Search

Objective: To provide data on the molecular characteristics of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae clinical isolates in Japan., Methods: A total of 100 clinical isolates of ESBL-producing K. pneumoniae collected throughout Japan between June and July 2018 were studied. ESBL genes were analyzed using PCR and DNA sequencing. Transferability of ESBL genes was investigated by conjugation experiments. Plasmid replicon types, virulence genes (rmpA, rmpA2, iucA, iroB, and peg-344) associated with hypervirulent K. pneumoniae (hvKp), and capsule types were detected using PCR. Genotyping was performed using multilocus sequence typing., Results: All ESBL-producing isolates carried bla CTX-M genes. The most predominant CTX-M-type identified was CTX-M-15 (n=55). We identified 24 sequence types (STs) among the CTX-M-15 producers, with ST25 (n=8) being the most common. Most of the transconjugants carrying bla CTX-M-15 contained the FIIk replicon. Of the 100 ESBL-producing isolates, 31 were hvKp defined by the presence of the virulence genes. These ESBL-producing hvKp isolates belonged to eight STs (STs 23, 25, 36, 65, 86, 268, 412, and 4492), with five capsule types (K1, K2, K20, K57, and undefined)., Conclusions: CTX-M-15 was the predominant ESBL among K. pneumoniae isolates from Japan. This study shows that ESBL-producing hvKp strains comprising various clones are emerging in Japan., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Carbapenem-resistant Klebsiella pneumoniae and Escherichia coli, multidrug-resistant Pseudomonas aeruginosa and vancomycin-resistant Enterococcus faecium were isolated from a single patient. The patient came to Japan for advanced medical treatment after having undergone laparoscopic cholecystectomy and hospitalization in Vietnam. Whole-genome sequence analysis revealed that K. pneumoniae harbored bla OXA-48 that was found on a Col156 -type small plasmid, E. coli harbored bla NDM-5 and P. aeruginosa harbored both bla NDM-1 and 16S rRNA methyltransferase (rmtB). To the best of our knowledge, this is the first report of detection of K. pneumoniae harboring bla OXA-48 on a Col156-type small plasmid in the world and P. aeruginosa coharboring genes encoding NDM-1 and RmtB in Japan., (Copyright © 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

The mcr-1 gene encodes a phosphoethanolamine transferase that confers resistance to colistin by transferring phosphoethanolamine to lipid A. A 33-kb IncX4 plasmid harboring mcr-1 was detected in a Klebsiella pneumoniae isolate and two Escherichia coli isolates, and a 66-kb IncI2 plasmid was detected in three E. coli isolates in hospitals in Okinawa, Japan., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

An NDM-5-producing Klebsiella pneumoniae ST147 strain was isolated from a Japanese patient who had not travelled abroad in at least 5 years. Whole-genome sequencing revealed a genomic rearrangement in an FII plasmid harbouring blaNDM-5 due to the replicative transposition of IS26. A hypothetical structure was proposed for its ancestral plasmid, and comparative genomic analysis of the plasmid suggested the dissemination of structurally similar plasmids harbouring blaNDM-5 in Asian and Middle Eastern countries.

In this study, the presence of the mcr-1 gene in Escherichia coli from retail meat in Japan was investigated. Nine E. coli isolates (eight from chickens and one from pork) carried the mcr-1 gene on the plasmid. In six isolates from domestic chickens, mcr-1 was located on the IncI2 plasmid, which is approximately 60 kb in size. In the remaining three isolates from imported chicken and pork, mcr-1 was located on the IncX4 plasmid (30 kb)., (© 2017 The Societies and John Wiley & Sons Australia, Ltd.)

Aims: In this study, we analyzed the molecular epidemiology of extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis isolates collected from the central region of Japan., Materials and Methods: Between 2005 and 2012, 820 clinical P. mirabilis isolates were obtained from ten acute care hospitals in Japan. We characterized ESBL confirmatory test-positive isolates by sequencing the ESBL genes and their flanking regions, detecting plasmid replicons, and performing pulsed-field gel electrophoresis (PFGE)., Results: Ninety-six isolates (12%) were positive according to the ESBL confirmatory test; all these isolates possessed bla CTX-M-2 with the same flanking structure of upstream ΔISEcp1 and a downstream region identical to downstream bla KLUA-1 . IncT was the prevalent, and only, replicon found in 63 isolates. PFGE analysis detected eight clusters with more than one isolate, among which three included 56 isolates and six included isolates from multiple hospitals., Conclusion: CTX-M-2-producing P. mirabilis with an identical genetic structure flanking bla CTX-M-2 is dominant in this Japanese region, and there is evidence for the clonal spread of isolates.

Six Klebsiella pneumoniae clinical isolates resistant to various cephalosporins and cephamycins were identified in a Japanese general hospital, a tertiary care hospital, between November 2009 and April 2010. All K. pneumoniae isolates carried bla GES-4 and bla SHV-1 , while 2 K. pneumoniae isolates also harbored bla CTX-M-15 . The pulsed-field gel electrophoresis patterns revealed that these 6 K. pneumoniae isolates were almost identical, suggesting their clonal relatedness. Plasmid profiles and conjugation assays revealed that these bla GES-4 genes were located on similar conjugative plasmids. These data indicate that nosocomial spread caused by K. pneumoniae isolates producing bla GES-4 carbapenemase occurred at a Japanese general hospital. K. pneumoniae isolate harboring bla GES-4 is rarely reported in Japan, and, to the best of our knowledge, this is the second report of K. pneumoniae isolates harboring bla GES-4 that occurred nosocomial spread in Japan., (Copyright © 2016. Published by Elsevier Ltd.)

Dissemination of antimicrobial resistance is a major global public health concern. To clarify the role of flies in disseminating antimicrobial resistance between farms, we isolated and characterized tetracycline-resistant Escherichia coli strains isolated from flies and feces of livestock from four locations housing swine (abattoir, three farms) and three cattle farms. The percentages of isolates from flies resistant to tetracycline, dihydrostreptomycin, ampicillin, and chloramphenicol (80.8%, 61.5%, 53.8%, and 50.0%, respectively) and those from animal feces (80.5%, 78.0%, 41.5%, and 46.3%, respectively) in locations housing swine were significantly higher than those from cattle farms (p<0.05). The rates of resistance in E. coli derived from flies reflected those derived from livestock feces at the same locations, suggesting that antimicrobial resistance spreads between livestock and flies on the farms. The results of pulsed-field gel electrophoresis (PFGE) analysis showed that, with a few exceptions, all E. coli isolates differed. Two pairs of tetracycline-resistant strains harbored similar plasmids with the same tetracycline-resistance genes, although the origin (fly or feces), site of isolation, and PFGE patterns of these strains differed. Therefore, flies may disseminate the plasmids between farms. Our results suggest that flies may be involved not only in spreading clones of antimicrobial-resistant bacteria within a farm but also in the widespread dissemination of plasmids with antimicrobial resistance genes between farms.

The acquisition of resistance to cephalosporins among Salmonella spp. is a major public health concern. This study identified clonal plasmids carrying bla(TEM-52) from 10 Salmonella enterica serovar Infantis and Manhattan isolates from retail chicken meats that originated from a common supplier in Japan. Whole-genome analyses of the representative plasmids, including pYM4, revealed that they are 38 kb in size and that pYM4 is identical to pDKX1 from beef in Denmark, suggesting a global dissemination of resistance mediated by the plasmids., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

In 2010, a total of 1327 clinical Escherichia coli isolates from five hospitals in the Kyoto and Shiga regions of Japan were analysed by PCR. The prevalences of plasmid-mediated AmpC β-lactamase (pAmpC)-producers, extended-spectrum β-lactamase (ESBL)-producers and co-producers of pAmpC and ESBL were 1.7%, 9.7% and 0.3%, respectively. Less than one-half of the pAmpC-producers were reported to be resistant to third-generation cephalosporins, cephamycins and β-lactam/β-lactam inhibitors using the old 2009 Clinical and Laboratory Standards Institute (CLSI) breakpoints. CMY-2 was the most prevalent pAmpC type (95%), and CTX-M-14 (38%), CTX-M-15 (26%) and CTX-M-27 (19%) were the most prevalent ESBL types. The worldwide O25b-ST131-B2 clone accounted for 11% of pAmpC-producers and 41% of ESBL-producers. The O25b-ST131-B2 clone was characterised by a CTX-M-27- or CTX-M-15-type ESBL and ciprofloxacin-non-susceptibility with quadruple mutations in the quinolone resistance-determining regions (S83L and D87N in GyrA and S80I and E84V in ParC). A significant proportion of pAmpC-producers and the O25b-ST131-B2 clone were found in Japan by a recent regional surveillance programme., (Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

Antimicrobial resistance in hospital and community-onset bacterial infections is a significant source of patient morbidity and mortality. In the past decade, we have witnessed the increasing recovery of carbapenem-resistant Gram-negative bacteria. For many isolates, carbapenem resistance is due to the production of carbapenemases, β-lactamases that can inactivate carbapenems and frequently other β-lactam antibiotics. Currently, these enzymes are mainly found in three different β-lactamase classes (class A, B and D). Regardless of the molecular classification, there are few antimicrobials available to treat infections with these organisms and data regarding agents in development are limited to in vitro studies. This article focuses on the epidemiology of carbapenemase-producing Gram-negative bacteria. We also review available agents and those in development with potential activity against this evolving threat.

Detection of plasmid DNA uptake in river bacteria at the single-cell level was carried out by rolling-circle amplification (RCA). Uptake of a plasmid containing the green fluorescent protein gene (gfp) by indigenous bacteria from two rivers in Osaka, Japan, was monitored for 506 h using this in situ gene amplification technique with optimized cell permeabilization conditions. Plasmid uptake determined by in situ RCA was compared to direct counts of cells expressing gfp under fluorescence microscopy to examine differences in detection sensitivities between the two methods. Detection of DNA uptake as monitored by in situ RCA was 20 times higher at maximum than that by direct counting of gfp-expressing cells. In situ RCA could detect bacteria taking up the plasmid in several samples in which no gfp-expressing cells were apparent, indicating that in situ gene amplification techniques can be used to determine accurate rates of extracellular DNA uptake by indigenous bacteria in aquatic environments.