Longitudinal Molecular Epidemiological Study of Thermophilic Campylobacters on One Conventional Broiler Chicken Farm

Abstract

Improved understanding of the ecology and epidemiology of Campylobacter in the poultry farm environment is key to developing appropriate farm-based strategies for preventing flock colonization. The sources of Campylobacter causing broiler flock colonization were investigated on one poultry farm and its environment, from which samples were obtained on three occasions during each of 15 crop cycles. The farm was adjacent to a dairy farm, with which there was a shared concreted area and secondary entrance. There was considerable variation in the Campylobacter status of flocks at the various sampling times, at median ages of 20, 26, and 35 days, with 3 of the 15 flocks remaining negative at slaughter. Campylobacters were recoverable from various locations around the farm, even while the flock was Campylobacter negative, but the degree of environmental contamination increased substantially once the flock was positive. Molecular typing showed that strains from house surroundings and the dairy farm were similar to those subsequently detected in the flock and that several strains intermittently persisted through multiple crop cycles. The longitudinal nature of the study suggested that bovine fecal Campylobacter strains, initially recovered from the dairy yard, may subsequently colonize poultry. One such strain, despite being repeatedly recovered from the dairy areas, failed to colonize the concomitant flock during later crop cycles. The possibility of host adaptation of this strain was investigated with 16-day-old chickens experimentally exposed to this strain naturally present in, or spiked into, bovine feces. Although the birds became colonized by this infection model, the strain may preferentially infect cattle. The presence of Campylobacter genotypes in the external environment of the poultry farm, prior to their detection in broiler chickens, confirms the horizontal transmission of these bacteria into the flock and highlights the risk from multispecies farms.

Campylobacter sequence typing databases: applications and future prospects

“…Some studies have identified a spatial relationship among genotypes, with isolates being more similar within rather than among farms (French et al, 2005;Kwan et al, 2008a;Rotariu et al, 2009). These data suggest that differences may be maintained among farms by localized transmission and continual reinfection, whilst animal movements on a regional scale may contribute to overall homogeneity of Campylobacter diversity (Ridley et al, 2011). Scottish cattle and sheep have been shown to harbour different Campylobacter populations, despite sharing the same farm environment (Sproston et al, 2011), and while the genotypes of Campylobacter isolates from pet dogs are diverse, they exhibit a high degree of similarity to human disease isolates (Parsons et al, 2009).…”

“…In one study of free-range chickens, the STs recovered at two separate locations were similar at the same time and could not be predicted by farm location, despite flocks being exposed to different local environments through minimal biosecurity (Colles et al, 2008b). Biosecurity remains a high priority in reducing Campylobacter levels in chickens, however, and MLST typing of strains provides a means by which 'environmental contamination' can more accurately be defined and attributed to agricultural or wildlife sources (Ridley et al, 2011).…”

“…With the chicken meat industry highly industrialized, it is possible that agricultural practices, for example the transfer of chicken-associated STs on travel crates, may promote the transfer of chicken-associated strains amongst farms (Hastings et al, 2011;Ridley et al, 2011). In New Zealand, particular genotypes were associated with different poultry producers; however, there were only three producers in New Zealand and the situation may be more complex in other, less remote, countries (Müllner et al, 2010).…”

Occurrence of Campylobacter on carcasses of slaughtered animals between 2009 and 2013

“…At the same time, 431 verified human campylobacteriosis cases were identified in Poland, with a low infectious rate (1.12 per 100 000), but this small number of infections may be due to an inadequate laboratory identification system (5). Poultry meat is the most important source of Campylobacter infection, especially with C. jejuni (5,6,8,10,18). It is estimated that 50% to 80% of human campylobacteriosis cases have been attributed to the chicken (broiler) reservoir (5).…”

Poultry flocks as a source of Campylobacter contamination of broiler carcasses

“…Poultry are asymptomatic carriers of Campylobacter and the infected flocks cannot be identified by clinical symptoms in birds (Berry et al 1988, Newell et al 2001, Newell and Fearnley 2003, Wieczorek and Osek 2005, Adkin et al 2006, Bull et al 2006, Allen et al 2007, Wirz et al 2010, Hue et al 2011, Ridley et al 2011, Habib et al 2012. The contamination of broiler meat with C. jejuni or C. coli from the chicken intestine may occur during slaughter processing through several routes, such as the air, water, previously slaughtered Campylobacter-positive flocks, equipment used in abattoirs, insects or slaughterhouse personnel (Rivoal et al 1999, Newell et al 2001, Nauta et al 2007, Normand et al 2008, Reich et al 2008, Wirz et al 2010, Hue et al 2011, Habib et al 2012).…”