[Show abstract][Hide abstract] ABSTRACT: We investigate the evolving molecular epidemiology of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa isolates collected in a 100 institution, nationwide surveillance study in Japan from 2004 to 2006.
MBL-producers were detected in 23/996 isolates (2.3%) in 2004 and 21/992 (2.1%) in 2006. Antimicrobial resistance (specifically, carbapenem resistance) rates between two periods did not differ significantly. MBL-producers were more prevalent in urinary tract isolates. bla IMP-1 group was the most predominant (38 isolates, 80%), followed by 3 bla IMP-7, 2 bla IMP-11 group, and 1 bla VIM-1. All MBL genes were identified in 16 different class 1 integrons, most of which were novel to INTEGRALL database. A total of 17 isolates of sequence type (ST) 235, a recognized worldwide drug-resistant lineage, were distributed in 5 geographic regions across Japan. ST235 isolates included a sublineage associated with In113-like integron. ST357 was identified in 14 isolates, 9 of which harboring a sole bla IMP-1 gene cassette (In994) were recovered from Chugoku region in 2004. ST357 isolates with bla IMP-11 group or ST235 with bla IMP-7 emerged in 2006. We also report for the first time the presence of novel fosI gene cassette in strains other than Mycobacterium spp.
Our data give an important "snapshot" of the molecular characteristics and dynamics of MBL-producing lineages in P. aeruginosa in Japan. The significant association of specific genotypes and integrons implies that dissemination and transmission of the preexisting resistant lineage, rather than horizontal gene transfer in situ, might largely explain their endemicity.
[Show abstract][Hide abstract] ABSTRACT: Pathogens encoding extended-spectrum β-lactamase (ESBL) genes represent a threat for failure of empirical antibiotic therapy and are associated with high mortality, morbidity and expenses. We examined surface water in Dhaka, capital of Bangladesh and isolated ESBL-producing Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae, suggesting the potential role of water for the dissemination and transmission of resistant genes among microorganisms. E. coli found most prevalent among isolated Enterobacteriaceae from environmental water. Molecular and genetic analysis revealed CTX-M-type and SHV-type ESBL genes in isolates that may influence the spread of multidrug resistant pathogenic bacteria causing human and animal infections in Bangladesh.
Journal of Infection and Chemotherapy 11/2014; 20(11). DOI:10.1016/j.jiac.2014.07.003 · 1.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to confirm the daptomycin (DAP)-susceptibility of bacteria isolated before the launch of DAP in Japan. DAP showed good activity against all 833 isolates (MIC90 = 0.25-0.5 mg/L for staphylococci, 0.5-4 mg/L for enterococci and 0.25-0.5mg/L for streptococci). This is the first report of the in vitro activity of DAP against Gram-positive cocci, including MRSA and enterococci, isolated in Japan.
[Show abstract][Hide abstract] ABSTRACT: Fluoroquinolone-resistant Enterobacteriaceae is one of the increasing health problems worldwide. In the present study, we developed a pyrosequencing-based high-throughput method for analyzing the nucleotide sequence of the quinolone resistance determining regions (QRDRs) of gyrA and parC. By using this method, we successfully determined the QRDR sequences of 139 out of 140 clinical Escherichia coli isolates, twenty-eight percent of which were non-susceptible to ciprofloxacin. Sequence results obtained by the pyrosequencing method were in complete agreement with those obtained by the Sanger method. All fluoroquinolone-resistant isolates (n = 35; 25%) contained mutations leading to three or four amino acid substitutions in the QRDRs. In contrast, all isolates lacking mutation in the QRDR (n = 81; 57%) were susceptible to ciprofloxacin, levofloxacin, and nalidixic acid. The qnr determinants, namely qnrA, qnrB, and qnrS genes, were not detected and aac(6')-Ib-cr gene was detected in 2 (1.4%) isolates. Multilocus sequence typing of 34 randomly selected isolates revealed sequence type (ST) 131 (n = 7; 20%) as the most prevalent lineage and significantly resistant to quinolones (p < 0.01). The genetic background of quinolone susceptible isolates seemed more diverse and, interestingly, neighbor STs of ST131 in the phylogenetic tree were all susceptible to ciprofloxacin. In conclusion, we could reveal the relationship between fluoroquinolone resistance caused by mutations of QRDRs and population structure in the clinical extra-intestinal E. coli isolates. This high-throughput method for analyzing QRDR mutations by pyrosequencing is a powerful tool for epidemiological studies of fluoroquinolone resistance in bacteria.
[Show abstract][Hide abstract] ABSTRACT: We evaluated the efficacy of ethylenediamine-N,N,N',N'-tetraacetic acid, disodium calcium salt (Ca-EDTA), as an inhibitor for New Delhi metallo-β-lactamase-1 (NDM-1) in vitro antibiotic susceptibility and in a mouse model of sepsis caused by Escherichia coli. Ca-EDTA drastically reduced the MICs of carbapenems for all NDM-producing bacteria [imipenem (IPM) ≤1-2 μg/ml; meropenem (MEPM) ≤1-4 µg/ml]. In the neutropenic murine model of sepsis, the bacterial burden was further reduced by combination therapy using imipenem/cilastatin sodium (IPM/CS) and Ca-EDTA to 2.3 × 10(3) CFU/liver, compared with 2.9 × 10(4) CFU/liver for IPM/CS alone. These data demonstrated the possibility of Ca-EDTA for clinical applications. In our understanding, this is the first report examining the effect of Ca-EDTA on a mouse sepsis model caused by NDM-1-producing bacteria.
Journal of Infection and Chemotherapy 12/2012; 19(5). DOI:10.1007/s10156-012-0528-y · 1.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We conducted an epidemiological study concerning carbapenem-non-susceptible clinical isolates of Acinetobacter spp. in Japan by molecular procedures including carbapenemase gene identification and amplified ribosomal DNA restriction analysis. Among 598 clinically isolated Acinetobacter spp. in 2007, 27 (4.5%) were non-susceptible to carbapenems. Most carbapenem-non-susceptible Acinetobacter baumannii (13/14) belonged to clonal complex (CC) 92, harbored bla (OXA-51-like) genes, including novel bla (OXA-206), downstream of ISAba1, and were recovered mainly from the Kanto region. Carbapenem-non-susceptible A. baumannii CC92 isolates were further divided by pulsed-field gel electrophoresis into two groups, one of which was characterized by the presence of bla (OXA-23). One A. baumannii CC276 isolate carried bla (IMP-1) and bla (OXA-58). Almost all non-baumannii Acinetobacter isolates (12/13), including Acinetobacter pittii (formerly Acinetobacter genomic species 3) and Acinetobacter nosocomialis (formerly Acinetobacter genomic species 13TU), produced IMP-type metallo-β-lactamases, and were recovered from various regions in Japan. This is the first report describing the nationwide molecular epidemiology of carbapenem-non-susceptible Acinetobacter spp. with genomic species-level identification in Japan.
Journal of Infection and Chemotherapy 02/2012; 18(4):522-8. DOI:10.1007/s10156-012-0374-y · 1.49 Impact Factor