Genome-Based Epidemiologic Analysis of VIM/IMP Carbapenemase-Producing Enterobacter spp., Poland

We sequenced all nonduplicate 934 VIM/IMP carbapenemase-producing Enterobacterales (CPE) reported in Poland during 2006-2019 and found ≈40% of the isolates (n = 375) were Enterobacter spp. During the study period, incidence of those bacteria gradually grew in nearly the entire country. The major factor affecting the increase was clonal spread of several E. hormaechei lineages responsible for multiregional and interregional outbreaks (≈64% of all isolates), representing mainly the pandemic sequence type (ST) 90 or the internationally rare ST89 and ST121 clones. Three main VIM-encoding integron types efficiently disseminated across the clone variants (subclones) with various molecular platforms. Those variants were predominantly Pseudomonas aeruginosa-derived In238-like elements, present with IncHI2+HI2A, IncFII+FIA, IncFIB, or IncN3 plasmids, or chromosomal genomic islands in 30 Enterobacter STs. Another prevalent type, found in 34 STs, were In916-like elements, spreading in Europe recently with a lineage of IncA-like plasmids.

MDR carbapenemase-producing Klebsiella pneumoniae of the hypervirulence-associated ST23 clone in Poland, 2009-19

OBJECTIVES

To characterize carbapenemase-producing isolates of the Klebsiella pneumoniae hypervirulent (hvKp) clone ST23 in Poland.

METHODS

Fifteen K. pneumoniae ST23 isolates were identified by the Polish surveillance of carbapenemase-producing Enterobacterales. These comprised a cluster with KPC-2 + NDM-1 (n = 7), KPC-2 (n = 1) or NDM-1 (n = 1) enzymes from one hospital from 2018, and sporadic isolates with KPC-2 (n = 1), NDM-1 (n = 1), VIM-1 (n = 1) or OXA-48 (n = 3), recovered from 2009 to 2019 in different towns. The isolates were sequenced by Illumina MiSeq, followed by MinION for six representatives. Clonality, phylogeny, serotypes, virulomes, resistomes and plasmids of the isolates were analysed and compared with international ST23 strains, using various bioinformatic tools.

RESULTS

Only two diverse isolates with KPC-2 or VIM-1 were of typical hvKp ST23 serotypes K1 and O1v.2, and its predominant phylogenetic clade. These contained multiple chromosomal (ybt, clb) and pK2044/KpVP-1 plasmid (iuc, iro, rmpADC, rmpA2) virulence loci, whereas carbapenemase and other antimicrobial resistance (AMR) genes were on single additional plasmids. All remaining isolates were of K57 and O2v.2 serotypes, and a minor, distant clade of unclear phylogeny, including also ∼10 isolates from other European countries. These had fewer virulence loci (ybt, iuc, rmpADC, rmpA2) but abounded in plasmids, which with several chromosomal AMR mutations conferred more extensive MDR phenotypes than in K1 O1v.2. Lower clonal diversity than in K1, and numerous common characteristics of the isolates supported the hypothesis of the emerging character of the ST23 K57 clade.

CONCLUSIONS

A new MDR ST23 lineage has emerged in Europe, causing a potential threat to public health.

Occurrence and Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated from Hospitalized Patients in Poland-A Single Centre Study

The global emergence and spread of genes responsible for the production of ESBL (extended-spectrum beta-lactamases) and carbapenemases in Klebsiella pneumoniae isolates poses a serious threat to public health. The aim of this study was to retrospectively analyze the frequency of occurrence and drug resistance of selected alarm agents isolated from patients of the specialist hospital in Wrocław. A total of 13,528 clinical materials collected from patients of a specialist hospital in Wrocław were analyzed in the period from 1 January 2020 to 31 December 2020. Overall, 3894 bacterial strains were isolated from clinical materials, including 416 K. pneumoniae isolates. K. pneumoniae that showed resistance to ETP (ertapenem) and/or MEM (meropenem) were tested using phenotypic tests for the detection of KPC (carbapenemase-producing Klebsiella), MBL (metallo-β-lactamase) and OXA-48 (oxacilinase-48) carbapenemases. In the case of a positive or doubtful result of the phenotypic test, immunochromatographic tests and the CarbaNP test were performed. In total, 58 K. pneumoniae isolates resistant to 1 or more carbapenem antibiotics were isolated. Of the 58 strains, 16 (27.6%) were isolated from rectal swabs conducted on CPE (carbapenemase-producing Enterobacteriaceae) carriers. In the case of CRE (carbapenem-resistant Enterobacteriaceae) K. pneumoniae, carbapenemases were detected in 28/58 (48.3%) isolates. Notably, 23/28 K. pneumoniae isolates produced MBL/NDM (New Delhi metallo-β-lactamase) (82.1%), 5/28 produced VIM (Verona-intergon-encoded metallo-β-lactamase) (14.3%), and one produced MBL/NDM + OXA-48. Carbapenemases were detected in 13 of 16 (81.3%) carbapenem-resistant K. pneumoniae isolates derived from rectal swabs. The significant participation of CRE and CPE isolates in the infections proves the need to test patients admitted to hospital wards for their status as a CPE carrier in order to limit the emergence of new epidemic outbreaks.

Dissemination of Klebsiella pneumoniae ST147 NDM-1 in Poland, 2015-19

OBJECTIVES

To assess the spread of New Delhi metallo-β-lactamase-1 (NDM-1)-producing Klebsiella pneumoniae ST147 organisms in Poland since an introduction from Tunisia in March 2015, including their phylogenetic position in the global population of the high-risk clone.

METHODS

Out of 8925 unique NDM-positive K. pneumoniae isolates identified in Poland from April 2015 till December 2019, 126 isolates, including the Tunisian imports, were related by PFGE and blaNDM gene-carrying Tn125 transposon derivatives. Forty-seven representative isolates were sequenced by Illumina MiSeq. The phylogeny, resistome, virulome and plasmid replicons were analysed and compared with the international ST147 strains. Plasmids of six isolates were studied by the MinION sequencing.

RESULTS

A high homogeneity of the 47 isolates was observed, with minor variations in their resistomes and plasmid replicon profiles. However, the detailed SNP comparison discerned a strict outbreak cluster of 40 isolates. All of the organisms were grouped within the ST147 phylogenetic international lineage, and four NDM-1 producers from Tunisia, Egypt and France were the closest relatives of the Polish isolates. Yersiniabactin genes (YbST280 type) were located within the ICEKpn12-like element in most of the outbreak isolates, characterized by O2v1 and KL64 antigen loci. The blaNDM-1 genes were located in double-replicon IncFIIK2+IncFIBK plasmids.

CONCLUSIONS

The continuous spread of K. pneumoniae ST147 NDM-1 in Poland since 2015, largely in the Warsaw area, is demonstrated by this genomic analysis. The isolates showed a high degree of homogeneity, and close relatedness to organisms spreading in the Mediterranean region.

Treatment for carbapenem-resistant Enterobacterales infections: recent advances and future directions

Carbapenem-resistant Enterobacterales (CRE) are a growing threat to human health worldwide. CRE often carry multiple resistance genes that limit treatment options and require longer durations of therapy, are more costly to treat, and necessitate therapies with increased toxicities when compared with carbapenem-susceptible strains. Here, we provide an overview of the mechanisms of resistance in CRE, the epidemiology of CRE infections worldwide, and available treatment options for CRE. We review recentlyapproved agents for the treatment of CRE, including ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, cefiderocol, and novel aminoglycosides and tetracyclines. We also discuss recent advances in phage therapy and antibiotics that are currently in development targeted to CRE. The potential for the development of resistance to these therapies remains high, and enhanced antimicrobial stewardship is imperative both to reduce the spread of CRE worldwide and to ensure continued access to efficacious treatment options.

Longitudinal analysis of ESBL and carbapenemase carriage among Enterobacterales and Pseudomonas aeruginosa isolates collected in Europe as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance programme, 2013-17

OBJECTIVES

To determine the spread of ESBLs and carbapenemases in Enterobacterales and Pseudomonas aeruginosa in Europe.

METHODS

45 335 Gram-negative bacilli were collected in 18 European countries as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance programme from 2013 to 2017. Antimicrobial susceptibility was determined using broth microdilution, and 9546 isolates were screened for β-lactamase genes by PCR and sequencing.

RESULTS

ESBLs were identified in 35.5% of Klebsiella pneumoniae and 18.5% of Escherichia coli. ESBL carriage was lowest among isolates in Northern/Western Europe and highest in Eastern Europe. CTX-M-15 was the dominant ESBL in all countries except Greece, where SHV-type ESBLs were more common. Carbapenemases (KPC, OXA-48-like, GES, NDM and VIM) were found in 3.4% of Enterobacterales and were most common among K. pneumoniae (10.5% of those collected). Carbapenemase carriage was lowest in Northern/Western and highest in Southern Europe. KPC-positive Enterobacterales were most abundant but the percentages of OXA-48-like-, NDM- and VIM-positive isolates increased over time and were correlated with an increase in meropenem non-susceptibility. Carbapenemases (VIM, IMP, NDM and GES) were also identified in 5.1% of P. aeruginosa and were commonly found in Eastern Europe. Carbapenemase carriage and meropenem non-susceptibility among P. aeruginosa fluctuated over the 5 years studied and were not well correlated.

CONCLUSIONS

ESBL and carbapenemase carriage varied by species and European subregion. Meropenem non-susceptibility in European isolates of Enterobacterales can be attributed to carbapenemase carriage and is increasingly caused by MBLs and OXA-48-like carbapenemases. Carbapenemases or other β-lactamases are not a common cause of meropenem non-susceptibility in P. aeruginosa in Europe.

Continuous Evolution: Perspective on the Epidemiology of Carbapenemase Resistance Among Enterobacterales and Other Gram-Negative Bacteria

The global emergence of carbapenemase-producing bacteria capable of hydrolyzing the once effective carbapenem antibiotics is considered a contemporary public health concern. Carbapenemase enzymes, once constrained to isolates of Klebsiella pneumoniae, are now routinely reported in different bacteria within the Enterobacterales order of bacteria, creating the acronym CRE which now defines Carbapenem-Resistant Enterobacterales. CRE harboring different types of enzymes, including the most prevalent types KPC, VIM, IMP, NDM, and OXA-48, are now routinely reported and more importantly, are now frequently present in many infections world-wide. Defining and updating the contemporary epidemiology of both the US and global burden of carbapenem-resistant infections is now more important than ever. This review describes the global distribution and continued evolution of carbapenemases which continue to spread at alarming rates. Informed understanding of the current epidemiology of CRE, coupled with advances in antibiotic options, and the use rapid diagnostics offers the potential for rapid identification and management of carbapenem-resistant infections.

The Impact of Insertion Sequences on O-Serotype Phenotype and Its O-Locus-Based Prediction in Klebsiella pneumoniae O2 and O1

Klebsiella pneumoniae is a nosocomial pathogen, pointed out by the World Helth Organisation (WHO) as “critical” regarding the highly limited options of treatment. Lipopolysaccharide (LPS, O-antigen) and capsular polysaccharide (K-antigen) are its virulence factors and surface antigens, determining O- and K-serotypes and encoded by O- or K-loci. They are promising targets for antibody-based therapies (vaccines and passive immunization) as an alternative to antibiotics. To make such immunotherapy effective, knowledge about O/K-antigen structures, drift, and distribution among clinical isolates is needed. At present, the structural analysis of O-antigens is efficiently supported by bioinformatics. O- and K-loci-based genotyping by polymerase chain reaction (PCR) or whole genome sequencing WGS has been proposed as a diagnostic tool, including the Kaptive tool available in the public domain. We analyzed discrepancies for O2 serotyping between Kaptive-based predictions (O2 variant 2 serotype) and the actual phenotype (O2 variant 1) for two K. pneumoniae clinical isolates. Identified length discrepancies from the reference O-locus resulted from insertion sequences (ISs) within rfb regions of the O-loci. In silico analysis of 8130 O1 and O2 genomes available in public databases indicated a broader distribution of ISs in rfbs that may influence the actual O-antigen structure. Our results show that current high-throughput genotyping algorithms need to be further refined to consider the effects of ISs on the LPS O-serotype.

Novel Target Exploration from Hypothetical Proteins of Klebsiella pneumoniae MGH 78578 Reveals a Protein Involved in Host-Pathogen Interaction

The opportunistic pathogen Klebsiella pneumoniae is a causative agent of several hospital-acquired infections. It has become resistant to a wide range of currently available antibiotics, leading to high mortality rates among patients; this has further led to a demand for novel therapeutic intervention to treat such infections. Using a series of in silico analyses, the present study aims to explore novel drug/vaccine candidates from the hypothetical proteins of K. pneumoniae. A total of 540 proteins were found to be hypothetical in this organism. Analysis of these 540 hypothetical proteins revealed 30 pathogen-specific proteins essential for pathogen survival. A motifs/domain family analysis, similarity search against known proteins, gene ontology, and protein–protein interaction analysis of the shortlisted 30 proteins led to functional assignment for 17 proteins. They were mainly cataloged as enzymes, lipoproteins, stress-induced proteins, transporters, and other proteins (viz., two-component proteins, skeletal proteins and toxins). Among the annotated proteins, 16 proteins, located in the cytoplasm, periplasm, and inner membrane, were considered as potential drug targets, and one extracellular protein was considered as a vaccine candidate. A druggability analysis indicated that the identified 17 drug/vaccine candidates were “novel”. Furthermore, a host–pathogen interaction analysis of these identified target candidates revealed a betaine/carnitine/choline transporters (BCCT) family protein showing interactions with five host proteins. Structure prediction and validation were carried out for this protein, which could aid in structure-based inhibitor design.

Epidemiology of β-Lactamase-Producing Pathogens

β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

Molecular characterization of plasmid-encoded Tripoli MBL 1 (TMB-1) in Enterobacteriaceae

Objectives

Available commercial tools (molecular methods or immunochromatographic assays) usually allow the detection of the five most prevalent carbapenemases (KPC, NDM, VIM, IMP and OXA-48-like), but miss minor carbapenemases. Here, we characterize two enterobacterial isolates with reduced susceptibility to carbapenems and negative for the most commonly encountered carbapenemase genes.

Methods

Enterobacter hormaechei and Citrobacter freundii isolates were recovered from a bile sample and rectal screening, respectively. Both isolates were investigated by WGS. Resistance genes were detected using ResFinder. The blaTMB-1-harbouring plasmid was reconstructed using CLC genomic workbench 10.0 and was annotated using the RAST tool. Transfer frequency was determined by conjugation experiments using the laboratory strain Escherichia coli J53.

Results

The two isolates were resistant to broad-spectrum cephalosporins and carbapenems. WGS revealed the presence of blaTMB-1, which has previously only been described in non-fermenters. blaTMB-1 was located within an ISKpn19-based composite class 1 transposon. Comparative genomics revealed that this structure was carried on a conjugative IncN-type plasmid within an integration hotspot. Conjugation experiments revealed high transfer frequencies of ∼1 × 10-3.

Conclusions

To the best of our knowledge, this study corresponds to the first report of Tripoli MBL 1-producing Enterobacteriaceae. Despite always being described as likely to be chromosomally located in non-fermenters, the blaTMB-1 gene is now found to be carried by a conjugative plasmid among Enterobacteriaceae, raising concern about the possible dissemination of this carbapenemase. The blaTMB-1 gene should now be suspected when PCRs targeting the main carbapenemases remain negative.

Tracking KPC-3-producing ST-258 Klebsiella pneumoniae outbreak in a third-level hospital in Granada (Andalusia, Spain) by risk factors and molecular characteristics

The objective of this study was to determine clinical-epidemiological characteristics of the patients and the genetic characteristics of carbapenemase KPC-3-producing Klebsiella pneumoniae isolates belonging to sequence type ST258. The eligible study population was all patients with isolates detected between October 2015 and March 2017. Clinical-epidemiological and microbiological data were gathered on risk factors associated with infection by this clone. Antimicrobial susceptibility was determined using MicroScan system and diffusion in agar. Genes encoding carbapenemases were detected using PCR and Sanger sequencing. The sequence type was assigned by MLST, and the genetic relationship among clinical isolates was determined by pulsed field electrophoresis and by analysis of the genetic environment. The study included 23 individuals with isolates of KPC-3/ST258; the mean age was 77 year, and mean stay pre-isolation was 32 days; 81% received empirical antimicrobial treatment. Isolates were only susceptible to gentamicin (CIM ≤ 2 mg/L), tigecycline (CIM ≤ 1 mg/L), and colistin (CIM ≤ 2 mg/L). The isolates belonged to ST258, with five pulse types or subgroups. All isolates showed amplification of KPC, which was identified as KPC-3 variant. Gene _blaKPC-3 was flanked by insertion sequences Kpn6 and Kpn7 within Tn4401 transposon isoform a. We report, for the first time in Spain, an 18-month outbreak by KPC-3-producing ST258 K. pneumoniae. Its acquisition was associated with a history of antimicrobial therapy, with three treatment options, and with high mortality. The detection of different pulse types is attributable to different introductions of the clone in our setting, supporting the need for multi-resistant isolate surveillance studies.

KPC-2-producing Klebsiella pneumoniae ST11 in a Children's Hospital in Poland

Four Klebsiella pneumoniae isolates from children hospitalized over 10 months in an intensive care unit in a children's teaching hospital in Poland were analyzed. All of the isolates belonged to a single pulsotype and sequence type (ST) 11, and produced the KPC-2 carbapenemase and extended-spectrum β-lactamase (ESBL) CTX-M-15. They were resistant to a variety of antimicrobials, and their β-lactam resistance patterns were typical for KPC producers. This is one of few cases of identification of KPC (or carbapenemase)-producing K. pneumoniae in a pediatric center in Poland.

Occurrence of Carbapenemase-Producing Klebsiella pneumoniae in Bat Guano

The aim of this study was to screen for the presence of carbapenemase-producing Enterobacteriaceae (CPE) isolates from bat guano in Bejaia, Algeria. Guano samples (n = 110) were collected in Aokas's cave, Bejaia, Algeria, between March and May 2016. Samples were plated on MacConkey agar supplemented with ertapenem (0.5 mg/L) and vancomycin (32 mg/L). The isolates were identified and antimicrobial susceptibility was determined using disk diffusion method. Carbapenemase, extended spectrum β-lactamases, plasmid-mediated AmpC, and plasmid-mediated quinolone resistance genes were studied using PCR and sequencing. Clonal relatedness was studied using multilocus sequence typing (MLST). Two CPE isolates were identified as Klebsiella pneumoniae. PCR and sequencing identified the blaOXA-48 in one K. pneumoniae strain (CS34) and blaKPC-3 in the other strain (CS63). K. pneumoniae CS63 was found to carry bla_TEM-1 and aac(6')-Ib genes. The MLST showed that K. pneumoniae CS63 was assigned to ST512, whereas K. pneumoniae CS34 belonged to ST1878. This is the first description of CPE from bats' guano.

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.

Multicentre investigation of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in Bulgarian hospitals - Interregional spread of ST11 NDM-1-producing K. pneumoniae

AIM

The aim of this study was to investigate the mechanisms of beta-lactam-resistance and the clonal relatedness of carbapenem-nonsusceptible Klebsiella pneumoniae and Escherichia coli isolates, collected consecutively in eight centers in five Bulgarian cities from November 2014 to March 2018. Carbapenemase-producing enterobacteria were detected in all but one centers. Overall, 104 K. pneumoniae and one E. coli were analysed.

MATERIALS AND METHODS

Antimicrobial susceptibility and beta-lactamases were analysed. Conjugation experiments, plasmid fingerprinting and replicon typing, as well as MLST and ERIC-PCR were carried out.

RESULTS

KPC-2 (51%) and NDM-1 (47%) were the main carbapenemases identified. KPC-2 producing K. pneumoniae were classified into 10 MLST-types. The four dominating MLST-types ST29, ST15, ST336 and ST902 comprised 79% of the KPC-2 producers. All but one of the NDM-1 producing isolates belonged to the MLST-type ST11 and were found in seven centers. Furthermore, single K. pneumoniae isolates producing VIM-1 (ST147) and OXA-48 (ST15) were identified. In addition to the carbapenemases, the ESBLs CTX-M-15, CTX-M-3, and SHV-12 as well as AmpC enzyme CMY-4 were found. The FIIAs-replicon-type was found in all KPC-2 producers while the A/C-replicons dominated in NDM-1 producing isolates. The single NDM-1 producing E. coli was determined as MLST-Type ST10 (Warwick scheme).

CONCLUSION

The interregional clonal expansion of NDM-1 producing ST11 K. pneumoniae and the dissemination of bla_KPC-2 carrying plasmids were responsible for the spread of carbapenemase-producing K. pneumoniae in Bulgaria. Our findings highlight the urgency to prevent dissemination of these highly transmissible and dangerous lineages.