Within-farm dynamics of ESBL-producing Escherichia coli in dairy cattle: Resistance profiles and molecular characterization by long-read whole-genome sequencing

A Pilot Study on Management Practices in Dairy Farms in the Basque Country: Focus on Colostrum Feeding and Vaccination

Colostrum feeding is crucial for calf rearing to guarantee passive immunity transfer (PIT) of antibodies. The present study aimed to evaluate the effect of different management practices on the calf's immunological parameters focusing on vaccination and colostrum management. Data were gathered on management routines, vaccination programs, and antimicrobial usage. Farmers were provided with colostrum management guidelines and a digital Brix refractometer to enhance colostrum feeding practices. Colostrum quality, PIT and lymphocyte subpopulations in both colostrum and blood were analyzed for further characterization. The combined farm and laboratory data were then examined to evaluate each farm's situation. Farmers reliably monitored colostrum quality by Brix refractometry and were able to modify colostrum management in a way that favored PIT. High-quality colostrum was linked to better PIT outcomes. Notably, Farm C, the sole non-vaccinated farm, reported higher antibiotic usage in both calves and lactating animals and showed reduced γδ T cell levels in colostrum. In conclusion, lymphocyte subpopulation content should be further studied as a trait of colostrum quality as well as of PIT. Failure to implement a vaccination program in the farm can have negative consequences on colostrum quality, as shown when analyzing both immunoglobulins and lymphocytes. This can result in a higher number of antibiotic treatments that may in turn be followed by different patterns of antimicrobial resistance.

Drivers of the emergence and dissemination of high-risk resistance genes in cattle farm

Extended spectrum β-lactamase (ESBL)- and carbapenemase-producing Enterobacterales (CPE) are recognized by WHO as critical concerns. The high cephalosporin resistance rate in a cattle farm in 2018 prompted us to conduct long-term (2019-2023) and extensive monitoring to explore risk factors for the import and transmission of ESBLs and CPE in this farm. Among 1288 samples from cattle, the environment, milk, and biological vectors, 48.8 % carried blaCTX-M-positive Enterobacterales with blaCTX-M-55 being dominant (76.4 %), and blaNDM-5-positive strains emerged in 2022 with a 1.9 % detection rate. blaCTX-M-55 and blaNDM-5 were likely introduced through various routes, especially wild birds, and have persisted due to overuse of cephalosporins in the farm. The spread of these genes was driven by the horizontal transmission of IncHI2 and IncX3 plasmids and clonal dissemination of certain clones. Cross-regional and cross-border transmission of blaCTX-M-55- and/or blaNDM-5-bearing bacteria and plasmids possibly occurred via wild birds, animal trade, and other means. Our findings suggest that the import, persistence, and dissemination of these genes within and beyond this farm, were fueled by suboptimal biosecurity practices and inadequate antibiotic stewardship, highlighting the urgency for integrated public and ecosystem health policies to prevent the spread of resistance genes as part of a holistic One Health strategy. ENVIRONMENTAL IMPLICATION: The high prevalence and long-term persistence of extended-spectrum β-lactamases and the emergence of carbapenemases in cattle and the environment signify a critical risk of transmitting high-risk resistance genes, posing a significant threat to human health. Consequently, bacteria carrying these genes in animal farms should be regarded as "hazardous materials". Import, persistence, and dissemination of these genes within and beyond this farm were exacerbated by suboptimal biosecurity practices and inadequate antibiotic stewardship, highlighting the urgency for integrated public and ecosystem health policies to mitigate the environmental risks associated with gene transmission as part of a comprehensive One Health strategy.

Extended-spectrum β-lactamase-producing Escherichia coli isolated from captive primates: characteristics and horizontal gene transfer ability analysis

The rapid spread of extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli (ESBL-EC) around the world has become a significant challenge for humans and animals. In this study, we aimed to examine the characteristics and horizontal gene transfer (HGT) capacity of ESBL-EC derived from captive primates. We screened for ESBL-EC among a total of 444 multidrug-resistant (MDR) E. coli strains isolated from 13 zoos in China using double-disk test. ESBL genes, mobile genetic elements (MGEs), and virulence-associated genes (VAGs) in ESBL-EC were detected through polymerase chain reaction (PCR). Furthermore, conjugation experiments were conducted to examine the HGT capacity of ESBL-EC, and the population structure (phylogenetic groups and MLST) was determined. Our results showed that a total of 69 (15.54%, 69/444) ESBL-EC strains were identified, and 5 variants of blaCTX and 3 variants of blaTEM were detected. The highest detection rate was blaCTX-M-55 (49.28%, 34/69), followed by blaCTX-M-15 (39.13%, 27/69). Ten MGEs were detected and the most prevalent was IS26 (78.26%, 54/69), followed by ISEcp1 (60.87%, 42/69). Eighteen combinations of MGEs were detected, in which ISEcp1 + IS26 was predominant (18.84%, n = 13). A total of 15 VAGs were detected and the most prevalent was fimC (84.06%, 58/69), followed by sitA (78.26%, 54/69). Furthermore, HGT ability analysis results showed that 40.58% (28/69) of ESBL-EC strains exhibited the ability to engage in conjugative transfer. Plasmid typing revealed that IncFIB (78.57%, 22/28) had the highest detection rates. Furthermore, antibiotic resistance genes (ARGs) of blaTEM-135, tetA and qnrS; MGEs of IS26, trbC and ISCR3/14 showed high rates of conjugative transfer. The population structure analysis showed that the phylogroup B1 and ST2161 were the most prevalent. ESBL-EC poses a potential threat to captive primates and may spread to other animals, humans, and the environment. It is imperative to implement measures to prevent the transmission of ESBL-EC among captive primates.

Genomic analysis of extended-spectrum beta-lactamase-producing E. coli from Czech diary calves and their caretakers

Introduction

The increasing prevalence of antimicrobial resistance in livestock, particularly the dissemination of extended-spectrum beta-lactamase-producing Escherichia coli, poses a significant zoonotic and public health risk. This study investigates the genomic characteristics of cefotaxime-resistant E. coli isolates from dairy calves across 23 Czech farms and their caretakers.

Materials and methods

Bacteriological cultivation on McConkey agar with cefotaxime was used for their isolation, susceptibility to selected antibiotics was determined by disc diffusion method, production of extended-spectrum beta-lactamases (ESBL) was demonstrated by double disc synergy test. The PCR was applied to confirm the presence of selected genes encoding resistance to some beta-lactams and genes encoding resistance to quinolones carried on plasmids. Using whole-genome sequencing, we evaluated resistance genotypes, sequence types, serotypes, plasmid replicons, and virulence genes.

Results and discussion

Among 266 rectal samples obtained from the calves, 128 (48%) harbored cefotaxime-resistant E. coli. Whole-genome analysis revealed blaCTX-M genes in 91% (116/128) of isolates, with bla CTX-M-14 (44%) and bla CTX-M-1 (34%) being the dominant variants. Other beta-lactamase gene blaTEM-1b was found in 40% (51/128) of isolates. Notably, no cephamycin resistance genes have been identified. The plasmid-mediated quinolone resistance (PMQR) gene qnrS1 was present at 21% (27/128) of isolates. The colistin resistance gene mcr-1 was found in a single ST2325 isolate. Sequence typing revealed significant clonal diversity, with 21 different STs detected among 68 sequenced isolates. ST10 was the most prevalent (27%), followed by ST69 (12%), ST29 (7%) and others. The phylogenetic distribution showed a predominance of commensal groups A (54%) and B1 (21%). The most common serotypes included O101:H9 (21%), O15:H18 (12%), H12, and O70:H11 (7%). Analysis of plasmid content revealed a complex distribution of 18 distinct plasmid replicon types, especially IncF, followed by Col-type and IncI1-type plasmids. Cross-species transmission was indicated by the detection of clonal strains shared between calves and caretakers, notably ST10-O101:H9 and ST34-O68:H30. The prevalence of high-risk clones and the presence of mobile resistance elements underscore the urgent need for stringent monitoring, antimicrobial stewardship, and improved biosecurity measures in livestock environments like increased caution and personal hygiene of animal handlers to mitigate the spread of resistant E. coli between animals and humans.

Gut colonization by extended-spectrum β-lactamase-producing Escherichia coli in dairy herd in Brazil: successful dissemination of a One Health clone

The overuse of antimicrobials in livestock has contributed to the emergence and selection of clinically relevant multidrug-resistant bacteria. In Brazil, there is no conclusive information on the occurrence of Escherichia coli producing extended-spectrum β-lactamase (ESβL) in cattle breeding, which is an important sector of agribusiness in this country. Herein, we investigated the presence of ESβL-positive E. coli strains in dairy cattle from a commercial farm with routine practice of therapeutic cephalosporins. Ninety-five rectal swab samples were collected from healthy dairy calves and cows under treatment with ceftiofur. Samples were screened for the presence of ESβL producers, and positive isolates were identified by MALDI-TOF, with subsequent screening for genes encoding ESβL variants by PCR and sequencing. The presence of ESβL (CTX-M-15)-producing E. coli was confirmed in calves, and lactating and dry cows. Most ESβL strains with genetic homologies ≥ 90% were grouped into two major PFGE clusters, confirming the suscessful expansion of clonally related lineages in animals from different lactating cycles, on the same property. Four representatives CTX-M-15-positive E. coli strains had their genomes sequenced, belonging to the clonal complex (CC) 23 and sequence type (ST) 90. A phylogeographical landscape of ST90 was performed revealing a global One Health linkage. Our results highlight the intestinal microbiota of dairy cattle as a hotspot for the spread of critical priority ESβL-producing E. coli and demonstrate that ST90 is an international clone genomically adapted to human and animal hosts, which deserve additional investigation to determine its zoonotic potential and impact in food chain.

Whole-genome sequencing-based antimicrobial resistance and shedding dynamics of Escherichia coli isolated from calves before and after antimicrobial group treatments

The fattening of calves is often associated with high antimicrobial use and the selection of antimicrobial resistance (AMR). The objective of this observational longitudinal study was to describe the AMR and strain dynamics, using whole-genome sequencing (WGS), of fecal Escherichia coli in a cohort of 22 calves. All calves received antimicrobial group treatments on Day (D) 1 (oxytetracycline, intramuscularly) and on D4 through D12 (doxycycline, in-feed). Additionally, eight calves received individual parenteral treatments between D7 and D59, including florfenicol, amoxicillin, marbofloxacin, and gamithromycin. Rectal swabs were collected from all calves on D1 (prior to treatment), D2, D9, and D82. The swabs were spread onto Enterobacterales-selective agar, and three E. coli colonies per plate were subjected to WGS. Out of 264 isolates across all calves and sampling times, 80 unique strains were identified, a majority of which harbored genes conferring resistance to tetracyclines, streptomycin, and sulfonamides. The diversity of strains decreased during the in-feed antimicrobial group treatment of the calves. On D82, 90% of isolates were strains that were not isolated at previous sampling times, and the median number per strain of AMR determinants to tetracyclines, florfenicol, β-lactams, quinolones, or macrolides decreased compared to D9. Additionally, clonal dissemination of some strains represented the main transmission route of AMR determinants. In this study, WGS revealed important variations in strain diversity and genotypic AMR of fecal E. coli over time in calves subjected to group antimicrobial treatments.

IMPORTANCE

The continued emergence and spread of antimicrobial resistance (AMR) determinants are serious global concerns. The dynamics of AMR spread and persistence in bacterial and animal host populations are complex and not solely driven by antimicrobial selection pressure. In calf fattening, both antimicrobial use and carriage prevalence of antimicrobial-resistant bacteria are generally recognized as high. This study provides new insights into the short-term, within-farm dynamics and transmission of AMR determinants in Escherichia coli from the dominant fecal flora of calves subjected to antimicrobial group treatments during the rearing period. The diversity of E. coli strains decreased over time, although, in contrast to previous observations in extended-spectrum β-lactamase-producing Enterobacterales, the predominance of a few clones was not observed. The spread of AMR determinants occurred through the dissemination of clonal strains among calves. The median number per strain of AMR determinants conferring resistance to selected antimicrobials decreased toward the end of the rearing period.

Monitoring within-farm transmission dynamics of antimicrobial-resistant Campylobacter in dairy cattle using broth microdilution and long-read whole genome sequencing

Campylobacter jejuni and Campylobacter coli are important foodborne zoonotic pathogens and cause for concern due to the increasing trend in antimicrobial resistance. A long-run surveillance study was conducted in animals from different age groups in five dairy cattle farms to investigate the within-farm diversity and transmission dynamics of resistant Campylobacter throughout time. The resistance phenotype of the circulating isolates (170 C. jejuni and 37 C. coli) was determined by broth microdilution and a selection of 56 isolates were whole genome sequenced using the Oxford-Nanopore long-fragment sequencing technology resulting in completely resolved and circularized genomes (both chromosomes and plasmids). C. jejuni was isolated from all farms while C. coli was isolated from only two farms, but resistance rates were higher in C. coli than in C. jejuni and in calves than in adult animals. Some genotypes (e.g. ST-48, gyrA_T86I/tet(O)/blaOXA-61 in farm F1; ST-12000, aadE-Cc/tet(O)/blaOXA-489 in F4) persisted throughout the study while others were only sporadically detected. Acquisition of extracellular genes from other isolates and intracellular mutational events were identified as the processes that led to the emergence of the resistant genotypes that spread within the herds. Monitoring with Oxford Nanopore Technologies sequencing helped to decipher the complex molecular epidemiology underlying the within-farm dissemination of resistant Campylobacter.

Antibiotic resistance mechanism and diagnosis of common foodborne pathogens based on genotypic and phenotypic biomarkers

The emergence of antibiotic-resistant bacteria due to the overuse or inappropriate use of antibiotics has become a significant public health concern. The agri-food chain, which serves as a vital link between the environment, food, and human, contributes to the large-scale dissemination of antibiotic resistance, posing a concern to both food safety and human health. Identification and evaluation of antibiotic resistance of foodborne bacteria is a crucial priority to avoid antibiotic abuse and ensure food safety. However, the conventional approach for detecting antibiotic resistance heavily relies on culture-based methods, which are laborious and time-consuming. Therefore, there is an urgent need to develop accurate and rapid tools for diagnosing antibiotic resistance in foodborne pathogens. This review aims to provide an overview of the mechanisms of antibiotic resistance at both phenotypic and genetic levels, with a focus on identifying potential biomarkers for diagnosing antibiotic resistance in foodborne pathogens. Furthermore, an overview of advances in the strategies based on the potential biomarkers (antibiotic resistance genes, antibiotic resistance-associated mutations, antibiotic resistance phenotypes) for antibiotic resistance analysis of foodborne pathogens is systematically exhibited. This work aims to provide guidance for the advancement of efficient and accurate diagnostic techniques for antibiotic resistance analysis in the food industry.

Intramammary and systemic use of antimicrobials and their association with resistance in generic Escherichia coli recovered from fecal samples from Canadian dairy herds: A cross-sectional study

Antimicrobial resistance (AMR) in animals, including dairy cattle, is a significant concern for animal and public health worldwide. In this study, we used data collected through the Canadian Dairy Network for Antimicrobial Stewardship and Resistance (CaDNetASR) to: (1) describe the proportions of AMR in fecal E. coli, and (2) investigate the relationship between antimicrobial use (AMU) (intramammary and systemic routes, while accounting for confounding by other variables) and AMR/multidrug resistance (MDR - resistance to ≥ 3 antimicrobial classes) in fecal E. coli from Canadian dairy farms. We hypothesized that an increase of the AMU was associated with an increase in AMR in E. coli isolates. A total of 140 dairy farms across five provinces in Canada were included in the study. Fecal samples from pre-weaned calves, post-weaned heifers, lactating cows, and farm manure storage were cultured, and E. coli isolates were identified using MALDI-TOF MS. The minimum inhibitory concentrations (MIC) to 14 antimicrobials were evaluated using a microbroth dilution methodology. AMU was quantified in Defined Course Dose (DCD - the dose for a standardized complete treatment course on a standard size animal) and converted to a rate indicator - DCD/100 animal-years. Of 1134 fecal samples collected, the proportion of samples positive for E. coli in 2019 and 2020 was 97.1% (544/560) and 94.4% (542/574), respectively. Overall, 24.5% (266/1086) of the E. coli isolates were resistant to at least one antimicrobial. Resistance towards tetracycline was commonly observed (20.7%), whereas resistance to third-generation cephalosporins, fluoroquinolones, and carbapenems was found in 2.2%, 1.4%, and 0.1% of E. coli isolates, respectively. E. coli isolates resistant to two or ≥ 3 antimicrobial classes (MDR) was 2.7% and 15%, respectively. Two multilevel models were built to explore risk factors associated with AMR with AMU being the main exposure. Systemic AMU was associated with increased E. coli resistance. For an increase in systemic AMU equivalent to its IQR, the odds of resistance to any antimicrobial in the model increased by 18%. Fecal samples from calves had higher odds of being resistant to any antimicrobial when compared to other production ages and farm manure storage. The samples collected in 2020 were less likely to be resistant when compared to samples collected in 2019. Compared to previous studies in dairy cattle in North America, AMR in E. coli was lower.

Extended-Spectrum β-Lactamases (ESBL) Producing Bacteria in Animals

Animals have been identified as potential reservoirs and vectors of resistance genes, with studies showing that Gram-negative bacteria can acquire resistance through the horizontal transmission of resistance genes on plasmids. It is important to understand the distribution of antimicrobial-resistant bacteria and their drug-resistant genes in animals. Previous review articles mostly focused on a single bacterium or a single animal. Our objective is to compile all ESBL-producing bacteria isolated from various animals in recent years and provide a comprehensive viewpoint. Using a thorough PubMed literature search spanning from 1 January 2020 to 30 June 2022, studies exploring extended-spectrum beta-lactamase (ESBL) producing bacteria in animals were included. ESBL-producing bacteria are present in animals from various countries around the world. The most common sources of these bacteria were farm animals, and the most frequently isolated bacteria were Escherichia coli and Klebsiella pneumoniae. The most detected ESBL genes were blaTEM, blaSHV, and blaCTX-M. The presence of ESBL-producing bacteria in animals highlights the importance of the One Health approach to address the issue of antibiotic resistance. Further research is needed to better understand the epidemiology and mechanisms of the spread of ESBL-producing bacteria in animal populations and their potential impact on human and animal health.