SEARCH · PubMed Health

Results for “Enterobacterales”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2026

In vitro susceptibility testing of aztreonam-avibactam against predominantly NDM-producing Enterobacterales in Peru.

Metallo-β-lactamase-producing Enterobacterales are distributed worldwide, but some Latin American countries show a higher prevalence. Aztreonam-avibactam (ATM-AVI) may be an option for treating these infections. To evaluate in vitro susceptibility to aztreonam (ATM) alone and ATM-AVI in carbapenem-non-susceptible Enterobacterales isolates, based on the type of carbapenemase production, we prospectively collected carbapenem-non-susceptible Enterobacterales isolates from Peruvian hospitals during 2023-2024. Identification and susceptibility testing were performed by commercial panels and disk diffusion. Carbapenemases were detected by immunochromatography. ATM and ATM-AVI MICs were determined using broth microdilution panels with avibactam fixed at 4 µg/mL. The non-susceptible isolates to ATM-AVI and those with double production of carbapenemases underwent whole-genome sequencing. A total of 438 Enterobacterales isolates were analyzed; carbapenemase production was detected in 422 (96.3%) and NDM was the most frequent (61.9%). Coproduction of NDM + KPC in K. pneumoniae and NDM + OXA-48-like in Escherichia coli was observed. Overall, 99.3% were susceptible to ATM-AVI; MIC50 and MIC90 were 0.12 and 2 µg/mL, respectively. Overall, K. pneumoniae isolates had lower MIC50 and MIC90 values to ATM-AVI (0.12 and 0.5 µg/mL) compared to E. coli (0.5 and 4 µg/mL). Three E. coli isolates were resistant to ATM-AVI (MIC ≥ 8 µg/mL), they belonged to ST410, ST167, and ST10 and harbored a YRIN insertion in PBP3 along with CYM-type, PER-type, and CTX-M-type beta-lactamase genes. ATM-AVI demonstrated potent activity against carbapenem-non-susceptible Enterobacterales, including those producing NDM, which is the carbapenemase most frequently detected in Peruvian hospitals.IMPORTANCEEnterobacterales isolates cause common illnesses in humans. Carbapenems are the antibiotics used to treat several of these infections, and increasingly, isolates resistant to these antibiotics are found. The most important mechanism of resistance to carbapenem among Enterobacterales is the production of enzymes called carbapenemases. Our results allowed us to recognize that NDM is the most frequent type of carbapenemase detected. Most of the antimicrobials available do not cover the Enterobacterales carrying NDM carbapenemase. In this scenario, we found that the new combination of drugs, aztreonam-avibactam, has high in vitro efficacy against most of the carbapenem-resistant isolates and against those isolates carrying NDM carbapenemase.

Aztreonam↗

PubMed2026

Activity of Aztreonam-avibactam and Ceftazidime-Avibactam against Enterobacterales and Pseudomonas aeruginosa causing infections in patients hospitalized in hematology, oncology, and transplant units from United States medical centres (2019-2024).

Immunosuppression increases the risks and severity of infections and is associated with a higher incidence of infection with multidrug-resistant (MDR) pathogens. We evaluated the antimicrobial susceptibility of Enterobacterales and Pseudomonas aeruginosa from patients hospitalized in hospital units where the frequency of immunosuppressed patients is very high. Bacterial isolates were consecutively collected (1/patient) from 75 US medical centres in 2019-2024 and susceptibility tested by broth microdilution. Enterobacterales (n = 2,407) and P. aeruginosa (n = 485) from patients hospitalized in hematology, oncology, and transplant units were evaluated. Carbapenem-resistant Enterobacterales (CRE) were screened for β-lactamases by whole genome sequencing. Enterobacterales were mainly from bloodstream infection (BSI; 53.6%) and urinary tract infection (19.9%) and P. aeruginosa were mainly from BSI (37.9%) and pneumonia (35.0%). Aztreonam-avibactam, ceftazidime-avibactam, and meropenem-vaborbactam were highly active against Enterobacterales (99.9-99.4% susceptible), including MDR isolates (99.6-98.1% susceptible), but only aztreonam-avibactam exhibited good activity against CRE (95.8% susceptible). Ceftolozane-tazobactam showed good activity against Escherichia coli (95.7% S) and Klebsiella pneumoniae (92.8% S), but limited activity against Enterobacter cloacae species complex (75.9% susceptible). All (100.0%) carbapenemase (CBase)-producing CRE isolates were aztreonam-avibactam-susceptible while 77.4% were ceftazidime-avibactam-susceptible and 67.7% were meropenem-vaborbactam-susceptible. The most common CBases were KPC (41.7%), NDM (12.5%), and OXA-48 types (10.4%). Metallo-β-lactamases represented 23.5% of CBases and were identified in 16.7% of CREs. The most active agents against P. aeruginosa were ceftazidime-avibactam (95.7% susceptible), ceftolozane-tazobactam (94.8% susceptible), and tobramycin (91.5% susceptible). Piperacillin-tazobactam and meropenem were active against 81.4% and 82.5% of P. aeruginosa, respectively, and aztreonam-avibactam inhibited 78.6% of P. aeruginosa at ≤8 mg/L.

Humans↗

PubMed2025

Characterization of ertapenem-resistant Enterobacterales in Canadian hospitals: 17 years of the CANWARD study (2007-23).

OBJECTIVES: To review phenotypic and genotypic characteristics of ertapenem-resistant Enterobacterales isolates identified by the CANWARD study from 2007 to 2023. METHODS: Bacterial isolates were collected as part of the CANWARD surveillance study from 2007 to 2023. CLSI M7 broth microdilution antimicrobial susceptibility testing (12th edition, 2024) was performed. MICs were interpreted by CLSI M100 breakpoints (34th edition, 2024). WGS was performed to identify antimicrobial resistance markers. RESULTS: Only 134 (0.7%) of the 19 642 Enterobacterales were ertapenem-resistant. Carbapenemase producing Enterobacterales (CPE) accounted for 17.9% (n = 24) of ertapenem-resistant isolates and were predominantly Klebsiella pneumoniae (54.2%) and Escherichia coli (20.8%). KPC was the most common carbapenemase identified (62.5%). K. pneumoniae ST834, ST16 and ST258, and E. coli ST131 were the most frequent STs detected. CPE percent resistant values ranged from 20.8% to 25.0% for ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam. Most non-CPE ertapenem-resistant isolates were Enterobacter spp. (51.8%), E. coli (15.5%) and K. pneumoniae (10.9%). Non-CPE STs were most commonly E. cloacae ST108, ST50 and ST133, and E. coli ST131. Non-CPE percent resistant values ranged from 2.7% to 4.5% for ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam. At least one of an AmpC, an ESBL or porin alternations were observed in most non-CPE isolates. CONCLUSIONS: In Canada, ertapenem-resistant Enterobacterales remain uncommon (0.7%). CPE isolates demonstrated higher percent resistant values for multiple antimicrobial classes and harboured more antimicrobial resistance genes than non-CPE isolates. Continued monitoring for ertapenem-resistant Enterobacterales, particularly CPE, is important given their associated multidrug resistance to both established and newer agents.

Ertapenem↗

PubMed2024

Spatiotemporal and genomic analysis of carbapenem resistance elements in Enterobacterales from hospital inpatients and natural water ecosystems of an Irish city.

Carbapenemase-producing Enterobacterales (CPE) is a diverse group of often multidrug-resistant organisms. Surveillance and control of infections are complicated due to the inter-species spread of carbapenemase-encoding genes (CEGs) on mobile genetic elements (MGEs), including plasmids and transposons. Due to wastewater discharges, urban water ecosystems represent a known reservoir of CPE. However, the dynamics of carbapenemase-bearing MGE dissemination between Enterobacterales in humans and environmental waters are poorly understood. We carried out whole-genome sequencing, combining short- and long-sequencing reads to enable complete characterization of CPE isolated from patients, wastewaters, and natural waters between 2018 and 2020 in Galway, Ireland. Isolates were selected based on their carriage of Class A blaKPC-2 (n = 6), Class B blaNDM-5 (n = 12), and Class D blaOXA-48 (n = 21) CEGs. CEGs were plasmid-borne in all but two isolates. OXA-48 dissemination was associated with a 64 kb IncL plasmid (62%), in a broad range of Enterobacterales isolates from both niches. Conversely, blaKPC-2 and blaNDM-5 genes were usually carried on larger and more variable multireplicon IncF plasmids in Klebsiella pneumoniae and Escherichia coli, respectively. In every isolate, each CEG was surrounded by a gene-specific common genetic environment which constituted part, or all, of a transposable element that was present in both plasmids and the bacterial chromosome. Transposons Tn1999 and Tn4401 were associated with blaOXA-48 and blaKPC-2, respectively, while blaNDM-5 was associated with variable IS26 bound composite transposons, usually containing a class 1 integron.IMPORTANCESince 2018, the Irish National Carbapenemase-Producing Enterobacterales (CPE) Reference Laboratory Service at University Hospital Galway has performed whole-genome sequencing on suspected and confirmed CPE from clinical specimens as well as patient and environmental screening isolates. Understanding the dynamics of CPE and carbapenemase-encoding gene encoding mobile genetic element (MGE) flux between human and environmental reservoirs is important for One Health surveillance of these priority organisms. We employed hybrid assembly approaches for improved resolution of CPE genomic surveillance, typing, and plasmid characterization. We analyzed a diverse collection of human (n = 17) and environmental isolates (n = 22) and found common MGE across multiple species and in different ecological niches. The conjugation ability and frequency of a subset of these plasmids were demonstrated to be affected by the presence or absence of necessary conjugation genes and by plasmid size. We characterize several MGE at play in the local dissemination of carbapenemase genes. This may facilitate their future detection in the clinical laboratory.

Humans↗

PubMed2026

Aztreonam-avibactam Activity against Enterobacterales from Asia Pacific and Latin American Medical Centres: Summary of 5 years of Surveillance prior to Clinical Use (2020-2024).

OBJECTIVES: To assess the in vitro activity of aztreonam-avibactam against Enterobacterales from the Asia Pacific region (APAC) and Latin America (LATAM) during a 5-year period prior to its approval for clinical use in these regions. METHODS: 12,039 Enterobacterales isolates were consecutively collected in 2020-2024 from 17 medical centres in APAC (n=7,369) and 10 in LATAM (n=4,670) then susceptibility tested by broth microdilution. Carbapenem-resistant Enterobacterales (CRE) and isolates with elevated aztreonam-avibactam MICs (>4 mg/L) were submitted to whole genome sequencing. RESULTS: Aztreonam-avibactam was active against 99.9% of Enterobacterales from APAC and LATAM and exhibited potent activity against CRE isolates (MIC50/90, 0.25/2 mg/L; 97.3% susceptible in APAC and MIC50/90, 0.25/0.5 mg/L; 99.4% susceptible in LATAM). Cefiderocol was active against 91.2% of CREs from APAC and LATAM. Ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-relebactam showed limited activity against CRE isolates from LATAM (53.5% to 64.8% susceptibility) and APAC (27.3% to 38.8% susceptible). The occurrence of carbapenemases varied clearly among the countries evaluated. In general, metallo-β-lactamases (MBLs) prevailed in APAC and KPCs predominated in LATAM, but with great variability among countries within a region. Decreased susceptibility to aztreonam-avibactam was largely due to PBP3 alterations plus the production of CMY and/or CTX-M β-lactamases among Escherichia coli, and decreased membrane permeability associated with KPC production among Klebsiella pneumoniae. CONCLUSIONS: The results of this investigation provide a baseline for monitoring the activity of aztreonam-avibactam in APAC and LATAM and emphasize the importance of surveillance programs to monitor the emergence of resistance markers.

Aztreonam-avibactam↗

PubMed2026

Gene transfer from NDM-5-producing and OXA-48-producing Enterobacter hormaechei ST79 on contaminated dicloxacillin capsules to other Enterobacterales in Europe, 2020-23: a retrospective, observational, molecular epidemiological study.

BACKGROUND: In February, 2023, an outbreak of Enterobacter hormaechei ST79 carrying blaNDM-5 and blaOXA-48 was linked to contaminated dicloxacillin capsules administered to approximately 79 000 individuals in Denmark. Initial clonal outbreak investigations identified 11 patients with the E hormaechei ST79 outbreak strain, which carried blaNDM-5 on a distinct IncX3 plasmid, and in nine cases, blaOXA-48 was on a distinct IncL plasmid. Interspecies plasmid transfer was observed in one patient, suggesting a potential plasmid-mediated outbreak involving other Enterobacterales. However, no studies have characterised the progression of a clonal outbreak originating from a contaminated medicine into plasmid-mediated dissemination of carbapenemase genes. Hence, we aimed to characterise the clonal and plasmid-mediated spread of carbapenemase genes in this outbreak. METHODS: We conducted a retrospective genomic and epidemiological investigation using existing short-read whole-genome sequencing data from all carbapenemase-producing Enterobacterales (CPE) from the Danish national surveillance, collected between Jan 1, 2014, and Oct 1, 2023. All confirmed CPE isolates were eligible for inclusion. Using in-silico screening for unique fragments of the two outbreak plasmids, we selected 160 isolates for long-read sequencing to obtain complete plasmid sequences for outbreak investigation. Analyses were descriptive and included comparison of sequence identity and coverage to define outbreak-associated plasmids and summary statistics of patient characteristics. FINDINGS: Data from 1829 isolates were obtained. We detected 16 of 53 isolates involved in the outbreak using conventional outbreak detection methods. The remaining 37 isolates were detected using plasmid-specific screening and long-read sequencing. 15 patients carried the outbreak E hormaechei strain, including the 11 patients previously reported. Three of the 15 patients presented with at least one additional bacterial species carrying one or both outbreak plasmids (pDcap_OXA-48 and pDcap_NDM-5). A further 24 patients, sampled between July 1, 2020, and Oct 1, 2023, presented with other Enterobacterales carrying one or both outbreak-associated plasmids but not the original E hormaechei ST79 strain. In four cases, outbreak-associated plasmids differed structurally from the original outbreak plasmid. INTERPRETATION: This study describes how a clonal CPE outbreak caused by a contaminated medicine evolved into a complex plasmid-mediated outbreak involving multiple Enterobacterales species. Most patients related to the outbreak did not present with the original E hormaechei ST79 outbreak strain and were therefore not identified using standard outbreak detection methods. These findings highlight the importance of using plasmid-focused approaches in outbreak investigations. FUNDING: The Danish Ministry of Health, SSI-Seq (cofunded by EU4Health).

Humans↗

PubMed2026

Evaluation of carbapenem inactivation method-based phenotypic assays for the detection of GES-type carbapenemases in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii.

UNLABELLED: Detection of GES-type carbapenemases remains challenging because of their low prevalence and frequently weak hydrolytic activity against carbapenems. Carbapenem inactivation method (CIM)-based assays are widely used as phenotypic screening tools for carbapenemase detection; however, their performance in large collections of GES producers has not been systematically evaluated. We assessed the performance of CIM, modified CIM (mCIM), and CIM-Tris in a diverse collection of GES-producing clinical isolates, including 110 Enterobacterales and 108 Pseudomonas aeruginosa, recovered from Spanish hospitals (2010-2024), and 10 Acinetobacter baumannii isolates, mostly obtained from a hospital in Egypt. Whole-genome sequencing was carried out for species confirmation and resistome analysis. Meropenem MICs were determined by broth microdilution. Overall, 92.1% of isolates were GES-carbapenemase producers (CP), whereas 7.9% expressed GES-type extended-spectrum β-lactamases (ESBLs). In Enterobacterales (predominantly carrying blaGES-6), mCIM improved sensitivity compared with CIM (63.6% vs 40.0%), although many isolates remained undetected due to low meropenem MICs (MIC50, 0.5 µg/mL). In CP-P. aeruginosa (mainly blaGES-5), CIM, mCIM, and CIM-Tris showed sensitivities of 89.1%, 94.6%, and 100%, respectively; however, CIM-Tris yielded false-positive results in 50% of non-CP isolates (mostly blaGES-1 producers). Meropenem MICs in P. aeruginosa were higher (MIC50, >32 µg/mL). In A. baumannii, CIM-Tris improved sensitivity compared with CIM (100% vs 25.0%). These findings indicate that CIM-based methods can detect GES-type carbapenemases, but performance varies according to bacterial species and GES variant, and reduced specificity may occur in isolates producing GES-type ESBLs. Complementary molecular testing may therefore be necessary to ensure accurate detection of GES-type carbapenemases in routine clinical laboratories. IMPORTANCE: GES-type carbapenemases represent an important but underrecognized diagnostic challenge due to their low global prevalence, heterogeneous hydrolytic activity, and the limited performance data available for routine phenotypic detection methods. Although CIM-based assays are widely implemented in clinical microbiology laboratories for carbapenemase screening, their performance against GES-producing organisms has not been comprehensively evaluated across different bacterial genera and GES variants. In this study, we evaluated the performance of CIM, modified CIM (mCIM), and CIM-Tris in a large multicenter collection of well-characterized GES-producing clinical isolates, including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii. Our findings demonstrate substantial variability in assay performance according to bacterial species and GES variant. Notably, mCIM improved sensitivity among Enterobacterales with low meropenem MICs, whereas CIM-Tris achieved excellent sensitivity in P. aeruginosa and A. baumannii but at the expense of reduced specificity in isolates producing GES-type ESBLs. To the best of our knowledge, this is the first study directly comparing multiple CIM-based approaches in such a large and taxonomically diverse collection of GES-producing isolates.

beta-Lactamases↗

PubMed2026

Wildlife as a reservoir of OXA-48-like carbapenemase-producing Enterobacterales.

Carbapenemase-producing Enterobacterales (CPEs) have globally emerged and spread beyond human compartments. However, data in wild animals, especially from low- and middle-income countries, such as Algeria, are still very scarce. Here, we investigated CPEs recovered from feces samples collected between October 2021 and June 2023 from wild terrestrial and aquatic mammals, wild migratory/nesters/sedentary birds, and zoo animals, including their environment (water, food, and fecal samples of animal care workers) distributed over six Algerian provinces. Carbapenem-resistant Enterobacterales were characterized using MALDI-TOF-MS, Carba NP, immunochromatographic assay NG-Test CARBA 5, antimicrobial susceptibility testing, and whole-genome sequencing. Thirty CPEs were identified out of the 1,899 samples collected (1.6%). The carriage rate was higher in captive animals (3.2%) than in wild animals (1.2%). Twenty-six produced OXA-48, three OXA-244, and one OXA-181, along with CTX-M-15 ESBL. Clonal expansion of Enterobacter hormaechei hoffmannii ST145 and Klebsiella pneumoniae ST13 was evidenced. Plasmid analysis confirmed that 24/30 isolates harbored a transferable 62 kb IncL pOXA-48 plasmid. Five/six E. coli isolates belonged to high-risk clones with chromosome-mediated blaOXA-244 gene in three isolates, blaOXA-48 in two isolates, and blaOXA-181 gene encoded on an IncFII-ColKP3 hybrid plasmid in one isolate. This study showed widespread dissemination of OXA-48-like producing Enterobacterales in free and captive wild animals, largely driven by epidemic plasmids and clones. It underscores the role of wild animals as a reservoir of CPEs, particularly species living close to humans, such as gulls and pigeons, and occasionally food-producing animals, increasing the risk of bidirectional dissemination between animal, environmental, and human sectors.IMPORTANCEThe global rise of carbapenemase-producing Enterobacterales (CPEs) harboring blaOXA-48-like has been increasingly documented in clinical settings. However, their emergence and transmission in wild and captive animals are less documented. This study provides a high-resolution genomic characterization of CPEs isolated from the feces of wild animals, especially migratory birds, and from captive wild animals, to evaluate the potential risk of dissemination through these animals. Whole-genome sequencing data, genetic investigations, and antimicrobial susceptibility results highlighted the spread of multidrug-resistant CPEs in both animals and humans. The widespread detection of blaOXA-48 across multiple niches suggests sustained circulation beyond hospital settings in Algeria. Human-associated lineages, such as E. coli ST131, ST38, and ST540, were identified with a clear link with humans. This study demonstrates carriage of CPEs in multiple bird species living in areas commonly inhabited by humans and provides further evidence for an effective dissemination of resistance in wildlife, facilitated by feeding habits.

Animals↗

PubMed2025

Molecular insights into carbapenemase-producing Enterobacterales from Senegal.

BACKGROUND: Carbapenemase-producing Enterobacterales (CPE) are an urgent global health threat, especially in resource-limited countries. Here we determined the prevalence and the molecular characteristics of CPE isolated from infections in Dakar, Senegal. METHOD: From January 2019 to December 2020, Enterobacterales with reduced susceptibility to ertapenem (diameter < 25 mm) from infections were collected at the Pasteur Institute of Dakar. Carbapenemases were detected using biochemical and immunochromatographical assays. WGS was used to determine resistome, MLST, plasmids, virulence genes and genetic relatedness. RESULTS: Of the 1045 Enterobacterales collected during the study period, 86 had a diameter around ertapenem of <25 mm (8%) and 19 were confirmed as CPE (2%). These included Escherichia coli (n = 6) [ST410 (n = 3), ST405 (n = 2) and ST2083], Enterobacter spp. (n = 6) [ST231 (n = 3), ST245, ST760 and ST960] and Klebsiella spp. (n = 5) (ST22, ST25, ST231, ST1535, ST4843), Citrobacter freundii ST22 (n = 1) and Citrobacter koseri with unknown ST (n = 1). blaOXA-48 (n = 7; 35%), blaOXA-181 (n = 7; 35%) and blaNDM-5 (n = 6; 30%) genes were identified. C. freundii ST22 harboured blaNDM-5, blaOXA-48 and blaCTX-M-15 genes. Some E. coli isolates belonging to the high-risk clone ST410 were closely related (<20 SNPs) to isolates recovered in France from patients returning from Senegal, suggesting transnational spread. In addition, 5/6 carbapenemase-producing E. coli isolates possessed a four amino acid insertion in PBP3, conferring reduced susceptibility to aztreonam/avibactam and cefiderocol. CONCLUSIONS: This study highlights the spread of NDM-5 and OXA-181 in Senegal, and reports the first co-occurrence of NDM-5 and OXA-48 in sub-Saharan Africa. The spread of CPE, especially in high-risk clones, underscores the urgent need for continued surveillance and targeted interventions.

Senegal↗

PubMed2026

Genomic characterization of carbapenemase-producing Enterobacterales from wastewater reveals the convergence of KPC-2 and GES-16 in Brazil.

Carbapenemase-producing Enterobacterales (CPE) pose a significant public health concern due to the limited therapeutic options and increasing dissemination outside clinical settings. Wastewater treatment plants (WWTPs) have been proposed as relevant environmental reservoirs for antimicrobial-resistant bacteria and mobile genetic elements. In this study, we performed genomic characterization of CPE strains recovered from raw wastewater samples from the influents of different WWTPs. Antimicrobial susceptibility testing revealed multidrug resistance, including coresistance to carbapenems and polymyxins, among Klebsiella pneumoniae, Enterobacter asburiae, and Enterobacter kobei strains. Whole-genome sequencing identified the convergence of the blaKPC-2 and blaGES-16 genes, as well as the presence of blaGES-5 in E. kobei sequence type (ST) 540 strains. Moreover, the blaKPC-2 gene was detected in K. pneumoniae strains belonging to high-risk clones ST11 (capsular types KL64 and KL15) and ST307 (capsular type KL102), and E. asburiae ST384. The blaGES-5 and blaGES-16 genes were associated with class 1 integrons, while the blaKPC-2 gene was embedded within transposons (Tn4401a, Tn4401i, and Tn3-like) and insertion sequences (ISKpn27 and ISKpn6). Notably, genomic analyses and literature review demonstrated that the blaGES-16 gene remains unique to Brazil. The putative pathogenic potential of carbapenem-resistant K. pneumoniae ST11 was also assessed. These findings support the environmental circulation of clinically relevant Enterobacterales genotypes and emphasize the potential role of WWTPs as conduits for CPE dissemination, if not adequately operated. Therefore, genomic surveillance in extra-hospital settings may contribute to a better understanding of antimicrobial resistance ecology and inform One Health mitigation strategies.

Brazil↗

PubMed2026

Meropenem-Colistin Combination Mitigates Porin-Associated Carbapenem Resistance Development in Ertapenem-Mono-Resistant Enterobacterales.

BACKGROUND: Non-carbapenemase-producing Enterobacterales with isolated ertapenem resistance (ETP-mono-R) may represent an early stage in the evolution toward broader carbapenem resistance, but whether further resistance induction occurs and its underlying mechanisms remain poorly understood. METHODS: Resistance induction was assessed in three Escherichia coli, four Klebsiella pneumoniae, and two Enterobacter cloacae isolates through serial exposure to subinhibitory concentrations of meropenem (MEM), imipenem, ceftazidime-avibactam, or colistin (COL), with antibiotic-free passaging for reversion. Resistance induction under MEM+COL was evaluated separately. Whole-genome sequencing (WGS), targeted porin-gene Sanger sequencing, and transcriptional analysis were used to characterize resistance mechanisms across induction stages. RESULTS: Subinhibitory MEM exposure rapidly selected for carbapenem resistance through porin-associated alterations in a species-specific manner. E. coli accumulated loop-region mutations in ompC, while K. pneumoniae predominantly developed disruptive mutations in ompK36, both accompanied by marked transcriptional downregulation. In contrast, E. cloacae retained wild-type porins but showed increased MEM MICs, suggesting a non-porin-mediated mechanism. Subinhibitory exposure to COL alone rapidly induced colistin resistance but was associated with decreased carbapenem MICs. Co-exposure to MEM and COL significantly delayed resistance development and reduced MIC increases (all P < 0.05). Targeted sequencing of 26 non-carbapenemase-producing K. pneumoniae isolates resistant to all carbapenems revealed widespread disruptive ompK36 alterations, including the S337P substitution identified experimentally, consistent with a shared permeability-loss pathway. CONCLUSIONS: In ETP-mono-R Enterobacterales, subinhibitory carbapenem exposure promotes carbapenem resistance, with porin-associated mechanisms predominating in E. coli and K. pneumoniae. Co-exposure to COL attenuates this process, suggesting a potential strategy to delay the emergence of carbapenem resistance.

Enterobacterales↗

PubMed2024

Extended-spectrum beta-lactamase-producing Enterobacterales in human health: Experience from the tricycle project, Ghana.

BACKGROUND: Vulnerable groups, such as pregnant women, are at increased risk of potentially life-threatening infections with extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) for both mother and newborn. However, data regarding ESBL-E carriage and associated risk factors in Ghanaian pregnant women remain scarce. OBJECTIVE: This study aimed to determine the prevalence of ESBL-E carriage and its associated risk factors among pregnant women attending the antenatal clinic at the Korle Bu Teaching Hospital. METHODS: A systematic sample of 700 pregnant women with gestational age ≥ 34 weeks attending the antenatal clinic at Korle Bu Teaching Hospital was included in the study. After administering a structured questionnaire to assess potential risk factors associated with ESBL-E carriage, patients were given a sterile stool container to submit at least 1 g of stool specimen. Recovered isolates from faecal specimens were identified using MALDI-TOF-MS technology. These isolates were then subjected to susceptibility testing and ESBL identification. A random subset of 24 ESBL-producing Escherichia coli isolates was whole-genome sequenced on the MiSeq Illumina platform. Risk factors associated with ESBL-E carriage were determined using multivariable logistic regression analysis. RESULTS: Among the 700 pregnant women, 42% (294) carried ESBL-E. The predominant ESBL-producing Enterobacterales were Escherichia coli (95%). Fifty percent (50%) of ESBL-E were multidrug resistant isolates (MDRs). Whole-genome sequencing of 24 ESBL-producing E. coli isolates revealed that blaCTX-M-15 (96%) was the most prevalent ESBL gene type. Notably, most isolates belonged to commensal phylogenetic groups (A, B1, and C; 88%). Having a primary level of education (aOR 1.45, 95% CI 1.05-1.96) and consuming legumes as the main source of protein (aOR 0.17, 0.40-0.83) were significantly associated with intestinal carriage of ESBL-E. CONCLUSION: This study identified a high prevalence of ESBL-E and MDR-ESBL-E carriage among pregnant women. Our findings underscore the urgent need for public health interventions to control the spread of AMR.

Humans↗

PubMed2026

Extended-Spectrum β-Lactamase-Producing Enterobacterales in Free-Roaming Cats in Israel.

Amid the rising prevalence of antimicrobial resistance (AMR), attention is increasingly directed toward investigating additional factors that may contribute to or mediate its development, among which companion animals have emerged as a potential reservoir and transmission interface. Despite this, the contribution of free-roaming animal populations living in proximity to humans and domestic animals has yet to be thoroughly investigated worldwide. Accordingly, this study aimed to determine the prevalence and antimicrobial resistance patterns of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales in free-roaming cats in Israel. Rectal swabs were collected from 214 free-roaming cats admitted to two veterinary clinics between 2023 and 2024. ESBL-PE were recovered from 51 cats (23.8%), yielding 61 isolates, which were tested for susceptibility to multiple antimicrobials. Eleven bacterial species were identified, with Escherichia coli being the most frequently recovered (62.3%, 38/61). Nine purposively selected E. coli isolates underwent whole-genome sequencing (WGS). Multidrug resistance (MDR), defined as non-susceptibility to at least one agent in three or more antimicrobial categories, was observed in 72.1% (44/61) of isolates, and four isolates were carbapenemase-producing Enterobacterales (CPE). These findings suggest that free-roaming cats may serve as a previously overlooked 'One Health' link, possibly connecting environmental contamination to human and animal health risks.

antimicrobial resistance↗

PubMed2026

Limited efficacy of plazomicin against carbapenem resistant Enterobacterales in a tertiary care centre in Eastern India.

The global escalation of carbapenem resistant Enterobacterales (CRE) represents a critical threat to public health, necessitating the investigation of alternative therapeutic agents. Plazomicin, a newer aminoglycoside, was engineered to evade common aminoglycoside-modifying enzymes. This study evaluated the susceptibility of plazomicin among 100 CRE isolates. The findings reveal a strikingly low plazomicin susceptibility rate of only 15/100 (15%). Whole-genome sequencing identified a high prevalence of 16S rRNA methyltransferase (RMTase) genes, such as armA and rmtB1, which confer high-level resistance to plazomicin. These results suggest that plazomicin may have limited utility against CRE in regions where RMTase-mediated resistance is prevalent.

Sisomicin↗

PubMed2026

Variations in carbapenem resistance associated with the VIM-1 metallo-β-lactamase across the Enterobacterales.

The VIM-1 metallo-β-lactamase enzyme, encoded within class 1 integrons, is found in Gram-negative clinical isolates worldwide and has been linked to outbreaks of bacterial pathogens in nosocomial settings. Six vim-1+ clinical isolates, from the genera Escherichia, Klebsiella and Enterobacter, were obtained from Kingston, Ontario, Canada. Whole-genome sequencing revealed that vim-1 was plasmid-borne in all strains and situated as the first gene in In916 or In110 integrons. Analysis of related plasmids suggested that these vim-1-containing plasmids are globally disseminated and have spread via horizontal gene transfer and autochthonous vertical spread within Ontario. Interestingly, the MICs of ertapenem and meropenem, two clinically relevant carbapenem antibiotics, against these six isolates varied more than tenfold, suggesting that the effects of VIM-1 are dependent on the genomic content of the host microbe. Introducing vim-1 into three common Enterobacterales laboratory strains was not sufficient to confer resistance to ertapenem and meropenem. Instead, adaptive laboratory evolution of the vim-1 + laboratory strains revealed that vim-1-mediated carbapenem resistance in these strains was dependent on epistatic interactions with ompC mutations, likely due to decreased outer membrane permeability to these antibiotics. Together, these results provide additional support for the role of gene epistasis in modulating the antimicrobial resistance phenotypes of acquired resistance genes, as well as previous results suggesting that the presence of a β-lactamase gene is insufficient to confer strong resistance to carbapenems without being paired with reduced outer membrane permeability.

beta-Lactamases↗

PubMed2025

Clinical carbapenem-resistant Enterobacterales in a University Hospital in Dakar, Senegal: genomic insights into Enterobacter hormaechei ST182 strains carrying blaNDM-5 and blaOXA-48 genes .

Senegal has witnessed the emergence and spread of carbapenem-resistant Enterobacterales (CRE), which often cause deadly infections. Accordingly, this study aimed to determine the antimicrobial susceptibility and prevalence of carbapenemases, as well as to perform a whole-genome sequence analysis of clinical CRE isolates from a university hospital in Dakar, Senegal. MALDI-TOF MS and VITEK2 systems were used for bacterial identification and antimicrobial susceptibility testing (AST). Carbapenemase- and cephalosporinase-encoding genes were screened using simplex end-point polymerase chain reaction. Whole-genome sequencing (WGS) was performed using the Illumina MiSeq platform. The CRE isolates were resistant to almost all the 34 antimicrobials tested. Nevertheless, colistin and amikacin remained active, with susceptibility rates of 96% and 71%, respectively. Only the carbapenemase genes blaOXA-48 (53.8%; 15/28) and blaNDM (35.7%; 10/28) and the cephalosporinase gene blaCMY-1 (25%; 7/28) were identified. In this context, two extensively drug-resistant Enterobacter hormaechei isolates were subjected to WGS analysis. These isolates were assigned as sequence type (ST) 182 and carried several genes related to antimicrobial resistance (AMR), metal tolerance, and virulence. An IncL/M plasmid with 61,054 bp in length was identified as carrying the blaOXA-48 gene, whereas an IncFIB(pECLA)/IncFII(pECLA)/IncX3 mutireplicon plasmid with 217,745 bp in length was detected as harboring the blaNDM-5 gene and other genes related to AMR and metal tolerance. Our study presents the first landscape of clinical CRE circulating in Senegal, along with additional genomic analysis of E. hormaechei ST182 strains, which could be useful for mitigating the burden associated with CRE in this country.IMPORTANCEThe investigation of global critical priority CRE isolates has become crucial to reduce morbidity and mortality associated with AMR. This study revealed that colistin and amikacin can be considered good alternatives for treating CRE-associated infections in Dakar. In addition, the genomic approach revealed that the CRE isolates carried both a wide resistome and virulome. Moreover, the abundance of horizontal gene transfer regions in the genomes suggests the great implications of mobile genetic elements in the spread of AMR in Dakar. Furthermore, this study reported the complete sequences of chromosomes and blaOXA-48 and blaNDM-5-carrying plasmids. Our findings are of great importance because complete genome sequences are still rarely characterized in the West African region. Finally, this study highlights the importance of strengthening genomic surveillance of CRE in sub-Saharan African countries to mitigate the burden associated with these pathogens.

Senegal↗

PubMed2026

Treatment strategies for imipenemase-producing Gram-negative infections: lessons from Japan.

Carbapenems remain essential for treating serious infections caused by drug-resistant Gram-negative bacteria because of their broad-spectrum activities and favourable safety profiles. However, the emergence of carbapenemase-producing Enterobacterales, which produce enzymes that efficiently hydrolyse β-lactams including carbapenems, continues to undermine their clinical utility. Although new antibiotics such as ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam, aztreonam-avibactam, and cefiderocol have expanded therapeutic options, their effectiveness varies substantially across different carbapenemase families. Carbapenemases produced by Enterobacterales include serine β-lactamases (Ambler classes A and D) and metallo-β-lactamases (MBLs; Ambler class B), each with distinct substrate and inhibitor profiles. Clinically relevant MBLs-including imipenemase (IMP), New Delhi MBL (NDM), and Verona integron-encoded MBL (VIM) variants-show markedly different biochemical properties and inhibitor susceptibilities. Despite their clinical relevance, optimal treatment strategies for infections caused by IMP-producing Enterobacterales remain poorly defined. The unique reactivity of IMP-type MBLs to inhibitors differs from that of other MBLs such as NDMs or VIMs, underscoring the need for tailored therapeutic approaches. In this Personal View, we summarise current evidence and, drawing on Japan's experience as an endemic setting for IMP producers, outline key scientific, clinical, and public health challenges that should be addressed globally to develop effective, evidence-based treatment strategies for IMP-producing Enterobacterales infections.

Humans↗

PubMed2026

Genomic Characterisation of Carbapenem-Resistant Klebsiella pneumoniae and Enterobacter hormaechei Clinical Isolates from Nigeria: Evidence of Resistance, Virulence, and Putative Plasmid-Mediated Gene Sharing.

The global proliferation of carbapenem-resistant Enterobacterales (CRE) constitutes one of the most urgent public health threats, yet high-resolution genomic data from sub-Saharan Africa remain critically scarce. We applied whole-genome sequencing (WGS) and comparative phylogenomics to characterise antimicrobial resistance determinants, virulence genes, and mobile genetic elements (MGEs) in three carbapenem-resistant clinical isolates originating from three tertiary hospitals (selected from a broader surveillance collection spanning four facilities) in Osun State, southwestern Nigeria. We purposively selected three isolates, two Klebsiella pneumoniae subsp. pneumoniae (K22, ST411; K31, ST17) and one Enterobacter hormaechei subsp. steigerwaltii (K32, ST45) from a broader surveillance collection of 27 carbapenem-non-susceptible Enterobacterales, to represent phenotypically and genotypically divergent lineages. Resistome analysis revealed extensive plasmid-associated β-lactam and aminoglycoside resistance in K31 (including blaCTX-M-15, blaOXA-1, and blaTEM-1). K32 harboured an intrinsic chromosomal blaACT-17 AmpC gene, while IS26 and ISEcp1 insertion sequences, consistent with transposon-mediated mobilisation, flanked its acquired aminoglycoside and sulfonamide resistance cassettes. K22 lacked detected acquired carbapenemase, ESBL, or plasmid-mediated AmpC genes, indicating that its carbapenem-resistant phenotype may involve non-carbapenemase mechanisms such as porin alteration or efflux-mediated reduced susceptibility; however, this mechanism requires confirmation by direct ompK35/ompK36 sequence analysis and/or phenotypic outer membrane protein profiling. Virulome profiling identified a broader repertoire of siderophore, adhesion, and biofilm genes in both K. pneumoniae isolates than in E. hormaechei. Phylogenomic analysis demonstrated that K22 and K31 cluster within the broader K. pneumoniae population framework but represent distinct high-risk lineages (ST411 and ST17) rather than a single clonal outbreak. Analysis also identified a shared plasmid backbone between K31 and K32, supporting interspecies horizontal gene transfer. These descriptive genomic findings identify clinically relevant resistance and virulence determinants in three purposively selected carbapenem-resistant Enterobacterales from Nigerian tertiary-care hospitals. The detection of shared resistance elements between K. pneumoniae and E. hormaechei suggests possible plasmid-mediated gene sharing. Still, larger WGS studies with long-read sequencing and patient-level epidemiological data are required to define transmission and dissemination patterns.

Nigeria↗