Detection of New Delhi Metallo-β-Lactamase Variants NDM-4, NDM-5, and NDM-7 in Enterobacter aerogenes Isolated from a Neonatal Intensive Care Unit of a North India Hospital: A First Report

Dramatic increase in antimicrobial resistance in ESKAPE clinical isolates over the 2010-2020 decade in India

RATIONALE AND OBJECTIVES

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) constitute a threat to humans worldwide. India is now the most populous country. The goal was to investigate the evolution of the rates of antimicrobial resistance in ESKAPE pathogens across India over the 2010-20 decade.

METHODS

The data (89 studies) were retrieved from the Medline PubMed repository using specific keywords.

RESULTS

The study of 20 177 ESKAPE isolates showed that A. baumannii isolates were the most represented (35.9%, n = 7238), followed by P. aeruginosa (25.3%, n = 5113), K. pneumoniae (19.5%, n = 3934), S. aureus (16.3%, n = 3286), E. faecium (2.6%, n = 517) and Enterobacter spp. (0.4%, n = 89). A notable increase in the resistance rates to antimicrobial agents occurred over the 2010-20 decade. The most important levels of resistance were observed in 2016-20 for A. baumannii (90% of resistance to the amoxicillin-clavulanate combination) and K. pneumoniae (81.6% of resistance to gentamycin). The rise in β-lactamase activities was correlated with an increase in the positivity of Gram-negative isolates for β-lactamase genes.

CONCLUSIONS

This review highlighted that, in contrast to developed countries that kept resistance levels under control, a considerable increase in resistance to various classes of antibiotics occurred in ESKAPE pathogens in India over the 2010-2020 decade.

Molecular characterization of IncFII plasmid carrying blaNDM-5 in a Salmonella enterica serovar Typhimurium ST34 clinical isolate in China

IMPORTANCE

In this study, an IncFII plasmid pIncFII-NDM5 carrying blaNDM-5 was found in carbapenem-resistant Salmonella enterica serovar Typhimurium (S. enterica serovar Typhimurium), which has conjugative transferability and carried blaNDM-5, bleMBL, mph(A), and blaTEM-1 four resistance genes that can mediate resistance to multiple antibiotics including cephalosporins, beta-lactamase inhibitor combinations, carbapenems, and macrolides. Phylogenetic analysis showed that 1104-65 and 1104-75 were closely related to other S. enterica serovar Typhimurium in this area. The above-mentioned S. enterica serovar Typhimurium chromosome carries blaCTX-M-55, qnrS1, and tet(A) genes, so the antibiotic resistance of isolates will be further enhanced after obtaining the pIncFII_NDM5-like plasmid. Meanwhile, we discovered a novel genetic structure of blaNDM-5 mediated by the IS26 composite transposon, which will expand our understanding of the emergence and spread of carbapenem-resistance genes. Altogether, the presence of the IncFII plasmid pIncFII-NDM5 further underscores the need for vigilant surveillance and appropriate infection control measures to mitigate the impact of carbapenem-resistant S. enterica serovar Typhimurium in clinical settings.

Molecular Screening of Carbapenem-Resistant K. pneumoniae (CRKP) Clinical Isolates for Concomitant Occurrence of Beta-Lactam Genes (CTX-M, TEM, and SHV) in the Kingdom of Bahrain

The emergence of extended-spectrum β-lactamase-producing Klebsiella pneumoniae, including CRKP infections, has resulted in significant morbidity and mortality worldwide. We aimed to explore the presence of bla genes (CTX-M, TEM, and SHV) in CRKP isolates. A total of 24 CRKP isolates were randomly selected from the Salmaniya Medical Complex Microbiology Laboratory. These isolates, which were positive for carbapenemases, were further explored for CTX-M, TEM, and SHV genes using PCR. All the CTX-M PCR amplicons were sent for sequencing. To determine genetic relatedness, molecular typing by ERIC-PCR was performed. The bla gene testing demonstrated that a significant proportion of these isolates harbored SHV, CTX-M, and TEM genes (100%, 91.6%, and 45.8%), respectively. Bioinformatic analyses confirmed CTX-M-15 in these isolates. ERIC-PCR analysis showed three clusters demonstrating genetic relatedness. The study findings reveal the concomitant carriage of the SHV and CTX-M-15 and a comparatively lower carriage of TEM genes in CRKP isolates. Our findings highlight the significance of routinely reporting the presence of antibiotic resistance genes along with regular antibiotic sensitivity reports, as this will aid clinicians in prescribing appropriate antibiotics.

Emergence of a clinical isolate of E. coil ST297 co-carrying blaNDM-13 and mcr-1.1 in China

BACKGROUND

The coexistence of carbapenem resistance genes and mcr-1.1 in Enterobacterales has been an urgent and persistent threat to global public health. In this study, we isolated a clinical NB4833, an Escherichia coli isolate that co-carries mcr-1.1 and blaNDM-13.

OBJECTIVES

This study aimed to isolate a clinical NB4833, an Escherichia coli isolate that co-carries mcr-1.1 and blaNDM-13 and investigated the phenotypic and genotypic characteristics of plasmids harbored by E. coli isolate NB4833.

METHODS

Antimicrobial susceptibility testing and conjugation assay were performed on E. coli isolate NB4833. Stability of the plasmid and growth rate determination were used to characterize the plasmids harboring mcr-1.1 and blaNDM-13. In addition, the genetic characteristics of the plasmids were analyzed based on whole-genome sequencing of the strain and comparative genetic analysis with related plasmids.

RESULTS

Whole-genome sequencing showed that the isolate carried multiple resistance genes and possessed phenotypes indicative of all antibiotic resistance except tigecycline. And the mcr-1.1- and blaNDM-13-harbouring plasmids showed relatively high similarity to the related plasmids. The pNB4833-NDM-13 plasmid was capable of trans conjugation with an efficiency of 1.04 × 10-2 in a filter mating experiment and the transconjugant J53/ pNB4833-NDM-13 was able to be stably inherited after 10 days of passage.

CONCLUSIONS

To our knowledge, this is the first report of the coexistence of the IncI2 plasmid carrying mcr-1.1 and a blaNDM-13-carrying integrated IncFIB/IncFII plasmid in an ST297 clinical E. coli isolate. In addition, we investigated a novel plasmid carrying blaNDM-13. Our study expands the diversity of plasmids carrying blaNDM-13, which exhibits epidemic importance in bacterial resistance. Therefore, there are important measures that should be taken to prevent the spread of these plasmids.

Detection of clinically relevant carbapenemase encoding genes in carbapenem-resistant Enterobacter cloacae complex and Klebsiella pneumoniae isolated from farmed freshwater fish

AIMS

The present study was aimed to detect clinically relevant carbapenemase encoding genes in carbapenem-resistant Enterobacter cloacae complex (CR-ECC), Klebsiella pneumoniae (CR-KP), and Serratia plymuthica (CR-SP) isolated from farmed freshwater fish.

METHODS AND RESULTS

Out of 243 spatially diverse freshwater fish samples analysed, 5.3% were contaminated with CR-ECC, 1.6% with CR-KP, and 0.4% with CR-SP. The CR-ECC was further identified as E. asburiae (38.5%), E. mori (23.1%), E. cloacae (15.4%), E. hormaechei (15.4%), and E. kobei (7.7%) by 16S rRNA gene sequencing. The CR-ECC were resistant to carbapenems and cefoxitin, whereas CR-KP and CR-SP were multi-drug resistant (MDR). The CR-ECC harboured the carbapenemase gene blaIMI alone or in combination with blaTEM, blaEBC, blaCIT, blaACC, and tet(E). Whereas, CR-KP harboured carbapenemase gene, blaNDM-5 along with blaOXA-48, blaSHV, blaOXA-1, blaCTX-M-15, tet(A), sul1, and qnrB. No carbapenemase-encoding genes were detected in CR-SP. The MLST analysis showed that CR-KP belonged to ST231 and ST1561 lineages, while CR-ECC did not show exact match with any reported STs. The plasmid replicons predominantly detected were IncF and IncI1. Broth mating assays of CR-KP and CR-ECC with recipient Escherichia coli J53 indicated that blaNDM-5 was transferable but not blaIMI.

CONCLUSION

This study highlights the low-level contamination of carbapenem-resistant Enterobacterales (CRE) harbouring clinically relevant carbapenemase-encoding genes in farmed freshwater fish from India. The CR-ECC of fish origin did not show the potential to spread carbapenem resistance.

Efficacy of Novel Combinations of Antibiotics against Multidrug-Resistant-New Delhi Metallo-Beta-Lactamase-Producing Strains of Enterobacterales

The emergence of multidrug-resistance (MDR)-New Delhi metallo-beta-lactamase (NDM)-producing microorganisms-has become a serious concern for treating such infections. Therefore, we investigated the effective antimicrobial combinations against multidrug-resistant New Delhi metallo-beta-lactamase-producing strains of Enterobacterales. The tests were carried out using the 2D(two-dimensional) checkerboard method. Of 7 antimicrobials, i.e., doripenem (DRP), streptomycin (STR), cefoxitin (FOX), imipenem (IPM), cefotaxime (CTX), meropenem (MER), and gentamicin (GEN), 19 different combinations were used, and out of them, three combinations showed synergistic effects against 31 highly drug-resistant strains carrying bla_NDM and other associated resistance markers. Changes in the minimum inhibitory concentration (MIC) values were interpreted using the test fractional inhibitory concentration index (FIC Index). The FIC Index values of these combinations were found in the range of 0.1562 to 0.5, which shows synergy, whereas no synergism was observed in the remaining antimicrobial combinations. We conclude that these antibiotic combinations can be analyzed in in vivo and pharmacological studies to establish an effective therapeutic approach.

Characterization of NDM-5-Producing Escherichia coli Strains Isolated from Pediatric Patients with Bloodstream Infections in a Chinese Hospital

Escherichia coli (E. coli) bloodstream infections (BSIs) are among the most predominant causes of death in infants and children worldwide. NDM-5 (New Delhi Metallo-lactamase-5) is responsible for one of the main mechanisms of carbapenem resistance in E. coli. To analyze the phenotypic and genomic characteristics of NDM-5-producing E. coli from bloodstream infections (BSIs), a total of 114 E. coli strains was collected from a children's hospital in Jiangsu province, China. Eight blaNDM-5-carrying E. coli strains were identified which were all carbapenem-resistant and carried diverse antimicrobial resistance genes apart from blaNDM-5. They belonged to six distinct sequence types (STs) and serotypes including one each for ST38/O7:H8, ST58/O?:H37, ST131/O25:H4, ST156/O11:H25 and ST361/O9:H30 and three strains are originating from a single clone belonging to ST410/O?:H9. Apart from blaNDM-5, the E. coli strains isolated from BSIs also carried other β-lactamase genes, including blaCMY-2 (n = 4), blaCTX-M-14 (n = 2), blaCTX-M-15 (n = 3), blaCTX-M-65 (n = 1), blaOXA-1 (n = 4) and blaTEM-1B (n = 5). The blaNDM-5 genes were located on three different types of plasmids, which were IncFII/I1 (n = 1), IncX3 (n = 4) and IncFIA/FIB/FII/Q1 (n = 3). The former two types were conjugatively transferable at frequencies of 10-3 and 10-6, respectively. The dissemination of NDM-producing strains, which exhibit resistance to the last-line antibiotics, carbapenems, may increase the muti-antimicrobial resistance burden among E. coli BSIs and further threaten public health.

Case Report of bla NDM-7-Harboring IncX3 Plasmid in ST196 Klebsiella quasipneumoniae in China

Klebsiella quasipneumoniae isolate SBH035 was recovered from a patient in Jiangsu Province, China. The isolate showed resistance to ampicillin, cefazolin, cefotaxime, meropenem, ceftazidime–avibactam, and fosfomycin. The carbapenemase-encoding gene bla_NDM-7 was identified, and whole genome sequencing analysis indicated that bla_NDM-7 was located in an IncX3 plasmid with a conserved structure of IS26-ΔcutA-tat-trpF-ble_MBL-bla_NDM-7-ISAba125-IS3000-ΔTn2. To date, this is the first identification of a bla_NDM-7-harboring IncX3 plasmid in ST196 K. quasipneumoniae from a patient in China. Greater attention to controlling the dissemination of IncX3 plasmids is needed owing to potential horizontal transfer via mobile genetic elements.

Emergence of a Salmonella Rissen ST469 clinical isolate carrying bla NDM-13 in China

New Delhi metallo-β-lactamase-13 (NDM-13) is an NDM variant that was first identified in 2015 and has not been detected in Salmonella species prior to this study. Here we describe the first identification of a Salmonella Rissen strain SR33 carrying bla NDM-13. The aim of this study was to molecularly characterize SR33's antimicrobial resistance and virulence features as well as investigate the genetic environment of bla NDM-13. The Salmonella Rissen SR33 strain was isolated from a patient with fever and diarrhea. SR33 belonged to ST469, and it was found to be multidrug-resistant (MDR) and to carry many virulence genes. Phylogenetic analysis showed that SR33 shared a close relationship with most of the Chinese S. Rissen ST469 strains. bla NDM-13 was located in a transmissible IncI1 plasmid pNDM13-SR33. Sequence analysis of bla NDM-13-positive genomes downloaded from GenBank revealed that a genetic context (ΔISAba125-bla NDM-13-ble MBL-trpF) and a hybrid promoter (consisting of -35 sequences provided by ISAba125 and -10 sequences) were conserved. ISAba125 was truncated by IS1294 in three plasmids carrying bla NDM-13, including pNDM13-SR33. To our knowledge, this is the first report of bla NDM-13 carried by Salmonella. The emergence of bla NDM-13 in a clinical MDR S. Rissen ST469 strain highlights the critical need for monitoring and controlling the dissemination of bla NDM-13. bla NDM-13 carried by a transmissible IncI1 plasmid may result in an increased risk of bla NDM-13 transmission. IS1294 may be involved in the movement of bla NDM-13.

A Yersiniabactin-producing Klebsiella aerogenes Strain Causing an Outbreak in an Austrian Neonatal Intensive Care Unit

BACKGROUND

Yersiniabactin, a siderophore with a high affinity to iron, has been described as a potential virulence factor in Enterobacteriaceae. Klebsiella aerogenes is a Gram-negative rod known to cause invasive infection in very low birth weight infants but is an unusual pathogen to cause outbreaks in neonatal intensive care units (NICU).

METHODS

We performed a retrospective analysis of all patients colonized with K. aerogenes in our NICU from September to December 2018. Each infant with an occurrence of K. aerogenes in any microbiological culture was defined as a case. Clinical data were taken from medical charts. K. aerogenes isolates were genotyped using whole-genome sequencing combined with core genome multilocus sequencing type analysis. Yersiniabactin production was evaluated by luciferase assay.

RESULTS

In total 16 patients were colonized with K. aerogenes over the 3-month period and 13 patients remained asymptomatic or developed late-onset neonatal sepsis from another pathogen. Three patients developed necrotizing enterocolitis, 2 complicated by sepsis and 1 of them died. All symptomatic patients were premature infants with low birth weight. Genetic sequencing confirmed an outbreak with the same strain, all samples expressed the high-pathogenicity island, necessary for the production of yersiniabactin. Six exemplary cases were proven to produce yersiniabactin in vitro.

CONCLUSION

This is the first report of an outbreak of a yersiniabactin-producing K. aerogenes strain causing invasive infection in preterm infants. We hypothesize that, due to improved iron uptake, this strain was associated with higher virulence than non-yersiniabactin-producing strains. Extended search for virulence factors and genetic sequencing could be pivotal in the management of NICU outbreaks in the future.

The Spread of NDM-1 and NDM-7-Producing Klebsiella pneumoniae Is Driven by Multiclonal Expansion of High-Risk Clones in Healthcare Institutions in the State of Pará, Brazilian Amazon Region

Carbapenem resistance among Klebsiella pneumoniae isolates is often related to carbapenemase genes, located in genetic transmissible elements, particularly the blaKPC gene, which variants are spread in several countries. Recently, reports of K. pneumoniae isolates harboring the blaNDM gene have increased dramatically along with the dissemination of epidemic high-risk clones (HRCs). In the present study, we report the multiclonal spread of New Delhi metallo-beta-lactamase (NDM)-producing K. pneumoniae in different healthcare institutions in the state of Pará, Northern Brazil. A total of 23 NDM-producing isolates were tested regarding antimicrobial susceptibility testing features, screening of carbapenemase genes, and genotyping by multilocus sequencing typing (MLST). All K. pneumoniae isolates were determined as multidrug-resistant (MDR), being mainly resistant to carbapenems, cephalosporins, and fluoroquinolones. The blaNDM-7 (60.9%-14/23) and blaNDM-1 (34.8%-8/23) variants were detected. MLST genotyping revealed the predomination of HRCs, including ST11/CC258, ST340/CC258, ST15/CC15, ST392/CC147, among others. To conclude, the present study reveals the contribution of HRCs and non-HRCs in the spread of NDM-1 and NDM-7-producing K. pneumoniae isolates in Northern (Amazon region) Brazil, along with the first detection of NDM-7 variant in Latin America and Brazil, highlighting the need for surveillance and control of strains that may negatively impact healthcare and antimicrobial resistance.

Companion Animals Emerged as an Important Reservoir of Carbapenem-Resistant Enterobacteriaceae: A Report from India

The emergence and spread of carbapenem-resistant Enterobacteriaceae (CRE) are perceived as a serious public-health threat world-wide. Despite sporadic reports, no systemic study has been carried out on CRE in companion animals in Indian subcontinent. In total, 237 canine specimens collected from five veterinary polyclinics in and around Kolkata were analyzed for isolation, antimicrobial resistance profiling and molecular characterization of carbapenem-resistant (CR) E. coli. Of the 29 CR isolates, 19 were identified as metallo-β-lactamase producers (MP-CRE) and 10 as metallo-β-lactamase non-producers (MNP-CRE). Eleven of them were extended spectrum β-lactamase and/or AmpC type β-lactamase producers and harboured fluoroquinolone-, tetracycline-, sulfonamide- and aminoglycoside-resistant genes. Beside uropathogenic virulence determinants, they carried the adhesion factors mediating biofilm production which was remarkably higher in 6 MP-CRE and one MNP-CRE isolates. Although the CRE were of diverse origin including the healthy and the diseased dogs, these were more frequently isolated from canine pyometra. The MP-CRE harboured plasmids of IncF and Inc_A/C types. Phylo-type B1 was observed in 38% of the CR isolates, followed by A0 in 31% and rest were attributed to A1 and D1. The Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) revealed that these isolates were genetically diverse and constituted of a heterogenous population. Detection of CRE in pet dogs despite the fact that carbapenems are not used in animals in India emphasizes the need for active surveillance to identify the transmission and dynamics of such pathogens in companion animals.

Whole Genomic analysis of a clinical isolate of Uropathogenic Escherichia coli strain of Sequence Type - 101 carrying the drug resistance NDM-7 in IncX3 plasmid

The emerging NDM-producing Enterobactereciae is a major threat to public health. The association of NDM-7 with sequence type 101 E.coli is identified in very few numbers. Therefore, it is of interest to analyse the whole genome sequence of NDM-producing uropathogenic E. coli XA31 that was found to carry numerous drug resistance genes of different antibiotic classes. The isolate E. coli belongs to ST-101 carrying blaNDM-7 coexisting with several resistance genes blaOXA-1, blaTEM1-A, blaCTX-M15, aac(6')-Ib-cr, catB3, tetB. Resfinder predicts this and four other plasmid replicons were identified using the Plasfinder in the CGE platform. The high transferable IncX3 plasmid was found to carry the NDM-7 gene. Thus, we the report the combination of NDM-7-ST101-IncX3 in India. The combination of this epidemic clone with NDM-7 is highly required to develop an effective infection control strategy.

Dissemination of blaNDM-5 via IncX3 plasmids in carbapenem-resistant Enterobacteriaceae among humans and in the environment in an intensive vegetable cultivation area in eastern China

The environment of a large-scale vegetable production area can be exposed to antibiotic residues and antibiotic-resistant bacteria (ARB) via animal manure and irrigation with contaminated water, which can facilitate the dissemination of ARB. However, the occurrence of ARB in plantation areas and their dissemination in this environment remain largely unexplored. In total, 382 samples including those from vegetable (n = 106), soil (n = 87), well water (n = 24), river water (n = 20), river sediments (n = 20), farmer feces (n = 58) and farmer hands (n = 67) were collected in 2019 from a large-scale cultivation area in Shandong, China. Selective agar plates were used to screen for carbapenem-resistant Enterobacteriaceae (CRE) and whole-genome sequencing and Southern blotting were used to characterise isolates and mobile genetic elements carrying carbapenem resistance determinants. A total of nine NDM-5-producing isolates of Escherichia coli, Klebsiella pneumoniae, and Citrobacter spp. were identified from environmental sources and human feces, all of which were multidrug-resistant. Single nucleotide polymorphism analysis suggested clonal transmission of carbapenem-resistant Citrobacter sedlakii within greenhouse soils in the area. Eight of the isolates carried closely related or identical IncX3 plasmids carrying blaNDM-5, which were shown to be conjugative via filter mating experiments, indicating the highly transmissible nature of this genetic element. Isolates of E. coli and Citrobacter freundii were detected in the feces of local farm workers and contained similar IncX3 plasmids with blaNDM-5 environmental isolates, suggesting a potential risk of CRE transfer from the work environment to the farm workers. Thus, further research is required to investigate the potential health risks associated with environmental exposure to CRE in vegetable cultivation areas.

The present danger of New Delhi metallo-β-lactamase: a threat to public health

The evolution of antimicrobial-resistant Gram-negative pathogens is a substantial menace to public health sectors, notably in developing countries because of the scarcity of healthcare facilities. New Delhi metallo-β-lactamase (NDM) is a potent β-lactam enzyme able to hydrolyze several available antibiotics. NDM was identified from the clinical isolates of Klebsiella pneumoniae and Escherichia coli from a Swedish patient in New Delhi, India. This enzyme horizontally passed on to various Gram-negative bacteria developing resistance against a variety of antibiotics which cause treatment crucial. These bacteria increase fatality rates and play an integral role in the economic burden. The efficient management of NDM-producing isolates requires the coordination between each healthcare setting in a region. In this review, we present the prevalence of NDM in children, fatality and the economic burden of resistant bacteria, the clonal spread of NDM harboring bacteria and modern techniques for the detection of NDM producing pathogens.

Global genotype distribution of human clinical isolates of New Delhi metallo-β-lactamase-producing Klebsiella pneumoniae; A systematic review

BACKGROUND AND AIM

The global rise of antimicrobial resistance among bacterial strains is a rapidly growing challenge and is becoming a major public health concern. This study documents the worldwide spread and genotype distribution of human clinical isolates of New Delhi metallo-β-lactamase-producing Klebsiella pneumoniae (NPKP).

METHODS

Several international databases, including Web of Science, Embase and Medline were searched (2010 - 2019) to identify studies addressing the frequency of NPKP regionally or worldwide.

RESULTS

Of 4779 articles identified, 202 studies fulfilled the eligibility criteria and were included in our analysis. The frequency of NPKP in Asia, Europe, America, Africa and Oceania was 64.6%, 20.1%, 9.0%, 5.6% and 0.4%, respectively. The most prevalent sequence types (STs) among NPKP were ST11, ST290, ST147, ST340, ST15, ST278 and ST14 based on published studies.

CONCLUSION

The dissemination of bla_NDM variants in different STs among NPKP in the various region of world is a serious concern to public health. The prevalence of NPKP should be controlled by comprehensive infection control measures and optimization of antibiotic therapy.

Carbapenem resistance in Escherichia coli and Klebsiella pneumoniae among Indian and international patients in North India

The aim of the study was to find out the carbapenem resistance rate and prevalence of different carbapenemase genes in Klebsiella pneumoniae and Escherichia coli from a North Indian corporate hospital that receives both Indian and international patients. A total of 528 clinical isolates of E. coli and K. pneumoniae were included in the study. All isolates that were found resistant to carbapenems by MIC testing (Vitek II Compact^®) were screened for NDM, OXA-48, VIM, and KPC genes by PCR. Sequencing of NDM gene and transmissibility by conjugation assay were checked on 22 randomly selected NDM-positive isolates. One hundred and fifty-six isolates (29.54%) were carbapenem-resistant. The rate of carbapenem resistance was significantly higher in K. pneumoniae as compared to E. coli (53.9% vs. 15.6%; p < 0.05). The NDM gene was found in 34.6% (54/156), OXA-48 in 31.4% (49/156), co-expression of NDM + OXA-48 in 15.3% (24/156) of the carbapenem-resistant isolates. VIM and KPC were absent in all isolates. NDM gene was significantly more prevalent in E. coli than K. pneumoniae (p < 0.05). All the tested isolates formed transconjugants and NDM-5 was the most common variant in both species (15/22). The presence of plasmid-based NDM calls for stricter surveillance measures in our hospital settings.

Outbreak of Efficiently Transferred Carbapenem-Resistant blaNDM-Producing Gram-Negative Bacilli Isolated from Neonatal Intensive Care Unit of an Indian Hospital

The emergence of bla_NDM particularly in Gram-negative bacteria is a burden on the health care system in developing countries. Hence, this study was initiated to screen New Delhi Metallo-β-lactamase (NDM)-producing Gram-negative bacterial strains from neonatal intensive care unit (NICU) of an Indian Hospital. A total of 18 bla_NDM-producing isolates were detected in the present study. Out of 18 bla_NDM variant isolates, 6 were Klebsiella pneumoniae, 4 Escherichia coli, 2 Enterobacter aerogenes, 1 Acinetobacter lwoffii, 1 Enterobacter cloacae, 3 Acinobacter baumannii, and 1 Cedecea davisae from NICU, showing resistance against all antibiotics, except colistin and polymixin. The transferability of resistance determinants was tested by conjugation. Transfer of bla_NDM-producing strains was successful in all 18 strains. In the case of transconjugants, the minimum inhibitory concentration values were found to decrease. The bla_NDM-producing isolates contained detectable plasmids of size 66, 38, and 6 kb. Plasmi/d-based replicon typing revealed the incompatibility types Inc (A/C, FIIA, FIC, K, F, W, FIA, P, X, FIB, B/O) in bla_NDM-carrying isolates. This study revealed the outbreak of multiple variants of bla_NDM (13 NDM-1, 4 NDM-5, and 1 NDM-7). Moreover, other resistance markers, viz. bla_OXA-1, bla_CMY-1, bla_VIM-1, and bla_SHV-1 coassociated with bla_NDM were also found. In this study, we reported NDM-producing C. davisae as a first report to the best of our knowledge. This study is an attempt to reveal the dissemination of bla_NDM isolated from neonates in NICU and their efficient transferability among Gram-negative bacilli through horizontal gene transfer.

Emergence of NDM-4-producing Klebsiella pneumoniae in a Korean hospital due to a patient hospitalized in Vietnam and case review

NDM-4-producing Klebsiella pneumoniae (NDM-4-KP) was detected from the patient who had previously been injured and hospitalized for 5 days in Vietnam in a neurosurgical intensive care unit (NSICU) of a Korean tertiary-care hospital in December 2016. He admitted with ventilator-associated pneumonia and NDM-4-KP was isolated, which was subsequently detected in two other NSICU patients. All NDM-4-KP isolates from patient and environmental surveillance cultures were sequence type 11. Colonization of three patients persisted for 5-12 months. Dedicated environmental cleaning was added to single room isolation of NDM-4-KP patients and universal chlorhexidine bathing, and no further transmission of NDM-4-KP occurred. This is the first report of NDM-4-KP in a Korean hospital where a patient with a history of hospitalization abroad was the index case initiating an outbreak involving three patients. The spread of newly introduced CPE was controlled using a bundle of infection control.

Frequency distribution, genotypes and prevalent sequence types of New Delhi metallo-β-lactamase-producing Escherichia coli among clinical isolates around the world: A review

OBJECTIVES

New Delhi metallo-β-lactamase (NDM)-producing Escherichia coli is perceived as one of the primary multidrug-resistant bacteria causing infections in hospitals and clinics. In this review, we present the frequency distribution, genotypes and most prevalent sequence types (STs) of NDM-producing E. coli among clinical isolates worldwide.

METHODS

Several international databases, including Medline, Embase, Scopus and Web of Science, were searched from 2008 to 2018 to identify studies addressing the prevalence of NDM-producing E. coli around the world.

RESULTS

Of 974 records identified from the databases, 110 studies fulfilled the eligibility criteria and were included in this analysis. The prevalence of NDM-producing E. coli was 82.6%, 12.9%, 1.5%, 1.0% and 2.0% in Asia, Europe, America, Africa and Oceania, respectively. The most common reported STs among NDM-producing E. coli were ST101, ST167, ST131, ST405, ST410 and ST648.

CONCLUSION

The spread of NDM variants among E. coli strains is a serious threat to global public health. In addition, the most prevalent E. coli clonal groups, such as ST101 and ST167, are one of the main causes of E. coli infection in different countries.

Detection and Genomic Characterization of a Morganella morganii Isolate From China That Produces NDM-5

The increasing prevalence and transmission of the carbapenem resistance gene bla NDM-5 has led to a severe threat to public health. So far, bla NDM-5 has been widely detected in various species of Enterobacterales and different hosts across various cities. However, there is no report on the bla NDM-5- harboring Morganella morganii. In January 2016, the first NDM-5-producing Morganella morganii L241 was found in a stool sample of a patient diagnosed as recurrence of liver cancer in China. Identification of the species was performed using 16S rRNA gene sequencing. Carbapenemase genes were identified through both PCR and sequencing. To investigate the characteristics and complete genome sequence of the bla NDM-5-harboring clinical isolate, antimicrobial susceptibility testing, S1 nuclease pulsed field gel electrophoresis, Southern blotting, transconjugation experiment, complete genome sequencing, and comparative genomic analysis were performed. M. morganii L241 was found to be resistant to broad-spectrum cephalosporins and carbapenems. The complete genome of L241 is made up from both a 3,850,444 bp circular chromosome and a 46,161 bp self-transmissible IncX3 plasmid encoding bla NDM-5, which shared a conserved genetic context of bla NDM-5 (ΔIS3000-ΔISAba125-IS5-bla NDM-5-ble-trpF-dsbC-IS26). BLASTn analysis showed that IncX3 plasmids harboring bla NDM genes have been found in 15 species among Enterobacterales from 13 different countries around the world thus far. In addition, comparative genomic analysis showed that M. morganii L241 exhibits a close relationship to M. morganii subsp. morganii KT with 107 SNPs. Our research demonstrated that IncX3 is a key element in the worldwide dissemination of bla NDM-5 among various species. Further research will be necessary to control and prevent the spread of such plasmids.

Emergence of ST147 Klebsiella pneumoniae carrying blaNDM-7 on IncA/C2 with ompK35 and ompK36 mutations in India

India is known to be endemic to NDM carbapenemases. However, NDM-7 among Klebsiella pneumoniae has not been described from India. Apart from carbapenemases, ompK35 and ompK36 also contribute to carbapenem resistance in K. pneumoniae. This study describes molecular mechanisms of antimicrobial resistance in an isolate from bacteraemia investigated through whole genome sequencing. bla_NDM-7 was found on IncA/C2 plasmid which also carried sul-1, aadA2, rmtC, bla_CMY-6 and ARR-2. ompK35 had mutations and changes from 39th amino acid. ompK36 was truncated to 248 amino acids. The isolate belonged to ST147. The patient was a known case systemic lupus erythematosus (SLE) and blood culture grew carbapenem resistant K. pneumoniae. Meropenem, colistin and tiecoplanin were administered and the patient was discharged on improvement. Emergence of new resistance variants and porin mutations among clones such as ST147 which has been prevalent has potential for rapid spread and thus challenges infection control.

Evaluation of co-transfer of plasmid-mediated fluoroquinolone resistance genes and bla NDM gene in Enterobacteriaceae causing neonatal septicaemia

Background

The bla_NDM-1 (New Delhi Metallo-β-lactamase-1) gene has disseminated around the globe. NDM-1 producers are found to co-harbour resistance genes against many antimicrobials, including fluoroquinolones. The spread of large plasmids, carrying both bla_NDM and plasmid-mediated fluoroquinolone resistance (PMQR) markers, is one of the main reasons for the failure of these essential antimicrobials.

Methods

Enterobacteriaceae (n = 73) isolated from the blood of septicaemic neonates, admitted at a neonatal intensive care unit (NICU) in Kolkata, India, were identified followed by PFGE, antibiotic susceptibility testing and determination of MIC values for meropenem and ciprofloxacin. Metallo-β-lactamases and PMQRs were identified by PCR. NDM-positive isolates were studied for mutations in GyrA & ParC and for co-transmission of bla_NDM and PMQR genes (aac(6′)-Ib-cr, qnrB, qnrS) through conjugation or transformation. Plasmid types, integrons, plasmid addiction systems, and genetic environment of the bla_NDM gene in NDM-positive isolates and their transconjugants/ transformants were studied.

Results

Isolated Enterobacteriaceae comprised of Klebsiella pneumoniae (n = 55), Escherichia coli (n = 16), Enterobacter cloacae (n = 1) and Enterobacter aerogenes (n = 1). The rates of ciprofloxacin (90%) and meropenem (49%) non-susceptibility were high. NDM was the only metallo-β-lactamase found in this study. NDM-1 was the predominant metallo-β-lactamase but NDM-5, NDM-7, and NDM-15 were also found. There was no significant difference in ciprofloxacin non-susceptibility (97% vs 85%) and the prevalence of PMQRs (85% vs 77%) between NDM-positive and NDM-negative isolates. Among the PMQRs, aac(6′)-Ib-cr was predominant followed by qnrB1 and qnrS1. Twenty-nine isolates (40%) co-harboured PMQRs and bla_NDM, of which 12 co-transferred PMQRs along with bla_NDM in large plasmids of IncFIIK, IncA/C, and IncN types. Eighty-two percent of NDM-positive isolates possessed GyrA and/or ParC mutations. Plasmids carrying only bla_NDM were of IncHIB-M type predominantly. Most of the isolates had ISAba125 in the upstream region of the bla_NDM gene.

Conclusion

We hypothesize that the spread of PMQRs was independent of the spread of NDM-1 as their co-transfer was confirmed only in a few isolates. However, the co-occurrence of these genes poses a great threat to the treatment of neonates.

Electronic supplementary material

The online version of this article (10.1186/s13756-019-0477-7) contains supplementary material, which is available to authorized users.

First Detection of New Delhi Metallo-β-Lactamase-5-Producing Escherichia coli from Companion Animals in Korea

The gene for New Delhi metallo-β-lactamase-5 (NDM-5) in Escherichia coli has been identified in many countries mainly from human clinical specimens. The isolates carrying this gene are even more rarely isolated from companion animals. In this study, four carbapenem-resistant isolates were recovered from four dogs in Korea. All isolates carried bla_NDM-5 and exhibited resistance to meropenem and imipenem, and were susceptible to colistin. Epidemiological analysis showed that all four isolates were sequence type 410 (ST410) and shared 99% similarity as determined by pulsed-field gel electrophoresis analysis. Among the four isolates, the Z0117EC0033 strain was randomly selected for whole-genome sequencing, composed of a 4.7Mb circularized chromosome carrying the CMY-2 gene and two plasmids. The first plasmid of the IncFIB type had 83 coding sequences (CDS) in ca. 74 kb. The second smaller plasmid of the IncX3 type had 57 CDS and carried only the bla_NDM-5 gene in ca. 46 kb. The plasmid structures were highly similar (> 99%) to those of the NDM-5 human-like IncX3 plasmid. This is the first report of carbapenemase-producing Enterobacteriaceae from companion animals in Korea. The human-like bla_NDM-5 IncX3 plasmid identified in this study suggests a potential transmission route of the NDM-5 plasmid between humans and companion animals.

Occurrence of blaNDM Variants Among Enterobacteriaceae From a Neonatal Intensive Care Unit in a Northern India Hospital

Carbapenem-resistance among enterobacteriaceae has become a global health concern. The objective of this study was to understand NDM producing enterobacteriaceae and their genetic basis of resistance, spreading in neonatal intensive care unit. Carbapenem resistant NDM producing enterobacteriaceae isolates were recovered from rectal swab and blood sample of infants admitted in NICU. These were determined by using Carba-NP test. All isolates were identified using BD Phoenix^TM−100 and MICs were determined by broth microdilution method. The bla_NDM and associated resistant markers were checked by PCR followed by sequencing. Moreover, ERIC-PCR and genetic environment of bla_NDM gene were also performed for the analysis of clonal relationship and genetic surrounding of the strains. We characterized 44 isolates with bla_NDM variants in Escherichia coli (45.5%), Klebsiella pneumoniae (40.9%), Citrobacter freundii (4.5%), Citrobacter braakii (2.3%), Klebsiella oxytoca (2.3%), Enterobacter cloacae (2.3%), Enterobacter aerogenes (2.2%) from NICU, showing resistance against all antibiotics except colistin and polymixin B. ISAba125 and bleomycin gene were found surrounding all bla_NDM variants, besides class I integron on plasmid. (ERIC)-PCR data revealed non-clonal relatedness among most of the isolates. The transfer of resistant markers was confirmed by conjugation experiment. The PCR-based replicon typing was carried out using DNA of transconjugants. These isolates carried NDM-1 (20.45%), NDM-4 (36.36%), NDM-5 (38.64%), NDM-7 (4.55%), along with OXA, CMY, and SHV variants on conjugative plasmid of IncFIA, IncFIC, IncF, IncK, IncFIB, IncB/O, IncHI1, IncP, IncY, IncFIIA, IncI1, and IncN types. An increased number of carbapenem-resistant NDM producing enterobacteriaceae isolates recovered from NICU which is alarming signal for health workers and policy makers. Hence, it is utmost important to think about infection control measures.