A repeated cross-sectional study of the epidemiology of Campylobacter and antimicrobial resistant Enterobacteriaceae in free-living Canada geese in Guelph, Ontario, Canada

Molecular Characterization and Antimicrobial Susceptibility of C. jejuni Isolates from Italian Wild Bird Populations

Poultry is considered a major reservoir of human campylobacteriosis. It also been reported that not only poultry, but also wild birds, are capable of carrying C. jejuni, thus demonstrating to be a risk of spreading the bacteria in the environment. To gain insight into the population structure and investigate the antimicrobial resistance genotypes and phenotypes, we analyzed a collection of 135 C. jejuni from 15 species of wild birds in Italy. MLST revealed the presence of 41 sequence types (STs) and 13 clonal complexes (CCs). ST-179 complex and the generalist ST-45 complex were the most prevalent. Core genome MLST revealed that C. jejuni from ST-45 complex clustered according to the bird species, unlike the ST-179 complex which featured 3 different species in the same cluster. Overall we found a moderate prevalence of resistance to tetracycline (12.5%), ciprofloxacin and nalidixic acid (10%). The novel ST isolated from one pigeon showed resistance to all the antibiotics tested. The ST-179 complex (33.3%) was identified with significantly higher nalidixic acid resistance relative to other tested STs. Nine AMR genes (tet(O), cmeA, cmeB, cmeC, cmeR, aad, blaOXA-61, blaOXA-184 and erm(B)) and 23S rRNA and gyrA-associated point mutations were also described, indicating a concordance level between genotypic and phenotypic resistance of 23.3%, 23.4% and of 37.5% for streptomycin, tetracycline and quinolones/fluoroquinolones, respectively. We recommend that particular attention should be given to wild birds as key sentinel animals for the ecosystem contamination surveillance.

Generalizability and comparability of prevalence estimates in the wild bird literature: methodological and epidemiological considerations

Wild birds have been the focus of a great deal of research investigating the epidemiology of zoonotic bacteria and antimicrobial resistance in the environment. While enteric pathogens (e.g. Campylobacter, Salmonella, and E. coli O157:H7) and antimicrobial resistant bacteria of public health importance have been isolated from a wide variety of wild bird species, there is a considerable variation in the measured prevalence of a given microorganism from different studies. This variation may often reflect differences in certain ecological and biological factors such as feeding habits and immune status. Variation in prevalence estimates may also reflect differences in sample collection and processing methods, along with a host of epidemiological inputs related to overall study design. Because the generalizability and comparability of prevalence estimates in the wild bird literature are constrained by their methodological and epidemiological underpinnings, understanding them is crucial to the accurate interpretation of prevalence estimates. The main purpose of this review is to examine methodological and epidemiological inputs to prevalence estimates in the wild bird literature that have a major bearing on their generalizability and comparability. The inputs examined here include sample type, microbiological methods, study design, bias, sample size, definitions of prevalence outcomes and parameters, and control of clustering. The issues raised in this review suggest, among other things, that future prevalence studies of wild birds should avoid opportunistic sampling when possible, as this places significant limitations on the generalizability of prevalence data.

Carriage of Campylobacter, Salmonella, and Antimicrobial-Resistant, Nonspecific Escherichia coli by Waterfowl Species Collected from Three Sources in Southern Ontario, Canada

Wild birds are considered a potential source of zoonotic pathogens. We report on the occurrence of Campylobacter, Salmonella, and antimicrobial-resistant, nonspecific Escherichia coli in ducks, grebes, and swans obtained by convenience while conducting related research with Canada Geese (Branta canadensis). Samples were obtained in southern Ontario, Canada, between 2013 and 2015 from hunter-caught birds, birds submitted for postmortem diagnosis, and fresh feces from live birds in parks. A secondary objective was to characterize Campylobacter genotypes using comparative genomic fingerprinting. Salmonella and E. coli isolates were tested for susceptibility to 15 antimicrobials using the Canadian Integrated Program for Antimicrobial Resistance Surveillance test panel. A total of 71 samples were collected from 15 different waterfowl species. We detected Campylobacter, Salmonella, and E. coli in 17, 3, and 84% of samples, respectively. Ten unique Campylobacter subtypes were identified, some of which had been identified previously in water, poultry, waterfowl, and human clinical cases. Both Salmonella isolates were pansusceptible and 15% of E. coli isolates were resistant to at least one antimicrobial, including resistance to antimicrobials of highest importance to human health. Source attribution studies should examine the role of waterfowl in the dissemination of these pathogens.