Molecular Epidemiology and Risk Factors of Carbapenemase-Producing Enterobacteriaceae Isolates in Portuguese Hospitals: Results From European Survey on Carbapenemase-Producing Enterobacteriaceae (EuSCAPE)

Tackling Carbapenem Resistance and the Imperative for One Health Strategies-Insights from the Portuguese Perspective

Carbapenemases, a class of enzymes specialized in the hydrolysis of carbapenems, represent a significant threat to global public health. These enzymes are classified into different Ambler's classes based on their active sites, categorized into classes A, D, and B. Among the most prevalent types are IMI/NMC-A, KPC, VIM, IMP, and OXA-48, commonly associated with pathogenic species such as Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The emergence and dissemination of carbapenemase-producing bacteria have raised substantial concerns due to their ability to infect humans and animals (both companion and food-producing) and their presence in environmental reservoirs. Adopting a holistic One Health approach, concerted efforts have been directed toward devising comprehensive strategies to mitigate the impact of antimicrobial resistance dissemination. This entails collaborative interventions, highlighting proactive measures by global organizations like the World Health Organization, the Center for Disease Control and Prevention, and the Food and Agriculture Organization. By synthesizing the evolving landscape of carbapenemase epidemiology in Portugal and tracing the trajectory from initial isolated cases to contemporary reports, this review highlights key factors driving antibiotic resistance, such as antimicrobial use and healthcare practices, and underscores the imperative for sustained vigilance, interdisciplinary collaboration, and innovative interventions to curb the escalating threat posed by antibiotic-resistant pathogens. Finally, it discusses potential alternatives and innovations aimed at tackling carbapenemase-mediated antibiotic resistance, including new therapies, enhanced surveillance, and public awareness campaigns.

Genomic and epidemiological insight of an outbreak of carbapenemase-producing Enterobacterales in a Portuguese hospital with the emergence of the new KPC-124

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) is an increasing problem in healthcare settings. This study aimed to identify the source of a CPE outbreak that occurred in 2022, in a tertiary hospital in the North of Portugal, to identify exposed patients, and to assess the risk of becoming CPE-positive following hospital admission.

METHODS

A multi-disciplinary investigation was conducted including descriptive, analytical, and molecular epidemiology, environmental screening, and assessment of infection control measures. Clinical and environmental isolates were analyzed using whole-genome sequencing and phylogenetic analysis. Additionally, a prospective observational cohort study was conducted to further investigate the risk factors associated with the emergence of new cases in cohorts of CPE-negative admitted patients.

RESULTS

We observed the presence of multispecies KPC-, IMP-, and/or NDM-producing isolates. Genetically indistinguishable clinical and environmental isolates were found on the same room/ward. The ST45 KPC-3-producing Klebsiella pneumoniae clone was the responsible for the outbreak. During patients' treatment, we detected the emergence of resistance to ceftazidime-avibactam, associated with mutations in the blaKPC-3 gene (blaKPC-46, blaKPC-66 and blaKPC-124, the last variant never previously reported), suggesting a vertical evolutionary trajectory. Patients aged ≥ 75 years, hygiene/feeding-care dependent, and/or subjected to secretion aspiration were risk factors for CPE colonization after hospital admission. Additionally, cases with previous admission to the emergency department suggest that CPE dissemination may occur not only during hospitalization but also in the emergency department.

CONCLUSION

Overall, the study highlights that selection pressure with antibiotics, like ceftazidime-avibactam, is a contributing factor to the emergence of new β-lactamase variants and antibiotic resistance. It also shows that the hospital environment can be a significant source of CPE transmission, and that routine use of infection control measures and real-time molecular epidemiology investigations are essential to ensure the long-term termination of CPE outbreaks and prevent future resurgences.

Bloodstream Infection in the Intensive Care Unit: Evolving Epidemiology and Microbiology

Bloodstream infections (BSIs) arising in the intensive care unit (ICUs) present a significant challenge and we completed a narrative review of the emerging literature on this issue. Multiple reports document that these infections are associated with substantial morbidity and mortality. Also, they can be caused by a variety of pathogens. Generally classified as either community or hospital in onset, or as either primary or secondary in origin, the microbiology of ICU BSIs varies across the globe. Gram-positive pathogens predominate in certain regions such as the United States while Gram-negative organisms occur more frequently in Europe, Asia, and Latin America. The incidence of ICU BSIs climbed during the recent pandemic. BSIs complicating the care of persons suffering from Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection significantly heighten the risk for death compared to patients who develop ICU BSIs but who are not infected with SARS-CoV-2. Furthermore, rates of antimicrobial resistance are generally increasing in ICU BSIs. This fact complicates attempts to ensure that the patient receives initially appropriate antimicrobial therapy and is of particular concern in Methicillin-resistant Staphylococcus aureus, Carbapenem-resistant Enterobacterales, and Acinetobacter baumannii. Fortunately, with respect to clinical application, preventive measures exist, and recent analyses suggest that increased collaboration between infectious disease specialists and intensivists can improve patient outcomes.

Prevalence of carbapenemase-producing Enterobacteriaceae from human clinical samples in Ethiopia: a systematic review and meta-analysis

INTRODUCTION

Carbapenemase-producing Enterobacteriaceae are by far the most public health and urgent clinical problems with antibiotic resistance. They cause longer hospital stays, more expensive medical care, and greater mortality rates. This systematic review and meta-analysis aimed to indicate the prevalence of carbapenemase-producing Enterobacteriaceae in Ethiopia.

METHODS

This systematic review and meta-analysis was conducted based on Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Electronic databases like PubMed, Google Scholar, CINAHL, Wiley Online Library, African Journal Online, Science Direct, Embase, ResearchGate, Scopus, and the Web of Sciences were used to find relevant articles. In addition, the Joanna Briggs Institute quality appraisal tool was used to assess the quality of the included studies. Stata 14.0 was used for statistical analysis. Heterogeneity was assessed by using Cochran's Q test and I² statistics. In addition, publication bias was assessed using a funnel plot and Egger's test. A random effect model was used to estimate the pooled prevalence. Sub-group and sensitivity analysis were also done.

RESULTS

The overall pooled prevalence of carbapenemase-producing Enterobacteriaceae in Ethiopia was 5.44% (95% CI 3.97, 6.92). The prevalence was highest [6.45% (95% CI 3.88, 9.02)] in Central Ethiopia, and lowest [(1.65% (95% CI 0.66, 2.65)] in the Southern Nations and Nationalities People Region. In terms of publication year, 2017-2018 had the highest pooled prevalence [17.44 (95% CI 8.56, 26.32)] and 2015-2016 had the lowest [2.24% (95% CI 0.87, 3.60)].

CONCLUSION

This systematic review and meta-analysis showed a high prevalence of carbapenemase-producing Enterobacteriaceae. So, to alter the routine use of antibiotics, regular drug susceptibility testing, strengthening the infection prevention approach, and additional national surveillance on the profile of carbapenem resistance and their determining genes among Enterobacteriaceae clinical isolates are required.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (2022: CRD42022340181).

Imipenem-Relebactam Susceptibility in Enterobacterales Isolates Recovered from ICU Patients from Spain and Portugal (SUPERIOR and STEP Studies)

Imipenem-relebactam is a novel β-lactam-β-lactamase inhibitor combination. We evaluated the in vitro activity of imipenem-relebactam and comparators against Enterobacterales clinical isolates recovered in 8 Spanish and 11 Portuguese intensive care units (ICUs) (SUPERIOR, 2016-2017; STEP, 2017-2018). Overall, 747 Enterobacterales isolates (378 Escherichia coli, 252 Klebsiella spp., 64 Enterobacter spp., and 53 other species) were prospectively collected from ICU patients with complicated intraabdominal (cIAI), complicated urinary tract (cUTI), and lower respiratory tract (LRTI) infections. MICs were determined (ISO-broth microdilution), and whole-genome sequencing (WGS) was performed in a subset of isolates displaying susceptible and resistant imipenem-relebactam MICs. Imipenem-relebactam (98.7% susceptible) showed similar activity to ceftazidime-avibactam (99.5% susceptible) and higher than ceftolozane-tazobactam (86.9% susceptible). Imipenem-relebactam was inactive against 1.3% (10/747) isolates, all of them due to carbapenemase production (9 K. pneumoniae and 1 E. cloacae). Imipenem-relebactam was active against 100% of extended-spectrum β-lactamase (ESBL)-E. coli and ESBL-Klebsiella spp. isolates and 80.4% of carbapenemase-Klebsiella spp. producers. Carbapenemase genes were confirmed by WGS in 41 Klebsiella spp.: OXA-48 (20/41), KPC-3 (14/41), OXA-181 (4/41), NDM-1 (1/41), OXA-48 + VIM-2 (1/41), and KPC-3 + VIM-2 (1/41). In Klebsiella spp. isolates, relebactam restored imipenem susceptibility in all KPC-3 producers, and resistant isolates (7/41) were mostly OXA-48 + CTX-M-15-K. pneumoniae high-risk clones (7/9). Intercountry differences were detected as follows: OXA-48 (17/21) was dominant in Spain, unlike KPC-3 (14/15) in Portugal. Imipenem-relebactam was 100% active against CTX-M-15-ST131-H30Rx-E. coli high-risk clone, predominant in both countries. Our results depict the potential role of imipenem-relebactam in ICU patients with cIAIs, cUTIs, and LRTIs due to wild-type ESBL- and carbapenemase-producing Enterobacterales, particularly KPC producers. IMPORTANCE We comparatively evaluate the in vitro activity of a drug combination consisting of a carbapenem (imipenem) and a novel inhibitor of beta-lactamases (relebactam), a mechanism that destroys beta-lactam antibiotics. We assess the activity against a collection of Enterobacterales clinical isolates recovered from difficult-to-treat infections in patients admitted to different intensive care units in Portugal and Spain. Imipenem-relebactam shows excellent activity in avoiding common resistance mechanisms in this setting, such as extended-spectrum beta-lactamases and carbapenemases widely distributed, including KPCs. We show few resistant isolates (<2%). Molecular characterization by whole-genome sequencing shows that most of the resistant isolates produced specific carbapenemase, such as OXA-48 or metalo-betalactamases. Our study updates the activity of imipenem-relebactam in light of current epidemiology in a hospital setting in which the use of this combination is needed due to the presence of infections due to multidrug-resistant isolates.

Genomic Epidemiology of Carbapenemase-Producing and Colistin-Resistant Enterobacteriaceae among Sepsis Patients in Ethiopia: a Whole-Genome Analysis

Sepsis due to carbapenemase-producing and colistin-resistant Enterobacteriaceae is a global health threat. A multicenter study was conducted between October 2019 and September 2020 at four hospitals located in different parts of Ethiopia. From a total of 1,416 sepsis patients, blood culture was performed. Enterobacteriaceae were confirmed using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Carbapenem and colistin susceptibility testing was performed using disk diffusion, broth microdilution, and Etest strip. Enterobacteriaceae isolates (n = 301) were subjected to whole-genome sequencing using Illumina HiSeq 2500. SPAdes version 3.9 was used for genome assembly. Carbapenem and colistin resistance genes, chromosomal point mutations, sequence types, and plasmid replicons were identified using tools at the Center for Genomic Epidemiology. Phylogeny structure was constructed using CSI Phylogeny 1.4. Visualization of trees and metadata was done using iTOL v6.5.2. Among 301 Enterobacteriaceae, 22 Klebsiella pneumoniae, 2 Klebsiella variicola, and 3 Enterobacter cloacae isolates showed reduced susceptibility to meropenem (7% of tested isolates). bla_NDM-1, bla_NDM-5, and bla_OXA-181 were variants of carbapenemase genes detected. Co-occurrence of bla_NDM-5 and bla_OXA-181 was detected with 4 K. pneumoniae strains. K. pneumoniae and K. variicola showed chromosomal alterations of ompK36 and ompk37. Plasmid incompatibility (Inc) groups Col, IncC, IncHI, IncF, IncFII, IncR, and IncX3 were identified among carbapenem-resistant K. pneumoniae and E. cloacae isolates. Two mcr-9 genes were detected from Salmonella species and K. pneumoniae. The dissemination of carbapenemase-producing Enterobacteriaceae in all hospitals is worrying. Multiple carbapenemase genes were detected, with bla_NDM variants the most frequent. The occurrence of colistin-resistant Enterobacteriaceae among sepsis patients is critical. Implementation of effective antimicrobial stewardship is urgently needed.

Aztreonam-avibactam may not replace ceftazidime/avibactam: the case of KPC-21 carbapenemase and penicillin-binding protein 3 with four extra amino acids

Aztreonam/avibactam is a promising antimicrobial combination with additional coverage for metallo-β-lactamases compared with ceftazidime/avibactam. A carbapenem-resistant bla_KPC-2-carrying Escherichia coli clinical isolate had four extra amino acids in penicillin-binding protein 3 (PBP3), which has been known to mediate reduced susceptibility to aztreonam/avibactam. This prompted us to investigate whether the strain could develop resistance to aztreonam/avibactam after exposure to the combination. A mutant with high-level resistance to aztreonam/avibactam [minimum inhibitory concentration (MIC), 512/4 mg/L] was obtained after 5-day exposure to 0.5 × MIC but it remained susceptible to ceftazidime/avibactam (MIC, 4/4 mg/L). The mutant had a single nucleotide polymorphism (SNP) in bla_KPC-2 to encode KPC-21 with a Trp105Arg amino acid substitution. By cloning into E. coli BL21, bla_KPC-21 could mediate reduced susceptibility to aztreonam/avibactam (MIC, from ≤0.03/4 to 1/4 mg/L), which was still below the breakpoint to define resistance. In contrast, when bla_KPC-21 was cloned in E. coli 035125ΔpCMY42 with four extra amino acids in PBP3, which was generated in our previous work, the strain exhibited high-level resistance to aztreonam/avibactam (MIC, 256/4 mg/L). The above findings highlight that although aztreonam/avibactam has a broader spectrum than ceftazidime/avibactam, strains may develop resistance to the former combination but remain susceptible to the latter. The discrepancy is due to mutation of KPC-2 to KPC-21 in combination with the insertion of four extra amino acids in PBP3.

KPC-3-, GES-5-, and VIM-1-Producing Enterobacterales Isolated from Urban Ponds

Carbapenems are antibiotics of pivotal importance in human medicine, the efficacy of which is threatened by the increasing prevalence of carbapenem-resistant Enterobacterales (CRE). Urban ponds may be reservoirs of CRE, although this hypothesis has been poorly explored. We assessed the proportion of CRE in urban ponds over a one-year period and retrieved 23 isolates. These were submitted to BOX-PCR, PFGE, 16S rDNA sequencing, antibiotic susceptibility tests, detection of carbapenemase-encoding genes, and conjugation assays. Isolates were affiliated with Klebsiella (n = 1), Raoultella (n = 11), Citrobacter (n = 8), and Enterobacter (n = 3). Carbapenemase-encoding genes were detected in 21 isolates: bla_KPC (n = 20), bla_GES-5 (n = 6), and bla_VIM (n = 1), with 7 isolates carrying two carbapenemase genes. Clonal isolates were collected from different ponds and in different campaigns. Citrobacter F6, Raoultella N9, and Enterobacter N10 were predicted as pathogens from whole-genome sequence analysis, which also revealed the presence of several resistance genes and mobile genetic elements. We found that bla_KPC-3 was located on Tn4401b (Citrobacter F6 and Enterobacter N10) or Tn4401d (Raoultella N9). The former was part of an IncFIA-FII pBK30683-like plasmid. In addition, bla_GES-5 was in a class 3 integron, either chromosomal (Raoultella N9) or plasmidic (Enterobacter N10). Our findings confirmed the role of urban ponds as reservoirs and dispersal sites for CRE.

Occurrence and distribution of Carbapenem-resistant Enterobacterales and carbapenemase genes along a highly polluted hydrographic basin

We determined the distribution and temporal variation of Carbapenem Resistant Enterobacterales (CRE), carbapenemase-encoding genes and other antibiotic resistance genes (ARGs) in a highly polluted river (Lis River; Portugal), also assessing the potential influence of water quality to this distribution. Water samples were collected in two sampling campaigns performed one year apart (2018/2019) from fifteen sites and water quality was analyzed. CRE were isolated and characterized. The abundance of four ARGs (bla_NDM, bla_KPC, tetA, bla_CTX-M), two Microbial Source Tracking (MST) indicators (HF183 and Pig-2-Bac) and the class 1 integrase gene (IntI1) was measured by qPCR. RESULTS: confirmed the poor quality of the Lis River water, particularly in sites near pig farms. A collection of 23 CRE was obtained: Klebsiella (n = 19), Enterobacter (n = 2) and Raoultella (n = 2). PFGE analysis revealed a clonal relationship between isolates obtained in different sampling years and sites. All CRE isolates exhibited multidrug resistance profiles. Klebsiella and Raoultella isolates carried bla_KPC while Enterobacter harbored bla_NDM. Conjugation experiments were successful for only four Klebsiella isolates. All ARGs were detected by qPCR on both sampling campaigns. An increase in ARGs and IntI1 abundances was detected in sites located downstream of wastewater treatment plants. Strong correlations were observed between bla_CTX-M, IntI1 and the human-pollution marker HF183, and also between tetA and the pig-pollution marker Pig-2-bac, suggesting that both human- and animal-derived pollution in the Lis River are a potential source of ARGs. Plus, water quality parameters related to eutrophication and land use were significantly correlated with ARGs abundances. Our findings demonstrated that the Lis River encloses high levels of antibiotic resistant bacteria and ARGs, including CRE and carbapenemase-encoding genes. Overall, this study provides a better understanding on the impacts of water pollution resulting from human and animal activities on the resistome of natural aquatic systems.

Beyond the ABCs—Discovery of Three New Plasmid Types in Rhodobacterales (RepQ, RepY, RepW)

Copiotrophic marine bacteria of the Roseobacter group (Rhodobacterales, Alphaproteobacteria) are characterized by a multipartite genome organization. We sequenced the genomes of Sulfitobacter indolifex DSM 14862^T and four related plasmid-rich isolates in order to investigate the composition, distribution, and evolution of their extrachromosomal replicons (ECRs). A combination of long-read PacBio and short-read Illumina sequencing was required to establish complete closed genomes that comprised up to twelve ECRs. The ECRs were differentiated in stably evolving chromids and genuine plasmids. Among the chromids, a diagnostic RepABC-8 replicon was detected in four Sulfitobacter species that likely reflects an evolutionary innovation that originated in their common ancestor. Classification of the ECRs showed that the most abundant plasmid system is RepABC, followed by RepA, DnaA-like, and RepB. However, the strains also contained three novel plasmid types that were designated RepQ, RepY, and RepW. We confirmed the functionality of their replicases, investigated the genetic inventory of the mostly cryptic plasmids, and retraced their evolutionary origin. Remarkably, the RepY plasmid of S. pontiacus DSM 110277 is the first high copy-number plasmid discovered in Rhodobacterales.

Prevalence and Molecular Characterization of Extended Spectrum β-Lactamase and Carbapenemase-Producing Enterobacteriaceae Isolates from Bloodstream Infection Suspected Patients in Addis Ababa, Ethiopia

Background

Production of Extended spectrum beta-lactamase (ESBL) and Carbapenemase is the most common strategy for drug resistance in clinical isolates of Enterobacteriaceae. This study was conducted to determine the magnitude of ESBL and Carbapenemase production (CPE) among clinical isolates of Enterobacteriaceae causing bloodstream infections (BSI) in Ethiopia.

Methods

A cross-sectional study was performed from September 2018 to January 2019 in Ethiopia. A total of 2397 BSI suspected patients were enrolled and blood culture was performed using a BacT/Alert instrument in combination with conventional methods for identification. After antimicrobial susceptibility test, phenotypic confirmation of ESBLs was done by combined disc-diffusion. Meanwhile carbapenemase production was done by modified carbapenem inactivation method. Multiplex PCR was conducted to detect the presence of bla_CTX-M,bla_SHV,bla_TEM, bla_KPC and bla_NDM genes.

Results

A total of 104 (4.3%) Enterobacteriaceae were isolated from 2397 BSI suspected patients. Klebsiella pneumoniae (55/104, 52%) was the predominant isolate followed by E. coli, (19.2%, 20/104) and K.oxytoca (17.3%, 18/104). ESBL and carbapenemase production were observed from 70 (67.3%, 57.4 −76.2% at 95% CI) and 8 (7.7%, 3.4–14.6% at 95% CI) isolates respectively. The highest frequency of ESBL and carbapenemase production was observed in K. pneumoniae 78.2% (43/55) and 9.1% (5/55), respectively. All the 70 isolates confirmed as ESBL producers harbored at least one of the ESBL genes and the majority of them carried multiple beta-lactamase genes (84.3%), where bla_CTX-M, type was the most predominant (67.3%). Similarly, the entire eight isolates positive for carbapenemase carried bla_NDM but none of them carried bla_KPC.

Conclusion

In our study, the rate of ESBL production among BSI-causing Enterobacteriaceae was alarming and most of the isolates carried multiple types of ESBL genes. A significant magnitude of CPE isolates causing BSI was recorded.

Intra- and Extra-Hospital Dissemination of IMP-22-Producing Klebsiella pneumoniae in Northern Portugal: The Breach of the Hospital Frontier Toward the Community

The emergence of infections (and colonization) with Enterobacteriaceae-producing carbapenemases is a threatening public health problem. In the last decades, we watched an isolated case becoming a brutal outbreak, a sporadic description becoming an endemic problem. The present study aims to highlight the dissemination of IMP-22-producing Klebsiella pneumoniae in the North of Portugal, through the phenotypic and genotypic characterization of isolates collected from hospitalized patients (n=5) and out-patients of the emergency ward of the same acute care hospital (n=2), and isolates responsible for the intestinal colonization of residents in a Long-Term Care Facility (n=4). Pulsed-field gel electrophoresis (PFGE) results, associated with conjugation experiments pointed to a pattern of both vertical and horizontal dissemination. Overall, and complementing other studies that give relevance to IMP-22-producing K. pneumoniae in the clinical settings, here we show for the first time the public health threatening breach of the hospital frontier of this resistance threat, toward the community.

Environmental and Pathogenic Carbapenem Resistant Bacteria Isolated from a Wastewater Treatment Plant Harbour Distinct Antibiotic Resistance Mechanisms

Wastewater treatment plants are important reservoirs and sources for the dissemination of antibiotic resistance into the environment. Here, two different groups of carbapenem resistant bacteria-the potentially environmental and the potentially pathogenic-were isolated from both the wastewater influent and discharged effluent of a full-scale wastewater treatment plant and characterized by whole genome sequencing and antibiotic susceptibility testing. Among the potentially environmental isolates, there was no detection of any acquired antibiotic resistance genes, which supports the idea that their resistance mechanisms are mainly intrinsic. On the contrary, the potentially pathogenic isolates presented a broad diversity of acquired antibiotic resistance genes towards different antibiotic classes, especially β-lactams, aminoglycosides, and fluoroquinolones. All these bacteria showed multiple β-lactamase-encoding genes, some with carbapenemase activity, such as the bla_KPC-type genes found in the Enterobacteriaceae isolates. The antibiotic susceptibility testing assays performed on these isolates also revealed that all had a multi-resistance phenotype, which indicates that the acquired resistance is their major antibiotic resistance mechanism. In conclusion, the two bacterial groups have distinct resistance mechanisms, which suggest that the antibiotic resistance in the environment can be a more complex problematic than that generally assumed.

Multidrug-resistant Klebsiella pneumoniae harboring extended spectrum β-lactamase encoding genes isolated from human septicemias

Klebsiella pneumoniae is a major pathogen implicated in nosocomial infections. Extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae isolates are a public health concern. We aim to characterize the type of β-lactamases and the associated resistance mechanisms in ESBL-producing K. pneumoniae isolates obtained from blood cultures in a Portuguese hospital, as well as to determine the circulating clones. Twenty-two cefotaxime/ceftazidime-resistant (CTX/CAZ^R) K. pneumoniae isolates were included in the study. Identification was performed by MALDI-TOF MS and the antimicrobial susceptibility testing by disk-diffusion. The screening test for ESBL-production was performed and ESBL-producer isolates were further characterized. The presence of different beta-lactamase genes (bla_CTX-M, bla_SHV, bla_TEM, bla_KPC, bla_NDM,bla_VIM,bla_OXA-48,bla_CMY-2, bla_DHA-1,bla_FOX,bla_MOX, and bla_ACC) was analyzed by PCR/sequencing in ESBL-producer isolates, as well as the presence of other resistance genes (aac(6’)-Ib-cr, tetA/B, dfrA, qnrA/B/S, sul1/2/3) or integron-related genes (int1/2/3). Multilocus-sequence-typing (MLST) was performed for selected isolates. ESBL activity was detected in 12 of the 22 CTX/CAZ^RK. pneumoniae isolates and 11 of them carried the bla_CTX-M-15 gene (together with bla_TEM)_, and the remaining isolate carried the bla_SHV-106 gene. All the bla_CTX-M-15 harboring isolates also contained a bla_SHV gene (bla_SHV-1, bla_SHV-11 or bla_SHV-27 variants). Both bla_SHV-27 and bla_SHV-106 genes correspond to ESBL-variants. Two of the CTX-M-15 producing isolates carried a carbapenemase gene (bla_KPC2/3 and bla_OXA-48) and showed imipenem resistance. The majority of the ESBL-producing isolates carried the int1 gene, as well as sulphonamide-resistance genes (sul2 and/or sul3); the tetA gene was detected in all eight tetracycline-resistant isolates. Three different genetic lineages were found in selected isolates: ST348 (one CTX-M-15/TEM/SHV-27/KPC-2/3-producer isolate), ST11 (two CTX-M-15/TEM/SHV-1- and CTX-M-15-TEM-SHV-11-OXA-48-producer isolates) and ST15 (one SHV-106/TEM-producer isolate). ESBL enzymes of CTX-M-15 or SHV-type are detected among blood K. pneumoniae isolates, in some cases in association with carbapenemases of KPC or OXA-48 type.

Antimicrobial Resistance Genes and Diversity of Clones among ESBL- and Acquired AmpC-Producing Escherichia coli Isolated from Fecal Samples of Healthy and Sick Cats in Portugal

The aim of the study was to analyze the mechanisms of resistance in extended-spectrum beta-lactamase (ESBL)- and acquired AmpC (qAmpC)-producing Escherichia coli isolates from healthy and sick cats in Portugal. A total of 141 rectal swabs recovered from 98 sick and 43 healthy cats were processed for cefotaxime-resistant (CTX^R) E. coli recovery (in MacConkey agar supplemented with 2 µg/mL cefotaxime). The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) method was used for E. coli identification and antimicrobial susceptibility was performed by a disk diffusion test. The presence of resistance/virulence genes was tested by PCR sequencing. The phylogenetic typing and multilocus sequence typing (MLST) were determined by specific PCR sequencing. CTX^RE. coli isolates were detected in seven sick and six healthy cats (7.1% and 13.9%, respectively). Based on the synergy tests, 11 of 13 CTX^RE. coli isolates (one/sample) were ESBL-producers (ESBL total rate: 7.8%) carrying the following ESBL genes: bla_CTX-M-1 (n = 3), bla_CTX-M-15 (n = 3), bla_CTX-M-55 (n = 2), bla_CTX-M-27 (n = 2) and bla_CTX-M-9 (n = 1). Six different sequence types were identified among ESBL-producers (sequence type/associated ESBLs): ST847/CTX-M-9, CTX-M-27, CTX-M-1; ST10/CTX-M-15, CTX-M-27; ST6448/CTX-M-15, CTX-M-55; ST429/CTX-M-15; ST101/CTX-M-1 and ST40/CTX-M-1. Three of the CTX^R isolates were CMY-2-producers (qAmpC rate: 2.1%); two of them were ESBL-positive and one ESBL-negative. These isolates were typed as ST429 and ST6448 and were obtained in healthy or sick cats. The phylogenetic groups A/B1/D/clade 1 were detected among ESBL- and qAmpC-producing isolates. Cats are carriers of qAmpC (CMY-2)- and ESBL-producing E. coli isolates (mostly of variants of CTX-M group 1) of diverse clonal lineages, which might represent a public health problem due to the proximity of cats with humans regarding a One Health perspective.

Multiplex Real-Time PCR Assay for Six Major Carbapenemase Genes

The global dissemination of carbapenemase-producing Enterobacteriaceae (CPE) is a major concern in public health. Due to the existence of the diversity of carbapenemases, development of an easily available, cost-effective multiplex detection assay for CPE is required worldwide. Using clinically available and reliable equipment, COBAS^® z480 (Roche Diagnostics K.K., Tokyo, Japan), we developed a multiplex real-time PCR assay for the detection of two combinations of carbapenemases; first, bla_NDM, bla_KPC, and bla_IMP (Set 1), and second, bla_GES, bla_OXA-48, and bla_VIM (Set 2). We constructed standard curves for each carbapenemase gene using serial dilutions of DNA standards, then applied reference or clinical isolates with each carbapenemase gene to this assay. The multiplex assay showed satisfactory accuracy to detect CPE genes, with the correlation coefficients of greater than 0.99 for all genotypes. The assay appropriately differentiated the reference or clinical strains harboring each carbapenemase gene without cross reactivity. Lastly, the assay successfully detected multiple genes without false-positive reactions by applying six clinical isolates carrying both NDM and OXA-48-like carbapenemase genes. Major advantages of our assay include multiplicity, simple operation, robustness, and speed (1 h). We believe that the multiplex assay potentially contributes to early diagnosis of CPE with a diverse genetic background.

Confronting Ceftolozane-Tazobactam Susceptibility in Multidrug-Resistant Enterobacterales Isolates and Whole-Genome Sequencing Results (STEP Study)

Ceftolozane-tazobactam (C/T) is frequently used for infections caused by multidrug-resistant (MDR)-Enterobacterales isolates. Whole-genome sequencing (WGS, Illumina-Hiseq 4000/NovaSeq 6000, OGC, UK) was used to study the population structure, the resistome and the virulome of C/T-susceptible and -resistant MDR Escherichia spp. (n=30) and Klebsiella spp. (n=78) isolates, recovered from lower respiratory, intra-abdominal and urinary tract infections of ICU patients from 11 Portuguese Hospitals (STEP study, 2017-2018). Minimum inhibitory concentrations (MICs) were determined (ISO-broth microdilution, breakpoints EUCAST-2020). In Escherichia spp., a weak concordance between the phenotypic and the WGS method (P=0.051) was observed in the carbapenemase detection (3/30) [bla_VIM-2 (2/3), bla_KPC-3 (1/3)]; VIM-2-Escherichia coli isolates were C/T-susceptible and only the KPC-3-Escherichia marmotae producer showed C/T-resistance. Overall, CTX-M-15-E. coli-ST131-O25:H4-H30-Rx (11/30) was the most frequent subclone, followed by CTX-M-27-E. coli-ST131-O25:H4-H30 (4/4). Moreover, a wide resistome and virulome were detected in all E. coli isolates. Among Klebsiella spp. isolates [K. pneumoniae (67/78), K. aerogenes (7/78), K. oxytoca (2/78), K. variicola (2/78)], concordance (P<0.001) was observed between the phenotypic and the genomic carbapenemase detection (21/78) [bla_KPC-3 (14/21), bla_OXA-48 (3/21), bla_OXA-181 (3/21)]. A high correlation between C/T-resistance and carbapenemase detection was established (P<0.05). Overall, a high clonal diversity was observed, mainly in KPC-3-producing K. pneumoniae isolates. An extensive resistome was detected in Klebsiella spp. isolates, whereas virulence determinants were mostly identified in carbapenemase producers (P<0.001). WGS is a powerful tool for typing characterization and microbiological study of MDR-Enterobacterales pathogens. Furthermore, carbapenemase genes are associated with C/T-resistance in Klebsiella spp., but other mechanisms might also be involved.

Multiplicity of Carbapenemase-Producers Three Years after a KPC-3-Producing K. pneumoniae ST147-K64 Hospital Outbreak

Carbapenem resistance rates increased exponentially between 2014 and 2017 in Portugal (~80%), especially in Klebsiella pneumoniae. We characterized the population of carbapanemase-producing Enterobacterales (CPE) infecting or colonizing hospitalized patients (2017-2018) in a central hospital from northern Portugal, where KPC-3-producing K. pneumoniae capsular type K64 has caused an initial outbreak. We gathered phenotypic (susceptibility data), molecular (population structure, carbapenemase, capsular type) and biochemical (FT-IR) data, together with patients' clinical and epidemiological information. A high diversity of Enterobacterales species, clones (including E. coli ST131) and carbapenemases (mainly KPC-3 but also OXA-48 and VIM) was identified three years after the onset of carbapenemases spread in the hospital studied. ST147-K64 K. pneumoniae, the initial outbreak clone, is still predominant though other high-risk clones have emerged (e.g., ST307, ST392, ST22), some of them with pandrug resistance profiles. Rectal carriage, previous hospitalization or antibiotherapy were presumptively identified as risk factors for subsequent infection. In addition, our previously described Fourier Transform infrared (FT-IR) spectroscopy method typed 94% of K. pneumoniae isolates with high accuracy (98%), and allowed to identify previously circulating clones. This work highlights an increasing diversity of CPE infecting or colonizing patients in Portugal, despite the infection control measures applied, and the need to improve the accuracy and speed of bacterial strain typing, a goal that can be met by simple and cost-effective FT-IR based typing.

Genetic Determinants of Resistance to Extended-Spectrum Cephalosporin and Fluoroquinolone in Escherichia coli Isolated from Diseased Pigs in the United States

Fluoroquinolones and cephalosporins are critically important antimicrobial classes for both human and veterinary medicine. We previously found a drastic increase in enrofloxacin resistance in clinical Escherichia coli isolates collected from diseased pigs from the United States over 10 years (2006 to 2016). However, the genetic determinants responsible for this increase have yet to be determined. The aim of the present study was to identify and characterize the genetic basis of resistance against fluoroquinolones (enrofloxacin) and extended-spectrum cephalosporins (ceftiofur) in swine E. coli isolates using whole-genome sequencing (WGS). bla_CMY-2 (carried by IncA/C2, IncI1, and IncI2 plasmids), bla_CTX-M (carried by IncF, IncHI2, and IncN plasmids), and bla_SHV-12 (carried by IncHI2 plasmids) genes were present in 87 (82.1%), 19 (17.9%), and 3 (2.83%) of the 106 ceftiofur-resistant isolates, respectively. Of the 110 enrofloxacin-resistant isolates, 90 (81.8%) had chromosomal mutations in gyrA, gyrB, parA, and parC genes. Plasmid-mediated quinolone resistance genes [qnrB77, qnrB2, qnrS1, qnrS2, and aac-(6)-lb′-cr] borne on ColE, IncQ2, IncN, IncF, and IncHI2 plasmids were present in 24 (21.8%) of the enrofloxacin-resistant isolates. Virulent IncF plasmids present in swine E. coli isolates were highly similar to epidemic plasmids identified globally. High-risk E. coli clones, such as ST744, ST457, ST131, ST69, ST10, ST73, ST410, ST12, ST127, ST167, ST58, ST88, ST617, ST23, etc., were also found in the U.S. swine population. Additionally, the colistin resistance gene (mcr-9) was present in several isolates. This study adds valuable information regarding resistance to critical antimicrobials with implications for both animal and human health.

IMPORTANCE Understanding the genetic mechanisms conferring resistance is critical to design informed control and preventive measures, particularly when involving critically important antimicrobial classes such as extended-spectrum cephalosporins and fluoroquinolones. The genetic determinants of extended-spectrum cephalosporin and fluoroquinolone resistance were highly diverse, with multiple plasmids, insertion sequences, and genes playing key roles in mediating resistance in swine Escherichia coli. Plasmids assembled in this study are known to be disseminated globally in both human and animal populations and environmental samples, and E. coli in pigs might be part of a global reservoir of key antimicrobial resistance (AMR) elements. Virulent plasmids found in this study have been shown to confer fitness advantages to pathogenic E. coli strains. The presence of international, high-risk zoonotic clones provides worrisome evidence that resistance in swine isolates may have indirect public health implications, and the swine population as a reservoir for these high-risk clones should be continuously monitored.

Molecular Characterization and Comparative Genomics of IncQ-3 Plasmids Conferring Resistance to Various Antibiotics Isolated from a Wastewater Treatment Plant in Warsaw (Poland)

As small, mobilizable replicons with a broad host range, IncQ plasmids are widely distributed among clinical and environmental bacteria. They carry antibiotic resistance genes, and it has been shown that they confer resistance to β-lactams, fluoroquinolones, aminoglycosides, trimethoprim, sulphonamides, and tetracycline. The previously proposed classification system divides the plasmid group into four subgroups, i.e., IncQ-1, IncQ-2, IncQ-3, and IncQ-4. The last two subgroups have been poorly described so far. The aim of this study was to analyze five newly identified IncQ-3 plasmids isolated from a wastewater treatment plant in Poland and to compare them with all known plasmids belonging to the IncQ-3 subgroup whose sequences were retrieved from the NCBI database. The complete nucleotide sequences of the novel plasmids were annotated and bioinformatic analyses were performed, including identification of core genes and auxiliary genetic load. Furthermore, functional experiments testing plasmid mobility were carried out. Phylogenetic analysis based on three core genes (repA, mobA/repB, and mobC) revealed the presence of three main clusters of IncQ-3 replicons. Apart from having a highly conserved core, the analyzed IncQ-3 plasmids were vectors of antibiotic resistance genes, including (I) the qnrS2 gene that encodes fluoroquinolone resistance and (II) β-lactam, trimethoprim, and aminoglycoside resistance genes within integron cassettes.

Carbapenemase-producing Enterobacteriaceae in a Portuguese hospital - a five-year retrospective study

BACKGROUND

Our hospital experienced an outbreak of OXA-48-producing Enterobacteriaceae, triggering this study. We aimed to describe the population with carbapenemase-producing Enterobacteriaceae (CPE) in our hospital from 2014 to 2018, the phenotypic and genotypic characteristics of isolates, and strategies to stop the outbreak.

METHODS

We performed a retrospective study, including every patient with CPE species in a clinical sample. Epidemiology, risk factors, treatment and outcomes were gathered from medical records.

RESULTS

A total 113 patients were included, ranging from 5 in 2015 to 83 in 2018. In 2018 the number of CPE went from 4 in May to 20 in July. With the implemented measures, propagation stopped. Implantable devices were present in 36% of patients and open wounds in 34%. Antibiotics had been prescribed to 71% of patients in the prior 30 days and most of the patients had been hospitalized for more than 5 days prior to sample collection or had a hospital stay in the previous year.Klebsiella pneumoniae was the most common species (87%). OXA-48 (62%) and Klebsiella pneumoniae-carbapenemase (KPC) (15%) were the most common carbapenemases, with OXA-48 being implicated in the 2018 outbreak. The case fatality rate at 30 days was 32%. Combination therapy resulted in less mortality.

CONCLUSIONS

While KPC is the most common carbapenemase in Europe and Portugal, we experienced an important OXA-48 outbreak. Surveillance should be in place as these isolates are probably spreading. Effective communication, multidisciplinary team work and proper infection control measures are some of the best strategies during outbreaks.

Epidemiology of Carbapenemase-Producing Klebsiella pneumoniae in a Hospital, Portugal

We aimed to provide updated epidemiologic data on carbapenem-resistant Klebsiella pneumoniae in Portugal by characterizing all isolates (N = 46) recovered during 2013–2018 in a 123-bed hospital in Lisbon. We identified bla_KPC-3 (n = 36), bla_OXA-181 (n = 9), and bla_GES-5 (n = 8) carbapenemase genes and observed co-occurrence of bla_KPC-3 and bla_GES-5 in 7 isolates. A single GES-5–producing isolate co-produced the extended-spectrum β-lactamase BEL-1; both corresponding genes were co-located on the same ColE1-like plasmid. The bla_OXA-181 gene was always located on an IncX3 plasmid, whereas bla_KPC-3 was carried on IncN, IncFII, IncFIB, and IncFIIA plasmid types. The 46 isolates were distributed into 13 pulsotypes and 9 sequence types. All isolates remained susceptible to ceftazidime/avibactam, but some exhibited reduced antimicrobial susceptibility (MIC = 3 mg/L).

Pathogenomics and Evolutionary Epidemiology of Multi-Drug Resistant Clinical Klebsiella pneumoniae Isolated from Pretoria, South Africa

Antibiotic-resistant Klebsiella pneumoniae is increasingly being implicated in invasive infections worldwide with high mortalities. Forty-two multidrug resistant (MDR) K. pneumoniae isolates were collected over a 4-month period. Antimicrobial susceptibility was determined using Microscan. The evolutionary epidemiology, resistome, virulome and mobilome of the isolates were characterised using whole-genome sequencing and bioinformatics analysis. All isolates contained the bla_CTX-M gene, whilst 41/42(97%) contained bla_TEM, 36/42(86%) contained bla_OXA and 35/42(83%) harboured bla_SHV genes. Other resistance genes found included bla_LEN, aac(6′)-lb-cr, qnrA, qnrB, qnrS, oqxAB, aad, aph, dfr, sul1, sul2, fosA, and cat genes. Fluoroquinolone and colistin resistance-conferring mutations in parC, gyrAB, pmrAB, phoPQ and kpnEF were identified. The bla_LEN gene, rarely described worldwide, was identified in four isolates. The isolates comprised diverse sequence types, the most common being ST152 in 7/42(17%) isolates; clone-specific O and K capsule types were identified. Diverse virulence genes that were not clone-specific were identified in all but one isolate. IncF, IncH and IncI plasmid replicons and two novel integrons were present. The bla_CTX-M-15 and bla_TEM-1 genes were bracketed by Tn3 transposons, ISEc9, a resolvase and IS91 insertion sequence. There were 20 gene cassettes in 14 different cassette arrays, with the dfrA and aadA gene cassettes being the most frequent. Phylogenetic analysis demonstrated that the isolates were evolutionarily associated with strains from both South Africa and abroad. These findings depict the rich resistome, mobilome and virulome repertoire in clinical K. pneumoniae strains, which are mainly transmitted by clonal, multiclonal and horizontal means in South Africa.

Transferable Mechanisms of Quinolone Resistance from 1998 Onward

While the description of resistance to quinolones is almost as old as these antimicrobial agents themselves, transferable mechanisms of quinolone resistance (TMQR) remained absent from the scenario for more than 36 years, appearing first as sporadic events and afterward as epidemics. In 1998, the first TMQR was soundly described, that is, QnrA. The presence of QnrA was almost anecdotal for years, but in the middle of the first decade of the 21st century, there was an explosion of TMQR descriptions, which definitively changed the epidemiology of quinolone resistance. Currently, 3 different clinically relevant mechanisms of quinolone resistance are encoded within mobile elements: (i) target protection, which is mediated by 7 different families of Qnr (QnrA, QnrB, QnrC, QnrD, QnrE, QnrS, and QnrVC), which overall account for more than 100 recognized alleles; (ii) antibiotic efflux, which is mediated by 2 main transferable efflux pumps (QepA and OqxAB), which together account for more than 30 alleles, and a series of other efflux pumps (e.g., QacBIII), which at present have been sporadically described; and (iii) antibiotic modification, which is mediated by the enzymes AAC(6')Ib-cr, from which different alleles have been claimed, as well as CrpP, a newly described phosphorylase.

Plasmid evolution in carbapenemase-producing Enterobacteriaceae: a review

Carbapenem-resistant Enterobacteriaceae (CRE) have been listed by the WHO as high-priority pathogens owing to their high association with mortalities and morbidities. Resistance to multiple β-lactams complicates effective clinical management of CRE infections. Using plasmid typing methods, a wide distribution of plasmid replicon groups has been reported in CREs around the world, including IncF, N, X, A/C, L/M, R, P, H, I, and W. We performed a literature search for English research papers, published between 2013 and 2018, reporting on plasmid-mediated carbapenem resistance. A rise in both carbapenemase types and associated plasmid replicon groups was seen, with China, Canada, and the United States recording a higher increase than other countries. bla_KPC was the most prevalent, except in Angola and the Czech Republic, where OXA-181 (n = 50, 88%) and OXA-48-like (n = 24, 44%) carbapenemases were most prevalent, respectively; bla_KPC-2/3 accounted for 70% (n = 956) of all reported carbapenemases. IncF plasmids were found to be responsible for disseminating different antibiotic resistance genes worldwide, accounting for almost 40% (n = 254) of plasmid-borne carbapenemases. bla_CTX-M , bla_TEM , bla_SHV , bla_OXA-1/9 , qnr, and aac-(6')-lb were mostly detected concurrently with carbapenemases. Most reported plasmids were conjugative but not present in multiple countries or species, suggesting limited interspecies and interboundary transmission of a common plasmid. A major limitation to effective characterization of plasmid evolution was the use of PCR-based instead of whole-plasmid sequencing-based plasmid typing.