Archive for August 21, 2015

Molecular characteristics of extended-spectrum cephalosporin-resistant Enterobacteriaceae from humans in the community.

PLoS One. 2015 Jun 1;10(6):e0129085.

van Hoek AH1, Schouls L1, van Santen MG1, Florijn A1, de Greeff SC1, van Duijkeren E1.

1Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.

Abstract

OBJECTIVE:

To investigate the molecular characteristics of extended-spectrum cephalosporin (ESC)-resistant Enterobacteriaceae collected during a cross-sectional study examining the prevalence and risk factors for faecal carriage of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in humans living in areas with high or low broiler density.

METHODS:

ESC-resistant Enterobacteriaceae were identified by combination disc-diffusion test. ESBL/AmpC/carbapenemase genes were analysed using PCR and sequencing. For E. coli, phylogenetic groups and MLST were determined. Plasmids were characterized by transformation and PCR-based replicon typing. Subtyping of plasmids was done by plasmid multilocus sequence typing.

RESULTS:

175 ESC-resistant Enterobacteriaceae were cultured from 165/1,033 individuals. The isolates were Escherichia coli(n=65), Citrobacter freundii (n=52), Enterobacter cloacae (n=38), Morganella morganii (n=5), Enterobacter aerogenes (n=4), Klebsiella pneumoniae (n=3), Hafnia alvei (n=2), Shigella spp. (n=2), Citrobacter amalonaticus (n=1), Escherichia hermannii (n=1), Kluyvera cryocrescens (n=1), and Pantoea agglomerans (n=1). The following ESBL genes were recovered in 55 isolates originating from 49 of 1,033 (4.7 %) persons: blaCTX-M-1 (n=17), blaCTX-M-15 (n=16), blaCTX-M-14 (n=9), blaCTX-M-2 (n=3), blaCTX-M-3 (n=2), blaCTX-M-24 (n=2), blaCTX-M-27 (n=1), blaCTX-M-32 (n=1), blaSHV-12 (n=2), blaSHV-65 (n=1) and blaTEM-52 (n=1). Plasmidic AmpC (pAmpC) genes were discovered in 6 out of 1,033 (0.6 %) persons. One person carried two different E. coli isolates, one with blaCTX-M-1 and the other with blaCMY-2 and therefore the prevalence of persons carrying Enterobacteriaceae harboring ESBL and/or pAmpC genes was 5.2 %. In eight E. coli isolates the AmpC phenotype was caused by mutations in the AmpC promoter region. No carbapenemase genes were identified. A large variety of E. coli genotypes was found, ST131 and ST10 being most common.

CONCLUSIONS:

ESBL/pAmpC genes resembled those from patients in Dutch hospitals, indicating that healthy humans form a reservoir for transmission of these determinants to vulnerable people. The role of poultry in the transmission to humans in the community remains to be elucidated.

PDF

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451282/pdf/pone.0129085.pdf

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August 21, 2015 at 8:16 am

Dissemination of NDM-1-Producing Enterobacteriaceae Mediated by the IncX3-Type Plasmid.

PLoS One. 2015 Jun 5;10(6):e0129454.

Yang Q1, Fang L2, Fu Y3, Du X3, Shen Y1, Yu Y4.

1State Key Laboratory for Diagnosis and Treatment of Infectious diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.

2Department of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.

3Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.

4Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; State Key Laboratory for Diagnosis and Treatment of Infectious diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.

Abstract

The emergence and spread of NDM-1-producing Enterobacteriaceae have resulted in a worldwide public health risk that has affected some provinces of China.

China is an exceptionally large country, and there is a crucial need to investigate the epidemic of blaNDM-1-positive Enterobacteriaceae in our province.

A total of 186 carbapenem-resistant Enterobacteriaceae isolates (CRE) were collected in a grade-3 hospital in Zhejiang province. Carbapenem-resistant genes, including blaKPC, blaIMP, blaVIM, blaOXA-48 and blaNDM-1 were screened and sequenced.

Ninety isolates were identified as harboring the blaKPC-2 genes, and five blaNDM-1-positive isolates were uncovered. XbaI-PFGE revealed that three blaNDM-1-positive K. pneumoniae isolates belonged to two different clones.

S1-PFGE and southern blot suggested that the blaNDM-1 genes were located on IncX3-type plasmids with two different sizes ranging from 33.3 to 54.7 kb (n=4) and 104.5 to 138.9 kb (n=1), respectively, all of which could easily transfer to Escherichia coli by conjugation and electrotransformation.

The high-throughput sequencing of two plasmids was performed leading to the identification of a smaller 54-kb plasmid, which had high sequence similarity with a previously reported pCFNDM-CN, and a larger plasmid in which only a 7.8-kb sequence of a common gene environment around blaNDM-1 (blaNDM-1-trpF- dsbC-cutA1-groEL-ΔInsE,) was detected. PCR mapping and sequencing demonstrated that four smaller blaNDM-1 plasmids contained a common gene environment around blaNDM-1 (IS5-blaNDM-1-trpF- dsbC-cutA1-groEL).

We monitored the CRE epidemic in our hospital and determined that KPC-2 carbapenemase was a major risk to patient health and the IncX3-type plasmid played a vital role in the spread of the blaNDM-1 gene among the CRE.

PDF

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457825/pdf/pone.0129454.pdf

August 21, 2015 at 8:15 am

Mechanisms of antimicrobial resistance in Gram-negative bacilli.

Ann Intensive Care. 2015 Dec;5(1):61.

REVIEW

Ruppé É1, Woerther PL, Barbier F.

1Department of Infectious Diseases, Genomic Research Laboratory, Geneva University Hospitals, Geneva, Switzerland, etienne.ruppe@gmail.com

Abstract

The burden of multidrug resistance in Gram-negative bacilli (GNB) now represents a daily issue for the management of antimicrobial therapy in intensive care unit (ICU) patients.

In Enterobacteriaceae, the dramatic increase in the rates of resistance to third-generation cephalosporins mainly results from the spread of plasmid-borne extended-spectrum beta-lactamase (ESBL), especially those belonging to the CTX-M family.

The efficacy of beta-lactam/beta-lactamase inhibitor associations for severe infections due to ESBL-producing Enterobacteriaceae has not been adequately evaluated in critically ill patients, and carbapenems still stands as the first-line choice in this situation.

However, carbapenemase-producing strains have emerged worldwide over the past decade. VIM- and NDM-type metallo-beta-lactamases, OXA-48 and KPC appear as the most successful enzymes and may threaten the efficacy of carbapenems in the near future.

ESBL- and carbapenemase-encoding plasmids frequently bear resistance determinants for other antimicrobial classes, including aminoglycosides (aminoglycoside-modifying enzymes or 16S rRNA methylases) and fluoroquinolones (Qnr, AAC(6′)-Ib-cr or efflux pumps), a key feature that fosters the spread of multidrug resistance in Enterobacteriaceae.

In non-fermenting GNB such as Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia, multidrug resistance may emerge following the sole occurrence of sequential chromosomal mutations, which may lead to the overproduction of intrinsic beta-lactamases, hyper-expression of efflux pumps, target modifications and permeability alterations.

P. aeruginosa and A. baumannii also have the ability to acquire mobile genetic elements encoding resistance determinants, including carbapenemases.

Available options for the treatment of ICU-acquired infections due to carbapenem-resistant GNB are currently scarce, and recent reports emphasizing the spread of colistin resistance in environments with high volume of polymyxins use elicit major concern.

PDF

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531117/pdf/13613_2015_Article_61.pdf

August 21, 2015 at 8:12 am

KPC-2-producing Klebsiella pneumoniae in a hospital in the Midwest region of Brazil.

Braz J Microbiol. 2015 Jun 1;46(2):501-4.

Biberg CA1, Rodrigues AC2, do Carmo SF2, Chaves CE3, Gales AC4, Chang MR1.

1Universidade Federal de Mato Grosso do Sul, Laboratório de Pesquisas Microbiológicas, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, Brasil, Laboratório de Pesquisas Microbiológicas, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, Brazil.

2Hospital Regional de Mato Grosso do Sul, Campo Grande, MS, Brasil, Laboratório de Microbiologia do Hospital Regional Rosa Pedrossian de Mato Grosso do Sul, Campo Grande, MS, Brazil.

3Hospital Regional de Mato Grosso do Sul, Campo Grande, MS, Brasil, Comissão de Controle de Infecção Hospitalar, Hospital Regional Rosa Pedrossian de Mato Grosso do Sul, Campo Grande, MS, Brazil.

4Universidade Federal de São Paulo, Laboratório Alerta, Divisão de Doenças Infecciosas, Universidade Federal de São Paulo, São Paulo, SP, Brasil, Laboratório Alerta, Divisão de Doenças Infecciosas, Universidade Federal de São Paulo, São Paulo, SP, Brazil.

Abstract

The emergence of β-lactamase-producing Enterobacteriaceae in the last few decades has become major challenge faced by hospitals.

In this study, isolates of Klebsiella pneumoniae carbapenemase-2 (KPC-2)-producing K. pneumoniae from a tertiary hospital in Mato Grosso do Sul, Brazil, were characterized.

Bacterial identification was performed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF; Bruker Daltonics, Germany) mass spectrometry.

The minimum inhibitory concentrations of carbapenems were determined using the agar dilution method as recommended by the Clinical Laboratory Standards Institute guidelines.

Carbapenemase production was detected using the modified Hodge test (MHT) and polymerase chain reaction (PCR), followed by DNA sequencing.

Of 360 (12.2%) K. pneumoniae isolates obtained between May 2009 and May 2010, 44 (12.2%) were carbapenem nonsusceptible. Of these 44 isolates, thirty-six K. pneumoniae isolates that were positive by MHT and PCR carried the bla KPC-2 gene.

Thus, KPC-2producing Klebsiella pneumoniae has been present in a Brazilian hospital located in the Midwest region since at least 2009.

PDF

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4507542/pdf/1517-8382-bjm-46-2-501.pdf

August 21, 2015 at 8:10 am


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