Identification of a New Delhi metallo-β-lactamase-4 (NDM-4)-producing Escherichia coli in Italy

Multicenter study on the prevalence of colonization due to carbapenem-resistant Enterobacterales strains before and during the first year of COVID-19, Italy 2018-2020

Background

Among multidrug-resistant (MDR) bacteria able to threaten human health, carbapenem-resistant Enterobacterales (CRE) have become a major public health threat globally. National and international guidelines point out the importance of active routine surveillance policies to prevent CRE transmission. Therefore, defining lines of intervention and strategies capable of containing and controlling the spread of CRE is considered determinant. CRE screening is one of the main actions to curb transmission and control outbreaks, outlining the presence and also the prevalence and types of carbapenemase enzymes circulating locally.

Objective

The purpose of this study was to outline the epidemiology of CRE colonization in Italy, detecting CRE-colonized patients at admission and during hospitalization, before and during the first year of COVID-19.

Materials and methods

A total of 11,063 patients admitted to seven different hospitals (Bologna, Catania, Florence, Genoa, Naples, Palermo, and Turin) in Intensive Care Units (ICU) and other wards (non-ICU) located in the North, Center, and South of Italy were enrolled and screened for CRE carriage at admission (T0) and during the first 3 weeks of hospitalization (T1-T3). The study spanned two periods, before (September 2018-Septemeber 2019, I observational period) and during the COVID-19 pandemic (October 2019-September 2020, II observational period).

Results

Overall, the prevalence of CRE-colonized patients at admission in ICU or in other ward, ranged from 3.9 to 11.5%, while a percentage from 5.1 to 15.5% of patients acquired CRE during hospital stay. There were large differences between the I and II period of study according to the different geographical areas and enrolling centers. Overall, comparison of prevalence of CRE-positive patients showed a significant increased trend between I and II observational periods both in ICU and non-ICU wards, mostly in the Southern participating centers. KPC-producing Klebsiella pneumoniae was the most frequent CRE species-carbapenemase combination reported in this study. In particular, the presence of KPC-producing K. pneumoniae was reported in period I during hospitalization in all the CRE-positive patients enrolled in ICU in Turin (North Italy), while in period II at admission in all the CRE-positive patients enrolled in ICU in Catania and in 58.3% of non-ICU CRE-positive patients in Naples (both centers in South Italy).

Conclusion

The prevalence of CRE in Italy highly increased during the COVID-19 pandemic, mostly in the Southern hospital centers. KPC-producing K. pneumoniae was the most frequent colonizing CRE species reported. The results of our study confirmed the crucial value of active surveillance as well as the importance of multicenter studies representing diverse geographical areas even in endemic countries. Differences in CRE colonization prevalence among centers suggest the need for diversified and center-specific interventions as well as for strengthening efforts in infection prevention and control practices and policies.

Enzyme Inhibitors: The Best Strategy to Tackle Superbug NDM-1 and Its Variants

Multidrug bacterial resistance endangers clinically effective antimicrobial therapy and continues to cause major public health problems, which have been upgraded to unprecedented levels in recent years, worldwide. β-Lactam antibiotics have become an important weapon to fight against pathogen infections due to their broad spectrum. Unfortunately, the emergence of antibiotic resistance genes (ARGs) has severely astricted the application of β-lactam antibiotics. Of these, New Delhi metallo-β-lactamase-1 (NDM-1) represents the most disturbing development due to its substrate promiscuity, the appearance of variants, and transferability. Given the clinical correlation of β-lactam antibiotics and NDM-1-mediated resistance, the discovery, and development of combination drugs, including NDM-1 inhibitors, for NDM-1 bacterial infections, seems particularly attractive and urgent. This review summarizes the research related to the development and optimization of effective NDM-1 inhibitors. The detailed generalization of crystal structure, enzyme activity center and catalytic mechanism, variants and global distribution, mechanism of action of existing inhibitors, and the development of scaffolds provides a reference for finding potential clinically effective NDM-1 inhibitors against drug-resistant bacteria.

Novel IncFII plasmid harbouring blaNDM-4 in a carbapenem-resistant Escherichia coli of pig origin, Italy

Objectives

To the best of our knowledge, we describe the first evidence in Europe of an MDR, bla_NDM-4-positive Escherichia coli isolated from a food-producing animal, harboured by a novel IncFII plasmid of which we report the complete sequence.

Methods

One bla_NDM-4-positive E. coli isolated in 2019 from the caecal contents of a fattening pig in Italy was in-depth characterized by combined bioinformatic analysis of Oxford Nanopore long reads and Illumina short reads, for in silico typing, determination of the bla_NDM-4 genetic context and full reconstruction of the bla_NDM-4–carrying plasmid.

Results

The isolate belonged to ST641 and to the genoserotype O108:H23 and tested positive for different virulence genes and plasmid replicons. The MDR phenotype of resistance to all β-lactams, carbapenems, sulfamethoxazole and trimethoprim was mediated by bla_TEM-1B, bla_NDM-4, sul1/sul3 and dfrA12, respectively. The bla_NDM-4 gene was harboured by a novel 53 043 bp IncFII plasmid (pMOL412_FII) composed of four main genetic regions, including an MDR region (MRR-NDM-4) of 16 kb carrying bla_NDM-4 and several antimicrobial resistance genes located in a class 1 integron. pMOL412_FII was closely related to another ∼90.3 kb plasmid (pM109_FII) harbouring bla_NDM-4 in an E. coli isolated from a human patient in Myanmar.

Conclusions

To the best of our knowledge, we have identified for the first time in Europe an NDM-producing Enterobacterales in livestock and resolved the complete sequence of the novel pMOL412_FII plasmid harbouring bla_NDM-4 in an MRR. A global One Health approach, comparing genomic data from different sources and geographical areas, may help to trace back and control possible plasmid-borne carbapenemase gene transmission between animals and humans and along the food chain at international level.

Overcoming bacterial resistance to antibiotics: the urgent need – a review

The discovery of antibiotics is considered one of the most crucial breakthroughs in medicine and veterinary science in the 20th century. From the very beginning, this type of drug was used as a ‘miraculous cure’ for every type of infection. In addition to their therapeutic uses, antibiotics were also used for disease prevention and growth promotion in livestock. Though this application was banned in the European Union in 2006, antibiotics are still used in this way in countries all over the world. The unlimited and unregulated use of antibiotics has increased the speed of antibiotic resistance’s spread in different types of organisms. This phenomenon requires searching for new strategies to deal with hard-to-treat infections. The antimicrobial activity of some plant derivatives and animal products has been known since ancient times. At the beginning of this century, even more substances, such as antimicrobial peptides, were considered very promising candidates for becoming new alternatives to commonly used antimicrobials. However, many preclinical and clinical trials ended without positive results. A variety of strategies to fight microbes exist, but we are a long way from approving them as therapies. This review begins with the discovery of antibiotics, covers the modes of action of select antimicrobials, and ends with a literature review of the newest potential alternative approaches to overcoming the drug resistance phenomenon.

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.

New Delhi metallo-β-lactamase (NDM-1)-producing Klebsiella pneumoniae of sequence type ST11: first identification in a hospital of central Italy

The emergence of novel resistant markers hampers the efficacy of beta-lactam antibiotics to treat infections caused by micro-organisms carrying such resistances. This study investigated the antimicrobial susceptibility pattern, the carpapenem-associated determinants and the molecular epidemiology of Klebsiella pneumoniae showing a New Delhi (NDM) metallo-β-lactamase phenotype, isolated from a patient admitted to intensive care unit of the main hospital for acute care of Molise region, central Italy. Antimicrobial susceptibility was assessed for nineteen antibiotics by disc diffusion and agar dilution methods. Carbapenem-associated resistance determinants were detected through gene-specific amplifications, targeting bla_NDM-1 , bla_SHV and bla_TEM , bla_CTX-M , bla_KPC , bla_VIM , bla_IMP , bla_GES and bla_OXA-48-lixe . Molecular characterization was carried out through multilocus sequence typing. The strain showed a multidrug resistant profile, and PCR and sequencing confirmed the presence of bla_NDM-1 gene. Among the multiple resistance-associated determinants tested, the isolate, which was assigned to the sequence type ST11, only harboured bla_SHV and bla_TEM genes. This is the first report of NDM-1 variant in the regional healthcare setting for acute patients, raising significant concerns about the increase in the antimicrobials resistance spread through a different mechanism from the endemic KPC carbapenemase, and underlining the circulation of a virulent clone never identified before in this area.

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.

Emergence of NDM-5-producing Escherichia coli sequence type 167 clone in Italy

The emergence of carbapenemase-producing Enterobacteriaceae (CPE) is a critical concern worldwide. In Italy, CPE isolates are very frequent, with the KPC enzyme types strongly predominant whereas the New Delhi metallo-β-lactamase (NDM) enzymes are extremely rare. Here we report the first detection of NDM-5-producing Escherichia coli sequence type 167 (ST167) isolates from two patients with urinary tract infection (Ec001 and Ec002 from urines), including one with colonisation (Ec003 from faeces) admitted to the same hospital 2 months apart in 2017. Minimum inhibitory concentrations (MICs) were determined by broth microdilution. The carbapenemase type was identified both by phenotypic and genotypic methods. Isolate genotypes were investigated by phylogenetic typing, multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Next-generation sequencing (NGS) was used to obtain complete sequences of plasmids. The three E. coli isolates carried the bla_NDM-5 gene, shared the same resistance phenotype and belonged to ST167. By PFGE, isolates showed the same profile, suggesting that they were the same strain. NGS revealed that the bla_NDM-5 gene was located on a 99-kb multireplicon plasmid (designed pNDM-5-IT) with a peculiar scaffold constituted by four replicons of the IncF type (FIA, FIB and two copies of the FII replicon). pNDM-5-IT plasmid harboured multiple resistance and virulence determinants, including the arginine deaminase (ADI) cluster never found associated with plasmids before. Since NDM-5-producing E. coli ST167 has been regarded as a successful epidemic clone in China, the emergence of such a clone carrying a plasmid associated both with multiresistance and virulence could be a public-health threat.

Cryptic transmission of ST405 Escherichia coli carrying bla NDM-4 in hospital

Three carbapenem-resistant Escherichia coli were recovered from rectal swabs of different patients in a tertiary hospital and were found carrying bla_NDM-4, an uncommon bla_NDM variant. Genome sequences of the isolates were obtained using Illumina technology and the long-read MinION sequencer. The isolates belonged to ST405 and phylogenetic group D, a globally distributed lineage associated with antimicrobial resistance. In addition to bla_NDM-4, the three isolates carried 14 known resistance genes including the extended-spectrum β-lactamase gene bla_CTX-M-15. There were only 1 or 2 SNPs between the isolates, suggesting a common origin and cryptic transmission in hospital. bla_NDM-4 was located on a 46.5-kb IncFIA self-transmissible plasmid, which may facilitate further dissemination of bla_NDM-4. Two copies of IS26 bracketed a 14.6-kb region containing bla_NDM-4 and have the potential to form a composite transposon for mediating the mobilization of bla_NDM-4.

Dissemination of Carbapenem-resistant Klebsiella pneumoniae clinical isolates with various combinations of Carbapenemases (KPC-2, NDM-1, NDM-4, and OXA-48) and 16S rRNA Methylases (RmtB and RmtC) in Vietnam

Methods

Twenty-seven clinical isolates of carbapenem-resistant Klebsiella pneumoniae with MICs ≥4 mg/L for imipenem or meropenem were obtained from inpatients in a hospital in Vietnam. Antimicrobial susceptibility tests and whole genome sequencing were performed. Multilocus sequence typing and the presence of drug resistant genes were determined and a maximum-likelihood phylogenetic tree was constructed by SNP alignment of whole genome sequencing data.

Results

All the isolates harbored one of genes encoding carbapenemases, including KPC-2, NDM-1, NDM-4 and OXA-48. Of the isolates, 13 were resistant to arbekacin with MICs ≥256 mg/L and to amikacin with MICs ≥512 mg/L. These isolates harbored a gene encoding a 16S rRNA methylase, either RmtB or RmtC. Eighteen and 4 isolates belonged to international clones, ST15 and ST16, respectively. None of the isolates had colistin-resistant factors.

Conclusion

Carbapenem-resistant K. pneumoniae isolates belonged to international clones spread in a medical setting in Vietnam, and that these isolates harbored genes encoding various combinations of carbapenemases and 16S rRNA methylases. This is the first report of KPC-2, NDM-4 and OXA-48 producers in a medical setting in Vietnam.

IncX3 plasmid mediated occurrence of blaNDM-4 within Escherichia coli ST448 from India

This study was designed to investigate bla_NDM-4 encoded within IncX3 type plasmid and their copy number alteration under carbapenem pressure within clinical isolates of Escherichia coli. NDM-4 producing E. coli isolates were collected from an Indian hospital and transferability as well as plasmid incompatibility typing was determined. Genetic environment and antibiogram profiling was carried out. Quantitative Real Time PCR was done to determine the change in plasmid copy number under concentration gradient carbapenem stress. Multilocus sequence typing and pulsed field gel electrophoresis was performed for typing of isolates. Four multidrug resistant isolates were found to harbour transconjugable bla_NDM-4 carrying within IncX3 type plasmid. The bla_NDM-4 was flanked by insertion sequences ISAba125 and IS5 in the upstream region whereas ble_MBL was present in the downstream area. Copy number results indicated that the bla_NDM-4 gene was maintained high in plasmid under exposure of ertapenem. All the strains belonged to ST448 and PFGE analysis revealed three different pulsotypes. This is the first report of bla_NDM-4 encoded IncX3 type plasmid in E. coli of ST448 and needs a systematic screening policy to rapid detection of NDM-4 poducing strains to prevent dissemination of this resistant determinant in future.

The use of whole-genome sequencing for molecular epidemiology and antimicrobial surveillance: identifying the role of IncX3 plasmids and the spread of blaNDM-4-like genes in the Enterobacteriaceae

AIMS

To characterise the resistome of a multi-drug resistant Klebsiella pneumoniae (Kp0003) isolated from an Australian traveller who was repatriated to a Sydney Metropolitan Hospital from Myanmar with possible prosthetic aortic valve infective endocarditis.

METHODS

Kp0003 was recovered from a blood culture of the patient and whole genome sequencing was performed. Read mapping and de novo assembly of reads facilitated in silico multi-locus sequence and plasmid replicon typing as well as the characterisation of antibiotic resistance genes and their genetic context. Conjugation experiments were also performed to assess the plasmid (and resistance gene) transferability and the effect on the antibiotic resistance phenotype.

RESULTS

Importantly, and of particular concern, the carbapenem-hydrolysing β-lactamase gene blaNDM-4 was identified on a conjugative IncX3 plasmid (pJEG027). In this respect, the blaNDM-4 genetic context is similar (at least to some extent) to what has previously been identified for blaNDM-1 and blaNDM-4-like variants.

CONCLUSIONS

This study highlights the potential role that IncX3 plasmids have played in the emergence and dissemination of blaNDM-4-like variants worldwide and emphasises the importance of resistance gene surveillance.

Emergence of a KPC-3-Producing Escherichia coli ST69 as a Cause of Bloodstream Infections in Italy

The spread of carbapenem-resistant gram negatives is a global emergency, and surveillance of new resistant clones is critical from both public health and clinical standpoints. Herein, we describe the emergence of a KPC-3-producing Escherichia coli ST69 as a cause of bloodstream infection in two Italian patients.