi metallo-β-lactamase (NDM-1) was determined by whole genome shotgun sequencing using Escherichia coli strain NDM-1_Dok01 (multilocus sequence typing type: ST38) and the transconjugant E. coli DH10B. The plasmid is an IncA/C incompatibility type composed of 225 predicted coding sequences in 195.5 kb and partially shares a sequence with bla(CMY-2)-positive IncA/C plasmids such as E. coli AR060302 pAR060302 (166.5 kb) and Salmonella enterica serovar Newport pSN254 (176.4 kb). The bla(NDM-1) gene in pNDM-1_Dok01 is terminally flanked by two IS903 elements that are distinct from those of the other characterized NDM-1 plasmids, suggesting that the bla(NDM-1) gene has been broadly transposed, together with various mobile elements, as a cassette gene. The chaperonin groES and groEL genes were identified in the bla(NDM-1)-related composite transposon, and phylogenetic analysis and guanine-cytosine content (GC) percentage showed similarities to the homologs of plant pathogens such as Pseudoxanthomonas and Xanthomonas spp., implying that plant pathogens are the potential source of the bla(NDM-1) gene. The complete sequence of pNDM-1_Dok01 suggests that the bla(NDM-1) gene was acquired by a novel composite transposon on an extensively disseminated IncA/C plasmid and transferred to the E. coli ST38 isolate.
PLoS ONE 01/2011; 6(9):e25334. · 4.09 Impact Factor
