Genomic Characterization of Campylobacter jejuni Strain M1

Recent studies have suggested a potential role for wild birds in zoonotic transmission of Campylobacter jejuni, the leading cause of gastroenteritis in humans worldwide. In this study, we detected Campylobacter spp. in 66.9% (85/127) of free-ranging American crows (Corvus brachyrhyncos) sampled in the Sacramento Valley of California in 2012 and 2013. Biochemical testing and sequence analysis of 16S rRNA revealed that 93% of isolates (n ‫؍‬ 70) were C. jejuni, with cytolethal distending toxin (CDT) and flagellin A genes detected by PCR in 20% and 46% of the C. jejuni isolates (n ‫؍‬ 59), respectively. The high prevalence of C. jejuni, coupled with the occurrence of known virulence markers CDT and flagellin A, demonstrates that crows shed Campylobacter spp. in their feces that are potentially pathogenic to humans. Crows are abundant in urban, suburban, and agricultural settings, and thus further study to determine their role in zoonotic transmission of Campylobacter will inform public health.

Section: Discussionmentioning

confidence: 99%

“…1A [C. coli clade]). None of the Campylobacter isolates from crows grouped in a clade with C. avium, a species recently found in poultry that is divergent from C. jejuni (32).…”

Section: Prevalencementioning

confidence: 90%

Prevalence and Pathogenic Potential of Campylobacter Isolates from Free-Living, Human-Commensal American Crows

Weis

Miller

Byrne

et al. 2014

“…When Friis and colleagues examined the genome of C. jejuni M1, they found a number of the genes, which have previously been described as being related to chicken colonization, to be present in this strain (21). These included genes such as cadF, which encodes the Campylobacter adhesion to fibronectin protein (28,29), and flpA, which has been shown to be important in chicken colonization (30).…”

Section: Figmentioning

confidence: 99%

Dynamics of Dual Infection with Campylobacter jejuni Strains in Chickens Reveals Distinct Strain-to-Strain Variation in Infection Ecology

Chaloner

Wigley

Humphrey

et al. 2014

bAlthough multiple genotypes of Campylobacter jejuni may be isolated from the same commercial broiler flock, little is known about the infection dynamics of different genotypes within individuals or their colonization sites within the gut. Single experimental infections with C. jejuni M1 (sequence type 137, clonal complex 45) and C. jejuni 13126 (sequence type 21, clonal complex 21) revealed that 13126 colonized the ceca at significantly higher levels. The dissemination and colonization sites of the two C. jejuni strains then were examined in an experimental broiler flock. Two 33-day-old broiler chickens were infected with M1 and two with 13126, and 15 birds were left unchallenged. Cloacal swabs were taken postinfection to determine the colonization and shedding of each strain. By 2 days postinfection (dpi), 8/19 birds were shedding M1 whereas none were shedding 13126. At 8 dpi, all birds were shedding both strains. At 18 dpi, liver and cecal levels of each isolate were quantified, while in 10 birds they also were quantified at nine sites throughout the gastrointestinal (GI) tract. 13126 was found throughout the GI tract, while M1 was largely restricted to the ceca and colon. The livers of 7/19 birds were culture positive for 13126 only. These data show that 13126 has a distinctly different infection biology than strain M1. It showed slower colonization of the lower GI tract but was more invasive and able to colonize at a high level throughout the GI tract. The finding that C. jejuni strains have markedly different infection ecologies within the chicken has implications for control in the poultry industry and suggests that the contamination risk of edible tissues is dependent on the isolate involved.

“…C. jejuni isolates from these birds have been implicated in human disease (11,16,17). Other studies indicate that some Campylobacter isolates found in wild birds may not be pathogenic to humans (14,(18)(19)(20)(21)(22)(23). These conflicting reports indicate that studies using higher resolution molecular methods …”

mentioning

confidence: 99%

“…To date, however, the application of taxonomically conserved housekeeping genes, while phylogenetically useful, does not include biologically informative genes, such as virulence factors (29), thereby limiting conclusions about potential pathogenicity. Recent studies have demonstrated the importance of whole-genome sequencing (WGS) in understanding C. jejuni pathogenicity and transmission (18,21,23,30); however, to date, studies of Campylobacter in wild birds have not taken advantage of WGS approaches to define the genotypes that are associated with zoonotic transmission and virulence.…”

mentioning

confidence: 99%

Genomic Comparison of Campylobacter spp. and Their Potential for Zoonotic Transmission between Birds, Primates, and Livestock

Weis

Storey

Taff

et al. 2016

Campylobacter is the leading cause of human gastroenteritis worldwide. Wild birds, including American crows, are abundant in urban, suburban, and agricultural settings and are likely zoonotic vectors of Campylobacter. Their proximity to humans and livestock increases the potential spreading of Campylobacter via crows between the environment, livestock, and humans. However, no studies have definitively demonstrated that crows are a vector for pathogenic Campylobacter. We used genomics to evaluate the zoonotic and pathogenic potential of Campylobacter from crows to other animals with 184 isolates obtained from crows, chickens, cows, sheep, goats, humans, and nonhuman primates. Whole-genome analysis uncovered two distinct clades of Campylobacter jejuni genotypes; the first contained genotypes found only in crows, while a second genotype contained "generalist" genomes that were isolated from multiple host species, including isolates implicated in human disease, primate gastroenteritis, and livestock abortion. Two major ␤-lactamase genes were observed frequently in these genomes (oxa-184, 55%, and oxa-61, 29%), where oxa-184 was associated only with crows and oxa-61 was associated with generalists. Mutations in gyrA, indicative of fluoroquinolone resistance, were observed in 14% of the isolates. Tetracycline resistance (tetO) was present in 22% of the isolates, yet it occurred in 91% of the abortion isolates. Virulence genes were distributed throughout the genomes; however, cdtC alleles recapitulated the crow-only and generalist clades. A specific cdtC allele was associated with abortion in livestock and was concomitant with tetO. These findings indicate that crows harboring a generalist C. jejuni genotype may act as a vector for the zoonotic transmission of Campylobacter. IMPORTANCEThis study examined the link between public health and the genomic variation of Campylobacter in relation to disease in humans, primates, and livestock. Use of large-scale whole-genome sequencing enabled population-level assessment to find new genes that are linked to livestock disease. With 184 Campylobacter genomes, we assessed virulence traits, antibiotic resistance susceptibility, and the potential for zoonotic transfer to observe that there is a "generalist" genotype that may move between host species. Campylobacter is a motile Gram-negative spiral bacterium that causes gastroenteritis in humans and other animals (1, 2). In livestock, Campylobacter may cause abortion in addition to gastroenteritis (3). It is one of the most common foodborne zoonotic pathogens worldwide and is often transmitted via the fecal-oral route through the consumption of contaminated food or water (1, 2). In the United States, campylobacteriosis is estimated to affect more than 1.3 million people each year, with symptoms including fever, abdominal cramping, and bloody diarrhea (1, 4, 5). Internationally, campylobacteriosis is a significant public health burden; the incidence in developed nations is estimated to be 4.4 to 9.3 per 1,000 people yearly and...