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BACKGROUNDCampylobacter jejuni,the most frequent cause of foodborne bacterial infection, is found on around 70% of retail chicken. As such there is a need for effective controls in chicken production. Microbial-based controls such as probiotics are attractive to the poultry industry, but of limited efficacy. Furthermore, as commercially-produced chickens have no maternal contact, their pioneer microbiome is likely to come from the hatchery environment. Early delivery of microbials that lead to a more ‘natural avian’ microbiome may, therefore, improve bird health and reduce susceptibility toC.jejunicolonisation.A faecal microbiota transplant (FMT) was used to transfer a mature cecal microbiome to newly-hatched broiler chicks and its effects onC.jejunichallenge assessed. We used both a seeder-bird infection model that mimics natural bird-to-bird infection alongside a direct-challenge model. We used a 16S rRNA gene sequencing-based approach to characterize the transplant material itself alongside changes to the chicken microbiome following FMT.RESULTSFMT changes the composition of the chicken intestinal microbiome. We observed little change in species richness following FMT compared to untreated samples, but there is an increase in phylogenetic diversity within those species. The most significant difference in the ceca is an increase inLactobacilli,although not a major component of the transplant material, suggesting the FMT results in a change in the intestinal milieu as much as a direct change to the microbiome.Upon direct challenge, FMT resulted in lower initial intestinal colonisation withC.jejuni.More significantly, in a seeder-bird challenge of infection transmission, FMT reduced transmission and intestinal colonisation until common UK retail age of slaughter. In a repeat experiment, transmission was completely blocked following FMT treatment. Delayed FMT administration at 7 days of-age had limited effect on colonisation and transmission.CONCLUSIONSWe show that transfer of a whole mature microbiome to newly-hatched chicks reduces transmission and colonisation ofC.jejuni.This indicates that modification of the broiler chick microbiome can reduce intestinal colonisation ofC.jejunito levels projected to lead to lower the human infection rate. We believe these findings offer a way to identify key taxa or consortia that are effective in reducingC.jejunicolonisation and improving broiler gut health.

Infection byCampylobacteris recognised as the most common cause of foodborne bacterial illness worldwide. Faecal contamination of meat, especially chicken, during processing represents a key route of transmission to humans. There is currently no licenced vaccine and noCampylobacter-resistant chickens. In addition, preventative measures aimed at reducing environmental contamination and exposure of chickens toCampylobacter jejuni(biosecurity) have been ineffective. There is much interest in the factors/mechanisms that driveC. jejunicolonisation and infection of animals, and survival in the environment. It is anticipated that understanding these mechanisms will guide the development of effective intervention strategies to reduce the burden ofC. jejuniinfection. Here we present a comprehensive analysis ofC. jejunifitness during growth and survival within and outside hosts. A comparative analysis of transposon (Tn) gene inactivation libraries in threeC. jejunistrains by Tn-seq demonstrated that a large proportion, 331 genes, of theC. jejunigenome is dedicated to (in vitro) growth. An extensive Tn library inC. jejuniM1cam (~10,000 mutants) was screened for the colonisation of commercial broiler chickens, survival in houseflies and under nutrient-rich and–poor conditions at low temperature, and infection of human gut epithelial cells. We reportC. jejunifactors essential throughout its life cycle and we have identified genes that fulfil important roles across multiple conditions, includingmaf3, fliW, fliD, pflBandcapM, as well as novel genes uniquely implicated in survival outside hosts. Taking a comprehensive screening approach has confirmed previous studies, that the flagella are central to the ability ofC. jejunito interact with its hosts. Future efforts should focus on how to exploit this knowledge to effectively control infections caused byC. jejuni.Author SummaryCampylobacter jejuniis the leading bacterial cause of human diarrhoeal disease.C. jejuniencounters and has to overcome a wide range of “stress” conditions whilst passing through the gastrointestinal tract of humans and other animals, during processing of food products, on/in food and in the environment. We have taken a comprehensive approach to understand the basis ofC. jejunigrowth and within/outside host survival, with the aim to inform future development of intervention strategies. Using a genome-wide transposon gene inactivation approach we identified genes core to the growth ofC. jejuni. We also determined genes that were required during the colonisation of chickens, survival in the housefly and under nutrient-rich and –poor conditions at low temperature, and during interaction with human gut epithelial tissue culture cells. This study provides a comprehensive dataset linkingC. jejunigenes to growth and survival in models relevant to its life cycle. Genes important across multiple models were identified as well as genes only required under specific conditions. We identified that a large proportion of theC. jejunigenome is dedicated to growth and that the flagella fulfil a prominent role in the interaction with hosts. Our data will aid development of effective control strategies.

This study investigated the prevalence of nasal carriage of staphylococci in dogs and determined the characteristics of the isolates. A total of 724 dogs from 87 veterinary practices across the mainland UK were screened for carriage of Staphylococcus spp. All isolates were examined for meticillin resistance (MR) and the presence of the mecA gene investigated in those isolates showing resistance. All coagulase-positive staphylococci and MR coagulase-negative staphylococci (MRCoNS) were subjected to antimicrobial susceptibility testing. Spa typing and DNA microarray analysis of resistance and virulence genes was carried out on all MR S. aureus (MRSA) and a subset of meticillin susceptible S. aureus (MSSA). Staphylococci were isolated from 399 (55.1%) of the dogs; only seven (1%) carried MRSA, all of which were identified as the dominant UK healthcare-associated strain (EMRSA-15, ST22). MSSA was identified in 47 (6.5%) dogs, the sequence types of which have been suggested as precursors to successful MRSA clones. Forty (5.5%) dogs carried MRCoNS, while no dogs carried MR S. pseudintermedius, although this is increasingly reported in mainland Europe. Resistance to antimicrobials among the isolates varied between species, with multidrug resistance (MDR) in 87.5% of MRCoNS and 21.8% of coagulase positive staphylococci. Microarray analysis of MRSA and a subset of MSSA isolates identified numerous virulence genes associated with pathogenesis, which are commonly identified in isolates of human origin. However, no isolates carried Panton-Valentine leukocidin (PVL) genes. This study suggests that MRSA carriage is low in the vet visiting dog population, but there is a diverse range of virulence and resistance determinants in canine S. aureus and MRCoNS isolates.

Summary Reasons for performing study: The increasing prevalence of antimicrobial resistant bacteria such as antimicrobial-resistant and extended spectrum β-lactamase (ESBL)-producing Escherichia coli represents a significant problem for human and veterinary medicine. Despite this, the risk factors for faecal carriage of such bacteria by horses in the UK, particularly those in the wider community, have not been well described. Objectives: To characterise the risk factors for faecal carriage of antimicrobial-resistant E. coli amongst horses in the mainland UK. Methods: A cross-sectional study of horses recruited by 65 randomly selected equine veterinary practices was conducted, with a faecal sample collected and self-administered questionnaire completed by the horse owner. Faecal samples were cultured for antimicrobial-resistant E. coli, with isolates confirmed as E. coli having their antimicrobial resistance profile determined. Multilevel, multivariable logistic regression models were used to investigate risk factors for the carriage of antimicrobial-resistant E. coli in the sample population. Results: Faecal samples and completed questionnaires were obtained for 627 horses located on 475 premises. Recent hospitalisation, contact with specific types of nonequid animals, the type of premises, the surrounding land use, the reason for veterinary treatment received in the last 6 months and antimicrobial treatment in the previous 10 days were identified as risk factors for many of the antimicrobial-resistance outcomes considered. Being stabled on the same yard as a recently hospitalised horse was identified as a risk factor for increased risk of carriage of ESBL-producing E. coli. Conclusions and potential relevance: Increasing antimicrobial resistance may have significant health implications for the horse population of Great Britain. This form of epidemiological investigation highlights potential risk factors that may be controlled to limit the extent of the problem.

Reasons for performing study: The increasing prevalence of antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and antimicrobial-resistant Escherichia coli represents a significant problem. However, the carriage of such bacteria by horses in the UK has not been well characterised. Objectives: To estimate the prevalence of nasal carriage of MRSA and faecal carriage of antimicrobial-resistant E. coli amongst horses in the general equine community of the mainland UK. Methods: A cross-sectional study of horses recruited by 65 randomly selected equine veterinary practices was conducted, with nasal swabs and faecal samples collected. Faecal samples were cultured for antimicrobial-resistant E. coli. Nasal swabs were cultured for staphylococcal species; methicillin-resistant isolates identified as S. aureus were characterised by SCCmec and spa gene typing. Multilevel logistic regression models were used to calculate prevalence estimates with adjustment for clustering at practice and premises levels. Spatial variation in risk of antimicrobial resistance was also examined. Results: In total, 650 faecal samples and 678 nasal swabs were collected from 692 horses located on 525 premises. The prevalence of faecal carriage of E. coli with resistance to any antimicrobial was 69.5% (95% CI 65.9-73.1%) and the prevalence of extended-spectrum beta-lactamase (ESBL)-producing E. coli was 6.3% (95% CI 4.1-9.6%). The prevalence of nasal carriage of MRSA was 0.6% (95% CI 0.2-1.5%). Spatial analysis indicated variation across the UK for risk of carriage of resistant and multidrug-resistant (resistant to more than 3 antimicrobial classes) E. coli. Conclusions and potential relevance: Carriage of MRSA by horses in the community appears rare, but the prevalence of antimicrobial-resistant E. coli (including ESBL-producing E. coli) is higher. A high prevalence of antimicrobial-resistant bacteria could have significant health implications for the horse population of the UK.

SIR, — There is a rising awareness of the development of, and increase in, antimicrobial-resistant infections encountered in veterinary medicine. However, there is a paucity of information regarding the prevalence of antimicrobial-resistant organisms and associated risk factors in companion

The prevalence of carriage of antimicrobial-resistant (AMR) and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli was determined in 183 healthy dogs from a semi-rural community in Cheshire. Isolates were tested against a panel of antimicrobials and by PCR to detect resistance genes. In the suspected ESBL-producing isolates, the presence of bla SHV , bla TEM , bla CTX-M and bla AmpC genes was determined by PCR and sequencing. A total of 53 (29 per cent, 95 per cent confidence interval [CI] 22.4 to 35.5 per cent) dogs carried at least one AMR E coli isolate. Twenty-four per cent (95 per cent CI 17.9 to 30.2 per cent) of dogs carried isolates resistant to ampicillin, 19.7 per cent (95 per cent CI 13.9 to 25.4 per cent) to tetracycline and 16.9 per cent (95 per cent CI 11.5 to 22.4 per cent) to trimethoprim. A bla TEM gene was detected in 39 of 54 ampicillin-resistant isolates, a tet(B) gene in 12 of 45 tetracycline-resistant isolates, and a dfr gene in 22 of 33 trimethoprimresistant isolates. Multidrug-resistant isolates were demonstrated in 15 per cent (28 of 183; 95 per cent CI 10.1 to 20.5 per cent) of dogs. Nine suspected ESBL-producing E coli were isolated, of which only one was confirmed by double disc diffusion testing. Two of these isolates carried the bla TEM-1 gene and seven carried the bla CMY-2 gene. ANTIMICROBIAL resistance (AMR) is a commonly encountered problem in both human and veterinary medicine. It can lead to failures in treatment, increased morbidity and mortality, and a greater financial burden on healthcare services. Use of antimicrobials may exert a selection pressure on, and therefore select for, bacteria that have acquired resistance. Such resistance can be acquired either by mutation of chromosomal DNA, or by horizontal transfer of resistance determinants via transmissible elements, such as plasmids. One particular mechanism of AMR is the production of extended-spectrum β-lactamases (ESBLs), enzymes capable of hydrolysing third-generation cephalosporins (Livermore 2008). A further important resistance