NDM-1 Hazard in the Balkan States: Evidence of the First Outbreak of NDM-1-Producing Klebsiella pneumoniae in Bulgaria

Occurrence and mechanisms of tigecycline resistance in carbapenem- and colistin-resistant Klebsiella pneumoniae in Thailand

Tigecycline has been regarded as one of the most important last-resort antibiotics for the treatment of infections caused by extensively drug-resistant (XDR) bacteria, particularly carbapenem- and colistin-resistant Klebsiella pneumoniae (C-C-RKP). However, reports on tigecycline resistance have been growing. Overall, ~ 4000 K. pneumoniae clinical isolates were collected over a five-year period (2017-2021), in which 240 isolates of C-C-RKP were investigated. Most of these isolates (91.7%) were resistant to tigecycline. Notably, a high-risk clone of ST16 was predominantly identified, which was associated with the co-harboring of blaNDM-1 and blaOXA-232 genes. Their major mechanism of tigecycline resistance was the overexpression of efflux pump acrB gene and its regulator RamA, which was caused by mutations in RamR (M184V, Y59C, I141T, A28T, C99/C100 insertion), in RamR binding site (PI) of ramA gene (C139T), in MarR (S82G), and/or in AcrR (L154R, R13Q). Interestingly, four isolates of ST147 carried the mutated tet(A) efflux pump gene. To our knowledge, this is the first report on the prevalence and mechanisms of tigecycline resistance in C-C-RKP isolated from Thailand. The high incidence of tigecycline resistance observed among C-C-RKP in this study reflects an ongoing evolution of XDR bacteria against the last-resort antibiotics, which demands urgent action.

A Comprehensive Genomic Analysis of the Emergent Klebsiella pneumoniae ST16 Lineage: Virulence, Antimicrobial Resistance and a Comparison with the Clinically Relevant ST11 Strain

Klebsiella pneumoniae is considered an opportunistic pathogen frequently involved with healthcare-associated infections. The genome of K. pneumoniae is versatile, harbors diverse virulence factors and easily acquires and exchanges resistance plasmids, facilitating the emergence of new threatening clones. In the last years, ST16 has been described as an emergent, clinically relevant strain, increasingly associated with outbreaks, and carrying virulence factors (such as ICEKp, iuc, rmpADC/2) and a diversity of resistance genes. However, a far-reaching phylogenetic study of ST16, including geographically, clinically and temporally distributed isolates is not available. In this work, we analyzed all publicly available ST16 K. pneumoniae genomes in terms of virulence factors, including capsular lipopolysaccharide and polysaccharide diversity, plasmids and antimicrobial resistance genes. A core genome SNP analysis shows that less than 1% of studied sites were variant sites, with a median pairwise single nucleotide polymorphism difference of 87 SNPs. The number and diversity of antimicrobial resistance genes, but not of virulence-related genes, increased consistently in ST16 strains during the studied period. A genomic comparison between ST16 and the high-risk clone ST11 K. pneumoniae, showed great similarities in their capacity to acquire resistance and virulence markers, differing mostly in the great diversity of capsular lipopolysaccharide and polysaccharide types in ST11, in comparison with ST16. While virulence and antimicrobial resistance scores indicated that ST11 might still constitute a more difficult-to-manage strain, results presented here demonstrate the great potential of the ST16 clone becoming critical in public health.

First Outbreak of NDM-1-Producing Klebsiella pneumoniae ST11 in a Portuguese Hospital Centre during the COVID-19 Pandemic

New Delhi metallo-β-lactamase (NDM) carbapenemase has been considered a global threat due to its worldwide widespread in recent years. In Portugal, a very low number of infections with NDM-producing Enterobacterales has been reported. A total of 52 strains from 40 patients and 1 environmental sample isolated during COVID-19 pandemic were included in this study. Wholegenome sequencing (WGS) was performed on 20 carbapenemase-producing strains, including 17 NDM-1-producing Klebsiella pneumoniae ST11-KL105 lineage strains, one NDM-1-producing Escherichia coli ST58 strain and one KPC-3-producing K. pneumoniae ST147 strain, recovered from a total of 19 patients. Of interest, also one NDM-1-producing K. pneumoniae ST11-KL105 was collected from the hospital environment. Genome-wide phylogenetic analysis revealed an ongoing dissemination of NDM-1-producing K. pneumoniae ST11 strains (n = 18) with the same genetic features seen across multiple wards. Furthermore, the ST58 E. coli strain, collected from a patient rectal swab that was also colonised with a K. pneumoniae strain, also showed the IncFIA plasmid replicon and the bla_NDM-1 gene (preceded by IS30 and followed by genes ble_MBL, trpF, dsbC, cutA, groES and groEL). The bla_NDM-1 is part of Tn125-like identical to those reported in Poland, Italy and India. The bla_KPC-3 K. pneumoniae ST147-KL64 strain has the genetic environment Tn4401d isoform. In conclusion, herein we report the molecular epidemiology, resistome, virulome and mobilome of the first NDM-1 carbapenemase outbreak caused by K. pneumoniae ST11-KL105 lineage during the COVID-19 pandemic in Portugal. Moreover, the outbreak strains characterised included seventeen different patients (infected and colonised) and one environmental sample which also emphasises the role of commensal and hospital environment strains in the dissemination of the outbreak.

A Patient With Multiple Carbapenemase Producers Including an Unusual Citrobacter sedlakii Hosting an IncC bla NDM-1- and armA-carrying Plasmid

Background.

Patients colonized with multiple species of carbapenemase-producing Enterobacterales (CPE) are increasingly observed. This phenomenon can be due to the high local prevalence of these pathogens, the presence of important host risk factors, and the great genetic promiscuity of some carbapenemase genes.

Methods.

We analyzed 4 CPE (Escherichia coli, Klebsiella pneumoniae, Providencia stuartii, Citrobacter sedlakii), 1 extended-spectrum cephalosporin-resistant K. pneumoniae (ESC-R-Kp), and 1 carbapenemase-producing Acinetobacter baumannii simultaneously isolated from a patient transferred from Macedonia. Susceptibility tests were performed using a microdilution MIC system. The complete genome sequences were obtained by using both short-read and long-read whole-genome sequencing technologies.

Results.

All CPE presented high-level resistance to all aminoglycosides due to the expression of the armA 16S rRNA methylase. In C. sedlakii and E. coli (ST69), both the carbapenemase bla_NDM-1 and armA genes were located on an identical IncC plasmid of type 1a. The K. pneumoniae (ST268) and P. stuartii carried chromosomal bla_NDM-1 and bla_OXA-48, respectively, while the ESC-R-Kp (ST395) harbored a plasmid-located bla_CTX-M-15. In the latter 3 isolates, armA-harboring IncC plasmids similar to plasmids found in C. sedlakii and E. coli were also detected. The A. baumannii strain possessed the bla_OXA-40 carbapenemase gene.

Conclusions.

The characterization of the genetic organization of IncC-type plasmids harbored by 3 different species from the same patient offered insights into the evolution of these broad-host-range plasmids. Moreover, we characterized here the first complete genome sequence of a carbapenemase-producing C. sedlakii strain, providing a reference for future studies on this rarely reported species.

Genetic support of carbapenemases: a One Health systematic review and meta-analysis of current trends in Africa

Antimicrobial resistance (AMR) is a public health threat globally. Carbapenems are β-lactam antibiotics used as last-resort agents for treating antibiotic-resistant infections. Mobile genetic elements (MGEs) play an important role in the dissemination and expression of antimicrobial resistance genes (ARGs), including the mobilization of ARGs within and between species. The presence of MGEs around carbapenem-hydrolyzing enzymes, called carbapenemases, in bacterial isolates in Africa is concerning. The association between MGEs and carbapenemases is described herein. Specific plasmid replicons, integrons, transposons, and insertion sequences were found flanking specific and different carbapenemases across the same and different clones and species isolated from humans, animals, and the environment. Notably, similar genetic contexts have been reported in non-African countries, supporting the importance of MGEs in driving the intra- and interclonal and species transmission of carbapenemases in Africa and globally. Technical and budgetary limitations remain challenges for epidemiological analysis of carbapenemases in Africa, as studies undertaken with whole-genome sequencing remained relatively few. Characterization of MGEs in antibiotic-resistant infections can deepen our understanding of carbapenemase epidemiology and facilitate the control of AMR in Africa. Investment in genomic epidemiology will facilitate faster clinical interventions and containment of outbreaks.

Gambogic acid protects LPS-induced apoptosis and inflammation in a cell model of neonatal pneumonia through the regulation of TrkA/Akt signaling pathway

Objective

In this work, we investigated the effects of gambogic acid (GA) on lipopolysaccharide (LPS)-induced apoptosis and inflammation in a cell model of neonatal pneumonia.

Method

Human WI-38 cells were maintained in vitro and incubated with various concentrations of GA to examine WI-38 survival. GA-preincubated WI-38 cells were then treated with LPS to investigate the protective effects of GA on LPS-induced death, apoptosis and inflammation. Western blot assay was utilized to analyze the effect of GA on tropomyosin receptor kinase A (TrkA) signaling pathway in LPS-treated WI-38 cells. In addition, human AKT serine/threonine kinase 1 (Akt) gene was knocked down in WI-38 cells to further investigate the associated genetic mechanisms of GA in protecting LPS-induced inflammation and apoptosis.

Results

Pre-incubating WI-38 cells with low and medium concentrations GA protected LPS-induced cell death, apoptosis and inflammatory protein productions of IL-6 and MCP-1. Using western blot assay, it was demonstrated that GA promoted TrkA phosphorylation and Akt activation in LPS-treated WI-38 cells. Knocking down Akt gene in WI-38 cells showed that GA-associated protections against LPS-induced apoptosis and inflammation were significantly reduced.

Conclusions

GA protected LPS-induced apoptosis and inflammation, possibly through the activations of TrkA and Akt signaling pathway. This work may broaden our understanding on the molecular mechanisms of human neonatal pneumonia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-021-00496-9.

Spread of ST348 Klebsiella pneumoniae Producing NDM-1 in a Peruvian Hospital

The aim of this study was to characterize carbapenem-resistant Klebsiella pneumoniae (CR-Kp) isolates recovered from adults and children with severe bacteremia in a Peruvian Hospital in June 2018. Antimicrobial susceptibility was determined by disc/gradient diffusion and broth microdilution when necessary. Antibiotic resistance mechanisms were evaluated by PCR and DNA sequencing. Clonal relatedness was assessed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Plasmid typing was performed with a PCR-based method. Thirty CR-Kp isolates were recovered in June 2018. All isolates were non-susceptible to all β-lactams, ciprofloxacin, gentamicin and trimethoprim-sulfamethoxazole, while mostly remaining susceptible to colistin, tigecycline, levofloxacin and amikacin. All isolates carried the bla_NDM-1 gene and were extended spectrum β-lactamase (ESBL) producers. PFGE showed four different pulsotypes although all isolates but two belonged to the ST348 sequence type, previously reported in Portugal. bla_NDM-1 was located in an IncFIB-M conjugative plasmid. To our knowledge, this is the first report of an New Delhi metallo-β-lactamase (NDM)-producing K. pneumoniae recovered from both children and adults in Lima, Peru, as well as the first time that the outbreak strain ST348 is reported in Peru and is associated with NDM. Studies providing epidemiological and molecular data on CR-Kp in Peru are essential to monitor their dissemination and prevent further spread.

Emergence of NDM-1-producing Klebsiella pneumoniae in Greece: evidence of a widespread clonal outbreak

OBJECTIVES

NDM-producing Enterobacteriaceae clinical isolates remain uncommon in the European region. We describe the emergence and broad dissemination of one successful NDM-1-producing Klebsiella pneumoniae clone in Greek hospitals.

METHODS

During a 4 year survey (January 2013-December 2016), 480 single-patient carbapenem non-susceptible K. pneumoniae isolates, phenotypically MBL positive, were consecutively recovered in eight Greek hospitals from different locations and subjected to further investigation. Antimicrobial susceptibility testing, combined-disc test, identification of resistance genes by PCR and sequencing, molecular fingerprinting by PFGE, plasmid profiling, replicon typing, conjugation experiments and MLST were performed.

RESULTS

Molecular analysis confirmed the presence of the blaNDM-1 gene in 341 (71%) K. pneumoniae isolates. A substantially increasing trend of NDM-1-producing K. pneumoniae was noticed during the survey (R2 = 0.9724). Most blaNDM-1-carrying isolates contained blaCTX-M-15, blaOXA-1, blaOXA-2 and blaTEM-1 genes. PFGE analysis clustered NDM-1 producers into five distinct clonal types, with five distinct STs related to each PFGE clone. The predominant ST11 PFGE clonal type was detected in all eight participating hospitals, despite adherence to the national infection control programme; it was identical to that observed in the original NDM-1 outbreak in Greece in 2011, as well as in a less-extensive NDM-1 outbreak in Bulgaria in 2015. The remaining four ST clonal types (ST15, ST70, ST258 and ST1883) were sporadically detected. blaNDM-1 was located in IncFII-type plasmids in all five clonal types.

CONCLUSIONS

This study gives evidence of possibly the largest NDM-1-producing K. pneumoniae outbreak in Europe; it may also reinforce the hypothesis of an NDM-1 clone circulating in the Balkans.

In vitro activity of the siderophore cephalosporin, cefiderocol, against molecularly characterized, carbapenem-non-susceptible Gram-negative bacteria from Europe

Objectives

Many carbapenem-resistant (CR) Gram-negative (GN) pathogens exhibit MDR, meaning few therapeutic options are available for CR-GN infections. Cefiderocol, a siderophore cephalosporin, has demonstrated in vitro efficacy against CR-GN bacteria. In the SIDERO-CR-2014–2016 surveillance study, European clinical isolates comprising carbapenem-non-susceptible (CarbNS) Enterobacterales and MDR non-fermenters were tested against cefiderocol and comparators.

Methods

Cefiderocol MICs were determined using iron-depleted CAMHB, and comparators using CAMHB, per recommended CLSI methodology. Carbapenemase gene profiles were determined using PCR.

Results

Isolates (N = 870) from 23 European countries comprised CarbNS Enterobacterales (n = 457), MDR Pseudomonas aeruginosa (n = 177) and MDR Acinetobacter baumannii (n = 236). The most common carbapenemases were KPC (52%), OXA-48-like (19%), VIM (14%) and NDM (8%) in Enterobacterales, VIM (41%) in P. aeruginosa and OXA-23-like (57%) and OXA-24/40-like (37%) in A. baumannii. Most carbapenemase-producing isolates (65%) co-carried ESBLs. Approximately half of P. aeruginosa isolates were negative for carbapenemases, compared with 10% of Enterobacterales and 3% of A. baumannii. A similar proportion of Enterobacterales were susceptible to cefiderocol (81.6%; 79.0% of VIM producers; 51.4% of NDM producers; based on EUCAST breakpoint values) compared with comparator antimicrobial agents, including colistin (76.4%; 93.5% of VIM producers; 78.4% of NDM producers) and ceftazidime/avibactam (76.6%; 1.6% of VIM producers; 2.7% of NDM producers). Of P. aeruginosa isolates, 98.3% were susceptible to cefiderocol (100% of VIM producers), similar to colistin (100%). Against A. baumannii, 94.9% had cefiderocol MIC ≤2 mg/L and 93.6% of isolates were susceptible to colistin.

Conclusions

Cefiderocol demonstrated potent activity against CarbNS and MDR GN bacteria, including non-fermenters and a wide variety of MBL- and serine-β-lactamase-producing strains.

Occurrence of two NDM-1-producing Raoultella ornithinolytica and Enterobacter cloacae in a single patient in China: probable a novel antimicrobial resistance plasmid transfer in vivo by conjugation

OBJECTIVES

To identify the general features of acquisition of drug-resistance genes in two multi-drug resistant Enterobacteriaceae strains isolated from a single patient in China.

METHODS

The whole-plasmid was sequenced by Illumina Hiseq 4000 and Pacbio RSII procedures. The plasmid conjugation transfer experiment were performed by the mating-out assay. Drug-resistance genes were amplified by PCR assay.

RESULTS

We identified two New Delhi metallo-β-lactamase type 1(NDM-1)-producing isolates, named Raoultella ornithinolytica B1645-1 and Enterobacter cloacae B1645-2, which shared the same sulfonamide-resistant dihydropteroate synthase sul2 gene and aminoglycoside O-phosphotransferase aph(3'')-Ib gene. A novel antimicrobial resistance plasmid pCYNDM01 was first discovered from the multi-drug resistant R. ornithinolytica B1645-1. Interestingly, plasmid pCYNDM01 carried a Gifsy-2 prophage gene. The bla_NDM-1 gene was located on a novel complex class 1 integron with a structure of sul1-qacEΔ1-ΔISAba125-bla_NDM-1-bla_MBL-trpC-ISCR1-catb8-aacA4-IS1-IS6100-dfrA14-intI1. The carrying the bla_NDM-1 gene plasmid pCYNDM01 was transferred to the E. cloacae B1645-2 recipient strain. This 149.44 kb plasmid pCYNDM01 belonged to the IncFII type.

CONCLUSIONS

A novel antimicrobial resistance plasmid pCYNDM01 was first recovered from a multi-drug resistance R. ornithinolytica B1645-1 isolated from China. The novel complex sul1-type class 1 integron might play an essential role in the mobilization of the bla_NDM-1 gene among different enterobacterial species. The occurrence of plasmid pCYNDM01 transfer from R. ornithinolytica to E. cloacae in vitro by conjugation showed that plasmid pCYNDM01 was a self-conjugative plasmid and might cause dissemination of drug-resistance genes within different enterobacterial species from a single patient in vivo by conjugation. The novel variant F-like T4SS of plasmid pCYNDM01 might be as a tool of R. ornithinolytica B1645-1 for resistance genes transfer. The emergence of the two NDM-1-producing Enterobacteriaceae strains should be attracted China attentions and required to prevent its future prevalence.

Soil types influence the characteristic of antibiotic resistance genes in greenhouse soil with long-term manure application

Composted livestock and poultry manure, which may contain antibiotic resistance genes (ARGs), is widely used as natural fertilizer in China. But the influence of soil types on ARGs is not well characterized, particularly at greenhouse sites with long-term manure application. We investigated the distribution of ARGs in the cinnamon, fluvo-aquic and saline-alkali soils in greenhouse of Yellow River Delta region, China. A total of 193 ARGs subtypes were detected, with multidrug and aminoglycoside resistance genes as the most universal ARGs subtypes. Soil types influenced the ARGs distribution, where higher levels of diversity and relative abundance of ARGs in the fluvo-aquic and saline-alkali soils compared with those in the cinnamon soils. Among abiotic factors, sand, pH and Zn contributed more to the pattern of ARGs in the cinnamon soils, whereas sand and Cd, clay and Pb contributed the most in the fluvo-aquic and saline-alkali soils respectively. Furthermore, positive correlations between the relative abundances of ARGs and mobile genetic elements (MGEs) in the fluvo-aquic soils, suggesting higher dissemination potential of ARGs in this type of soil. Overall, MGEs played a positive primary role in the ARGs distribution in greenhouse soil than heavy metal co-selection and soil physicochemical properties.

Clonal dissemination of KPC-2-producing Klebsiella pneumoniae ST11 and ST48 clone among multiple departments in a tertiary teaching hospital in Jiangsu Province, China

Background

The world-wide prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a threat to the public health. The objective of this study was to determine the epidemiological and molecular patterns of KPC-producing Klebsiella pneumoniae (K. pneumoniae) clinical isolates.

Methods

In this study, a total of 82 non-duplicated CRKP isolates were analyzed for the prevalence of resistant determinants including carbapenemase, extended spectrum β-lactamase (ESBLs), and AmpC as well as integrons and cassette regions by polymerase chain reaction (PCR) and DNA sequencing. The genetic relatedness was investigated by pulsed field gel electrophoresis (PFGE) and multi-locus sequencing typing (MLST).

Results

Overall, bla _KPC-2 (n=75) was the predominant carbapenemase gene, followed by high prevalence of bla _SHV (92.7%) and bla _CTX-M (90.2%). PFGE and MLST analysis revealed that 65 out of 68 KPC-2-producing CRKP belonged to the ST11 clone and were distributed mainly in the department of neurology ICU. Moreover, first report on clonal dissemination of KPC-2-producing CRKP ST48 clone and NDM-5-producing CRKP ST337 clone was also identified. Class I integron were detected in 17 (20.7%) of 82 isolates with aadA2 being the most common cassette. And a novel cassette array of integron, aac(6')-II-bla _CARB/PSE-1 was identified.

Conclusions

All in all, KPC-2-producing CRKP ST11 and ST48 clone were widely disseminated in multiple departments of our hospital, which triggers the need for active surveillance and implementation of infection control measures.

Occurrence of super antibiotic resistance genes in the downstream of the Yangtze River in China: Prevalence and antibiotic resistance profiles

The super antibiotic resistance genes (SARGs) demonstrate more severe threats than other antibiotic resistance genes while have not received enough attention in the environment. The study explored the prevalence and the antibiotic tolerance profiles of two typical SARGs, MCR-1 and NDM-1, and their hosting bacteria in the downstream of the Yangtze River and the nearby wastewater treatment plant (WWTP) and drinking water treatment plant (DWTP). Results indicated that MCR-1 and NDM-1 were prevalent in the influent and biological units of the WWTP. Their hosting bacteria were effectively removed, but 2.49 × 10⁸ copies/L MCR-1 and 7.00 × 10⁶ copies/L NDM-1 were still persistent in the effluent. In the Yangtze River, MCR-1 and NDM-1 were detected with higher abundance and antibiotic tolerance than the WWTP effluent and were significantly affected by nearby water contamination and human activities. In the DWTP, MCR-1 and NDM-1 were detected with average values 5.56 × 10⁷ copies/L and 2.14 × 10⁵ copies/L in the influent. Their hosting bacteria were undetectable in the effluent, but the two SARGs were still persistent with 1.39 × 10⁷ copies/L and 6.29 × 10⁴ copies/L, and were greatly enriched in the sludge. Molecular ecological networks demonstrated wide hosting relationships between MCR-1/NDM-1 and bacteria community in the DWTP. Redundancy analysis found that MCR-1 positively correlated with COD and NH₃-N, while negatively correlated with turbidity. Additionally, MCR-1 hosting bacteria positively correlated with NO₃^--N and negatively correlated with COD and NH₃-N. NDM-1 positively correlated with turbidity and NDM-1 hosting bacteria positively correlated with COD and NO₂^--N. The study demonstrated that the WWTP could not effectively remove SARGs with high amount of them being discharged into the Yangtze River. Then they were transported into the DWTP and the persistent SARGs in the effluent would probably be transferred into human, thus imposing great threats on public health.

NDM Metallo-β-Lactamases and Their Bacterial Producers in Health Care Settings

New Delhi metallo-β-lactamase (NDM) is a metallo-β-lactamase able to hydrolyze almost all β-lactams. Twenty-four NDM variants have been identified in >60 species of 11 bacterial families, and several variants have enhanced carbapenemase activity. Klebsiella pneumoniae and Escherichia coli are the predominant carriers of bla _NDM, with certain sequence types (STs) (for K. pneumoniae, ST11, ST14, ST15, or ST147; for E. coli, ST167, ST410, or ST617) being the most prevalent. NDM-positive strains have been identified worldwide, with the highest prevalence in the Indian subcontinent, the Middle East, and the Balkans. Most bla _NDM-carrying plasmids belong to limited replicon types (IncX3, IncFII, or IncC). Commonly used phenotypic tests cannot specifically identify NDM. Lateral flow immunoassays specifically detect NDM, and molecular approaches remain the reference methods for detecting bla _NDM Polymyxins combined with other agents remain the mainstream options of antimicrobial treatment. Compounds able to inhibit NDM have been found, but none have been approved for clinical use. Outbreaks caused by NDM-positive strains have been reported worldwide, attributable to sources such as contaminated devices. Evidence-based guidelines on prevention and control of carbapenem-resistant Gram-negative bacteria are available, although none are specific for NDM-positive strains. NDM will remain a severe challenge in health care settings, and more studies on appropriate countermeasures are required.

First report of New Delhi metallo-β-lactamase-6 (NDM-6) among Klebsiella pneumoniae ST147 strains isolated from dialysis patients in Iran

There has been an alarming health-related concern about the growth of New Delhi metallo-β-lactamase. The aims of this study include the phenotypic detection of β-lactamases and molecular characterization of NDM in Klebsiella pneumoniae isolates in Tehran, Iran. A total of 120 K. pneumoniae isolates were collected from hospitalized haemodialysis patients, Tehran, Iran from March 2014 to February 2017. Antibiotic susceptibility tests were conducted using Kirby-Bauer disc diffusion and Broth Microdilution methods according to Clinical and Laboratory Standards Institute guidelines. Metallo-β-lactamase was detected using the Combined Disc Diffusion Test (CDDT), and production of carbapenemase was screened using the Modified Hodge Test. NDM-producing K. pneumoniae strains were screened for the presence of mcr-1 gene, β-lactamase genes, and 16S rRNA methylase genes by Polymerase Chain Reaction and sequencing. Molecular typing of the strains was determined using Repetitive Sequence Based-PCR and Multilocus Sequence Typing. The bla_NDM-6 gene was detected in 3 (2.5%) out of 120 isolates from dialysis patients. Also, the three isolates were positive for bla_CTX-M-15,bla_TEM extended-spectrum β-lactamase genes, armA type plasmid-mediated 16S rRNA methylase and CMY-type plasmid-mediated AmpC β-lactamase. The isolates were identified as MLST sequence type 147 (ST147). This is the first report of bla_NDM-6 in K. pneumoniae strains, isolated in Iran.

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.

Isolation of the first New Delhi metallo-ß-lactamase-1 (NDM-1)-producing and colistin-resistant Klebsiella pneumoniae sequence type ST15 from a digestive carrier in Albania, May 2018

OBJECTIVES

Carbapenemases represent a public health threat, as they can spread through horizontal gene transfer and cause outbreaks. New Delhi metallo-ß-lactamase-1 (NDM-1) is a metallo-ß-lactamase that has spread rapidly in the last decade, causing worldwide alarm. This study aimed to describe the first isolate of NDM-1-producing and extensively drug resistant Klebsiella pneumoniae in Albania, its clinical context and genetic characterization.

METHODS

Strain was isolated from both oral and rectal intensive care unit admission screening swabs of a 70-year-old male patient with no history of international travel in the previous 6 months. Sequencing was performed by Illumina NextSeq500 platform, with a paired-end run of 2 by 150bp, after Nextera XT paired-end library preparation. Sequencing reads were assembled using SPAdes Genome (version 3.6.1) with accurate de novo settings. The assembled contigs were uploaded into the online tools: BIGSdb-Kp, ResFinder and PlasmidFinder.

RESULTS

Isolate was resistant to all tested antibiotics but tigecycline and trimethoprim-sulfamethoxazole. Sequencing revealed the presence of acquired resistance genes conferring resistance to β-lactams (bla_NDM-1, bla_CMY-6, bla_CTX-M-15and bla_SHV-28), aminoglycosides (rmtC, aac(6')-Ib3), fluoroquinolones (oqxA, oqxB, aac(6')-Ib-cr), fosfomycin (fosA) and sulfonamides (sul1). The bla_NDM-1 gene was located on an IncA/C2 plasmid. Plasmid mediated mcr-1 to mcr-8 genes were absent in both isolates. Resistance to colistin was due to an amino acid substitution (Thr157Pro) in PmrB protein.

CONCLUSIONS

NDM-1-producing Enterobacteriaceae are spreading in the Balkans. Identification of NDM-1-producing and extensively drug resistant K. pneumoniae ST15 in Albania is a cause for serious concern. There should be a continuous national and Balkan multinational surveillance of bla_NDM-1-carrying isolates.

Discovery of a Novel Metallo-β-Lactamase Inhibitor That Potentiates Meropenem Activity against Carbapenem-Resistant Enterobacteriaceae

Infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are increasingly prevalent and have become a major worldwide threat to human health. Carbapenem resistance is driven primarily by the acquisition of β-lactamase enzymes, which are able to degrade carbapenem antibiotics (hence termed carbapenemases) and result in high levels of resistance and treatment failure. Clinically relevant carbapenemases include both serine β-lactamases (SBLs; e.g., KPC-2 and OXA-48) and metallo-β-lactamases (MBLs), such as NDM-1. MBL-producing strains are endemic within the community in many Asian countries, have successfully spread worldwide, and account for many significant CRE outbreaks. Recently approved combinations of β-lactam antibiotics with β-lactamase inhibitors are active only against SBL-producing pathogens. Therefore, new drugs that specifically target MBLs and which restore carbapenem efficacy against MBL-producing CRE pathogens are urgently needed. Here we report the discovery of a novel MBL inhibitor, ANT431, that can potentiate the activity of meropenem (MEM) against a broad range of MBL-producing CRE and restore its efficacy against an Escherichia coli NDM-1-producing strain in a murine thigh infection model. This is a strong starting point for a chemistry lead optimization program that could deliver a first-in-class MBL inhibitor-carbapenem combination. This would complement the existing weaponry against CRE and address an important and growing unmet medical need.