Integration of the blaNDM-1 carbapenemase gene into a novel SXT/R391 integrative and conjugative element in Proteus vulgaris

2020 ◽  
Vol 75 (6) ◽  
pp. 1439-1442
Author(s):  
Ling-Han Kong ◽  
Rong Xiang ◽  
Yu-Long Wang ◽  
Shun-Kang Wu ◽  
Chang-Wei Lei ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Bioinformatics Analysis ◽  
Carbapenem Resistance ◽  
Resistance Determinant ◽  
Proteus Vulgaris ◽  
Genetic Environment ◽  
Carbapenem Resistant ◽  
Carbapenemase Gene ◽  
Integrative And Conjugative Element

Abstract Objectives To characterize the genetic environment of the carbapenem resistance determinant in Proteus vulgaris of swine origin. Methods The carbapenem-resistant P. vulgaris strain BC22 was isolated from a faecal swab from a diseased pig with diarrhoea in Sichuan Province of China in 2018. The presence of carbapenemase genes was screened by PCR. WGS and bioinformatics analysis were performed to analyse the genetic environment of the carbapenem resistance determinant. Results P. vulgaris strain BC22 was found to harbour the carbapenemase gene blaNDM-1. WGS data revealed that blaNDM-1 was located in a truncated ISAba125 composite transposon. The carbapenem resistance gene blaNDM-1 and 20 other resistance genes, including the multiresistance gene cfr and the bifunctional aminoglycoside/quinolone resistance gene aac(6′)-lb-cr, were located in a novel SXT/R391 integrative and conjugative element (ICE). This new SXT/R391 ICE of 148.7 kb was chromosomally located, and could be transferred to Escherichia coli. Conclusions Here, we report a carbapenemase gene, blaNDM-1, integrated into an SXT/R391 ICE. Our study highlights that this SXT/R391 ICE may facilitate the dissemination of clinically important resistance genes such as blaNDM-1, cfr and aac(6′)-lb-cr.

scholarly journals Detection and Characterization of Carbapenem resistant Gram-negative bacilli isolates recovered from hospitalized patients at Soba University Hospital, Sudan

2020 ◽  
Author(s):  
Hana S. Elbadawi ◽  
Kamal M. Elhag ◽  
Elsheikh Mahgoub ◽  
Hisham N Altayb ◽  
Francine Ntoumi ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Nosocomial Infections ◽  
Carbapenem Resistance ◽  
Clinical Isolates ◽  
University Hospital ◽  
P Value ◽  
Relative Distribution ◽  
Gram Negative ◽  
Carbapenem Resistant ◽  
Carbapenemase Gene

Abstract Background:Antimicrobial resistance (AMR) poses a threat to global health security. Whilst over the past decade, there has been an increase in reports of nosocomial infections globally caused by carbapenem resistant Gram-negative bacilli (GNB), data from Africa have been scanty. We performed a study of carbapenem resistance genes among GNB isolated from patients treated in hospitals in Khartoum state, Sudan.Methods:A cross-sectional study was conducted at Soba University Hospital (SUH) and Institute of Endemic Diseases, University of Khartoum for the period October 2016 to February 2017. A total of 206 GNB isolates from different clinical specimens were analyzed for carbapenem resistance genes using phenotypic tests and affirmed by genes detection. Multiplex PCR was performed for each strain to detect the carbapenemase genes, including the blaNDM, blaVIM, blaIMP, blaKPC, and blaOXA-48. In addition to blaCTXM, blaTEM and blaSHV. DNA sequencing and bioinformatics analysis were used to detect genes subtypes.Findings:Of 206 isolates, 171 (83%) were confirmed resistant phenotypically and 121 (58.7%) isolates were positive for the presence of one or more carbapenemase gene. New Delhi metallo-β-lactamase (NDM) types were the most predominant genes, blaNDM 107(88.4%). Others included blaIMP 7 (5.7%), blaOXA-48 5(4.1%), blaVIM 2 (1.6%) and blaKPC 0 (0%). Co- resistance genes with NDM producing GNB were detected in 87 (81.3%) of all blaNDM positive isolates. A significant association between phenotypic and genotypic resistance was observed (P- value < 0.001). NDM-1 was the most sub type was observed in 75 isolates (70 %), other subtypes were NDM- 5 and NDM-6. Infections due to Carbapenem resistant GNB are increasing at SUH, with the blaNDM being the prevalent genes among clinical isolates and belong to the Indian lineage.Conclusions:The frequency of carbapenemase producing bacilli was found to be improperly high in Khartoum hospitals. NDM was found to be the most prevalent carbapenemase gene among clinical isolates. Close surveillance across all hospitals in Sudan is required. The relative distribution of Carbapenemase genes among GNB in nosocomial infections in Africa needs to be defined.

scholarly journals The Acquisition of Resistance to Carbapenem and Macrolide-mediated Quorum Sensing Inhibition byPseudomonas aeruginosavia a Novel Integrative and Conjugative Element ICETn43716385

2017 ◽  
Author(s):  
Yichen Ding ◽  
Jeanette Teo ◽  
Daniela I. Drautz-Moses ◽  
Stephan Christoph Schuster ◽  
Michael Givskov ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Resistance Gene ◽  
Carbapenem Resistance ◽  
World Health ◽  
Fourth Generation ◽  
Sequencing Analysis ◽  
Quorum Sensing Inhibition ◽  
Carbapenem Resistant ◽  
Integrative And Conjugative Element

AbstractPseudomonas aeruginosacan cause persistant and life-threatening infections in immunocompromised patients. Carbapenems are the first-line agents to treatP. aeruginosainfections; therefore, the emergence of carbapenem-resistantP. aeruginosastrains has greatly challenged effective antibiotic therapy. In this study, we characterised the full-length genomes of two carbapenem resistantP. aeruginosaclinical isolates that produce the carbapebemase New Delhi metallo-β-lactamase-1 (NDM-1). We found that theblaNDM-1gene is encoded by a novel intergrative and conjugative element (ICE) ICETn43716385, which also carries the macrolide resistance genemsr(E)and the florfenicol resistance genefloR. Themsr(E)gene has rarely been described inP. aeruginosagenomes. To investigate the functional roles ofmsr(E)inP. aeruginosa, we exogeneously expressed this gene inP. aeruginosalaboratory strains and found that the acquisition ofmsr(E)could abolish the azithromycin-mediated quorum sensing inhibitionin vitroand the anti-Pseudomonas effect of azithromycinin vivo. In addition, the expression ofmsr(E)almost completely restored the azithromycin-affectedP. aeruginosatranscriptome, as shown by our RNA sequencing analysis. We present the first evidence ofblaNDM-1to be carried by intergrative and conjugative elements, and the first evidence of co-transfer of carbapenem resistance and the resistance to macrolide-mediated quorum sensing inhibition intoP. aeruginosagenomes.ImportanceCarbapenem resistantP. aeruginosahas recently been listed as the top three most dangerous superbugs by World Health Organisation. The transmission ofblaNDM-1gene intoP. aeruginosacan cause extreme resistance to carbapenems and fourth generation cephalosporins, which greatly compromises the effectiveness of these antibiotics against Pseudomonas infections. However, the lack of complete genome sequence of NDM-1-producingP. aeruginosahas limited our understanding of the transmisibility ofblaNDM-1in this organism. Here we showed the co-transfer ofblaNDM-1andmsr(E)intoP. aeruginosagenome by a novel integrative and conjugative element (ICE). The acquisition of these two genes confersP. aeruginosawith resistance to carbapenem and macrolide-mediated quorum sensing inhibition, both of which are important treatment stretagies forP. aeruginosainfections. Our findings highlight the potential of ICEs in transmitting carbapenem resistance, and that the anti-virulence treatment ofP. aeruginosainfections by macrolides can be challenged by horizontal gene transfer.

scholarly journals 1348. In vitro Activity of Plazomicin, a Next-Generation Aminoglycoside, Against Carbapenemase-Producing Klebsiella pneumoniae

2018 ◽  
Vol 5 (suppl_1) ◽  
pp. S412-S413
Author(s):  
Michael R Jacobs ◽  
Caryn E Good ◽  
Ayman M Abdelhamed ◽  
Daniel D Rhoads ◽  
Kristine M Hujer ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Carbapenem Resistance ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Next Generation ◽  
Aminoglycoside Resistance ◽  
Carbapenem Resistant ◽  
Carbapenemase Gene ◽  
Research Grant

Abstract Background Plazomicin is a next-generation aminoglycoside with in vitro activity against multidrug-resistant Gram-negative species, including carbapenem-resistant isolates. The Consortium on Resistance Against Carbapenems in Klebsiella and other Enterobacteriaceae (CRACKLE) is a federally funded, prospective multicenter consortium of 20 hospitals from nine US healthcare systems to track carbapenem-resistant Enterobacteriaceae. Methods Minimum inhibitory concentrations (MICs) of plazomicin were determined by broth microdilution according to current CLSI guidelines against a collection of 697 carbapenem-resistant Klebsiella pneumoniae with defined carbapenem resistance mechanisms, including KPC and OXA carbapenemases. Isolates were submitted by participating CRACKLE centers. Results Carbapenemases present in study isolates included KPC-2 (n = 323), KPC-3 (n = 364), KPC-4 (n = 2), OXA-48 like (n = 7), and NDM (n = 1). Plazomicin MICs ranged from ≤0.12 to &gt;32 mg/L, with MIC50 and MIC90 values of 0.25 and 1 mg/L, respectively (figure). MICs of 689 (98.8%) isolates were ≤4 mg/L, while MICs of the remaining eight isolates were &gt;32 mg/L. Plazomicin MICs were related to specific carbapenemases present in isolates: of eight isolates with MICs &gt;32 mg/L, seven contained OXA-48 like and one contained KPC-3, suggesting that these isolates possess an aminoglycoside-resistance mechanism on the same plasmid as their carbapenemase gene, such as a 16S ribosomal RNA methyltransferase, against which plazomicin is not active. Conclusion Plazomicin has good in vitro potency against a collection of carbapenemase-producing K. pneumoniae, with MIC90 value of 1 mg/L and MICs of ≤4 mg/L for 98.9% of isolates. Disclosures M. R. Jacobs, Achaogen: Investigator, Research grant. Shionogi: Investigator, Research grant. L. Connolly, Achaogen, Inc.: Consultant, Consulting fee. K. M. Krause, Achaogen: Employee, Salary. S. S. Richter, bioMerieux: Grant Investigator, Research grant. BD Diagnostics: Grant Investigator, Research grant. Roche: Grant Investigator, Research grant. Hologic: Grant Investigator, Research grant. Diasorin: Grant Investigator, Research grant. Accelerate: Grant Investigator, Research grant. Biofire: Grant Investigator, Research grant. D. Van Duin, achaogen: Scientific Advisor, Consulting fee. shionogi: Scientific Advisor, Consulting fee. Allergan: Scientific Advisor, Consulting fee. Astellas: Scientific Advisor, Consulting fee. Neumedicine: Scientific Advisor, Consulting fee. Roche: Scientific Advisor, Consulting fee. T2 Biosystems: Scientific Advisor, Consulting fee.

scholarly journals Investigation of Carbapenemase Genes in Carbapenem Resistant Enterobacterales Isolates: First KPC Report From Dokuz Eylul University Hospital

2021 ◽  
Author(s):  
Şeyda Şilan Okalin ◽  
Ayşe Nur Sarı Kaygısız ◽  
Mahmut Cem Ergon ◽  
İbrahim Mehmet Ali Öktem
Keyword(s):  
Treatment Options ◽  
Carbapenem Resistance ◽  
Tracheal Aspirate ◽  
University Hospital ◽  
Chain Reaction ◽  
Specific Primers ◽  
E Coli ◽  
Carbapenem Resistant ◽  
Carbapenemase Gene ◽  
Polymerase Chain

Objective: In recent years, increasing carbapenem resistance of Enterobacterales bacteria limits treatment options, considerably. The main mechanism of this resistance is the production of carbapenemase enzymes. The aim of this study is to determine carbapenemase gene types in Enterobacterales isolates from our hospitalized patients and assess the clonal associations of the isolates with KPC gene. Method: A total of 48 clinical Enterobacterales isolates resistant to at least one carbapeneme and received between January 2019 and March 2019 were included in the study. Sample types were consisted of urine, blood, tracheal aspirate, wound and sputum. Of these isolates, three were Escherichia coli while 45 were Klebsiella pneumoniae. Types of carbapenemases were investigated by polymerase chain reaction, using specific primers for VIM, IMP, NDM, KPC and OXA-48 genes. PFGE was performed to determine the clonal associations between blaKPC positive K. pnemoniae isolates. Results: According to the results, blaOXA-48 (n=2) and blaKPC (n=1) were found to be present among E. coli isolates. Regarding 45 K. pneumoniae isolates; only blaOXA-48 and only blaNDM were present in 30 and two isolates, respectively. Seven K. pneumoniae isolates were found positive for both blaOXA-48 and blaNDM. Remaining K. pneumoniae isolates (n=6) harboured only blaKPC. None of the isolates were positive for blaIMP and blaVIM. PFGE analysis showed four isolates had the same pulsotype (A), while two had different pulsotypes (B-C). Conclusion: To our knowledge, this is the first report of KPC gene isolated in Dokuz Eylul University Hospital.

scholarly journals Genome-Wide Identification of Carbapenem-Resistant Gram- Negative Bacterial (CR-GNB) Isolates Retrieved From Hospitalized Patients in Bihar, India

2021 ◽  
Author(s):  
Namrata Kumari ◽  
Mukesh Kumar ◽  
Amit Katiyar ◽  
Abhay Kumar ◽  
Pallavi Priya ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Carbapenem Resistance ◽  
Cross Sectional Study ◽  
Clinical Isolates ◽  
Cross Sectional ◽  
Gram Negative ◽  
Carbapenem Resistant ◽  
Genome Wide ◽  
Synergy Test ◽  
Global Threat

Abstract Carbapenemase-producing clinical isolates are becoming more common over the world, posing a severe public health danger, particularly in developing nations like India. Carbapenem-resistant Gram-negative bacterial (CR-GNB) infection has become a fast-expending global threat with limited antibiotic choice and significant mortality. The aim of this study was to highlight the carbapenem-resistance among clinical isolates of hospital admitted patients in Bihar, India. A cross-sectional study was conducted with 101 clinical isolates of E. coli, K. pneumoniae, A. baumannii, and P. aeruginosa. All GNB isolates were tested for their antimicrobial susceptibility using double disc synergy test / modified hodge test (DDST/MHT) and subsequently confirmed carbapenemase-producing isolates were evaluated for carbapenem-resistance genes using whole-genome sequencing (genotypically) method. The overall percentage of carbapenem-resistance among GNB was (17/101) 16.83%. The AMR analysis demonstrates a significantly high prevalence of blaCTX−M followed by blaSHV, blaTEM, blaOXA and blaNDM β-lactams carbapenem-resistance genes among clinical isolates of GNB. Co-occurrence of carbapenemase-encoding genes with blaNDM was found in 70.6% of carbapenemase-producing isolates. Our study highlights the mechanism of carbapenem-resistance to curb the overwhelming threat posed by emergence of drug-resistance in India.

Determination of carbapenemase genes in clinical isolates using Cepheid Xpert Carba-R

2021 ◽  
pp. 16-19
Author(s):  
N. I. Gabrielyan ◽  
V. G. Kormilitsyna ◽  
V. K. Zaletaeva ◽  
A. V. Krotevich ◽  
I. A. Miloserdov ◽  
...  
Keyword(s):  
Targeted Therapy ◽  
Infection Control ◽  
Resistance Genes ◽  
Carbapenem Resistance ◽  
Critical Issue ◽  
Sensitivity Study ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Carbapenem Resistant

Detection of carbapenem resistance genes is a critical issue for hospitals due to possible recommendations for infection control and targeted therapy. The Cepheid Xpert instrument, a Carba-R test for the detection and differentiation of five common carbapenemase genes, was tested from September 2020 to February 2021. As part of the approbation, 20 tests were provided. This review presents the results of the approbation of a relatively regular sensitivity study on Siemens WalkAway‑96 plus. Cepheid Xpert Carba-R analysis has been shown to be an accurate and fast tool for detecting colonization by carbapenem-resistant gram-negative bacteria, which can help limit the spread of these organisms in hospitals.

scholarly journals The carbapenem resistance gene blaOXA-23 is disseminated by a conjugative plasmid containing the novel transposon Tn6681 in Acinetobacter johnsonii M19

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Gongli Zong ◽  
Chuanqing Zhong ◽  
Jiafang Fu ◽  
Yu Zhang ◽  
Peipei Zhang ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Resistance Gene ◽  
Carbapenem Resistance ◽  
Conjugative Plasmid ◽  
The Novel ◽  
Illumina Hiseq ◽  
Discovery Studio ◽  
Acinetobacter Johnsonii ◽  
Type Iv ◽  
Carbapenem Resistant

Abstract Background Carbapenem resistant Acinetobacter species have caused great difficulties in clinical therapy in the worldwide. Here we describe an Acinetobacter johnsonii M19 with a novel blaOXA-23 containing transposon Tn6681 on the conjugative plasmid pFM-M19 and the ability to transferand carbapenem resistance. Methods A. johnsonii M19 was isolated under selection with 8 mg/L meropenem from hospital sewage, and the minimum inhibitory concentrations (MICs) for the representative carbapenems imipenem, meropenem and ertapenem were determined. The genome of A. johnsonii M19 was sequenced by PacBio RS II and Illumina HiSeq 4000 platforms. A homologous model of OXA-23 was generated, and molecular docking models with imipenem, meropenem and ertapenem were constructed by Discovery Studio 2.0. Type IV secretion system and conjugation elements were identified by the Pathosystems Resource Integration Center (PATRIC) server and the oriTfinder. Mating experiments were performed to evaluate transfer of OXA-23 to Escherichia coli 25DN. Results MICs of A. johnsonii M19 for imipenem, meropenem and ertapenem were 128 mg/L, 48 mg/L and 24 mg/L, respectively. Genome sequencing identified plasmid pFM-M19, which harbours the carbapenem resistance gene blaOXA-23 within the novel transposon Tn6681. Molecular docking analysis indicated that the elongated hydrophobic tunnel of OXA-23 provides a hydrophobic environment and that Lys-216, Thr-217, Met-221 and Arg-259 were the conserved amino acids bound to imipenem, meropenem and ertapenem. Furthermore, pFM-M19 could transfer blaOXA-23 to E. coli 25DN by conjugation, resulting in carbapenem-resistant transconjugants. Conclusions Our investigation showed that A. johnsonii M19 is a source and disseminator of blaOXA-23 and carbapenem resistance. The ability to transfer blaOXA-23 to other species by the conjugative plasmid pFM-M19 raises the risk of spread of carbapenem resistance. Graphic abstract The carbapenem resistance gene blaOXA-23 is disseminated by a conjugative plasmid containing the novel transposon Tn6681 in Acinetobacter johnsonii M19.

Characterization of the genetic environment of blaKPC in Escherichia coli isolates from hospitals in China

2020 ◽  
Vol 367 (11) ◽  
Author(s):  
Xuejing Yang ◽  
Yan Qi ◽  
Guoping Li ◽  
Yuying Wang ◽  
Zhengqing Lou ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Carbapenem Resistance ◽  
Pcr Analysis ◽  
Genetic Environment ◽  
E Coli ◽  
Carbapenem Resistant ◽  
Infection Treatment ◽  
Hospital Infection Control ◽  
Klebsiella Pneumoniae Carbapenemases

ABSTRACT Carbapenem resistance in Enterobacteriaceae members has become a major challenge, and the genetic environment of blaKPC, encoding Klebsiella pneumoniae carbapenemases, has not been fully clarified in China. In this study, we aimed to explore the genetic environment of blaKPC in 25 carbapenem-resistant E. coli isolates from hospitals in Hangzhou Province, China. Antimicrobial susceptibility against 22 common antimicrobial agents was tested. Polymerase chain reaction (PCR) analysis was performed for screening of the resistent genes, such as blaKPC, blaCTX-M, blaTEM, blaSHV, blaNDM, qnrA, qnrB, qnrS, aac(6’)-Ib, armA and rmtB. The genetic environment of blaKPC were determinedin one isolate. blaKPC was detected by PCR in all the clinical E. coli isolates. There were no strains carrying blaNDM, qnrA and armA. The genetic environment of blaKPC showed that blaKPC dissemination is plasmid mediated and that it is located in the Tn3–Tn4401 transposon complex. Encoding of blaKPC-2 was responsible for carbapenem resistance in the 25 E. coli isolates. The genetic environment of blaKPC was characterized by the Tn3–Tn4401 complex. Our findings may provide a theoretical basis for clinical drug-resistance monitoring, anti-infection treatment and hospital infection control.

scholarly journals Accumulation of Antibiotic Resistance Genes in Carbapenem-Resistant Acinetobacter baumannii Isolates Belonging to Lineage 2, Global Clone 1, from Outbreaks in 2012–2013 at a Tehran Burns Hospital

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Masoumeh Douraghi ◽  
Johanna J. Kenyon ◽  
Parisa Aris ◽  
Mahla Asadian ◽  
Sedighe Ghourchian ◽  
...  
Keyword(s):  
Middle East ◽  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Carbapenem Resistance ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Carbapenem Resistant ◽  
East Region ◽  
Lineage 2 ◽  
Middle East Region

ABSTRACT The worldwide distribution of carbapenem-resistant Acinetobacter baumannii (CRAB) has become a global concern, particularly in countries where antibiotic prescription is not tightly regulated. However, knowledge of the genomic aspects of CRAB from many parts of the world is still limited. Here, 50 carbapenem-resistant A. baumannii isolates recovered at a single hospital in Tehran, Iran, during several outbreaks in 2012 and 2013 were found to be resistant to multiple antibiotics. They were examined using PCR mapping and multilocus sequence typing (MLST). All Iranian strains belonged to sequence type 328 in the Institut Pasteur MLST scheme (ST328IP), a single-locus variant of ST81IP, and all Iranian strains contained two carbapenem resistance genes, oxa23 and oxa24. The oxa23 gene is in the transposon Tn2006 in AbaR4, which interrupts the chromosomal comM gene. Phylogenetic analysis using whole-genome sequence (WGS) data for 9 isolates showed that they belonged to the same clade, designated the ST81/ST328 clade, within lineage 2 of global clone 1 (GC1). However, there were two groups that included either KL13 or KL18 at the K locus (KL) for capsular polysaccharide synthesis and either a tet39 or an aadB resistance gene, respectively. The genetic context of the resistance genes was determined, and the oxa24 (OXA-72 variant) and tet39 (tetracycline resistance) genes were each in a pdif module in different plasmids. The aadB gene cassette (which encodes gentamicin, kanamycin, and tobramycin resistance) was harbored by pRAY*, and the aphA6 gene (which encodes amikacin resistance) and sul2 gene (which encodes sulfamethoxazole resistance) were each harbored by a different plasmid. The sequences obtained here will underpin future studies of GC1 CRAB strains from the Middle East region. IMPORTANCE Carbapenem-resistant Acinetobacter baumannii strains are among the most critical antibiotic-resistant bacteria causing hospital-acquired infections and treatment failures. The global spread of two clones has been responsible for the bulk of the resistance, in particular, carbapenem resistance. However, there is a substantial gap in our knowledge of which clones and which specific lineages within each clone are circulating in many parts of the world, including Africa and the Middle East region. This is the first genomic analysis of carbapenem-resistant A. baumannii strains from Iran. All the isolates, from a single hospital, belonged to lineage 2 of global clone 1 (GC1) but fell into two groups distinguished by genes in the locus for capsule biosynthesis. The analysis suggests a potential origin of multiply antibiotic-resistant lineage 2 in the Middle East region and highlights the ongoing evolution of carbapenem-resistant GC1 A. baumannii strains. It will enhance future studies on the local and global GC1 population structure.

scholarly journals Horizontal Transfer of the OXA-24 Carbapenemase Gene via Outer Membrane Vesicles: a New Mechanism of Dissemination of Carbapenem Resistance Genes in Acinetobacter baumannii

2011 ◽  
Vol 55 (7) ◽  
pp. 3084-3090 ◽  
Author(s):  
Carlos Rumbo ◽  
Esteban Fernández-Moreira ◽  
María Merino ◽  
Margarita Poza ◽  
Jose Antonio Mendez ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Resistance Genes ◽  
Carbapenem Resistance ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Content Type ◽  
Class D ◽  
Carbapenemase Gene

ABSTRACTThe resistance ofAcinetobacter baumanniistrains to carbapenems is a worrying problem in hospital settings. The main mechanism of carbapenem resistance is the expression of β-lactamases (metalloenzymes or class D enzymes). The mechanisms of the dissemination of these genes amongA. baumanniistrains are not fully understood. In this study we used two carbapenem-resistant clinical strains ofA. baumannii(AbH12O-A2 and AbH12O-CU3) expressing the plasmid-borneblaOXA-24gene (plasmids pMMA2 and pMMCU3, respectively) to demonstrate thatA. baumanniireleases outer membrane vesicles (OMVs) duringin vitrogrowth. The use of hybridization studies enabled us to show that these OMVs harbored theblaOXA-24gene. The incubation of these OMVs with the carbapenem-susceptibleA. baumanniiATCC 17978 host strain yielded full resistance to carbapenems. The presence of the original plasmids harboring theblaOXA-24gene was detected in strain ATCC 17978 after the transformation of OMVs. New OMVs harboringblaOXA-24were released byA. baumanniiATCC 17978 after it was transformed with the original OMV-mediated plasmids, indicating the universality of the process. We present the first experimental evidence that clinical isolates ofA. baumanniimay release OMVs as a mechanism of horizontal gene transfer whereby carbapenem resistance genes are delivered to surroundingA. baumanniibacterial isolates.

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