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Extended-spectrum β-lactamase (ESBL)- and plasmid mediated AmpC-type cephalosporinase (pAmpC)-producing Escherichia coli (ESBL/pAmpC E. coli) in food-producing animals is a major public health concern. This study aimed at quantifying ESBL/pAmpC-E. coli occurrence and transfer in Italy's broiler production pyramid. Three production chains of an integrated broiler company were investigated. Cloacal swabs were taken from parent stock chickens and offspring broiler flocks in four fattening farms per chain. Carcasses from sampled broiler flocks were collected at slaughterhouse. Samples were processed on selective media, and E. coli colonies were screened for ESBL/pAmpC production. ESBL/pAmpC genes and E. coli phylogroups were determined by PCR and sequencing. Average pairwise overlap of ESBL/pAmpC E. coli gene and phylogroup occurrences between subsequent production stages was estimated using the proportional similarity index, modelling uncertainty in a Monte Carlo simulation setting. In total, 820 samples were processed, from which 513 ESBL/pAmpC E. coli isolates were obtained. We found a high prevalence (92.5%, 95%CI 72.1-98.3%) in day-old parent stock chicks, in which blaCMY-2 predominated; prevalence then dropped to 20% (12.9-29.6%) at laying phase. In fattening broilers, prevalence was 69.2% (53.6-81.3%) at the start of production, 54.2% (38.9-68.6%) at slaughter time, and 61.3% (48.1-72.9%) in carcasses. Significantly decreasing and increasing trends for respectively blaCMY-2 and blaCTX-M-1 gene occurrences were found across subsequent production stages. ESBL/pAmpC E. coli genetic background appeared complex and bla-gene/phylogroup associations indicated clonal and horizontal transmission. Modelling revealed that the average transfer of ESBL/pAmpC E. coli genes between subsequent production stages was 47.7% (42.3-53.4%). We concluded that ESBL/pAmpC E. coli in the broiler production pyramid is prevalent, with substantial transfer between subsequent production levels.

The aim of this study was to assess the dynamics of microbial communities and antimicrobial resistance genes (ARGs) in the chicken gut following amoxicillin and thiamphenicol treatments and potential co-selection of ARGs. To this purpose, the microbial community composition, using 16S rRNA NGS, and the abundance of ARGs conferring resistance to β-lactams and phenicols, using qPCRs, were determined. Results revealed that the administered antimicrobials did not significantly reduce the gut microbiota diversity, but changed its composition, with taxa (e.g. Gallibacterium and Megamonas ) being enriched after treatment and replacing other bacteria (e.g. Streptococcus and Bifidobacterium ). Positive correlations were found between ARGs (e.g. cmlA , bla CMY-2 , and bla SHV ) and the relative abundance of specific taxa (e.g. Lactobacillus and Subdoligranulum ). The selective pressure exerted by both amoxicillin and thiamphenicol resulted in an increased abundance of ARGs conferring resistance to β-lactams (e.g. bla TEM-1 , bla SHV , and bla CTX-M1-like ) and phenicols (e.g. floR and cmlA ). These findings, together with the co-occurrence of genes conferring resistance to the two antimicrobial classes (e.g. bla TEM-1 and cmlA ), suggest a possible interaction among antimicrobials on resistance emergence, possibly due to the presence of mobile genetic elements (MGEs) carrying multiple resistance determinants.

The aim of this study was to evaluate, through a systematic review and meta-analysis, the efficacy of antibiotics in controlling colibacillosis in broiler production, by synthesizing evidence from randomized controlled trials (RCTs). The Cochrane method and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and the databases CAB abstract, Agricola, PubMed and Web of Science were searched using relevant keywords to identify studies. Eligible studies had to report at least one of the following outcomes: mortality, feed conversion ratio (FCR), condemnations at slaughter and total antibiotic use. Risk of bias (RoB) by outcome of individual study and pairwise meta-analysis by outcome and antibiotic or antibiotics combination, when at least three studies were available, were also conducted. Out of 24,778 articles found in the searched databases, 48 studies were eventually selected. Most of the studies reported mortality as outcome (n = 43) and tested the antibiotic as metaphylactic treatment (n = 41). A total of 47 antibiotics belonging to 18 different classes were tested in the selected studies with enrofloxacin as the most studied. The overall RoB was “some concerns” in 78.2% of studies for mortality outcome and 73.7% for FCR outcome. Meta-analysis showed that doxycycline (0.04; 95% CI 0.02-0.10; P < 0.001) had the highest protective effect against mortality due to colibacillosis, followed by spectinomycin (0.11; 95% CI 0.05-0.26; P < 0.001), enrofloxacin (0.12; 95% CI 0.06-0.25; P < 0.001), lincomycin plus spectinomycin (0.22; 95% CI 0.13-0.38; P < 0.001), flumequine (0.25; 95% CI 0.14-0.44; P < 0.001) and oxytetracycline (0.31; 95% CI 0.20-0.50; P < 0.001). However, these results should be interpreted with caution due to the low number of studies included in the meta-analysis and the high variability in the animal models and study designs across RCTs. This review underscores the necessity for continued research to refine treatment strategies of colibacillosis in broiler production in line with the evolving regulatory and public health guidelines related to antibiotic use in animals.

Colibacillosis, a disease caused by Escherichia coli in broiler chickens has serious implications on food safety, security, and economic sustainability. Antibiotics are required for treating the disease, while vaccination and biosecurity are used for its prevention. This systematic review and meta-analysis, conducted under the COST Action CA18217—European Network for Optimization of Veterinary Antimicrobial Treatment (ENOVAT), aimed to assess the efficacy of E . coli vaccination in broiler production and provide evidence-based recommendations. A comprehensive search of bibliographic databases, including, PubMed, CAB Abstracts, Web of Science and Agricola, yielded 2,722 articles. Following a defined protocol, 39 studies were selected for data extraction. Most of the studies were experimental infection trials, with only three field studies identified, underscoring the need for more field-based research. The selected studies reported various types of vaccines, including killed (n = 5), subunit (n = 8), outer membrane vesicles/protein-based (n = 4), live/live-attenuated (n = 16), and CpG oligodeoxynucleotides (ODN) (n = 6) vaccines. The risk of bias assessment revealed that a significant proportion of studies reporting mortality (92.3%) or feed conversion ratio (94.8%) as outcomes, had “unclear” regarding bias. The meta-analysis, focused on live-attenuated and CpG ODN vaccines, demonstrated a significant trend favoring both vaccination types in reducing mortality. However, the review also highlighted the challenges in reproducing colibacillosis in experimental setups, due to considerable variation in challenge models involving different routes of infection, predisposing factors, and challenge doses. This highlights the need for standardizing the challenge model to facilitate comparisons between studies and ensure consistent evaluation of vaccine candidates. While progress has been made in the development of E . coli vaccines for broilers, further research is needed to address concerns such as limited heterologous protection, practicability for application, evaluation of efficacy in field conditions and adoption of novel approaches.

Biosecurity in poultry farms represents the first line of defense against the entry and spread of pathogens that may have animal health, food safety, and economic consequences. The aim of this study was to assess biosecurity compliance in poultry farms located in a densely populated poultry area in North East Italy. A total of 259 poultry farms (i.e., broilers, turkeys, and layers) were surveyed between 2018 and 2019 using standardized checklists, and differences in biosecurity compliance between the poultry sectors and years (only for turkey farms) were tested for significance. Among the three sectors, turkey farms showed the highest compliance. Farm hygiene, infrastructure condition, cleaning and disinfection tools, and procedures were the biosecurity measures most complied with. Some deficiencies were observed in the cleanliness of the farm hygiene lock in broiler farms, as well as the presence of the house hygiene lock in broiler and layer farms and an adequate coverage of built-up litter in turkey and broiler farms. In conclusion, this study highlighted a generally high level of biosecurity in the visited poultry farms (probably due to the stringent national regulation and the integration of the poultry industry) and identified some measures that still need to be improved.

Norovirus, an ssRNA + virus of the family Caliciviridae, is a leading disease burden in humans worldwide, causing an estimated 600 million cases of acute gastroenteritis every year. Since the discovery of norovirus in the faeces of swine in Japan in the 1990s, swine norovirus has been reported in several countries on several continents. The identification of the human-associated GII.4 genotype in swine has raised questions about this animal species as a reservoir of norovirus with zoonotic potential, even if species-specific P-types are usually detected in swine. This review summarises the available data regarding the geographic distribution of norovirus in swine, the years of detection, the genotype characterisation, and the prevalence in specific production groups. Furthermore, we discuss the major bottlenecks for the detection and characterisation of swine noroviruses.

Tetracycline resistance genes ( genes) are among the most prevalent antimicrobial resistance determinants in poultry, raising concerns about their dissemination across animal, human, and environmental interfaces. This study aimed to develop and validate rapid, sensitive, and cost-effective SYBR Green-based quantitative PCR (qPCR) assays for the detection and quantification of , and genes in bacterial isolates and complex matrices. Following and end-point PCR screening of ten published primer pairs, the most specific combinations were optimized for annealing temperature and primer concentration, and their analytical and diagnostic performances were evaluated. The assays exhibited efficiencies of 80.7-93.6%, strong linearity ( > 0.99), and high repeatability (CV < 5%). Diagnostic sensitivity and specificity ranged from 92.11-100% and 91.38-100%, respectively. Application of the assays to fecal, cecal, and drinking water samples collected from free-range and short-chain poultry farms revealed that all but one samples were positive for at least one of the investigated genes, with prevalence ranging from 65.79% ( ) to 93.33% ( ). These SYBR Green-based qPCR assays provide a robust, quantitative, and affordable tool for monitoring genes dissemination in poultry and associated environments. Their simplicity and reproducibility make them particularly suitable for large-scale surveillance programs and for use in settings where resources or access to probe-based platforms are limited.

[This corrects the article DOI: 10.3389/fvets.2025.1754015.].

The level of implementation of biosecurity measures (BMs), the reasons for not implementing BMs and the effectiveness of BMs were assessed according to the perceptions of stakeholders (i.e., farmers and advisors) in Italian poultry farms. For this purpose, data were collected using a questionnaire administered to advisors (n = 37) and farmers (n = 30) of conventional broiler (n = 13) and layer (n = 13), free-range broiler (n = 8) and layer (n = 10), turkey (n = 13), duck (n = 3) and breeder (n = 7) farms between April and September 2021. The frequency of the implementation of BMs was 66.97% and 81.14% according to the answers provided by the advisors and farmers, respectively, with the breeder sector showing the highest level of implementation (85.71%). “Not knowing advantages” (21.49% for advisors) and “other/specific reasons” (21.49% for advisors and 38.32% for farmers) were the most common answers regarding the lack of implementation of BMs for all poultry sectors. Only 31.09% of farmers acknowledged the effectiveness of not-implemented BMs in contrast to 61.02% of advisors, with the layers’ stakeholders being the most aware. The findings of this study may be useful for identifying failures in biosecurity and failures to develop intervention strategies to fulfil the biosecurity gaps still present in Italian poultry farms.

Escherichia coli able to produce extended spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (pAmpCs) represents a serious threat to public health, since these genes confer resistance to critically important antimicrobials (i.e., third generation cephalosporins) and can be transferred to non-resistant bacteria via plasmids. E. coli are known to be able to form a biofilm, which represents a favorable environment for the exchange of resistance determinants. Here, we assessed the ability of 102 ESBL/pAmpC-producing E. coli isolated from the broiler production pyramid to form a biofilm and to identify genetic factors involved in biofilm formation. All but one of the ESBL/pAmpC-producing E. coli were able to form a biofilm, and this represents a great concern to public health. E. coli belonging to phylogroups D, E, and F, as well as strains harboring the blaCTX-M-type gene, seem to be associated with an increased biofilm capability (p < 0.05). Furthermore, virulence genes involved in adherence and invasion (i.e., csgBAC, csgDEFG, matABCDEF, and sfaX) seem to enhance biofilm formation in E. coli. Efforts should be made to reduce the presence of ESBL/pAmpC- and biofilm-producing E. coli in the broiler production pyramid and, therefore, the risk of dissemination of resistant bacteria and genes.