Carbapenemase Genes Research Articles

Mortality factors and antibiotic options in carbapenem-resistant Enterobacterales bloodstream infections: Insights from a high-prevalence setting with co-occurring NDM-1 and OXA-48.

Bloodstream infections (BSI) caused by carbapenem-resistant Enterobacterales (CRE) are associated with a high mortality rate. This study aimed to investigate factors associated with 14-day mortality and identify a potential treatment option. A retrospective cohort study was conducted on patients with CRE-BSI in Thailand from 2015 to 2020. The multivariate Cox proportional-hazards model was employed to identify factors influencing 14-day mortality. Out of 134 diagnosed cases of CRE-BSI, the all-cause 14-day mortality rate was 35.1%. The most prevalent organism isolated was Klebsiella pneumoniae (85.8%), followed by Escherichia coli (11.9%). Among the 60 isolates tested for carbapenemase genes, the majority exhibited co-occurring blaNDM-1 and blaOXA-48 (51.7%), followed by blaOXA-48 (31.7%) and blaNDM-1 (15.0%). In the multivariate analysis, neutropenia (adjusted hazard ratio [aHR] 2.55; 95% confidence interval [95%CI] 1.28-5.06; p = 0.008), sepsis/septic shock (aHR 3.02; 95%CI 1.33-6.86; p = 0.008), and previous metronidazole exposures (aHR 3.58; 95%CI 1.89-6.71; p < 0.001) were identified as independent factors for 14-day mortality. The fosfomycin-based regimen was found to be protective (aHR 0.37; 95%CI 0.15-0.92; p = 0.032). In patients with CRE-BSI, particularly in regions with a high occurrence of co-occurring blaNDM-1 and blaOXA-48, neutropenia, sepsis/septic shock, and previous metronidazole exposures emerged as independent risk factors for mortality. Moreover, the fosfomycin-based regimen showed an improvement in the survival rate.

Co-occurrence of the cephalosporinase cepA and carbapenemase cfiA genes in a Bacteroides fragilis division II strain, an unexpected finding.

Bacteroides fragilis, an anaerobic gut bacterium and opportunistic pathogen, comprises two genetically divergent groups (or divisions) at the species level. Differences exist both in the core and accessory genomes and the beta-lactamase genes, with the cephalosporinase gene cepA represented only in division I and the carbapenemase gene cfiA only in division II. Multidrug resistance in a clinical B. fragilis strain was examined by whole-genome sequencing. Strain CNM20200260 carried the antimicrobial resistance genes cepA, cfiA2, ant(6'), erm(F), mef(En2), est(T), tet(Q) and cat(A), along with 82-Phe mutation in gyrA (together with 47 amino acid changes in gyrA/B and parC/parE). bexA/B and other efflux pump genes were also observed. None of the detected insertion sequences was located upstream of cfiA2. The genome-based taxonomy coefficients (average nucleotide identity, DNA-DNA hybridization similarity and difference in genomic G + C%) with respect to genomes of the strains of B. fragilis division II and the novel species Bacteroides hominis (both cfiA-positive) met the criteria for CNM20200260 to belong to either species (>95%, >70% and <1%, respectively). No such similarity was seen with type strain NCTC 9343 or the representative genome FDAARGOS 1225 of B. fragilis (division I, cfiA-negative). Strain CNM20200260 harboured four out of nine Kyoto Encyclopedia of Genes and Genomes orthologues defined for division I and one of two defined for division II. This is the first description of the co-occurrence of cepA and cfiA in a Bacteroides strain, confirming the complexity of the taxonomy of this species.

Analysis of the Class 1 Integrons, Carbapenemase Genes and Biofilm Formation Genes Occurrence in Acinetobacter baumannii Clinical Isolates.

Acinetobacter baumannii is a non-fermentative Gram-negative bacterium that can cause nosocomial infections in critically ill patients. Carbapenem-resistant A. baumannii (CRAB) has spread rapidly in clinical settings and has become a key concern. The main objective of this study was to identify the distribution of integrons and biofilm-formation-related virulence genes in CRAB isolates. A total of 269 A. baumannii isolates (219 isolates of CRAB and 50 isolates of carbapenem-sensitive A. baumannii (CSAB)) were collected. Carbapenemase genes (bla KPC, bla VIM, bla IMP, bla NDM, and bla OXA-23-like) and biofilm-formation-related virulence genes (abal, bfms, bap, and cusE) were screened with PCR. Class 1 integron was screened with PCR, and common promoters and gene cassette arrays were determined with restriction pattern analysis combined with primer walking sequencing. Whole-genome sequencing was conducted, and data were analyzed for a bla OXA-23-like-negative isolate. All 219 CRAB isolates were negative for bla KPC, bla VIM, bla IMP, and bla NDM, while bla OXA-23-like was detected in 218 isolates. The detection rates for abal, bfms, bap, and cusE in 219 CRAB were 93.15%, 63.93%, 88.13%, and 77.63%, respectively. Class 1 integron was detected in 75 CRAB (34.25%) and in 3 CSAB. The single gene cassette array aacA4-catB8-aadA1 with relatively strong PcH2 promoter was detected in class 1 integrons. The bla OXA-23-like-negative CRAB isolate was revealed to be a new sequence type (Oxford 3272, Pasteur 2520) carrying bla OXA-72, bla OXA-259, and bla ADC-26. In conclusion, bla OXA-23-like was the main reason for CRAB's resistance to carbapenems. A new (Oxford 3272, Pasteur 2520) CRAB sequence type carrying the bla OXA-72, bla OXA-259, and bla ADC-26 was reported.

Activity of ceftolozane/tazobactam and imipenem/relebactam against clinical isolates of Enterobacterales and Pseudomonas aeruginosa collected in Greece and Italy—SMART 2017–2021

PurposeThe current study evaluated the in vitro activities of ceftolozane/tazobactam (C/T), imipenem/relebactam (IMI/REL), and comparators against recent (2017–2021) clinical isolates of gram-negative bacilli from two countries in southern Europe.MethodsNine clinical laboratories (two in Greece; seven in Italy) each collected up to 250 consecutive gram-negative isolates per year from lower respiratory tract, intraabdominal, urinary tract, and bloodstream infection samples. MICs were determined by the CLSI broth microdilution method and interpreted using 2022 EUCAST breakpoints. β-lactamase genes were identified in select β-lactam-nonsusceptible isolate subsets.ResultsC/T inhibited the growth of 85–87% of Enterobacterales and 94–96% of ESBL-positive non-CRE NME (non-Morganellaceae Enterobacterales) isolates from both countries. IMI/REL inhibited 95–98% of NME, 100% of ESBL-positive non-CRE NME, and 98–99% of KPC-positive NME isolates from both countries. Country-specific differences in percent susceptible values for C/T, IMI/REL, meropenem, piperacillin/tazobactam, levofloxacin, and amikacin were more pronounced for Pseudomonas aeruginosa than Enterobacterales. C/T and IMI/REL both inhibited 84% of P. aeruginosa isolates from Greece and 91–92% of isolates from Italy. MBL rates were estimated as 4% of Enterobacterales and 10% of P. aeruginosa isolates from Greece compared to 1% of Enterobacterales and 3% of P. aeruginosa isolates from Italy. KPC rates among Enterobacterales isolates were similar in both countries (7–8%). OXA-48-like enzymes were only identified in Enterobacterales isolates from Italy (1%) while GES carbapenemase genes were only identified in P. aeruginosa isolates from Italy (2%).ConclusionWe conclude that C/T and IMI/REL may provide viable treatment options for many patients from Greece and Italy.

Genetic characterization of plasmid-borne blaOXA-58 and blaOXA-72 in Acinetobacter pittii in Shaanxi, China

ObjectivesAcinetobacter pittii has emerged as an opportunistic nosocomial pathogen associated with hospital-acquired infections. The purpose of this study was to investigate the genetic structures of plasmids carrying carbapenemase genes blaOXA-58 and blaOXA-72 in A. pittii strains AR3676 and AR3651 isolated from patients. MethodsAntimicrobial susceptibility testing was performed using broth microdilution. Whole-genome sequencing and bioinformatics analysis were performed to characterize the genome of A. pittii AR3676 and AR3651. Conjugation experiments were conducted to evaluate plasmid transferability. Phylogenetic and comparative genomic analysis were performed to explore the characteristics of carbapenem-resistant A. pittii isolates worldwide. ResultsThe AR3676 strain showed resistance to imipenem. The 19 700-bp plasmid pAR3676-OXA-58 harboured blaOXA-58 with genetic contexts consisting of a truncated ISAba3-like-blaOXA58-ISAba3. Additionally, the AR3651 strain showed resistance to imipenem and meropenem. The AR3651 genome comprised one 9,837-bp RepA_AB plasmid pAR3651-OXA-72 harbouring blaOXA-72. This blaOXA-72 was flanked by XerC/XerD recombination sites. The conjugation of plasmids pAR3676-OXA-58 and pAR3651-OXA-72 from A. pittii to Acinetobacter baumannii ATCC 17978RIFR failed three independent times. Phylogenetic analysis of A. pittii strains AR3676, AR3651, and a further 504 A. pittii strains collected between 1966 and 2022 from various geographic localities revealed genetic diversity with a heterogeneous distribution of carbapenemase genes. ConclusionsA. pittii strains with a plasmid carrying blaOXA-58 or blaOXA-72 may serve as an important reservoir of carbapenemase genes. Carbapenemase genes on a single plasmid may facilitate their dissemination and persistence. Additionally, pdif sites and mobile elements play an important role in the mobilization of resistance genes and plasmid evolution.

β-lactam resistant phenotypes reported by VITEK®2 advanced expert systemTM (AES) compared to whole genome sequencing in Enterobacterales from North and Latin America

The VITEK®2 AES β-lactam phenotypes of 488 Enterobacterales from North and Latin America generated by the VITEK®2 were compared to the resistance genotypes provided by whole genome sequencing (WGS). The AES provided phenotypic reports for 447 (91.6 %) isolates, including isolates harbouring carbapenemases (195; 43.6 %), ESBLs (103; 23.0 %) and transferable AmpCs (tAmpC; 28; 6.3 %) genes, as well as wildtype isolates (WT; 121; 27.1 %). Overall, the AES report was accurate for 433/447 (96.9 %) isolates. The AES accurately reported carbapenemase, ESBL, and tAmpC phenotypes for 93.7 %, 93.7 %, and 98.4 % of isolates, respectively, and sensitivity/specificity rates were 96.4 %/91.7 %, 98.1 %/92.4 %, 82.1 %/99.5 %, and 100 %/98.8 %. 14 isolates carrying carbapenemase (7 total; 3 KPC, 2 MBL, 2 OXA-48–like), ESBL (2), and tAmpC-encoding genes (5) were not correctly identified by AES. The AES phenotypic report detected resistance mechanisms among Enterobacterales rapidly and could significantly aid future antimicrobial stewardship initiatives and patient care.

Occurrence and characteristics of blaOXA-181-carrying Klebsiella aerogenes from swine in China

Klebsiella aerogenes is a largely understudied opportunistic pathogen that can cause sepsis and lead to high mortality rates. In this study, we reported the occurrence of carbapenem-resistant blaOXA-181-carrying Klebsiella aerogenes from swine in China and elucidate their genomic characteristics. A total of 126 samples, including 109 swine fecal swabs, 14 environmental samples, and three feed samples were collected from a pig farm in China. The samples were enriched with LB broth culture and then inoculated into MacConkey agar plates for bacterial isolation. After PCR detection of carbapenemases genes, the blaOXA-181-carrying isolates were subjected to antimicrobial susceptibility testing, and whole-genome sequence analysis. Four Klebsiella aerogenes isolates carrying the blaOXA-181 gene were obtained from swine faecal samples. All the 4 strains were belonged to ST438. The blaOXA-181 genes were located in IncX3-ColKP3 hybrid plasmids with the core genetic structure of IS26-ΔIS3000-ΔISEcp1-blaOXA-181-ΔlysR-ΔereA-ΔrepA-ISKpn19-tinR-qnrS1-ΔIS2-IS26, which suggests the potential for horizontal transfer and further dissemination of this resistance gene among Enterobacteriaceae and other sources. This study represents the first instance of OXA-181-producing K. aerogenes being identified from swine faeces in China. It is crucial to maintain continuous monitoring and ongoing attention to the detection of K. aerogenes carrying blaOXA-181 and other resistance genes in pigs.

Genomic Characterization of Carbapenemase-Producing Enterobacter hormaechei, Serratia marcescens, Citrobacter freundii, Providencia stuartii, and Morganella morganii Clinical Isolates from Bulgaria.

Carbapenemase-producing Enterobacter spp. Serratia marcescens, Citrobacter freundii, Providencia spp., and Morganella morganii (CP-ESCPM) are increasingly identified as causative agents of nosocomial infections but are still not under systematic genomic surveillance. In this study, using a combination of whole-genome sequencing and conjugation experiments, we sought to elucidate the genomic characteristics and transferability of resistance genes in clinical CP-ESCPM isolates from Bulgaria. Among the 36 sequenced isolates, NDM-1 (12/36), VIM-4 (11/36), VIM-86 (8/36), and OXA-48 (7/36) carbapenemases were identified; two isolates carried both NDM-1 and VIM-86. The majority of carbapenemase genes were found on self-conjugative plasmids. IncL plasmids were responsible for the spread of OXA-48 among E. hormaechei, C. freundii, and S. marcescens. IncM2 plasmids were generally associated with the spread of NDM-1 in C. freundii and S. marcescens, and also of VIM-4 in C. freundii. IncC plasmids were involved in the spread of the recently described VIM-86 in P. stuartii isolates. IncC plasmids carrying blaNDM-1 and blaVIM-86 were observed too. blaNDM-1 was also detected on IncX3 in S. marcescens and on IncT plasmid in M. morganii. The significant resistance transfer rates we observed highlight the role of the ESCPM group as a reservoir of resistance determinants and stress the need for strengthening infection control measures.

Characterizing carbapenemase-producing Escherichia coli isolates from Spain: high genetic heterogeneity and wide geographical spread.

Carbapenemase-Producing Escherichia coli (CP-Eco) isolates, though less prevalent than other CP-Enterobacterales, have the capacity to rapidly disseminate antibiotic resistance genes (ARGs) and cause serious difficult-to-treat infections. The aim of this study is phenotypically and genotypically characterizing CP-Eco isolates collected from Spain to better understand their resistance mechanisms and population structure. Ninety representative isolates received from 2015 to 2020 from 25 provinces and 59 hospitals Spanish hospitals were included. Antibiotic susceptibility was determined according to EUCAST guidelines and whole-genome sequencing was performed. Antibiotic resistance and virulence-associated genes, phylogeny and population structure, and carbapenemase genes-carrying plasmids were analyzed. The 90 CP-Eco isolates were highly polyclonal, where the most prevalent was ST131, detected in 14 (15.6%) of the isolates. The carbapenemase genes detected were bla OXA-48 (45.6%), bla VIM-1 (23.3%), bla NDM-1 (7.8%), bla KPC-3 (6.7%), and bla NDM-5 (6.7%). Forty (44.4%) were resistant to 6 or more antibiotic groups and the most active antibiotics were colistin (98.9%), plazomicin (92.2%) and cefiderocol (92.2%). Four of the seven cefiderocol-resistant isolates belonged to ST167 and six harbored bla NDM. Five of the plazomicin-resistant isolates harbored rmt. IncL plasmids were the most frequent (45.7%) and eight of these harbored bla VIM-1. bla OXA-48 was found in IncF plasmids in eight isolates. Metallo-β-lactamases were more frequent in isolates with resistance to six or more antibiotic groups, with their genes often present on the same plasmid/integron. ST131 isolates were associated with sat and pap virulence genes. This study highlights the genetic versatility of CP-Eco and its potential to disseminate ARGs and cause community and nosocomial infections.

Clonal transmission of blaIMP-4-carrying ST196 Klebsiella pneumoniae isolates mediated by the IncN plasmid in China

ObjectivesTo investigate the clinical and molecular epidemiological characteristics of blaIMP-4-carrying Klebsiella pneumoniae in a tertiary hospital in China. MethodsTen carbapenem-resistant K. pneumoniae (CRKP) isolates carrying the blaIMP-4 gene were collected. Molecular characteristics were analysed using whole-genome sequencing. Plasmid conjugation experiments were used to analyse conjugation of the plasmids. We compared and analysed K. pneumoniae-carrying blaIMP-4 genomic datasets obtained from the National Center for Biotechnology Information (NCBI) with the strains in this study. ResultsAll 10 CRKP isolates carrying blaIMP-4 were collected from 10 adult patients in the respiratory intensive care unit. These strains were only sensitive to polymyxins and tigecycline due to them simultaneously carrying multiple resistance genes, namely blaOKP-A-5, fosA, oqxA, and oqxB. Notably, R29 harboured two carbapenemase genes (blaNDM-1 and blaIMP-4). These strains had similar drug-resistant phenotypes and genes, all belonging to sequence type (ST)196. Additionally, the patients had experienced spatiotemporal intersection during hospitalization, suggesting that these strains underwent clonal transmission, but they belonged to different clonal clusters from the blaIMP-4-positive K. pneumoniae currently published in the NCBI. Among the 10 strains, blaIMP-4 was located on the IncN plasmid, and six strains had successfully transferred the plasmid to the recipient strain EC600 through plasmid conjugation. ConclusionsThe blaIMP-4-positive ST196 CRKP isolate showed clonal distribution in the respiratory intensive care unit, which was mediated by the IncN plasmid. Consequently, there should be increased monitoring of carbapenem-resistant strains in clinical settings to prevent and control its transmission.

Gene Expression of Carbapenemase-Encoding Genes in Multi-Drug Resistant Staphylococcus aureus from Clinical Sources

The emergence of multi-drug resistant (MDR) Staphylococcus aureus strains, particularly those expressing carbapenemase genes, poses a significant challenge in clinical settings. This study investigates the prevalence and expression profiles of carbapenemase genes (blaVIM, blaOXA-143, blaGES, blaOXA-23, and blaOXA-24) in S. aureus isolates from burn and wound patients in Tehran hospitals. A cross-sectional study was conducted using 100 S. aureus samples, which underwent biochemical testing for identification and antibiotic susceptibility testing. Gene expression analysis was performed using real-time PCR, and the results were analyzed with GRAPH PAD PRISM software. The study highlights the importance of understanding the molecular mechanisms of antibiotic resistance in S. aureus and contributes to the development of effective treatment strategies against MDR infections.

Co-occurrence of triple carbapenemase genes, bla VIM-2, bla NDM-1, and bla OXA-48 in Enterobacter hormaechei clinical isolates –first report from Croatia

Two Enterobacter hormaechei isolates harbouring three carbapenemase genes each, were isolated from two patients from different ICUs at University Hospital Centre Zagreb, Croatia, which is to our knowledge, the first report of triple carbapenemase (bla VIM-2, bla NDM-1, and bla OXA-48 ) co-existence in E. hormachei strains and also among Enterobacterales members in Croatia. Antimicrobial susceptibility testing showed susceptibility only to colistin and amikacin. The production of carbapenemases was phenotypically tested by immunochromatographic assay and confirmed by PCR. Detailed analysis by Whole Genome Sequencing (WGS) of short reads by Illumina and long reads by Oxford Nanopore Technologies (ONT) was additionally performed and showed that both isolates belonged to ST200. They were separated by 98 Single Nucleotide Polymorphisms (SNPs) having variations in the number of bla VIM-2 genes on the chromosome, the number of bla NDM-1 genes on the plasmid, non-identical bla NDM-1 plasmids, different plasmid content in general, and only one isolate carried a 94 kb prophage.

Genome analysis of extensively drug-resistant Pseudomonas aeruginosa ST1971 from a patient in China hospitalized for severe pneumonia

The emergence and outbreak of carbapenem-resistant Pseudomonas aeruginosa are a major global public threat. In this study we aimed to characterize the genome of drug-resistant and virulent genes in an extremely drug-resistant (XDR) P. aeruginosa strain to understand its antimicrobial resistance trends and pathogenicity. An XDR P. aeruginosa strain was isolated in China from a patient with severe pneumonia. Antimicrobial susceptibility testing, genome sequencing, and phylogenetic analysis were performed. Predictions were fulfilled using curated bioinformatics tools. Assembly of the strain (CRPA190) comprised 76 contigs with a total length of 7 009 318 bp. CRPA190 belongs to sequence type 1971 (ST1971) and the O11 serogroup. Nine prophage regions, three CRISPR arrays, and two Cas clusters were identified. However, no plasmids were predicted. Antibiotic susceptibility tests showed that CRPA190 was resistant to all the tested antibiotics, including carbapenem, polymyxin B, and ceftazidime-avibactam. Forty antimicrobial resistance genes were predicted in CRPA190, including several carbapenemase genes such as blaPDC-142, blaPME-1, blaNDM-1, and blaOXA-902. The isolate was predicted to be pathogenic and possess strong biofilm-forming ability. It harbours virulence genes that are associated with an arsenal of virulence determinants involved in adherence, motility, exotoxins, exoenzymes, immune modulation, biofilms, nutritional/metabolic factors, and effector delivery systems. These findings enhance our understanding of the resistance and pathogenicity of the ST1971 P. aeruginosa strain that is unique in China and provide a broader perspective on the global epidemiological landscape, suggesting the emergence of P. aeruginosa ST1971, which requires control measures to limit its dissemination.

Utility of a multiplex pathogen detection system directly from respiratory specimens for treatment and diagnostic stewardship.

The availability of syndrome-based panels for various ailments has widened the scope of diagnostics in many clinical settings. These panels can detect a multitude of pathogens responsible for a particular condition, which can lead to a timely diagnosis and better treatment outcomes. In contrast to traditional identification methods based on pathogen growth on culture, syndrome-based panels offer a quicker diagnosis, which can be especially beneficial in situations requiring urgent care, such as intensive care units. One such panel is the Biofire Filmarray Pneumonia plus Panel (BFP), which we have compared against microbiological culture and identification. The lower respiratory samples from patients were tested with BFP, culture, and identification with culture considered the gold standard. The phenotypic antibiotic susceptibility results (Vitek 2) were compared with the antimicrobial resistance (AMR) genes detected in BFP. Statistical analysis was carried out using GraphPad 7.0 and MS Excel (Microsoft Inc.). The results showed a positive percent agreement of 100% and a negative percent agreement of 47.8% with an overall agreement of 76.72% compared to culture. BFP was better at identifying fastidious bacteria, and the agreement with culture was higher for high bacterial identification numbers (107 and 106). There was also a correlation between the number of pathogens detected and growth in culture. Carbapenemase genes were detected in around 80% of phenotypically resistant samples and correlated with in-house PCR 60% of the time. Hence, BFP results need to be interpreted with caution especially when multiple pathogens are detected. Similarly, the presence or absence of AMR genes should be used to guide the therapy while being watchful of unusual resistance or susceptibility. The cost constraints and low throughput call for patient selection criteria and prioritization in emergency or resource-limited conditions.IMPORTANCEApplication of syndrome-based panels in clinical microbiology is of huge support in infectious conditions requiring urgent interventions, such as pneumonia. Interpreting the results requires caution; hence, we have compared the results obtained from Biofire Filmarray Pneumonia plus Panel with standard microbiological methods.

Predominance of blaKPC carbapenemase gene in multi-drug resistant Pseudomonas aeruginosa isolated from ICUs and surgical wards in Egypt

Predominance of blaKPC carbapenemase gene in multi-drug resistant Pseudomonas aeruginosa isolated from ICUs and surgical wards in Egypt

Characterizing the loss and acquisition of Tn2-like transposon in Klebsiella pneumoniae: Implications for carbapenemase gene dissemination

Over 1 year, two KPC-producing and two non-KPC-producing Klebsiella pneumoniae strains were isolated from a patient. Genome and DNA hybridization analyses revealed the first three strains as a clonal lineage, with carbapenem resistance changes due to a Tn2-like transposon on an IncR/IncFII plasmid. The fourth strain, carrying three plasmids, caused a lethal infection and represented a different lineage. All strains belonged to the ST11-SL47-OL101 type. This study highlights the Tn2-like transposon's role in carbapenemase gene spread and the importance of distinguishing between bacterial colonization and infection.

Emergence of an IncX3 plasmid co-harbouring the carbapenemase genes blaNDM-5 and blaOXA-181.

The spread of transmissible plasmids with carbapenemase genes has contributed to a global increase in carbapenemase-producing Enterobacterales over the past two decades, with blaNDM and blaOXA among the most prevalent carbapenemase genes. To characterize an Escherichia coli isolate co-carrying blaNDM-5 and blaOXA-181 (JBEHAAB-19-0176) that was isolated in the Japan Antimicrobial Resistant Bacterial Surveillance in 2019-20, and to evaluate the functional advantage of carrying both genes as opposed to only one. The whole-genome sequence of the isolate was determined using long- and short-read sequencing. Growth assay and co-culture experiments were performed for phenotypic characterization in the presence of different β-lactam antibiotics. WGS analysis showed that blaNDM-5 and blaOXA-181 were carried by the same IncX3 plasmid, pJBEHAAB-19-0176_NDM-OXA. Genetic characterization of the plasmid suggested that the plasmid emerged through the formation of a co-integrate and resolution of two typical IncX3 plasmids harbouring blaNDM-5 and blaOXA-181, which involved two recombination events at the IS3000 and IS26 sequences. When cultured in the presence of piperacillin or cefpodoxime, the growth rate of the transformant co-harbouring blaNDM-5 and blaOXA-181 was significantly higher than the transformant with only blaNDM-5. Furthermore, in co-culture where the two blaNDM-5-harbouring transformants were allowed to compete directly, the strain additionally harbouring blaOXA-181 showed a marked growth advantage. The additional carriage of blaOXA-181 confers a selective advantage to bacteria in the presence of piperacillin and cefpodoxime. These findings may explain the current epidemiology of carbapenemase-producing Enterobacterales, in which bacteria carrying both blaNDM-5 and blaOXA-48-like genes have emerged independently worldwide.

Molecular Detection of Carbapenemase Genes among Carbapenem Resistant Gram-Negative Bacilli in Tertiary Care Hospital, Bangladesh

Molecular Detection of Carbapenemase Genes among Carbapenem Resistant Gram-Negative Bacilli in Tertiary Care Hospital, Bangladesh

Carbapenem Resistance in Animal-Environment-Food from Africa: A Systematic Review, Recommendations and Perspectives.

The World Health Organization (WHO) has classified carbapenem-resistant Enterobacteriaceae, Pseudomonas aeruginosa (P. aeruginosa), and Acinetobacter baumannii (A. baumannii) as high-priority pathogens, and carbapenem-resistant bacteria (CRB) have been reported to spread between humans, animals, and the environment. This study aimed to conduct a systematic review of carbapenem resistance in animals, foods, and the environment on the African continent and to provide recommendations and perspectives for better prevention and control of carbapenem resistance in Africa. A total of 137 research articles collected from 2009 to 2023 were selected for this review, including articles reporting carbapenem-resistant bacteria in animals (81/137; 59.1%), the environment (66/137; 48.2%), and foods (26/137; 19%). Carbapenem-resistant bacterial species belonged to 31 genera and 17 families, including mainly Escherichia spp. (68/127; 53.5%); Klebsiella spp. (45/127; 35.4%); Pseudomonas spp. (20/127; 15.7%), Enterobacter spp. (19/127; 15%) and Acinetobacter spp. (15/127; 11.8%). The prevalence of CRBs by country ranged from 1.1% to 48.5%, and the pooled prevalence of CRBs isolated from animal-environment-food in Africa was 19.1% (2804/14,684; Standard Deviation = 15). Twenty carbapenemase families belonging to A, B, C, and D Ambler classes were reported, including mainly carbapenemase genes from blaOXA (44/84; 52.4%), blaNDM (34/84; 40.5%), blaSHV (23/84; 27.4%), blaKPC (22/84; 26.2%), blaVIM (19/84; 22.6%), and blaIMP (12/84; 14.3%) families. The reported mobile genetic elements (MGE) carrying carbapenemase-encoding genes included plasmids (16/19; 84.2%), integrons (3/19; 15.8%), transposons (3/19; 15.8%), and insertion sequences (2/19; 10.5%). blaOXA-48 was often carried by (60kb-65kb) IncL/M-type pOXA-48 plasmids, while blaNDM-5 was often carried by (45-50kb) IncX-type plasmids. Moreover, 25 articles investigated and reported virulent and hypervirulent CRBs that carried multiple virulence factors. Animal-environment-food ecosystems would constitute reservoirs of CRBs involved in human infections. The One Health approach and constant collaboration between governments are necessary to drastically reduce the mortality rates linked to antimicrobial resistance.

Comparative In Vitro Activity of Ceftazidime-Avibactam, Imipenem-Relebactam, and Meropenem-Vaborbactam against Carbapenem-Resistant Clinical Isolates of Klebsiella pneumoniae and Pseudomonas aeruginosa.

Co-infection with carbapenem-resistant Klebsiella pneumoniae (CRKP) and Pseudomonas aeruginosa (CRPA) is associated with poor outcomes and historically relied on combination therapy with toxic agents for management. However, several novel β-lactam/β-lactamase inhibitor combination agents have been developed, offering potential monotherapy options. Here, we compare the in vitro activity of ceftazidime-avibactam (CZA), imipenem-relebactam (IRL), and meropenem-vaborbactam (MVB) against both CRKP and CRPA clinical isolates. Minimum inhibitory concentrations (MICs) for each agent were determined using broth microdilution. Carbapenemase gene detection was performed for representative isolates of varying carbapenem resistance phenotypes. IRL demonstrated excellent activity against CRKP and CRPA with susceptibility rates at 95.8% and 91.7%, respectively. While CZA and MVB showed comparable susceptibility to IRL against CRKP (93.8%), susceptibility of CRPA to CZA was modest at 79.2%, whereas most CRPA strains were resistant to MVB. Of the 35 CRKP isolates tested, 91.4% (32/35) carried a blaKPC gene. Only 1 of 37 (2.7%) CRPA isolates tested carried a blaVIM gene, which conferred phenotypic resistance to all three agents. None of the CRKP strains were cross-resistant to all three agents. Source of infection and co-infection did not significantly influence antimicrobial activity for IRL and CZA; none of the CRPA isolates from co-infected patients were susceptible to MVB. Our results suggest that novel β-lactam agents with antipseudomonal activity and stability against carbapenemases, such as IRL and CZA, offer potential monotherapy options for the treatment of co-infection involving both CRKP and CRPA, but not MVB.