Chromosome-Borne CTX-M-65 Extended-Spectrum ß-Lactamase-Producing Salmonella enterica Serovar Infantis, Taiwan.

A CTX-M-65‒producing Salmonella enterica serovar Infantis clone, probably originating in Latin America and initially reported in the United States, has emerged in Taiwan. Chicken meat is the most likely primary carrier. Four of the 9 drug resistance genes have integrated into the chromosome: blaCTX-M-65, tet(A), sul1, and aadA1.

Tn3-like structures co-harboring of blaCTX-M-65, blaTEM-1 and blaOXA-10 in the plasmids of two Escherichia coli ST1508 strains originating from dairy cattle in China.

The purpose of this study was to determine the level of horizontal transmission of the blaCTX-M-65 gene and the role of its associated mobile genetic elements (MGEs) in the bovine-derived Escherichia coli. After PCR identification, two plasmids carrying blaCTX-M-65 were successfully transferred to the recipient E. coli J53 Azr through conjugation assays and subsequently selected for Whole-Genome sequencing (WGS) analysis. The resistance profiles of these two positive strains and their transconjugants were also determined through antimicrobial susceptibility tests. Whole genome data were acquired using both the PacBio sequencing platform and the Illumina data platform. The annotated results were then submitted to the Genbank database for accession number recording. For comparison, the genetic environment of plasmids carrying the resistance gene blaCTX-M-65 was mapped using the Easyfig software. WGS analysis revealed Tn3-like composite transposons bearing blaCTX-M-65, blaTEM-1, and blaOXA-10 in the IncHI2-type plasmids of these two E. coli ST1508 strains. A phylogenetic tree was generated from all 48 assembled E. coli isolates blaCTX-M-65, blaTEM-1, and blaOXA-10 from the NCBI Pathogen Detection database with our two isolates, showing the relationships and the contribution of SNPs to the diversity between genetic samples. This study suggests that the transmissibility of blaCTX-M-65 on Tn3-like composite transposons contributes to an increased risk of its transmission in E. coli derived from dairy cattle.

Characterization of IncI1/ST71 and IncF18:A-:B1 multidrug-resistance plasmids from an avian Escherichia coli isolate.

To characterize IncI1 and IncF18:A-:B1 multidrug-resistance plasmids from an avian Escherichia coli isolate, antibiotic susceptibility testing, conjugation assays, transformation assays, S1-PFGE, and WGS analysis were performed. The 119,457-bp plasmid pEC014-1 with a multidrug-resistance region (MRR) containing four different segments interspersed with six IS26 elements, belonged to incompatibility group I1 and sequence type 71. The 154,516-bp plasmid pEC014-2 with two replicons, typed as FII-18 and FIB-1, carried 14 resistance determinants including blaTEM-1b, blaOXA-1, oqxAB, dfrA17, aac(6')-Ib-cr, sul1, sul2, tet(A), floR, catB3, hph(aph(4)-Ia), aacC4(aac(3)-IV), aadA5, arr-3, and a merEDACPTR loci in MRR, and additionally encoded three virulence loci: iroNEDCB, sitABCD, and iucABCD-iutA. Plasmid stability assays showed that pEC014-1 and pEC014-2 were stable in recipient E. coli C600 for at least 15 days of passage. Competition assays were carried out to evaluate the fitness impact of pEC014-2 carriage in vitro, revealing a decrease in host fitness. Growth kinetics showed that the growth rate for pEC014-1 or/and pEC014-2 bearing cells was significantly slower than that of the E. coli C600 host strain in the exponential stage (p < 0.01), with only cells carrying pEC014-1 sustaining rapid growth after 6 h of exponential growth. Our findings highlight the mosaic structures of epidemic plasmid IncI1/ST71 and F18:A-:B1 lineages and contribute to a better understanding of the evolution and dissemination of these multidrug resistance and virulence plasmids.

Abundance of colistin-resistant Escherichia coli harbouring mcr-1 and extended-spectrum ß-lactamase-producing E. coli co-harbouring blaCTX-M-55 or -65 with blaTEM isolates from chicken meat in Vietnam.

Although the spread of plasmid-mediated antibiotic-resistant bacteria is a public health concern, food contamination with plasmid-mediated antibiotic-resistant Escherichia coli in Vietnam has not been well investigated. This study aimed to describe the prevalence of colistin-resistant, carbapenem-resistant, and endemic blaCTX-M in extended-spectrum ß-lactamase (ESBL) producing E. coli isolates. Colistin and carbapenem-resistant ESBL-producing E. coli were isolated from chickens in Vietnam and Japan. Colistin-resistant and AmpC/ESBL-producing E. coli (52% and 93%, respectively) were detected in chickens from Vietnam, in comparison to 52.7%, AmpC/ESBL-producing E. coli found in chicken from Japan. Carbapenem-resistant E. coli has not been isolated in Vietnam and Japan. Genotyping revealed that colistin-resistant E. coli harboured mcr-1, and most of the AmpC/ESBL-related genes were blaCTX-M-55 and blaCTX-M-65 together with blaTEM in Vietnamese chickens and blaCMY-2 in Japanese chickens. Multi-drug resistance analysis showed that ESBL-producing E. coli isolates had greater resistance to quinolones, streptomycin, and chloramphenicol than colistin-resistant E. coli isolates from Vietnam, suggesting the selection of multiple antibiotic resistance genes in ESBL-producing E. coli. In conclusion, colistin-resistant E. coli was detected in approximately half of the chicken samples, the majority of which harboured mcr-1. The high prevalence of ESBL-producing E. coli has remained constant in the last 5 years. The predominant blaCTX-M in ESBL-producing E. coli was blaCTX-M-55 or blaCTX-M-65, with the coexistence of blaTEM in Vietnam. These results can be implemented in monitoring systems to overcome the development of antimicrobial resistance.

Antibiotic resistance of Salmonella strains from layer poultry farms in central Ecuador.

AIMS: This study evaluated the antimicrobial resistance of Salmonella enterica strains from layer poultry farms in central Ecuador isolated during 2017. This geographical area is responsible for around 60% of total domestic egg production, yet, as of 2019, no reports had been published on the phenotypic and genotypic antibiotic resistance patterns of Salmonella in the layer poultry farms of this area. METHODS AND RESULTS: Thirty-one isolates from layer poultry farms in central Ecuador obtained during 2017 were evaluated. The resistance profiles exhibited considerable differences in serovar and sample origin, grouping into nine clades by phenotype. S. Infantis strains were of the MDR phenotype in 94·4% of isolates. S. Typhimurium strains were of a reduced antimicrobial resistance phenotype and 50% showed resistance to one antimicrobial compound. One of the S. enterica nontyped strains had an MDR profile to 11 of the 20 antibiotics evaluated (eight groups). And the two remaining S. enterica nontyped strains showed resistance to two and three antibiotics respectively. The ESBL phenotype, which is resistant to clinically notable antibiotics such as ceftriaxone, ampicillin and cefepime, was observed only in S. Infantis (15/18). These strains harbour the emerging blaCTX-M-65 gene, and co-harbour tetA and sul1 resistance genes in four strains. Additional ß-lactamase genes, carbapenemase-producing genes (blaIMP, blaVIM , blaOXA48 , blaKPC , blaNDM ) and colistin-mobile resistance gene mcr-1 were not detected. CONCLUSIONS: The findings highlight the potential role of layer poultry farm environments in central Ecuador as reservoirs of MDR Salmonella strains. SIGNIFICANCE AND IMPACT OF THE STUDY: These results suggest the necessity of reinforcing biosecurity practices to reduce the probability of transmission of MDR Salmonella across the food chain.

Comparative analysis of multidrug resistance plasmids and genetic background of CTX-M-producing Escherichia coli recovered from captive wild animals.

Multiple interlinked factors are associated with the global resistome, whereas multidrug-resistant (MDR) pathogens have been related to increased mortality rates in humans and animals. CTX-M-type is the most prevalent extended-spectrum ß-lactamase (ESBL) among Enterobacteriaceae, which raises concern worldwide. Zoological gardens have a high density of animals that live very close to each other and to humans. Therefore, this study aimed to investigate through the whole-genome sequencing (WGS) MDR Escherichia coli lineages obtained from captivity wild animals in a zoo. Genetic background showed a wide resistome for antimicrobials (e.g., blaCTX-M-65, blaCTX-M-8, blaCMY-2, qnrB19), metals (e.g., pcoABCDERS, silABCEP, merACDEPRT), and antibacterial biocides (e.g., sugE, mdfA) among MDR CTX-M-producing E. coli belonging to CC155 and CC156. Mobilome analysis revealed several plasmids, and eight of them were completely characterized, which showed different backbone-encoding genes. Comparative analysis of plasmids blaCTX-M-65/IncHI2-ST3, blaCTX-M-8/IncI1-ST113, and IncQ1 showed a high identity among plasmids obtained from humans and animals worldwide distributed. Besides, several virulence genes, CRISPR, and prophage-related sequences were also detected. The occurrence of MDR E. coli belonging to CCs closely related to humans and food-producing animals and the high similarity among the plasmids from MDR E. coli carrying clinically significant antimicrobial resistance genes may indicate intercontinental dissemination of these lineages and plasmids. Therefore, these findings contribute to the monitoring of antimicrobial resistance and the human-animal-environment interface worldwide. Key Points • Wide resistome for antimicrobials, metals, and antibacterial biocides. • Multidrug resistance plasmids (blaCTX-M-65/IncHI2-ST3, blaCTX-M-8/IncI1-ST113). • Co-occurrence of plasmid-mediated resistance and virulence genes.

CTX-M-65 Extended-Spectrum ß-Lactamase-Producing Salmonella enterica Serotype Infantis, United States1.

Extended-spectrum ß-lactamases (ESBLs) confer resistance to clinically important third-generation cephalosporins, which are often used to treat invasive salmonellosis. In the United States, ESBLs are rarely found in Salmonella. However, in 2014, the US Food and Drug Administration found blaCTX-M-65 ESBL-producing Salmonella enterica serotype Infantis in retail chicken meat. The isolate had a rare pulsed-field gel electrophoresis pattern. To clarify the sources and potential effects on human health, we examined isolates with this pattern obtained from human surveillance and associated metadata. Using broth microdilution for antimicrobial susceptibility testing and whole-genome sequencing, we characterized the isolates. Of 34 isolates, 29 carried the blaCTX-M-65 gene with <9 additional resistance genes on 1 plasmid. Of 19 patients with travel information available, 12 (63%) reported recent travel to South America. Genetically, isolates from travelers, nontravelers, and retail chicken meat were similar. Expanded surveillance is needed to determine domestic sources and potentially prevent spread of this ESBL-containing plasmid.

Genomic characterisation of the population structure and antibiotic resistance of Salmonella enterica serovar Infantis in Chile, 2009-2022.

Background: Multidrug-resistant (MDR) Salmonella Infantis has disseminated worldwide, mainly linked to the consumption of poultry products. Evidence shows dissemination of this pathogen in Chile; however, studies are primarily limited to phenotypic data or involve few isolates. As human cases of Salmonella Infantis infections have substantially increased in recent years, this study aimed to characterise the genomic epidemiology and antimicrobial-resistance profiles of isolates obtained from different sources, aiming to inform effective surveillance and control measures. Methods: We sequenced 396 Salmonella Infantis genomes and analysed them with all publicly available genomes of this pathogen from Chile (440 genomes in total), representing isolates from environmental, food, animal, and human sources obtained from 2009 to 2022. Based on bioinformatic and phenotypic methods, we assessed the population structure, dissemination among different niches, and antimicrobial resistance (AMR) profiles of Salmonella Infantis in the country. Findings: The genomic and phylogenetic analyses showed that Salmonella Infantis from Chile comprised several clusters of highly related isolates dominated by sequence type 32. The HC20_343 cluster grouped an important proportion of all isolates. This was the only cluster associated with pESI-like megaplasmids, and up to 12 acquired AMR genes/mutations predicted to result in an MDR phenotype. Accordingly, antimicrobial-susceptibility testing revealed a strong concordance between the AMR genetic determinants and their matching phenotypic expression, indicating that a significant proportion of HC20_343 isolates produce extended-spectrum ß-lactamases and have intermediate fluoroquinolone resistance. HC20_343 Salmonella Infantis were spread among environmental, animal, food, and human niches, showing a close relationship between isolates from different years and sources, and a low intra-source genomic diversity. Interpretation: Our findings show a widespread dissemination of MDR Salmonella Infantis from the HC20_343 cluster in Chile. The high proportion of isolates with resistance to first-line antibiotics and the evidence of active transmission between the environment, animals, food, and humans highlight the urgency of improved surveillance and control measures in the country. As HC20_343 isolates predominate in the Americas, our results suggest a high prevalence of ESBL-producing Salmonella Infantis with intermediate fluoroquinolone resistance in the continent. Funding: Partially supported by the Food and Drug Administration (FDA) of the U.S. Department of Health and Human Services as part of an award, FDU001818, with 30% percent funded by FDA/HHS; and by Agencia de Investigación y Desarrollo de Chile (ANID) through FONDECYT de Postdoctorado Folio 3230796 and Folio 3210317, FONDECYT Regular Folio 1231082, and ANID-Millennium Science Initiative Program-ICN2021_044.

Prevalence of Antimicrobial Resistance and Clonal Relationship in ESBL/AmpC-Producing Proteus mirabilis Isolated from Meat Products and Community-Acquired Urinary Tract Infection (UTI-CA) in Southern Brazil.

The present study aimed to evaluate the prevalence of antimicrobial resistance and clonal relationships in Proteus mirabilis isolated from chicken meat, beef, pork, and community-acquired urinary tract infections (UTI-CA). Chicken meat isolates showed the highest multidrug resistance (MDR), followed by those from pork and UTI-CA, whereas beef had relatively few MDR strains. All sources had strains that carried blaCTX-M-65, whereas blaCTX-M-2 and blaCMY-2 were only detected in chicken meat and UTI-CA isolates. This indicates that chicken meat should be considered an important risk factor for the spread of P. mirabilis carrying ESBL and AmpC. Furthermore, ESBL/AmpC producing strains were resistant to a greater number of antimicrobials and possessed more resistance genes than non-producing strains. In addition, the antimicrobial resistance genes qnrD, aac(6')-Ib-cr, sul1, sul2, fosA3, cmlA, and floR were also found. Molecular typing showed a genetic similarity between chicken meat and UTI-CA isolates, including some strains with 100% similarity, indicating that chicken can be a source of P. mirabilis causing UTI-CA. It was concluded that meat, especially chicken meat, can be an important source of dissemination of multidrug-resistant P. mirabilis in the community.

IS26 mediated blaCTX-M-65 amplification in Escherichia coli increase the antibiotic resistance to cephalosporin in vivo.

OBJECTIVES: To characterize two Escherichia coli strains isolated from a patient pre- and post-treatment, using ß-lactams and ß-lactam/ß-lactamase inhibitor combinations (BLBLIs). METHODS: A combination of antibiotic susceptibility testing (AST) with whole genome sequencing using Illumina and Oxford Nanopore platforms. Long-read sequencing and reverse transcription-quantitative PCR were performed to determine the copy numbers and expression levels of antibiotic resistance genes (ARGs), respectively. Effect on fitness costs were assessed by growth rate determination. RESULTS: The strain obtained from the patient after the antibiotic treatment (XH989) exhibited higher resistance to cefepime, BLBLIs and quinolones compared with the pre-treatment strain (XH987). Sequencing revealed IS26-mediated duplications of a IS26-fosA3-blaCTX-M-65 plasmid-embedded element in strain XH989. Long-read sequencing (7.4 G data volume) indicated a variation in copy numbers of blaCTX-M-65 within one single culture of strain XH989. Increased copy numbers of the IS26-fosA3-blaCTX-M-65 element were correlated with higher CTX-M-65 expression level and did not impose fitness costs, while facilitating faster growth under high antibiotic concentrations. CONCLUSION: Our study is an example from the clinic how BLBLIs and ß-lactams exposure in vivo possibly promoted the amplification of an IS26-multiple drug resistance (MDR) region. The observation of a copy number variation seen with the blaCTX-M-65 gene in the plasmid of the post-treatment strain expands our knowledge of insertion sequence dynamics and evolution during treatment.

Emergence and Clonal Spread of CTX-M-65-Producing Escherichia coli From Retail Meat in Portugal.

The emergence and dissemination of resistance to third- and fourth-generation cephalosporins among Enterobacteriaceae from different sources impose a global public health threat. Here, we characterized by whole-genome sequencing four Escherichia coli strains harboring the bla CTX-M-65 gene identified among 49 isolates from beef and pork collected at retail. The genomic content was determined using the Center for Genomic Epidemiology web tools. Additionally, the prediction and reconstruction of plasmids were conducted, the genetic platform of the bla CTX-M-65 genes was investigated, and phylogenetic analysis was carried out using 17 other genomes with the same sequence type and harboring the bla CTX-M-65 gene. All strains harbored bla CTX-M-65, bla OXA-1, and bla TEM-1B, and one also carried the bla SHV-12 gene. Other resistance genes, namely, qnrS2, aac(6')-Ib-c, dfrA14, sul2, tetA, and mphA, were present in all the genomes; the mcr-1.1 gene was identified in the colistin-resistant strains. They belong to sequence type 2179, phylogenetic group B1, and serotype O9:H9 and carried plasmids IncI, IncFIC(FII), and IncFIB. All strains share an identical genetic environment with IS903 and ISEcp1 flanking the bla CTX-M-65 gene. It seems likely that the bla CTX-M-65 gene is located in the chromosome in all isolates based on deep in silico analysis. Our findings showed that the strains are clonally related and belong to two sub-lineages. This study reports the emergence of CTX-M-65-producing E. coli in Portugal in food products of animal origin. The chromosomal location of the bla CTX-M-65 gene may ensure a stable spread of resistance in the absence of selective pressure.

Integrated Surveillance for Antimicrobial Resistance in Salmonella From Clinical and Retail Meat Sources Reveals Genetically Related Isolates Harboring Quinolone- and Ceftriaxone-Resistant Determinants.

BACKGROUND: Antimicrobial resistance in foodborne pathogens, including nontyphoidal Salmonella (NTS), is a public health concern. Pennsylvania conducts integrated surveillance for antimicrobial resistance in NTS from human and animal sources. METHODS: During 2015-2017, clinical laboratories submitted 4478 NTS isolates from humans and 96 isolates were found in 2520 retail meat samples. One hundred nine clinical isolates that shared pulsed-field gel electrophoresis patterns with meat isolates and all strains from meat samples were tested for susceptibility to antimicrobial agents. Six clinical and 96 NTS isolates from meat sources (total 102) were analyzed by whole-genome sequencing (WGS). RESULTS: Twenty-eight (25.7%) of the 109 clinical NTS and 21 (21.9%) of strains from meat sources had resistance to ≥3 antimicrobial drug classes (multidrug resistance). Sixteen of the 102 (15.7%) isolates analyzed by WGS had resistance mechanisms that confer resistance to expanded-spectrum cephalosporins, such as ceftriaxone. We identified bla CTX-M-65 in 2 S. Infantis isolates from clinical and 3 S. Infantis isolates from meat sources. These 5 bla CTX-M-65-positive S. Infantis strains carried ≥5 additional resistance genes plus a D87Y mutation in gyrA that encodes fluoroquinolone resistance. WGS showed that isolates from patients and meat samples were within ≤10 and ≤5 alleles for S. Infantis and S. Reading, respectively. CONCLUSIONS: A significant proportion of NTS isolates from human and animal sources were multidrug resistant and 16% had genetic mechanisms that confer resistant to ceftriaxone. These results emphasize need for integrated surveillance in healthcare and agricultural settings.

Whole genome sequencing of Salmonella enterica serovar Saintpaul for elucidating the mechanisms of resistance to third generation cephalosporins.

An increase in the number of Salmonella enterica serovar Saintpaul observed in Singapore in 2015-2016 in humans was accompanied by increased resistance to third generation cephalosporins. We aimed to understand the genetic mechanisms contributing to this resistance. Whole genome sequencing using MiSeq was performed on 49 S. Saintpaul isolates collected between 2014-2016. Nanopore sequencing was also performed in an attempt to obtain a full genome of the plasmids. All but one S. Saintpaul isolates sequenced belonged to a single sequence type based on an in silico 7-gene multi-locus sequence typing scheme suggesting a clonal lineage. In total 27/49 were resistant to third generation cephalosporins as confirmed by the broth microdilution method; the resistance was due to the presence of either blaCTX-M-55 (n=23), blaCTX-M-27 (n=1) or blaCMY-2 (n=3) carried on a plasmid. Two isolates were also found to carry the mcr-1 gene on a different plasmid. Our study showed that all S. Saintpaul isolates resistant to third generation cephalosporins carried either blaCTX-M-55, blaCTX-M-27 or blaCMY-2 on a plasmid. Continuous monitoring of Salmonella serovars is warranted to track the potential spread of these plasmids.

A Novel bla CTX-M-65-Harboring IncHI2 Plasmid pE648CTX-M-65 Isolated from a Clinical Extensively-Drug-Resistant Escherichia coli ST648.

BACKGROUND: An ESBL, carbapenemase- and MCR-1-producing Escherichia coli ST648 strain was isolated from the urine sample of a patient in a Chinese tertiary hospital in 2016. METHODS: The strain was fully sequenced by GridION X5 platform of Oxford Nanopore Technology. RESULTS: The sequence analysis showed that the extended-spectrum ß-lactamases CTX-M-65 and OXA-1, the carbapenemase NDM-5, the MCR-1 were encoded, respectively, by three different resistance plasmids. The pE648CTX-M-65-carrying bla CTX-M-65 was a novel conjugative plasmid belonging to IncHI2 type; except for the bla CTX-M-65, it also carried resistance genes ble, floR, sul1, aph(4)-Ia, aac(3)-VI, aac(6')-II, bla OXA-1, catB, arr3 and tetA. Besides, an IncX4 plasmid pE648MCR-1-carrying mcr-1 and an IncX3 plasmid pE648NDM-5-carrying bla NDM-5 were also identified. CONCLUSION: The three transferable resistance plasmids coexisting in the E. coli ST648 isolate indicated the high risk to disseminate the extensively-drug-resistance among Enterobacteriaceae.

Draft genome sequence of a multidrug-resistant CTX-M-65-producing Escherichia coli ST156 colonizing a giant anteater (Myrmecophaga tridactyla) in a Zoo.

OBJECTIVES: This study aimed to report the draft genome sequence of a multidrug-resistant (MDR) Escherichia coli colonizing a giant anteater (Myrmecophaga tridactyla) in a Brazilian Zoo. METHODS: The genome was sequenced using the Illumina MiSeq Platform and de novo genome assembly was performed using SPAdes v. 3.9. The draft genome sequence was annotated using NCBI Prokaryotic Genome Annotation Pipeline. Antibiotic resistance genes, virulence genes, sequence type, serotype and plasmid incompatibility groups were identified using tools from the Center for Genomic Epidemiology. RESULTS: The genome presented 4970 coding sequences and a GC content of 50.2%. Several antimicrobial resistance genes associated with resistance to ß-lactams (blaTEM-1A and blaCTX-M-65), aminoglycosides [aph(6)-ld, aph(3″)-lb, aph(4)-la, aac(3)-lVa, aadA1 and aadA2], tetracyclines (tetB), sulphonamides (sul2 and sul3), trimethoprim (dfrA8 and dfrA12) and phenicols (floR and cmlA1) were identified. Moreover, mutations in quinolone resistance-determining regions (QRDR) were found. This E. coli isolate also presented virulence genes and belonged to serotype ONT:H25 and ST156 (CC156). CONCLUSION: This is the first report of a draft genome sequence of a CTX-M-65-producing E. coli ST156 obtained from a zoo animal, which can be used by genomic surveillance platforms, in order to track transmission dynamics of extended-spectrum ß-lactamase (ESBL)-producing E. coli at the human-animal interface.

Occurrence, genotypes and antimicrobial susceptibility of Salmonella collected from the broiler production chain within an integrated poultry company.

Salmonella is a common foodborne pathogen in the poultry production systems. Its presence in this food industry is determined by the fact that it can survive and pass throughout the different steps in the poultry production. In this study we aimed to study the occurrence, genotypes and antimicrobial resistance of Salmonella collected from the broiler production chain within an integrated poultry company. Three hundred fourteen samples were collected in the feeding plant, farms and the slaughterhouse. Samples were cultured for Salmonella isolation according to the ISO6579/Amd 1. Isolates were further typed by Kauffmann-White scheme and pulse field gel electrophoresis (PFGE). Antimicrobial resistance to 11 antimicrobials was studied by disk diffusion tests and sequencing of ESBL genes. From the collected samples 70 (22%) were found to be Salmonella positive. The lowest Salmonella rates were found in feed samples while in farm and slaughterhouse samples Salmonella presence ranged from 5% to 88%. S. Infantis was the most common serotype (94%, 66/70). PFGE demonstrated that isolates belonged to 11 genotypes. Some genotypes were continuously identified throughout the production chain. 97% of the isolates showed resistance to at least one antimicrobial. Moreover, all S. Infantis isolates and one auto-agglutinable isolate showed resistance to at least 6 antimicrobials. 30 and 8 isolates were positive to blaCTX-M-65 and blaCTX-M-14 genes respectively. No blaKPC resistance genes were identified in any isolate. This study highlights the predominance of S. Infantis in the integrated poultry company. Genotypes showed that cross-contamination between stages of poultry production can occur, stressing the importance of implementing good hygiene practices in every level of the production. Moreover, multidrug resistance patterns and the presence of important ESBL genes have public health implications that need to be deeply discussed with a one health approach.

Occurrence and characterisation of ESBL-encoding plasmids among Escherichia coli isolates from fresh vegetables.

Extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli isolates have been increasingly reported in different reservoirs. The aims of this study were to investigate the presence of ESBL-producing E. coli in fresh vegetables and to characterise their ESBL gene-carrying plasmids. Among the 245 samples from vegetables investigated during 2011-2013, seven putative ESBL-producing E. coli (salad n = 2, sprouts n = 5) were found. They were subjected to ESBL phenotypic confirmatory tests, detection/sequencing of ESBL genes, antimicrobial susceptibility testing (AST), phylotyping, XbaI-macrorestriction analysis, multilocus sequence typing and transformation. Transformants were characterised by AST, S1-nuclease PFGE, replicon typing, conjugation and investigated for co-located antimicrobial resistance genes. Two ESBL gene-carrying plasmids were sequenced using a HiSeq 2500 system. The seven isolates were confirmed as ESBL producers, displayed unrelated XbaI-patterns and unique sequence types (STs) and belonged to the phylogroups A, B1 or D. The ESBL genes were located on plasmids. Two plasmids carrying blaCTX-M-14 genes (incompatibility group IncK or IncHI2) were seen in isolates from salad (ST973) and sprout (ST527). Two blaCTX-M-15- (IncFIB; non-typeable) and the IncN blaCTX-M-65- and IncHI2 blaCTX-M-125-carrying plasmids were found in isolates from sprouts (ST410, ST847, ST10, ST542). All plasmids were conjugative, except for the IncFIA-FIB blaCTX-M-2-carrying plasmid. Sequence analysis of two plasmids identified the ESBL genes in close location to other resistance genes: sulfonamide resistance gene sul2, streptomycin resistance genes strA and strB, the plasmid-mediated quinolone resistance gene qnrS1 and blaTEM-1 (sul2-strA-strB-IS66-blaTEM-1-tnpR-ΔtnpA-ISEcp1-blaCTX-M-15-Δorf477-ΔtnpA-qnrS1) or the fosfomycin resistance gene fosA3 (ΔISEcp1-blaCTX-M-125-ΔIS903B-fosA3). These observations underline the importance of vegetables as reservoirs for multidrug resistant ESBL-producing E. coli.