Characterization of OXA-181, a carbapenem-hydrolyzing class D beta-lactamase from Klebsiella pneumoniae

Plasmid analysis of Escherichia coli isolates from South Korea co-producing NDM-5 and OXA-181 carbapenemases

Recently, Escherichia coli isolates co-producing New Delhi metallo-β-lactamase (NDM)-5 and oxacillinase (OXA)-181 were identified in a tertiary-care hospital of South Korea. Isolate CC1702-1 was collected from urine in January 2017 and isolate CC1706-1 was recovered from a transtracheal aspirate of a hospitalized patient in May 2017. Carbapenemase genes were identified by multiplex PCR and sequencing, and whole genome sequencing was performed subsequently using the PacBio RSII system. Both E. coli isolates belonged to the same clone (ST410) and were resistant to all β-lactams including carbapenems. We obtained whole plasmid sequences of the isolates: pCC1702-NDM-5 from CC1702-1 and pCC1706-NDM-5 and pCC1706-OXA-181 from CC1706-1. The two E. coli isolates belonged to the same clone (ST410) and they were completely resistant to all β-lactams, as well as carbapenems. Two bla_NDM-5-harboring plasmids belonged to the same incompatibility group, IncFIA/B, and consisted of 79,613 bp and 111,890 bp with 87 and 130 coding sequences, respectively. The genetic structures of the two bla_NDM-5-bearing plasmids, which were distinct from the bla_NDM-5-bearing plasmids from the Klebsiella pneumoniae isolates previously transmitted from the United Arab Emirates (UAE) to South Korea, differed from each other. While pCC1702-NDM-5 showed high degree of identity with the plasmid from a multidrug-resistant isolate of Citrobacter fruendii P5571 found in China, pCC1706-NDM-5 was very similar to the plasmid from a multidrug-resistant isolate of E. coli AMA1176 found in Denmark. pCC1706-OXA-181, which was a 51 kb, self-transmissible IncX3 plasmid, was identical to the E. coli plasmids pAMA1167-OXA-181 from Denmark and pOXA-181-WCHEC14828 from China. Plasmids harboring bla_NDM-5 in E. coli isolates might not be transferred from K. pneumoniae isolates co-producing NDM-5 and OXA-181. They probably originated from multiple sources.

Carbapenem-Susceptible OXA-23-Producing Proteus mirabilis in the French Community

Nineteen Proteus mirabilis isolates producing the carbapenemase OXA-23 were recovered over a 2-year period in 19 French hospitalized patients, of whom 12 had community onset infections. The isolates exhibited a slightly reduced susceptibility to carbapenems. Whole-genome analysis revealed that all 19 isolates formed a cluster compared to 149 other P. mirabilis isolates. Because of its susceptibility to carbapenems, this clone may be misidentified as a penicillinase producer while it constitutes a reservoir of the OXA-23-encoding gene in the community.

Carbapenemase-producing bacteria in food-producing animals, wildlife and environment: A challenge for human health

Antimicrobial resistance is an increasing global health problem and one of the major concerns for economic impacts worldwide. Recently, resistance against carbapenems (doripenem, ertapenem, imipenem, meropenem), which are critically important antimicrobials for human cares, poses a great risk all over the world. Carbapenemases are β-lactamases belonging to different Ambler classes (A, B, D) and encoded by both chromosomal and plasmidic genes. They hydrolyze a broad variety of β-lactams, including carbapenems, cephalosporins, penicillins and aztreonam. Despite several studies in human patients and hospital settings have been performed in European countries, the role of livestock animals, wild animals and the terrestrial and aquatic environment in the maintenance and transmission of carbapenemase- producing bacteria has been poorly investigated. The present review focuses on the carbapenemase-producing bacteria detected in pigs, cattle, poultry, fish, mollusks, wild birds and wild mammals in Europe as well as in non-European countries, investigating the genetic mechanisms for their transmission among food-producing animals and wildlife. To shed light on the important role of the environment in the maintenance and genetic exchange of resistance determinants between environmental and pathogenic bacteria, studies on aquatic sources (rivers, lakes, as well as wastewater treatment plants) are described.

Characterization of OXA-48-like carbapenemase producers in Canada, 2011-14

Objectives

Since the first identification of the OXA-48 carbapenemase in 2001, Enterobacteriaceae harbouring OXA-48-like enzymes have been reported globally. Here, we applied WGS to characterize the molecular epidemiology of these bacterial isolates.

Methods

Enterobacteriaceae non-susceptible to carbapenems isolated from patients between 2011 and 2014 were voluntarily submitted to the Canadian National Microbiology Laboratory where they were screened for carbapenemase genes. WGS was conducted on OXA-48-like producers using the Illumina MiSeq platform. WGS data were used for single nucleotide variant (SNV) analysis, MLST analysis, detection of resistance genes and partial plasmid characterization. Susceptibilities were determined using Vitek2 and Etest. Patient data provided from sites were reviewed.

Results

Sixty-seven non-duplicated cases were identified among Escherichia coli (n = 21) and Klebsiella pneumoniae (n = 46). Recent international travel was observed in 40.4% of cases. OXA-181 (52.2%) and OXA-48 (31.3%) were the most common variants, one E. coli OXA-48 producer was found to harbour the acquired colistin resistance gene mcr-1. The dominant STs were ST38 and ST410 in E. coli and ST14 in K. pneumoniae. Three common plasmid types were observed among isolates: IncL/M associated with OXA-48 producers, and ColKP3 and IncX3 associated with OXA-181/232 producers.

Conclusions

Enterobacteriaceae with OXA-48-like carbapenemases are emerging in Canada. This study highlights the complexity of OXA-48-types identified in Canada owing to travel and the successful clones and plasmids harbouring the OXA-48-like enzyme.

Enterobacteriaceae producing OXA-48-like carbapenemases in Poland, 2013-January 2017

Objectives

To analyse OXA-48 (OXA-48/181)-type carbapenemase-producing Enterobacteriaceae reported in Poland from 2013 until January 2017.

Methods

Bacterial isolates were typed by PFGE and MLST. Genes coding for OXA-48/181 types and other β-lactamases were amplified and sequenced. Mobile elements with blaOXA-48/181-like genes were PCR mapped. blaOXA-48/181-carrying plasmids were characterized by nuclease S1-hybridization profiling, transfer assays and PCR-based replicon typing, while the chromosomal location of the genes was confirmed by the I-CeuI analysis.

Results

Fifty-four isolates from 52 patients in 20 hospitals (14 cities) were included, in 14 cases having probable foreign origins indicated. The organisms were genetically diverse and represented numerous pandemic clones, including Klebsiella pneumoniae ST395 (n = 23), ST11, ST15 and ST101, Escherichia coli ST38, ST410 and ST648, and Enterobacter cloacae complex ST78. These produced OXA-48 (n = 49), OXA-181 (n = 4) or OXA-232 (n = 1). One of five K. pneumoniae ST395 pulsotypes caused a multicentre outbreak with 18 cases, which significantly contributed to the total number of patients. Depending on the variant, the blaOXA-48/181-like genes were parts of the Tn1999-, Tn2013- or Tn2016-like transposons, with blaOXA-48 found in an ISEcp1-associated module (Tn2016-like) for the first time. Three genotypes, including E. coli ST38, had chromosomal blaOXA-48 genes, while others carried transmissible IncL (∼60 kb; blaOXA-48; n = 30), IncM (∼80-95 kb; blaOXA-48; n = 4), IncX3 (∼50 kb; blaOXA-181; n = 4) or non-typeable (∼90-160 kb; blaOXA-48 or blaOXA-232) plasmids.

Conclusions

Even though OXA-48/181 producers seem to occur infrequently in Poland, their epidemiology has been marked by various phenomena, namely multiple imports, several limited transmissions plus one larger clonal outbreak, and possible plasmid transfers.

Horizontal Transfer of Antimicrobial Resistance Determinants Among Enteric Pathogens Through Bacterial Conjugation

Multi-drug resistance and transfer of mobile genetic elements among enteric pathogens is being reported to have increased rapidly. Commensal Escherichia coli was previously known to acquire mobile genetic elements from other genus/species. E. coli is also capable of disseminating these elements containing antimicrobial resistance determinants through horizontal transfer. Similarly, for Shigellae the antimicrobial resistance are on rise for fluoroquinolones and cephalosporins due to accumulation of mobile elements. Thus the study was hypothesized to investigate the role of transferable plasmids in commensal MDR E. coli vs Salmonella spp, and MDR Shigella flexneri vs Salmonella spp. pKP3-A plasmid containing qnrS1 was successfully transferred from E. coli to Salmonella spp. Similarly, a plasmid containing qnrS1 and bla_CTX-M-15 was transferred from Shigella to Salmonella spp. However, bla_CTX-M-15 was not transferred from E. coli as it was integrated into chromosome that was revealed by next-generation sequencing. This might be a reason that fluoroquinolone-resistant determinants are more frequently transferred than the cephalosporin resistant determinants. Findings from the study emphasize that mobile elements with AMR determinants are significant public health concern that has potential to rapidly disseminate.

Emergence of OXA-232 Carbapenemase-Producing Klebsiella pneumoniae That Carries a pLVPK-Like Virulence Plasmid among Elderly Patients in China

This study reported the clonal dissemination of OXA-232-producing sequence type 15 (ST15) carbapenem-resistant Klebsiella pneumoniae among elderly patients in China. All patients were immunocompromised, suffered from multiple underlying diseases, and were hospitalized for a prolonged period; however, they slowly recovered on antimicrobial therapy. The bla _OXA-232 gene was in a 6.1-kb ColKP3-type nonconjugative plasmid. The strains displayed a multidrug resistance phenotype and were not hypervirulent despite harboring a virulence plasmid. Active surveillance should be enforced to control further transmission.

Phenotypic and Genotypic Characterization of Enterobacteriaceae Producing Oxacillinase-48-Like Carbapenemases, United States

Oxacillinase (OXA)-48-like carbapenemases remain relatively uncommon in the United States. We performed phenotypic and genotypic characterization of 30 Enterobacteriaceae producing OXA-48-like carbapenemases that were recovered from patients during 2010-2014. Isolates were collected from 12 states and not associated with outbreaks, although we could not exclude limited local transmission. The alleles β-lactamase OXA-181 (bla_OXA-181) (43%), bla_OXA-232 (33%), and bla_OXA-48 (23%) were found. All isolates were resistant to ertapenem and showed positive results for the ertapenem and meropenem modified Hodge test and the modified carbapenem inactivation method; 73% showed a positive result for the Carba Nordmann-Poirel test. Whole-genome sequencing identified extended-spectrum β-lactamase genes in 93% of isolates. In all bla_OXA-232 isolates, the gene was on a ColKP3 plasmid. A total of 12 of 13 isolates harboring bla_OXA-181 contained the insertion sequence ΔISEcp1. In all isolates with bla_OXA-48, the gene was located on a TN1999 transposon; these isolates also carried IncL/M plasmids.

In Vitro Activity of Ceftazidime-Avibactam and Aztreonam-Avibactam against OXA-48-Carrying Enterobacteriaceae Isolated as Part of the International Network for Optimal Resistance Monitoring (INFORM) Global Surveillance Program from 2012 to 2015

Enterobacteriaceae producing the Ambler class D OXA-48 carbapenemase, combined with additional resistance mechanisms, such as permeability defects or cocarriage of class A, B, or C β-lactamases, can become highly resistant to most β-lactams currently in use, including carbapenems. A total of 45,872 Enterobacteriaceae clinical isolates collected in 39 countries as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance study in 2012 to 2015 were tested for susceptibility to β-lactams and comparator agents using the Clinical and Laboratory Standards Institute broth microdilution methodology and screened for the presence of β-lactamases. The bla _OXA-48 and bla _OXA-48-like genes were detected in 333 isolates across 14 species of Enterobacteriaceae collected in 20 countries across the globe. Few agents tested were effective in vitro against the overall collection of OXA-48-producers (n = 265), with tigecycline (MIC₉₀, 2 µg/ml; 92.5% susceptible), ceftazidime-avibactam (MIC₉₀, 4 µg/ml; 92.5% susceptible), and aztreonam-avibactam (MIC₉₀, 0.5 µg/ml; 99.6% of isolates with MIC ≤8 µg/ml) demonstrating the greatest activity. Similarly, colistin (MIC₉₀, 1 µg/ml; 94.2% susceptible), tigecycline (MIC₉₀, 2 µg/ml; 92.6% susceptible), ceftazidime-avibactam (MIC₉₀, >128 µg/ml; 89.7% susceptible), and aztreonam-avibactam (MIC₉₀, 4 µg/ml; 100% of isolates with MIC ≤8 µg/ml) were most active against OXA-48-like-positive isolates (n = 68). The in vitro activity of ceftazidime-avibactam was improved against the subset of metallo-β-lactamase (MBL)-negative, OXA-48- and OXA-48-like-positive isolates (99.2% and 100% susceptible, respectively). The data reported here support the continued investigation of ceftazidime-avibactam and aztreonam-avibactam for the treatment of infections caused by carbapenem-resistant Enterobacteriaceae carrying OXA-48 and OXA-48-like β-lactamases in combination with serine- or metallo-β-lactamases.

Treatment of Infections by OXA-48-Producing Enterobacteriaceae

Carbapenemase-producing Enterobacteriaceae (CPE) contribute significantly to the global public health threat of antimicrobial resistance. OXA-48 and its variants are unique carbapenemases with low-level hydrolytic activity toward carbapenems but no intrinsic activity against expanded-spectrum cephalosporins. bla _OXA-48 is typically located on a plasmid but may also be integrated chromosomally, and this gene has progressively disseminated throughout Europe and the Middle East. Despite the inability of OXA-48-like carbapenemases to hydrolyze expanded-spectrum cephalosporins, pooled isolates demonstrate high variable resistance to ceftazidime and cefepime, likely representing high rates of extended-spectrum beta-lactamase (ESBL) coproduction. In vitro data from pooled studies suggest that avibactam is the most potent beta-lactamase inhibitor when combined with ceftazidime, cefepime, aztreonam, meropenem, or imipenem. Resistance to novel avibactam combinations such as imipenem-avibactam or aztreonam-avibactam has not yet been reported in OXA-48 producers, although only a few clinical isolates have been tested. Although combination therapy is thought to improve the chances of clinical cure and survival in CPE infection, successful outcomes were seen in ∼70% of patients with infections caused by OXA-48-producing Enterobacteriaceae treated with ceftazidime-avibactam monotherapy. A carbapenem in combination with either amikacin or colistin has achieved treatment success in a few case reports. Uncertainty remains regarding the best treatment options and strategies for managing these infections. Newly available antibiotics such as ceftazidime-avibactam show promise; however, recent reports of resistance are concerning. Newer choices of antimicrobial agents will likely be required to combat this problem.

Characterizing Mobilized Virulence Factors and Multidrug Resistance Genes in Carbapenemase-Producing Klebsiella pneumoniae in a Sri Lankan Hospital

Limited data is available on the epidemiology and characteristics of carbapenem-resistant Enterobacteriaceae (CRE) and their associated plasmids or virulence determinants from Sri Lanka. Through whole genome sequencing of CREs from the intensive care units of a Sri Lankan teaching hospital, we identified a carbapenemase gene, bla_OXA–181 in 10 carbapenemase-producing Klebsiella pneumoniae isolates (two strains of ST437 and eight strains of ST147) from 379 respiratory specimens. bla_OXA–181 was carried in three variants of ColE-type plasmids. K. pneumoniae strains with ompK36 variants showed high minimum inhibitory concentrations to carbapenem. Furthermore, genes encoding for extended spectrum β-lactamases (ESBL), plasmid-mediated quinolone resistance (PMQR) determinants (qnr, aac(6′)-Ib-cr, and oqxAB) were present in all 10 strains. Amino acid substitution in chromosomal quinolone resistance-determining regions (QRDRs) gyrA (Ser83Ile) and parC (Ser80Ile) were also observed. All strains had yersiniabactin genes on mobile element ICEkp. Strict infection control practices and judicious use of antibiotics are warranted to prevent further spread of multidrug-resistant K. pneumoniae.

Screening and Characterization of Multidrug-Resistant Gram-Negative Bacteria from a Remote African Area, São Tomé and Príncipe

The occurrence of resistance to last-resort antibiotics was evaluated among Enterobacteriaceae isolates recovered from hospitalized children in a remote African archipelago, São Tomé and Príncipe, where there is limited access to those antibiotics. Fifty patients were screened for colonization by carbapenem-, pan-aminoglycoside-, or polymyxin-resistant Enterobacteriaceae A total of 36 isolates (including 30 Escherichia coli and 4 Klebsiella pneumoniae) were recovered from 23 patients, including 26 isolates harboring the bla_OXA-181 carbapenemase gene, a single isolate harboring the 16S rRNA methylase gene rmtB encoding pan-resistance to aminoglycosides, and 8 isolates coharboring both genes. A single isolate possessed the plasmid-borne colistin resistance gene mcr-1 A high clonal relationship was found for OXA-181-producing E. coli (4 clones), and conversely, three of the four OXA-181-producing K. pneumoniae isolates were clonally unrelated. This study overall showed a high prevalence of resistance to last-resort antibiotics in this country, where no epidemiological data were previously available.

Genetic and Biochemical Characterization of OXA-519, a Novel OXA-48-Like β-Lactamase

A multidrug-resistant Klebsiella pneumoniae 1210 isolate with reduced carbapenem susceptibility revealed the presence of a novel plasmid-encoded bla_OXA-48-like gene, named bla_OXA-519 The 60.7-kb plasmid (pOXA-519) was similar to the IncL-OXA-48 prototypical plasmid except for a ca. 2-kb deletion due to an IS1R insertion. OXA-519 differed from OXA-48 by a Val120Leu substitution, which resulted in an overall reduced β-lactam-hydrolysis profile, except those for ertapenem and meropenem, which were increased. Thus, detection of OXA-519 producers using biochemical tests that monitor imipenem hydrolysis will be difficult.

Extended-spectrum β-lactamase-producing and carbapenemase-producing Enterobacteriaceae

Antimicrobial resistance (AMR) is a global public-health emergency, which threatens the advances made by modern medical care over the past century. The World Health Organization has recently published a global priority list of antibiotic-resistant bacteria, which includes extended-spectrum β-lactamase-producing Enterobacteriaceae and carbapenemase-producing Enterobacteriaceae. In this review, we highlight the mechanisms of resistance and the genomic epidemiology of these organisms, and the impact of AMR.

Proteus mirabilis harboring carbapenemase NDM-5 and ESBL VEB-6 detected in Austria

We describe a case of carbapenemase-harboring Proteus mirabilis together with detection of NDM-5 in Austria accompanied by other bacterial strains with a wide range of beta-lactamases including OXA-181 and VEB-6. Isolates were obtained from a subphrenic abscess from one patient who was previously treated with broad-spectrum antibiotics in Bangladesh.

Antibiotic Resistance of Acinetobacter spp. Isolates from the River Danube: Susceptibility Stays High

Acinetobacter spp. occur naturally in many different habitats, including food, soil, and surface waters. In clinical settings, Acinetobacter poses an increasing health problem, causing infections with limited to no antibiotic therapeutic options left. The presence of human generated multidrug resistant strains is well documented but the extent to how widely they are distributed within the Acinetobacter population is unknown. In this study, Acinetobacter spp. were isolated from water samples at 14 sites of the whole course of the river Danube. Susceptibility testing was carried out for 14 clinically relevant antibiotics from six different antibiotic classes. Isolates showing a carbapenem resistance phenotype were screened with PCR and sequencing for the underlying resistance mechanism of carbapenem resistance. From the Danube river water, 262 Acinetobacter were isolated, the most common species was Acinetobacter baumannii with 135 isolates. Carbapenem and multiresistant isolates were rare but one isolate could be found which was only susceptible to colistin. The genetic background of carbapenem resistance was mostly based on typical Acinetobacter OXA enzymes but also on VIM-2. The population of Acinetobacter (baumannii and non-baumannii) revealed a significant proportion of human-generated antibiotic resistance and multiresistance, but the majority of the isolates stayed susceptible to most of the tested antibiotics.

Dissemination and Characteristics of a Novel Plasmid-Encoded Carbapenem-Hydrolyzing Class D β-Lactamase, OXA-436, Found in Isolates from Four Patients at Six Different Hospitals in Denmark

The diversity of OXA-48-like carbapenemases is continually expanding. In this study, we describe the dissemination and characteristics of a novel carbapenem-hydrolyzing class D β-lactamase (CHDL) named OXA-436. In total, six OXA-436-producing Enterobacteriaceae isolates, including Enterobacter asburiae (n = 3), Citrobacter freundii (n = 2), and Klebsiella pneumoniae (n = 1), were identified in four patients in the period between September 2013 and April 2015. All three species of OXA-436-producing Enterobacteriaceae were found in one patient. The amino acid sequence of OXA-436 showed 90.4 to 92.8% identity to the amino acid sequences of other acquired OXA-48-like variants. Expression of OXA-436 in Escherichia coli and kinetic analysis of purified OXA-436 revealed an activity profile similar to that of OXA-48 and OXA-181, with activity against penicillins, including temocillin; limited or no activity against extended-spectrum cephalosporins; and activity against carbapenems. The bla_OXA-436 gene was located on a conjugative ∼314-kb IncHI2/IncHI2A plasmid belonging to plasmid multilocus sequence typing sequence type 1 in a region surrounded by chromosomal genes previously identified to be adjacent to bla_OXA genes in Shewanella spp. In conclusion, OXA-436 is a novel CHDL with functional properties similar to those of OXA-48-like CHDLs. The described geographical spread among different Enterobacteriaceae and the plasmid location of bla_OXA-436 illustrate its potential for further dissemination.

A blaOXA-181-harbouring multi-resistant ST147 Klebsiella pneumoniae isolate from Pakistan that represent an intermediate stage towards pan-drug resistance

Carbapenem resistant Klebsiella pneumoniae (CR-KP) infections are an ever-increasing global issue, especially in the Indian subcontinent. Here we report genetic insight into a bla_OXA-181 harbouring Klebsiella pneumoniae, belonging to the pandemic lineage ST147, that represents an intermediate stage towards pan-drug resistance. The CR-KP isolate DA48896 was isolated from a patient from Pakistan and was susceptible only to tigecycline and colistin. It harboured bla_OXA-181 and was assigned to sequence type ST147. Analysis from whole genome sequencing revealed a very high sequence similarity to the previously sequenced pan-resistant K. pneumoniae isolate MS6671 from the United Arab Emirates. The two isolates are very closely related with only 46 chromosomal nucleotide differences, 14 indels and differences in plasmid content. Both carry a substantial number of plasmid-borne and chromosomally encoded resistance determinants. Interestingly, the two differences in susceptibility between the isolates could be attributed to DA48896 lacking an insertion of bla_OXA-181 into the mgrB gene that results in colistin resistance in MS6671 and SNPs affecting AcrAB efflux pump expression likely to result in tigecycline resistance. These differences between the otherwise very similar isolates indicate that strong selection has occurred for resistance towards these last-resort drugs and illustrates the trajectory of resistance evolution of OXA-181-producing versions of the ST147 international risk clone.

Analysis of OXA-204 carbapenemase-producing Enterobacteriaceae reveals possible endoscopy-associated transmission, France, 2012 to 2014

OXA-48-like beta-lactamase producing bacteria are now endemic in several European and Mediterranean countries. Among this carbapenemase family, the OXA-48 and OXA-181 variants predominate, whereas other variants such as OXA-204 are rarely reported. Here, we report the molecular epidemiology of a collection of OXA-204-positive enterobacterial isolates (n = 29) recovered in France between October 2012 and May 2014. This study describes the first outbreak of OXA-204-producing Enterobacteriaceae in Europe, involving 12 isolates of an ST90 Escherichia coli clone and nine isolates of an ST147 Klebsiella pneumoniae clone. All isolates co-produced the cephalosporinase CMY-4, and 60% of them co-produced the extended-spectrum beta-lactamase CTX-M-15. The bla_OXA-204 gene was located on a 150-kb IncA/C plasmid, isolated from various enterobacterial species in the same patient, indicating a high conjugative ability of this genetic vehicle.

Structural genomics of pNDM-BTR harboring In191 and Tn6360, and other bla NDM-carrying IncN1 plasmids

Aim: To characterize a conjugative bla NDM-1-carrying plasmid pNDM-BTR from a clinical Escherichia coli isolate. Materials & methods: The complete nucleotide sequence of pNDM-BTR was determined using next-generation sequencing technology. Comparative genomic analysis of bla NDM-carrying IncN1 plasmids, including pNDM-BTR, was performed, and the antimicrobial resistance phenotypes were determined. Results: pNDM-BTR contained three accessory modules, namely IS26, a novel Tn3-family transposon Tn6360 and the dfrA14 region composed of In191, ecoRII–ecoRIImet and ΔIS1X2. The relatively small IncN1 backbones could integrate massive accessory modules, most of which were integrated at two ‘hotspots’. These IncN1 plasmids contained distinct profiles of accessory modules, which included those carrying various resistance genes. Conclusion: This study provides a deeper insight into horizontal transfer of resistance genes among IncN1 plasmids.

Emergence of sequence type 252 Enterobacter cloacae producing GES-5 carbapenemase in a Czech hospital

ST252 Enterobacter cloacae, producing GES-5 carbapenemase, was isolated in a Czech hospital. bla_GES-5 was part of a novel class 1 integron, In1406, which also included a new allele of the aadA15 gene cassette. In1406 was located on a ColE2-like plasmid, pEcl-35771cz (6953bp).

OXA-48-like carbapenemases producing Enterobacteriaceae in different niches

The emergence of carbapenem-resistant enterobacterial species poses a serious threat to public health worldwide. OXA-48-type carbapenem-hydrolyzing class D β-lactamases are widely distributed among Enterobacteriaceae, with significant geographical differences. To date, 11 OXA-48-like variants have been identified, with classical OXA-48 being the most widespread. These enzymes show high-level hydrolytic activity against penicillins and low-level hydrolysis towards carbapenems. Since the first description of the OXA-48 carbapenemase in Turkey, bacterial strains producing the enzyme have been extensively reported in nosocomial and community outbreaks in many parts of the word, particularly in the Mediterranean area and European countries. The rapid spread of Enterobacteriaceae producing OXA-48-like enzymes in different ecosystems has become a serious issue recently. The number of reservoirs for such organisms is increasing, not only in hospitals, but also in the community, among animals (e.g., livestock, companion animals, and wildlife) and in the environment. This review aims to summarize the main characteristics of the OXA-48-type carbapenemases, covering genetic and enzymatic traits, their epidemiology, clonality and associated genes, correlation with extended-spectrum β-lactamases (ESBLs) or plasmidic AmpC (pAmpC) in different bacterial species worldwide.

Identification of Carbapenem-Resistant Klebsiella pneumoniae with Emphasis on New Delhi Metallo-Beta-Lactamase-1 (blaNDM-1) in Bandar Abbas, South of Iran

BACKGROUND AND OBJECTIVE

The spread of carbapenem-resistant Klebsiella pneumoniae especially bla_NDM-1-carrying isolates is a great concern worldwide. In this study we describe the molecular basis of carbapenem-resistant K. pneumoniae in three teaching hospitals at Bandar Abbas, south of Iran.

MATERIALS AND METHODS

A total of 170 nonduplicate clinical isolates of K. pneumoniae were investigated. Antimicrobial susceptibility test was performed by disc diffusion method. PCR was carried out for detection of carbapenemase (bla_KPC, bla_IMP, bla_VIM, bla_NDM, bla_SPM, bla_OXA-48, and bla_OXA-181) and extended-spectrum β-lactamase (bla_CTX-M, bla_SHV, bla_TEM, bla_VEB, bla_GES, and bla_PER). Clonal relatedness of bla_NDM-1-positive isolates was evaluated by multilocus sequence typing (MLST).

RESULTS

Tigecycline was the most effective antimicrobial agent with 96.5% susceptibility. In addition, 6.5% of the isolates were carbapenem resistant. Bla_NDM-1 was identified in four isolates (isolate A-D) and all of them were multidrug-resistant. MLST revealed that bla_NDM-1-positive isolates were clonally related and belonged to two distinct clonal complexes, including sequence type (ST) 13 and ST 392. In addition to bla_NDM-1, isolate A coharbored bla_SHV-11, bla_CTX-M-15, and bla_TEM-1, isolate B harbored bla_SHV-11 and bla_CTX-M-15, and isolates C and D contained both bla_SHV-1 and bla_CTX-M-15.

CONCLUSION

Our results indicate that NDM-1-producing K. pneumoniae ST 13 and ST 392 are disseminated in our region. Moreover, one of our major concerns is that these isolates may be more prevalent in the near future. Tracking and urgent intervention is necessary for control and prevention of these resistant isolates.

Structure, activity and thermostability investigations of OXA-163, OXA-181 and OXA-245 using biochemical analysis, crystal structures and differential scanning calorimetry analysis

The first crystal structures of the class D β-lactamases OXA-181 and OXA-245 were determined to 2.05 and 2.20 Å resolution, respectively; in addition, the structure of a new crystal form of OXA-163 was resolved to 2.07 Å resolution. All of these enzymes are OXA-48-like and have been isolated from different clinical Klebsiella pneumoniae strains and also from other human pathogens such as Pseudomonas aeruginosa and Escherichia coli. Here, enzyme kinetics and thermostability studies are presented, and the new crystal structures are used to explain the observed variations. OXA-245 had the highest melting point (Tm = 55.8°C), as determined by differential scanning calorimetry, compared with OXA-163 (Tm = 49.4°C) and OXA-181 (Tm = 52.6°C). The differences could be explained by the loss of two salt bridges in OXA-163, and an overall decrease in the polarity of the surface of OXA-181 compared with OXA-245.

Characterization of OXA-48-like-producing Enterobacteriaceae isolated from river water in Algeria

The spread of carbapenemase-producing Enterobacteriaceae (CPE) is a significant problem for healthcare worldwide. The prevalence of carbapenem-resistant Enterobacteriaceae (CPE) in water environments in Algeria are unknown. The aim of this study was to screen for the presence of CPE isolates in the Soummam River in Bejaia, Algeria. Isolates of Enterobacteriaceae recovered from twelve samples of river water and showing reduced susceptibility to carbapenems were included in this study. The isolates were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Isolates were subjected to antimicrobial susceptibility testing and the modified Carba NP test. Carbapenemase and extended-spectrum β-lactamase (ESBL) determinants were studied by PCR amplification and sequencing. The clonal relatedness between isolates was studied by Multilocus Sequence Typing (MLST) method. A total of 20 carbapenem-resistant Enterobacteriaceae strains were included in this study, identified as Escherichia coli (n = 12), Klebsiella pneumoniae (n = 3), Raoultella ornithinolytica (n = 3), Citrobacter freundii (n = 1) and Citrobacter braakii (n = 1). Carbapenemase genes identified in this study included bla_OXA-48, observed in 17 isolates (9 E. coli, 3 K. pneumoniae, 3 R. ornithinolytica, 1 C. freundii and 1 C. braakii), and bla_OXA-244, a variant of bla_OXA-48, was found in three E. coli isolates. MLST showed that 12 E. coli strains belonged to six different sequence types (ST559, ST38, ST212, ST3541, 1972 and ST2142), and we identified three different STs in K. pneumoniae isolates, including ST133, ST2055, and a new sequence type: ST2192. This study showed the presence of OXA-48-like-producing Enterobacteriaceae in water environments and highlighted the potential role of aquatic environments as reservoirs of clinically relevant antimicrobial-resistant bacteria, with the potential to spread throughout the community.

First report of blaOXA-181-mediated carbapenem resistance in Aeromonas caviae in association with pKP3-A: Threat for rapid dissemination

OBJECTIVES

Carbapenemase-producing Aeromonas spp. are of great concern in healthcare settings and are also known to acquire clinically relevant resistance genes. In this study, carbapenem-non-susceptible Aeromonas isolates were characterised for their molecular mechanisms of resistance.

METHODS

Among 180 Aeromonas isolates, 10 carbapenem-non-susceptible isolates were selected based on their antimicrobial susceptibility profile. Carbapenemase production was investigated by the CarbaNP test. ESBL-, AmpC- and carbapenemase-encoding genes were screened by PCR. Isolates VBF557 and VBF856 with high MICs for imipenem were selected for whole-genome sequencing (WGS). Conjugation experiments were performed to determine the transmissibility of resistance.

RESULTS

WGS remarkably revealed the presence of class D β-lactamases (AmpS/AmpH), class C β-lactamases and class B2 metallo-β-lactamase (cphA3) in VBF557. In contrast, VBF856 had multiple resistance genes coding for aminoglycoside, sulphonamide, carbapenem (bla_OXA-181 class D β-lactamase), macrolide, fluoroquinolone, rifampicin, phenicol, tetracycline and trimethoprim resistance. This is the first global report of bla_OXA-181 in Aeromonas spp. Interestingly, bla_OXA-181 was identified in association with transposon Tn2013 in plasmid pKP3-A. Additionally, an IncQ2 plasmid with qnrS2 was identified. Among the tested isolates, VBF1116 and VBF888 possessed bla_NDM and bla_VEB, respectively, by PCR. None of the other isolates harboured any tested β-lactamase genes. The resistance gene was transmissible in the presence of imipenem.

CONCLUSIONS

Presence of such resistance genes in plasmids further adds complexity for control of spread of carbapenem resistance. This study reveals the emergence of carbapenem resistance among Aeromonas spp. and the importance of mobile genetic elements such as plasmids in interchanging resistance determinants between species.

Rapid Identification of Five Classes of Carbapenem Resistance Genes Directly from Rectal Swabs by Use of the Xpert Carba-R Assay

Carbapenemase-producing organisms (CPO) have been identified by global health leaders as an urgent threat. Detection of patients with gastrointestinal carriage of CPO is necessary to interrupt their spread within health care facilities. In this multisite study, we assessed the performance of the Xpert Carba-R test, a rapid real-time quantitative PCR (qPCR) assay that detects five families of carbapenemase genes (bla_IMP, bla_KPC, bla_NDM, bla_OXA-48, and bla_VIM) directly from rectal swab specimens. Using dual swabs, specimens from 755 patients were collected and tested prospectively. An additional 432 contrived specimens were prepared by seeding well-characterized carbapenem-susceptible and -nonsusceptible strains into a rectal swab matrix and inoculating them onto swabs prior to testing. Antimicrobial susceptibility testing, broth enriched culture, and DNA sequencing were performed by a central laboratory blind to the Xpert Carba-R results. The Xpert Carba-R assay demonstrated a positive percentage of agreement (PPA) between 60 and 100% for four targets (bla_KPC, bla_NDM, bla_VIM, and bla_OXA-48) and a negative percentage of agreement (NPA) ranging between 98.9 and 99.9% relative to the reference method (culture and sequencing of any carbapenem-nonsusceptible isolate). There were no prospective bla_IMP-positive samples. Contrived specimens demonstrated a PPA between 95 and 100% and an NPA of 100% for all targets. Testing of rectal swabs directly using the Xpert Carba-R assay is effective for rapid detection and identification of CPO from hospitalized patients.

Emergence and nosocomial spread of carbapenem-resistant OXA-232-producing Klebsiella pneumoniae in Brunei Darussalam

OBJECTIVES

Carbapenem-resistant Enterobacteriaceae (CRE) are identified as a major global health concern. The success of CRE is facilitated by the emergence, acquisition and spread of successful clones carrying plasmid-encoded resistance genes. In this study, an outbreak of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in patients hospitalised in Brunei Darussalam was investigated.

METHODS

Over a 3-month period (May-July 2015), five multidrug-resistant K. pneumoniae were recovered from individual patients admitted to intensive care units at two hospitals (RIPAS and PMMPMHAB) in Brunei. Antimicrobial susceptibility was determined by broth microtitre dilution using a Micronaut-S β-lactamase VII kit or by Etest. Carbapenemase production was confirmed using the RAPID CARB Blue screen, and classes A-D β-lactamases were detected by multiplex PCR. Molecular typing was performed by random amplified polymorphic DNA (RAPD) PCR and multilocus sequence typing (MLST), with associated virulence and capsular types identified by PCR and sequencing. Plasmids were extracted, sized and characterised by PCR-based replicon typing.

RESULTS

All isolates were resistant to cephalosporins, carbapenems, aminoglycosides, quinolones and sulfonamides but remained susceptible to polymyxins. Isolates were indistinguishable by RAPD-PCR and all belonged to sequence type (ST231). Resistance was due to the production of OXA-232 and CTX-M-15 β-lactamases, with the bla_OXA-232 carbapenemase gene located on a ColE-like plasmid.

CONCLUSIONS

This is the first report of plasmid-encoded OXA-232-producing CRKP in Brunei hospitals. All isolates were members of ST231, which may be representatives of a high-risk CRKP clone disseminating across Southeast Asia.

Molecular Characterization of OXA-48-Like-Producing Enterobacteriaceae in the Czech Republic and Evidence for Horizontal Transfer of pOXA-48-Like Plasmids

The aim of this study was to characterize the first cases and outbreaks of OXA-48-like-producing Enterobacteriaceae recovered from hospital settings in the Czech Republic. From 2013 to 2015, 22 Klebsiella pneumoniae isolates, 3 Escherichia coli isolates, and 1 Enterobacter cloacae isolate producing OXA-48-like carbapenemases were isolated from 20 patients. Four of the patients were colonized or infected by two or three different OXA-48-like producers. The K. pneumoniae isolates were classified into nine sequence types (STs), with ST101 being predominant (n = 8). The E. coli isolates were of different STs, while the E. cloacae isolate belonged to ST109. Twenty-four isolates carried blaOXA-48, while two isolates carried blaOXA-181 or blaOXA-232 Almost all isolates (n = 22) carried blaOXA-48-positive plasmids of a similar size (∼60 kb), except the two isolates producing OXA-181 or OXA-232. In an ST45 K. pneumoniae isolate and an ST38 E. coli isolate, S1 nuclease profiling plus hybridization indicated a chromosomal location of blaOXA-48 Sequencing showed that the majority of blaOXA-48-carrying plasmids exhibited high degrees of identity with the pOXA-48-like plasmid pE71T. Additionally, two novel pE71T derivatives, pOXA-48_30715 and pOXA-48_30891, were observed. The blaOXA-181-carrying plasmid was identical to the IncX3 plasmid pOXA181_EC14828, while the blaOXA-232-carrying plasmid was a ColE2-type plasmid, being a novel derivative of pOXA-232. Finally, sequencing data showed that the ST45 K. pneumoniae and ST38 E. coli isolates harbored the IS1R-based composite transposon Tn6237 containing blaOXA-48 integrated into their chromosomes. These findings underlined that the horizontal transfer of pOXA-48-like plasmids has played a major role in the dissemination of blaOXA-48 in the Czech Republic. In combination with the difficulties with their detection, OXA-48 producers constitute an important public threat.

High Prevalence of Carbapenemase-Producing Enterobacteriaceae among Hospitalized Children in Luanda, Angola

This study aimed to evaluate the prevalence of carbapenemase-producing Enterobacteriaceae in Luanda, Angola. A total of 157 rectal samples were collected from children visiting a pediatric hospital in Luanda in March 2015. Fifty-seven imipenem-nonsusceptible enterobacterial isolates were recovered, most of which were non-clonally related. The blaOXA-181 (50/57) and blaNDM-1 (7/57) carbapenemase genes were identified. Notably, OXA-181-producing Escherichia coli isolates rarely coproduced extended-spectrum β-lactamases and consequently remained susceptible to broad-spectrum cephalosporins. The blaOXA-181 gene was always located on an IncX3 plasmid, while the blaNDM-1 gene was located on either IncFIA or IncA/C plasmids. The study identified a high prevalence of OXA-181 among hospitalized children in Angola.

Global Dissemination of Carbapenemase-Producing Klebsiella pneumoniae: Epidemiology, Genetic Context, Treatment Options, and Detection Methods

The emergence of carbapenem-resistant Gram-negative pathogens poses a serious threat to public health worldwide. In particular, the increasing prevalence of carbapenem-resistant Klebsiella pneumoniae is a major source of concern. K. pneumoniae carbapenemases (KPCs) and carbapenemases of the oxacillinase-48 (OXA-48) type have been reported worldwide. New Delhi metallo-β-lactamase (NDM) carbapenemases were originally identified in Sweden in 2008 and have spread worldwide rapidly. In this review, we summarize the epidemiology of K. pneumoniae producing three carbapenemases (KPCs, NDMs, and OXA-48-like). Although the prevalence of each resistant strain varies geographically, K. pneumoniae producing KPCs, NDMs, and OXA-48-like carbapenemases have become rapidly disseminated. In addition, we used recently published molecular and genetic studies to analyze the mechanisms by which these three carbapenemases, and major K. pneumoniae clones, such as ST258 and ST11, have become globally prevalent. Because carbapenemase-producing K. pneumoniae are often resistant to most β-lactam antibiotics and many other non-β-lactam molecules, the therapeutic options available to treat infection with these strains are limited to colistin, polymyxin B, fosfomycin, tigecycline, and selected aminoglycosides. Although, combination therapy has been recommended for the treatment of severe carbapenemase-producing K. pneumoniae infections, the clinical evidence for this strategy is currently limited, and more accurate randomized controlled trials will be required to establish the most effective treatment regimen. Moreover, because rapid and accurate identification of the carbapenemase type found in K. pneumoniae may be difficult to achieve through phenotypic antibiotic susceptibility tests, novel molecular detection techniques are currently being developed.

OXA β-lactamases

The OXA β-lactamases were among the earliest β-lactamases detected; however, these molecular class D β-lactamases were originally relatively rare and always plasmid mediated. They had a substrate profile limited to the penicillins, but some became able to confer resistance to cephalosporins. From the 1980s onwards, isolates of Acinetobacter baumannii that were resistant to the carbapenems emerged, manifested by plasmid-encoded β-lactamases (OXA-23, OXA-40, and OXA-58) categorized as OXA enzymes because of their sequence similarity to earlier OXA β-lactamases. It was soon found that every A. baumannii strain possessed a chromosomally encoded OXA β-lactamase (OXA-51-like), some of which could confer resistance to carbapenems when the genetic environment around the gene promoted its expression. Similarly, Acinetobacter species closely related to A. baumannii also possessed their own chromosomally encoded OXA β-lactamases; some could be transferred to A. baumannii, and they formed the basis of transferable carbapenem resistance in this species. In some cases, the carbapenem-resistant OXA β-lactamases (OXA-48) have migrated into the Enterobacteriaceae and are becoming a significant cause of carbapenem resistance. The emergence of OXA enzymes that can confer resistance to carbapenems, particularly in A. baumannii, has transformed these β-lactamases from a minor hindrance into a major problem set to demote the clinical efficacy of the carbapenems.

High-level carbapenem-resistant OXA-48-producing Klebsiella pneumoniae with a novel OmpK36 variant and low-level, carbapenem-resistant, non-porin-deficient, OXA-181-producing Escherichia coli from Thailand

Five blaOXA-48-like-carrying Enterobacteriaceae isolates collected from two Thai patients in December 2012 were characterized. Three Klebsiella pneumoniae isolates giving two different pulsed-field gel electrophoresis patterns and sequence types (ST11 and ST37) from patient 1 harbored blaOXA-48 locating on Tn1999.2, whereas two Escherichia coli isolates with the same pulsotype and ST5 from Patient 2 carried ISEcp1-associated blaOXA-181. One K. pneumoniae strain had blaSHV-12, blaDHA-1, qnrB, and qnrS, while another strain harbored blaCTX-M-15, qnrS and aac(6')-Ib-cr. The E. coli strain contained blaCTX-M-15, blaCMY-2, qnrS, and aac(6')-Ib-cr. Interestingly, the OXA-48 producers with a novel OmpK36 variant by a substitution of Gly to Asp in the L3 loop-borne PEFXG motif exhibited high-level resistance to ertapenem, imipenem, and meropenem. In contrast, the OXA-181 producer with non-porin-deficient background showed low-level resistance to ertapenem only. Both patients died because of either septic shock or pneumonia. This study showed the impact of OXA-48-like carbapenemases in porin-defective clinical isolate background, which may lead to serious therapeutic problems in the near future.

Colistin-Nonsusceptible Pseudomonas aeruginosa Sequence Type 654 with blaNDM-1 Arrives in North America

This study describes 3 different blaNDM-1 genetic platforms in 3 different species obtained from the same patient who was directly transferred to an institution in Calgary, Alberta, Canada, following a prolonged hospital stay in India. The blaNDM-1 in the Escherichia coli isolate was located on a 176-kb IncA/C plasmid contained within an ISCR1 region. The blaNDM-1 in the Providencia rettgeri isolate was located on a 117-kb IncT plasmid contained within Tn3000, while the blaNDM-1 in the Pseudomonas aeruginosa isolate was located on the chromosome within an ISCR3 region. This report highlights the plasticity of the genetic regions and environments associated with blaNDM-1. To the best of our knowledge, this is the first report of P. aeruginosa with blaNDM-1 identified in North America and the first report of blaOXA-181 in P. rettgeri. The P. aeruginosa isolate belonged to the international high-risk sequence type 654 clone and was nonsusceptible to colistin. This case emphasizes the need for the use of appropriate infection prevention and control measures and vigilant screening for carbapenem-resistant Gram-negative bacteria in patients with a history of travel to areas of endemicity, such as the Indian subcontinent.

Laboratory Detection and Clinical Implication of Oxacillinase-48 like Carbapenemase: The Hidden Threat

Carbapenemase producing Gram-negative pathogen is of great concern for physician. The challenging aspects are treatment option and infection control. Monitoring of respective carbapenemase resistance mechanism is necessary to prevent the outbreaks. Currently, the rapid emergence of oxacillinase (OXA-48) like is alarming. Increasing frequency of OXA-48 is seen than the classical carbapenemase (KPC, NDM, IMP, and VIM) across the world. The bla OXA-48 gene is commonly identified in Escherichia coli and Klebsiella pneumoniae. The transferrable plasmid of OXA-48 is associated with rapid spread and inter-species dissemination. In general, OXA-48-like enzymes weakly hydrolyzes both carbapenem and broad spectrum cephalosporins. Except OXA-163, which effectively hydrolyze cephalosporin. This poor hydrolytic profile obscures the detection of OXA-48-like. It may go undetected in routine diagnosis and complicates the treatment option. Co-production of OXA-48-like with CTX-M-15 and other carbapenemase (NDM, VIM) leads to the emergence of multidrug resistant strains.

Evaluation of an Immunochromatographic Lateral Flow Assay (OXA-48 K-SeT) for Rapid Detection of OXA-48-Like Carbapenemases in Enterobacteriaceae

We evaluated an immunochromatographic lateral flow assay to detect OXA-48-like carbapenemases (OXA-48 K-SeT) in Enterobacteriaceae (n = 82). One hundred percent sensitivity and specificity were observed using bacteria recovered from both solid medium and spiked blood culture bottles, and the results were obtained in <10 min.

Stepwise evolution of pandrug-resistance in Klebsiella pneumoniae

Carbapenem resistant Enterobacteriaceae (CRE) pose an urgent risk to global human health. CRE that are non-susceptible to all commercially available antibiotics threaten to return us to the pre-antibiotic era. Using Single Molecule Real Time (SMRT) sequencing we determined the complete genome of a pandrug-resistant Klebsiella pneumoniae isolate, representing the first complete genome sequence of CRE resistant to all commercially available antibiotics. The precise location of acquired antibiotic resistance elements, including mobile elements carrying genes for the OXA-181 carbapenemase, were defined. Intriguingly, we identified three chromosomal copies of an ISEcp1-bla(OXA-181) mobile element, one of which has disrupted the mgrB regulatory gene, accounting for resistance to colistin. Our findings provide the first description of pandrug-resistant CRE at the genomic level, and reveal the critical role of mobile resistance elements in accelerating the emergence of resistance to other last resort antibiotics.

Dissemination of carbapenemases producing Gram negative bacteria in the Middle East

The emergence and spread of carbapenemase-producing bacteria, that hydolyze most β-lactams, including carbapenems, are a major concern of public health system worldwide, particularly in the Middle East area. Since the plasmids harboring resistance genes could be spread across other bacterial populations, detection of carbapenemase-producing organisms has become more problematic. These organisms produce different types of enzymes including the most prevalent types including KPC, VIM, IMP, NDM, and OXA-48. Carbapenemase producers are mostly identified among Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii. This study reviewed almost all papers, which conducted in the Middle East. In order to decrease the spread of resistance, the regional cooperation has been emphasized by the Middle East countries. The highest resistance, which is mediated by KPC has been observed in Afghanistan, Saudi Arabia and Jordan followed by NDM in Pakistan and OXA in Turkey and Pakistan. It is important to mention that the spread of these types have been reported sporadically in the other countries of this area. This review described the widespread carbapenemases in the Middle East area, which have been identified in an alarming rate.

Characterization of Carbapenem-Resistant Enterobacteriaceae with High Rate of Autochthonous Transmission in the Arabian Peninsula

To establish the role of local transmission versus possible pathogen import due to previous foreign exposure in infections caused by carbapenem non-susceptible Enterobacteriaceae in the Arabian Peninsula, 200 independent isolates collected in 16 hospitals of Saudi Arabia, Kuwait, Oman and the United Arab Emirates were studied. All strains were multidrug resistant; 42.5% of them also qualified as extremely drug resistant. The frequency of various carbapenemases varied according to the participating countries, but in the collection, as a whole, bla_NDM-1 was the most frequently encountered carbapenemase gene (46.5%) followed by bla_OXA-48-like gene (32.5%). A comparatively high rate (8.9%) of multi-clonal strains carrying both bla_NDM and bla_OXA-48-like genes in the United Arab Emirates, representing the most resistant subgroup, was encountered. No KPC-expressing isolates were detected. Three major clones of bla_NDM-1 carrying Klebsiella pneumoniae of ST152 (n = 22, Saudi Arabia), ST14 (n = 7, United Arab Emirates) and ST147 types (n = 9, Oman) were identified, the latter two clones carrying similar, but not identical HI1b incompatibility type plasmids of >170kb. While from 78.6% of the cases with documented foreign hospitalization bla_NDM positive strains were isolated, these strains formed only 25.6% of all the isolates expressing this enzyme. In fact, 56.8% of the NDM, 75.7% of OXA-48-like and 90.9% of VIM positive strains were recovered from patients without documented foreign exposure, neither in the form of travel or prior hospitalization abroad, suggesting a high rate of autochthonous infections. This, considering the extensive links of these countries to the rest of the world, predicts that trends in the local epidemiology of carbapenem resistant strains may increasingly affect the spread of these pathogens on the global scale. These results call for improved surveillance of carbapenem resistant Enterobacteriaceae in the countries of the Arabian Peninsula.

The difficult-to-control spread of carbapenemase producers among Enterobacteriaceae worldwide

The spread of carbapenemase producers in Enterobacteriaceae has now been identified worldwide. Three main carbapenemases have been reported; they belong to three classes of β-lactamases, which are KPC, NDM, and OXA-48. The main reservoirs of KPC are Klebsiella pneumoniae in the USA, Israel, Greece, and Italy, those of NDM are K. pneumoniae and Escherichia coli in the Indian subcontinent, and those of OXA-48 are K. pneumoniae and Escherichia coli in North Africa and Turkey. KPC producers have been mostly identified among nosocomial isolates, whereas NDM and OXA-48 producers are both nosocomial and community-acquired pathogens. Control of their spread is still possible in hospital settings, and relies on the use of rapid diagnostic techniques and the strict implemention of hygiene measures.

First Report of OXA-181-Producing Escherichia coli in China and Characterization of the Isolate Using Whole-Genome Sequencing

We report the first OXA-181-producing strain in China. blaOXA-181 was found in sequence type 410 (ST410) Escherichia coli strain WCHEC14828 from a Chinese patient without recent travel history. Genome sequencing and conjugation experiments were performed. blaOXA-181 was carried on a 51-kb self-transmissible IncX3 plasmid and was linked with qnrS1, a quinolone resistance gene. blaOXA-181 was introduced onto the IncX3 plasmid from a ColE2-type plasmid, and IncX3 plasmids have the potential to mediate the dissemination of blaOXA-181.