Common isolation of New Delhi metallo-beta-lactamase 1-producing Enterobacteriaceae in a large surgical hospital in Vietnam

Large-scale analysis of putative plasmids in clinical multidrug-resistant Escherichia coli isolates from Vietnamese patients

Introduction

In the past decades, extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant (CR) Escherichia coli isolates have been detected in Vietnamese hospitals. The transfer of antimicrobial resistance (AMR) genes carried on plasmids is mainly responsible for the emergence of multidrug-resistant E. coli strains and the spread of AMR genes through horizontal gene transfer. Therefore, it is important to thoroughly study the characteristics of AMR gene-harboring plasmids in clinical multidrug-resistant bacterial isolates.

Methods

The profiles of plasmid assemblies were determined by analyzing previously published whole-genome sequencing data of 751 multidrug-resistant E. coli isolates from Vietnamese hospitals in order to identify the risk of AMR gene horizontal transfer and dissemination.

Results

The number of putative plasmids in isolates was independent of the sequencing coverage. These putative plasmids originated from various bacterial species, but mostly from the Escherichia genus, particularly E. coli species. Many different AMR genes were detected in plasmid contigs of the studied isolates, and their number was higher in CR isolates than in ESBL-producing isolates. Similarly, the bla_KPC-2, bla_NDM-5, bla_OXA-1, bla_OXA-48, and bla_OXA-181 β-lactamase genes, associated with resistance to carbapenems, were more frequent in CR strains. Sequence similarity network and genome annotation analyses revealed high conservation of the β-lactamase gene clusters in plasmid contigs that carried the same AMR genes.

Discussion

Our study provides evidence of horizontal gene transfer in multidrug-resistant E. coli isolates via conjugative plasmids, thus rapidly accelerating the emergence of resistant bacteria. Besides reducing antibiotic misuse, prevention of plasmid transmission also is essential to limit antibiotic resistance.

Quantitative Risk Assessment for the Introduction of Carbapenem-Resistant Enterobacteriaceae (CPE) into Dutch Livestock Farms

Early detection of emerging carbapenem-resistant Enterobacteriaceae (CPE) in food-producing animals is essential to control the spread of CPE. We assessed the risk of CPE introduction from imported livestock, livestock feed, companion animals, hospital patients, and returning travelers into livestock farms in The Netherlands, including (1) broiler, (2) broiler breeder, (3) fattening pig, (4) breeding pig, (5) farrow-to-finish pig, and (6) veal calf farms. The expected annual number of introductions was calculated from the number of farms exposed to each CPE source and the probability that at least one animal in an exposed farm is colonized. The total number of farms with CPE colonization was estimated to be the highest for fattening pig farms, whereas the probability of introduction for an individual farm was the highest for broiler farms. Livestock feed and imported livestock are the most likely sources of CPE introduction into Dutch livestock farms. Sensitivity analysis indicated that the number of fattening pig farms determined the number of high introductions in fattening pigs from feed, and that uncertainty on CPE prevalence impacted the absolute risk estimate for all farm types. The results of this study can be used to inform risk-based surveillance for CPE in livestock farms.

High diversity of blaNDM-1-encoding plasmids in Klebsiella pneumoniae isolated from neonates in a Vietnamese hospital

OBJECTIVES

The carbapenemase-encoding gene blaNDM-1 has been reported in Vietnam during the last 10 years, and blaNDM-producing Enterobacteriaceae are now silently and rapidly spreading. A key factor behind dissemination of blaNDM-1 is plasmids, mobile genetic elements that commonly carry antibiotic resistance genes and spread via conjugation. The diversity of blaNDM-1-encoding plasmids from neonates at a large Vietnamese hospital was characterized in this study.

METHODS

18 fecal Klebsiella pneumoniae and Klebsiella quasipneumoniae isolates collected from 16 neonates at a large pediatric hospital in Vietnam were studied using optical DNA mapping (ODM) and next-generation sequencing (NGS). Plasmids carrying the blaNDM-1 gene were identified by combining ODM with Cas9 restriction. The plasmids in the isolates were compared to investigate whether the same plasmid was present in different patients.

RESULTS

Although the same plasmid was found in some isolates, ODM confirmed that there were at least 10 different plasmids encoding blaNDM-1 among the 18 isolates, thus indicating wide plasmid diversity. The ODM results concur with the NGS data. Interestingly, some isolates had two distinct plasmids encoding blaNDM-1 that could be readily identified with ODM. The coexistence of different plasmids carrying the same blaNDM-1 gene in a single isolate has rarely been reported, probably because of limitations in plasmid characterization techniques.

CONCLUSIONS

The plasmids encoding the blaNDM-1 gene in this study cohort were diverse and may represent a similar picture in Vietnamese society. The study highlights important aspects of the usefulness of ODM for plasmid analysis.

Expansion of KPC-producing Enterobacterales in four large hospitals in Hanoi, Vietnam

OBJECTIVES

The incidence of carbapenem resistance among nosocomial Gram-negative bacteria in Vietnam is high and increasing, including among Enterobacterales. In this study, we assessed the presence of one of the main carbapenemase genes, blaKPC, among carbapenem-resistant Enterobacterales (CRE) from four large hospitals in Hanoi, Vietnam, between 2010 and 2015, and described their key molecular characteristics.

METHODS

KPC-producing Enterobacterales were detected using conventional PCR and were further analysed using S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), Southern blotting and whole-genome sequencing (WGS) for sequence typing and genetic characterisation.

RESULTS

blaKPC genes were detected in 122 (20.4%) of 599 CRE isolates. blaKPC-carrying plasmids were diverse in size. Klebsiella pneumoniae harbouring blaKPC genes belonged to ST15 and ST11, whereas KPC-producing Escherichia coli showed more diverse sequence types including ST3580, ST448, ST709 and ST405. Genotypic relationships supported the hypothesis of circulation of a population of 'resident' resistant bacteria in one hospital through the years and of transmission among these hospitals via patient transfer. WGS results revealed co-carriage of several other antimicrobial resistance genes and three different genetic contexts of blaKPC-2. Among these, the combination of ISEcp1-blaCTX-M and ISKpn27-blaKPC-ΔISKpn6 on the same plasmid is reported for the first time.

CONCLUSION

We describe the dissemination of blaKPC-expressing Enterobacterales in four large hospitals in Hanoi, Vietnam, since 2010, which may have started earlier, along with their resistance patterns, sequence types, genotypic relationship, plasmid sizes and genetic context, thereby contributing to the overall picture of the antimicrobial resistance situation in Enterobacterales in Vietnam.

Epidemiology of Extended-Spectrum Beta-Lactamase and Carbapenemase-Producing Enterobacterales in the Greater Mekong Subregion: A Systematic-Review and Meta-Analysis of Risk Factors Associated With Extended-Spectrum Beta-Lactamase and Carbapenemase Isolation

Background: Despite the rapid spread of extended-spectrum beta-lactamase (ESBL) producing-Enterobacterales (ESBL-E) and carbapenemase-producing Enterobacterales (CPE), little is known about the extent of their prevalence in the Greater Mekong Subregion (GMS). In this systematic review, we aimed to determine the epidemiology of ESBL-E and CPE in clinically significant Enterobacterales: Escherichia coli and Klebsiella pneumoniae from the GMS (comprising of Cambodia, Laos, Myanmar, Thailand, Vietnam and Yunnan province and Guangxi Zhuang region of China). Methods: Following a list of search terms adapted to subject headings, we systematically searched databases: Medline, EMBASE, Scopus and Web of Science for articles published on and before October 20th, 2020. The search string consisted of the bacterial names, methods involved in detecting drug-resistance phenotype and genotype, GMS countries, and ESBL and carbapenemase detection as the outcomes. Meta-analyses of the association between the isolation of ESBL from human clinical and non-clinical specimens were performed using the "METAN" function in STATA 14. Results: One hundred and thirty-nine studies were included from a total of 1,513 identified studies. Despite the heterogeneity in study methods, analyzing the prevalence proportions on log-linear model scale for ESBL producing-E. coli showed a trend that increased by 13.2% (95%CI: 6.1-20.2) in clinical blood specimens, 8.1% (95%CI: 1.7-14.4) in all clinical specimens and 17.7% (95%CI: 4.9-30.4) increase in carriage specimens. Under the log-linear model assumption, no significant trend over time was found for ESBL producing K. pneumoniae and ESBL-E specimens. CPE was reported in clinical studies and carriage studies past 2010, however a trend could not be determined because of the small dataset. Twelve studies were included in the meta-analysis of risk factors associated with isolation of ESBL. Recent antibiotic exposure was the most studied variable and showed a significant positive association with ESBL-E isolation (pooled OR: 2.9, 95%CI: 2.3-3.8) followed by chronic kidney disease (pooled OR: 4.7, 95%CI: 1.8-11.9), and other co-morbidities (pooled OR: 1.6, 95%CI: 1.2-2.9). Conclusion: Data from GMS is heterogeneous with significant data-gaps, especially in community settings from Laos, Myanmar, Cambodia and Yunnan and Guangxi provinces of China. Collaborative work standardizing the methodology of studies will aid in better monitoring, surveillance and evaluation of interventions across the GMS.

Multidrug-Resistant Gram-Negative Bacteria: Infection Prevention and Control Update

Multidrug-resistant gram-negative bacteria (MDR-GNB) pose one of the greatest challenges to health care today because of their propensity for human-to-human transmission and lack of therapeutic options. Containing the spread of MDR-GNB is challenging, and the application of multifaceted infection control bundles during an evolving outbreak makes it difficult to measure the relative impact of each measure. This article will review the utility of various infection control measures in containing the spread of various MDR-GNB and will provide the supporting evidence for these interventions.

Plasmid analysis of NDM metallo-β-lactamase-producing Enterobacterales isolated in Vietnam

Carbapenem-resistant Enterobacterales (CRE) represent a serious threat to public health due to the lack of treatment and high mortality. The rate of antimicrobial resistance of Enterobacterales isolates to major antimicrobials, including carbapenems, is much higher in Vietnam than in Western countries, but the reasons remain unknown due to the lack of genomic epidemiology research. A previous study suggested that carbapenem resistance genes, such as the carbapenemase gene blaNDM, spread via plasmids among Enterobacterales in Vietnam. In this study, we characterized blaNDM-carrying plasmids in Enterobacterales isolated in Vietnam, and identified several possible cases of horizontal transfer of plasmids both within and among species of bacteria. Twenty-five carbapenem-nonsusceptible isolates from a medical institution in Hanoi were sequenced on Illumina short-read sequencers, and 13 blaNDM-positive isolates, including isolates of Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii, Morganella morganii, and Proteus mirabilis, were further sequenced on an Oxford Nanopore Technologies long-read sequencer to obtain complete plasmid sequences. Almost identical 73 kb IncFII(pSE11)::IncN hybrid plasmids carrying blaNDM-1 were found in a P. mirabilis isolate and an M. morganii isolate. A 112 kb IncFII(pRSB107)::IncN hybrid plasmid carrying blaNDM-1 in an E. coli isolate had partially identical sequences with a 39 kb IncR plasmid carrying blaNDM-1 and an 88 kb IncFII(pHN7A8)::IncN hybrid plasmid in a C. freundii isolate. 148-149 kb IncFIA(Hl1)::IncA/C2 plasmids and 75-76 kb IncFII(Yp) plasmids, both carrying blaNDM-1 were shared among three sequence type 11 (ST11) isolates and three ST395 isolates of K. pneumoniae, respectively. Most of the plasmids co-carried genes conferring resistance to clinically relevant antimicrobials, including third-generation cephalosporins, aminoglycosides, and fluoroquinolones, in addition to blaNDM-1. These results provide insight into the genetic basis of CRE in Vietnam, and could help control nosocomial infections.

Resistance mechanisms and genetic relatedness among carbapenem-resistant Pseudomonas aeruginosa isolates from three major hospitals in Hanoi, Vietnam (2011-15)

Background

MDR bacteria including carbapenem-resistant Pseudomonas aeruginosa are recognized as an important cause of hospital-acquired infections worldwide. This investigation seeks to determine the molecular characterization and antibiotic resistance genes associated with carbapenem-resistant P. aeruginosa.

Methods

We conducted WGS and phylogenetic analysis of 72 carbapenem-resistant P. aeruginosa isolated from hospital-acquired infection patients from August 2011 to March 2015 in three major hospitals in Hanoi, Vietnam.

Results

We identified three variants of IMP gene, among which bla_IMP-15 was the most frequent (n = 34) in comparison to bla_IMP-26 (n = 2) and bla_IMP-51 (n = 12). We observed two isolates with imipenem MIC >128 mg/L that co-harboured bla_IMP-15 and bla_DIM-1 genes and seven isolates (imipenem MIC > 128 mg/L) with a bla_KPC-1 gene from the same hospital. MLST data shows that these 72 isolates belong to 18 STs and phylogenetic tree analysis has divided these isolates into nine groups.

Conclusions

Our results provide evidence that not only bla_IMP-26 but other IMP variants such as bla_IMP-15 and bla_IMP-51 genes and several STs (ST235, ST244, ST277, ST310, ST773 and ST3151) have been disseminating in healthcare settings in Vietnam. In addition, we report the emergence of two isolates belonging to ST1240 and ST3340 that harboured two important carbapenemase genes (bla_IMP-15 and bla_DIM-1) and seven isolates belonging to ST3151 of P. aeruginosa that carried the bla_KPC-1 gene in Vietnam, which could potentially cause serious restricted availability of treatment options in healthcare settings.

Discovery of a Novel Natural Allosteric Inhibitor That Targets NDM-1 Against Escherichia coli

At present, the resistance of New Delhi metallo-β-lactamase-1 (NDM-1) to carbapenems and cephalosporins, one of the mechanisms of bacterial resistance against β-lactam antibiotics, poses a threat to human health. In this work, based on the virtual ligand screen method, we found that carnosic acid (CA), a natural compound, exhibited a significant inhibitory effect against NDM-1 (IC50 = 27.07 μM). Although carnosic acid did not display direct antibacterial activity, the combination of carnosic acid and meropenem still showed bactericidal activity after the loss of bactericidal effect of meropenem. The experimental results showed that carnosic acid can enhance the antibacterial activity of meropenem against Escherichia coli ZC-YN3. To explore the inhibitory mechanism of carnosic acid against NDM-1, we performed the molecular dynamics simulation and binding energy calculation for the NDM-1-CA complex system. Notably, the 3D structure of the complex obtained from molecular modeling indicates that the binding region of carnosic acid with NDM-1 was not situated in the active region of protein. Due to binding to the allosteric pocket of carnosic acid, the active region conformation of NDM-1 was observed to have been altered. The distance from the active center of the NDM-1-CA complex was larger than that of the free protein, leading to loss of activity. Then, the mutation experiments showed that carnosic acid had lower inhibitory activity against mutated protein than wild-type proteins. Fluorescence experiments verified the results reported above. Thus, our data indicate that carnosic acid is a potential NDM-1 inhibitor and is a promising drug for the treatment of NDM-1 producing pathogens.

Genetics of Acquired Antibiotic Resistance Genes in Proteus spp

Proteus spp. are commensal Enterobacterales of the human digestive tract. At the same time, P. mirabilis is commonly involved in urinary tract infections (UTI). P. mirabilis is naturally resistant to several antibiotics including colistin and shows reduced susceptibility to imipenem. However higher levels of resistance to imipenem commonly occur in P. mirabilis isolates consecutively to the loss of porins, reduced expression of penicillin binding proteins (PBPs) PBP1a, PBP2, or acquisition of several antibiotic resistance genes, including carbapenemase genes. In addition, resistance to non-β-lactams is also frequently reported including molecules used for treating UTI infections (e.g., fluoroquinolones, nitrofurans). Emergence and spread of multidrug resistant P. mirabilis isolates, including those producing ESBLs, AmpC cephalosporinases and carbapenemases, are being more and more frequently reported. This review covers Proteus spp. with a focus on the different genetic mechanisms involved in the acquisition of resistance genes to multiple antibiotic classes turning P. mirabilis into a dreadful pandrug resistant bacteria and resulting in difficult to treat infections.

Plasmid evolution in carbapenemase-producing Enterobacteriaceae: a review

Carbapenem-resistant Enterobacteriaceae (CRE) have been listed by the WHO as high-priority pathogens owing to their high association with mortalities and morbidities. Resistance to multiple β-lactams complicates effective clinical management of CRE infections. Using plasmid typing methods, a wide distribution of plasmid replicon groups has been reported in CREs around the world, including IncF, N, X, A/C, L/M, R, P, H, I, and W. We performed a literature search for English research papers, published between 2013 and 2018, reporting on plasmid-mediated carbapenem resistance. A rise in both carbapenemase types and associated plasmid replicon groups was seen, with China, Canada, and the United States recording a higher increase than other countries. bla_KPC was the most prevalent, except in Angola and the Czech Republic, where OXA-181 (n = 50, 88%) and OXA-48-like (n = 24, 44%) carbapenemases were most prevalent, respectively; bla_KPC-2/3 accounted for 70% (n = 956) of all reported carbapenemases. IncF plasmids were found to be responsible for disseminating different antibiotic resistance genes worldwide, accounting for almost 40% (n = 254) of plasmid-borne carbapenemases. bla_CTX-M , bla_TEM , bla_SHV , bla_OXA-1/9 , qnr, and aac-(6')-lb were mostly detected concurrently with carbapenemases. Most reported plasmids were conjugative but not present in multiple countries or species, suggesting limited interspecies and interboundary transmission of a common plasmid. A major limitation to effective characterization of plasmid evolution was the use of PCR-based instead of whole-plasmid sequencing-based plasmid typing.

Prevalence of extensive drug resistance in bacterial isolates harboring blaNDM-1 in Quetta Pakistan

Objective:

Extensive drug resistant Gram-negative bacilli, harboring New Delhi metallo-β-lactamase-1 (bla_NDM-1) having the ability to hydrolyze β-lactams, have become a vital global clinical threat. The present study was, therefore, designed to investigate the prevalence and epidemiology of NDM-1 producers in Quetta, Pakistan.

Methods:

This study was carried out in Microbiology Laboratory, Bolan Medical Complex Hospital Quetta, Biotechnology laboratory, BUITEMS Quetta and Hi-tech laboratory, CASVAB, University of Balochistan, Quetta, from March to June 2018, during the hot season. Biochemical and molecular approaches were applied for the identification of bacterial isolates. Minimum Inhibitory Concentrations (MICs) were determined using E-test method. Carbapenemase activity was ascertained by Modified Hodge Test (MHT) and the presence of bla_NDM-1 gene was recognized by Polymerase Chain Reaction (PCR).

Results:

We isolated five bla_NDM-1 harboring isolates of three different species namely Morganella morganii (n=2) Enterobacter cloacae (n=2) and Citrobacter freundii (n=1), from 300 pus samples. These isolates were found extensive drug resistant (XDR). Strikingly, two isolates of M. morganii were displaying resistance against 23 antibiotics of sulphonamides, aminoglycosides, polypeptide, monobactams, tetracyclines, quinolones, macrolides, cephalosporins, phosphonic acid and β-lactams groups, suggesting Pan Drug Resistance (PDR).

Conclusion:

This is the first report on emergence of PDR strain of M. morganii producing NDM-1 in the province of Balochistan, Pakistan. The presence of bla_NDM-1 in different bacterial species and their extensive rather pan drug resistance pattern poses a momentous clinical threat.

NDM-1-producing Enterobacter aerogenes isolated from a patient with a JJ ureteric stent in situ

Urinary tract infections after JJ stent insertion are among the most common complications, and the associated microorganisms carry more antibiotic resistance determinants than those found in urine prior to stent insertion. In line with the trends in healthcare epidemiology which implicate multi-resistant microorganisms in a plethora of healthcare-associated infections, prosthetic stent material also represents an ideal milieu for biofilm formation and subsequent infection development with resistant bacterial agents. Here we describe a case of a 73-year-old Caucasian woman presenting with urinary tract infection after JJ ureteric stent insertion due to ureteric obstruction and hydronephrosis of her left kidney. Extensive microbiological work-up and comprehensive molecular analysis identified the putative microorganism as carbapenem-resistant Enterobacter aerogenes carrying New Delhi metallo-beta-lactamase 1 (NDM-1). This is a first literature report implicating such extensively resistant strain of this species in early indwelling ureteric stent complications, and also the first report of NDM-1 in Enterobacter aerogenes in Croatia and Europe.

Rapid detection of the New Delhi metallo-b-lactamase 1 (NDM-1) gene by loop-mediated isothermal amplification (LAMP)

BACKGROUND

New Delhi Metallo-b-lactamase (NDM-1) is an enzyme emerging around the world conferring resistance to a wide range of β-lactams agents and whose early detection is extremely important. We proposed to standardize the detection of the bla_NDM-1 gene using the LOOP-mediated isothermal amplification technique (LAMP).

METHODS

In all, 14 Gram-negative bacterial strains isolated from patients presenting pneumonia associated with mechanical ventilation were used for the bla_NDM-1 standardization by LAMP. Klebsiella pneumoniae ATCC BAA-2473 and two clinical strains were used as a positive control. All results were compared to the reaction in polymerase chain reaction (PCR), considered gold standard for this detection.

RESULTS

There was an excellent correlation between the two techniques employed, since all measured clinical strains were negative in both employed tests and two clinical, and a reference strains were positive.

CONCLUSIONS

The lamp technique seems to be an excellent option for the rapid detection of bla_NDM-1. The amplification time is much shorter than other molecular techniques, the PCR machine is not necessary, it is easy of implementation and costs is low.

Carbapenem-Resistant Enterobacteriaceae: A Strategic Roadmap for Infection Control

The incidence of carbapenem-resistant Enterobacteriaceae (CRE) has increased worldwide with great regional variability. Infections caused by these organisms are associated with crude mortality rates of up to 70%. The spread of CRE in healthcare settings is both an important medical problem and a major global public health threat. All countries are at risk of falling victim to the emergence of CRE; therefore, a preparedness plan is required to avoid the catastrophic natural course of this epidemic. Proactive and adequate preventive measures locally, regionally, and nationally are required to contain the spread of these bacteria. The keys to success in preventing the establishment of CRE endemicity in a region are early detection through targeted laboratory protocols and containment of spread through comprehensive infection control measures. This guideline provides a strategic roadmap for infection control measures based on the best available evidence and expert opinion, to enable preparation of a multifaceted preparedness plan to abort epidemics of CRE. Infect Control Hosp Epidemiol 2017;38:580-594.

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia

Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread.

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia

Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread.

Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam

Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.

Multidrug-Resistant Gram-Negative Bacilli: Infection Control Implications

Antimicrobial resistance is a common iatrogenic complication of both modern life and medical care. Certain multidrug resistant and extensively drug resistant Gram-negative organisms pose the biggest challenges to health care today, predominantly owing to a lack of therapeutic options. Containing the spread of these organisms is challenging, and in reality, the application of multiple control measures during an evolving outbreak makes it difficult to measure the relative impact of each measure. This article reviews the usefulness of various infection control measures in containing the spread of multidrug-resistant Gram-negative bacilli.

High Prevalence of New Delhi Metallo-β-Lactamase-1 (NDM-1) Producers among Carbapenem-Resistant Enterobacteriaceae in Kuwait

The aim of the study was to determine the prevalence of New Delhi metallo-β lactamase-1 (NDM-1) producing Enterobacteriaceae in Kuwait over a one year period. Consecutive Enterobacteriaceae isolates with reduced susceptibility to carbapenems were collected from four government hospitals in Kuwait from January–December 2014. Their susceptibility to 18 antibiotics was performed by determining the minimum inhibitory concentration. Isolates resistant to carbapenems were tested by PCR for resistant genes. Finger printing of the positive isolates was done by DiversiLab^®. Clinical data of patients harboring NDM-1 positive isolates were analyzed. A total of 764 clinically significant Enterobacteriaceae isolates were studied. Of these, 61 (8%) were carbapenem-resistant. Twenty one out of these 61 (34.4%) were NDM-1-producers. All patients positive for NDM-1-carrying bacteria were hospitalized. About half were females (11/21 [52.3%]), average age was 53.3 years and the majority were Kuwaitis (14/21 [66.6%]). Six patients (28.5%) gave a history of travel or healthcare contact in an endemic area. Mortality rate was relatively high (28.6%). The predominant organism was Klebsiella pneumoniae (14 [66.6%]) followed by E. coli (4 [19%]). All NDM-1-positive isolates were resistant to meropenem, ertapenem, cefotaxime, cefoxitin and ampicillin, while 95.2% were resistant to imipenem, cefepime, and piperacillin-tazobactam. They were multidrug resistant including resistance to tigecycline, but 90% remained susceptible to colistin. About two-thirds of isolates (61.9%) co-produced-extended spectrum β-lactamases. During the study period, an outbreak of NDM-1 positive K. pneumoniae occurred in one hospital involving 3 patients confirmed by DiversiLab^® analysis. In conclusion, NDM-1-producing Enterobacteriaceae is a growing healthcare problem with increasing prevalence in Kuwait, especially in hospitalized patients, leaving few therapeutic options. A high prevalence of NDM-1 necessitates the implementation of strict infection control to prevent the spread of these organisms.

Molecular Characterization and Computational Modelling of New Delhi Metallo-β-Lactamase-5 from an Escherichia coli Isolate (KOEC3) of Bovine Origin

Emergence of antimicrobial resistance mediated through New Delhi metallo-β-lactamases (NDMs) is a serious therapeutic challenge. Till date, 16 different NDMs have been described. In this study, we report the molecular and structural characteristics of NDM-5 isolated from an Escherichia coli isolate (KOEC3) of bovine origin. Using PCR amplification, cloning and sequencing of full blaNDM gene, we identified the NDM type as NDM-5. Cloning of full gene in E. coli DH5α and subsequent assessment of antibiotic susceptibility of the transformed cells indicated possible role of native promoter in expression blaNDM-5. Translated amino acid sequence had two substitutions (Val88Leu and Met154Leu) compared to NDM-1. Theoretically deduced isoelectric pH of NDM-5 was 5.88 and instability index was 36.99, indicating a stable protein. From the amino acids sequence, a 3D model of the protein was computed. Analysis of the protein structure elucidated zinc coordination and also revealed a large binding cleft and flexible nature of the protein, which might be the reason for broad substrate range. Docking experiments revealed plausible binding poses for five carbapenem drugs in the vicinity of metal ions. In conclusion, results provided possible explanation for wide range of antibiotics catalyzed by NDM-5 and likely interaction modes with five carbapenem drugs.

Dissemination of clonal complex 2 Acinetobacter baumannii strains co-producing carbapenemases and 16S rRNA methylase ArmA in Vietnam

BACKGROUND

Acinetobacter baumannii strains co-producing carbapenemase and 16S rRNA methylase are highly resistant to carbapenems and aminoglycosides.

METHODS

Ninety-three isolates of multidrug-resistant A. baumannii were obtained from an intensive care unit in a hospital in Vietnam. Antimicrobial susceptibility tests and whole genome sequencing were performed. Multilocus sequence typing and the presence of drug resistant genes were determined and a maximum-likelihood phylogenetic tree was constructed by SNP alignment of whole genome sequencing data.

RESULTS

The majority of isolates belonged to clonal complex 2 (ST2, ST570 and ST571), and carried carbapenemase encoding genes bla OXA-23 and bla OXA-66. Two isolates encoded carbapenemase genes bla NDM-1 and bla OXA-58 and the 16S rRNA methylase encoding gene armA and did not belong to clonal complex 2 (ST16).

CONCLUSION

A. baumannii isolates producing 16S rRNA methylase ArmA and belonging to clonal complex 2 are widespread, and isolates co-producing NDM-1 and ArmA are emerging, in medical settings in Vietnam.