The Dynamics of Antimicrobial-Resistant Campylobacter jejuni on Japanese Broiler Farms

The transmission dynamics of Campylobacter jejuni among broilers in semi-commercial farms in Jordan

Campylobacter is the leading cause of foodborne bacterial gastroenteritis in humans worldwide, often associated with the consumption of undercooked poultry. In Jordan, the majority of broiler chicken production occurs in semi-commercial farms, where poor housing conditions and low bio-security are likely to promote campylobacter colonisation. While several studies provided estimates of the key parameters describing the within-flock transmission dynamics of campylobacter in typical high-income countries settings, these data are not available for Jordan and Middle-East in general. A Bayesian model framework was applied to a longitudinal dataset on Campylobacter jejuni infection in a Jordan flock to quantify the transmission rate of C. jejuni in broilers within the farm, the day when the flock first became infected, and the within-flock prevalence (WFP) at clearance. Infection with C. jejuni is most likely to have occurred during the first 8 days of the production cycle, followed by a transmission rate value of 0.13 new infections caused by one infected bird/day (95% CI 0.11–0.17), and a WFP at clearance of 34% (95% CI 0.24–0.47). Our results differ from published studies conducted in intensive poultry production systems in high-income countries but are well aligned with the expectations obtained by means of structured questionnaires submitted to academics with expertise on campylobacter in Jordan. This study provides for the first time the most likely estimates and credible intervals of key epidemiological parameters driving the dynamics of C. jejuni infection in broiler production systems commonly found in Jordan and the Middle-East and could be used to inform Quantitative Microbial Risk Assessment models aimed to assess the risk of human exposure/infection to campylobacter through consumption of poultry meat.

Effect of climatic elements on Campylobacter colonization in broiler flocks reared in southern Japan from 2008 to 2012

To demonstrate the effect of climatic elements on Campylobacter colonization in broiler chickens reared in Japan, the correlation between Campylobacter isolated from chickens (191 of 236 flocks, 80.9%) between 2008 and 2012 and climatic elements was analyzed by logistic regression. We divided the rearing process into 13 terms of 5 d each (total: 65 d). Terms were numbered backwards, wherein a 0-term lag was considered as the sampling day plus 4 d before sampling; 1-term lag was the 5-d term before the 0-term lag, and so on, until the 12-term lag. We obtained climatic data tracing back from the 0-term to the 12-term lags. For evaluation in each season, we divided chickens reared during periods of rising temperature (spring, summer) and decreasing temperature (autumn, winter). Air temperature showed a positive correlation with Campylobacter colonization from the 0- to 12-term lags in chickens reared during the period of rising temperature (odds ratio [OR], 1.069 to 1.104), and from the 0- to 4- and 6-term lags (OR, 1.079 to 1.105) in chickens reared during the period of decreasing temperature. The strong positive effect of air temperature on Campylobacter colonization, particularly during the period of rising temperature, may be associated with the effect on the Campylobacter environmental sources and/or vectors. A positive correlation was observed between Campylobacter colonization and humidity when chicken houses were empty and new chicks were introduced (from the 9- to 12-term lags) during the period of decreasing temperature (OR, 1.076 to 1.141). Thus, high humidity would be an important factor causing carry-over of Campylobacter infection during the period of decreasing temperature. We also found that solar radiation increased Campylobacter colonization during the period of decreasing temperature, from the 2- to 8-term lags, except for the 4- and 5-term lags, in Japan. The results of this study demonstrate the effects of air temperature, humidity, and solar radiation on Campylobacter colonization in broiler chickens, and are potentially important for developing strategies to reduce the risk of Campylobacter contamination in broiler chickens.

Distribution of Antimicrobial Resistance in Campylobacter Strains Isolated from Poultry at a Slaughterhouse and Supermarkets in Japan

Fifty strains of Campylobacter jejuni/coli were detected in 108 specimens of chicken meat and organs sampled at six supermarkets and one poultry slaughterhouse (large scale) between April and October 2013 (isolation rates: 84.8% from the slaughterhouse, 29.3% from the supermarkets). 46/50 strains were successfully recovered and subjected to the E-test to examine their susceptibility to three fluoroquinolone antibacterial agents authorized for use in poultry in Japan: enrofloxacin (ERFX), ofloxacin (OFLX), and norfloxacin (NLFX). 29 isolates (63%) were resistant to all three agents and 2 isolates (4.3%) were resistant to two agents (ERFX and OFLX). The resistance rates of strains isolated fom the supermarkets and slaughterhouse were 61.9% and 72.0%, respectively. Because the chickens processed at the slaughterhouse were raised without the use of fluoroquinolone, the results did not suggest a positive relationship between the use of these agents and the distribution of antimicrobial-resistant bacteria. Susceptibility to macrolide antibiotics (erythromycin [EM]) was also tested in 42 strains, and one strain (2.4%), C. coli from a retailer sample, showed resistance. Previous studies have detected high rates of fluoroquinolone-resistant strains, suggesting an expanding distribution of resistant bacteria. The detection of EM-resistant bacteria downstream in the food distribution chain (i.e., closer to consumers) is a concern for human health.

Intestinal carriage and excretion of Campylobacter jejuni in chickens exposed at different ages

Campylobacter jejuni is usually recovered from chickens in commercial broiler farms after 2 to 3 weeks of age. This study was conducted to clarify whether fecal excretion is associated with the age of exposure to this bacterium. Day-of-hatch broiler chickens were separated from a flock in a local commercial farm, kept in isolation rooms, and esophageally inoculated with C. jejuni (5.5 × 10(7) to 5.4 × 10(8) CFU) at 0, 7, 14, 21, 28, and 35 days of age. The remaining chicks were placed on the farm. Fecal samples obtained from the birds with the experimental infection and those reared on the farm were monitored for C. jejuni. Cecal contents obtained on necropsy were also cultured. In chickens inoculated with C. jejuni at 0 to 14 days of age, fecal excretion of C. jejuni was not observed until 42 days of age, although the organism was recovered from the cecal contents of these birds. When chickens were inoculated at 21 to 35 days of age, C. jejuni was isolated from fecal samples 2 or 3 days after inoculation, and the birds continually shed the organism until they reached 49 days of age, with the maximal numbers of the organism ranging from 1.7 × 10(8) to 1.0 × 10(10) CFU/g. In the commercial broiler farm, C. jejuni was first isolated from fecal samples obtained from two of five chickens at 28 days of age, and the organism was isolated from all five birds tested at 43 days of age. Restriction fragment length polymorphism analysis of the fla gene of C. jejuni isolates revealed that birds on the farm were colonized with C. jejuni after placement of the chickens on the farm. These observations indicate that chickens younger than 2 to 3 weeks old may carry C. jejuni in the ceca if they were exposed to this organism. Our results also suggest that fecal excretion of C. jejuni in commercial broiler chickens older than 3 to 4 weeks of age may be mainly caused by exposure of chickens at this age to this organism.

Colonization of chicken flocks by Campylobacter jejuni in multiple farms in Japan

Campylobacter jejuni was monitored in 4 chicken farms during the period 2003 to 2006 to elucidate the mechanisms of transmission. Three farms (1 to 3), located at least 14 km from each other, belonged to an integrated poultry company, which also provided the farms with day-old chicks from several hatcheries as well as chicken feed. Another farm (4), which belonged to a different company, was located 270 m from farm 1. A total of 206 C. jejuni isolates obtained from the 4 farms were classified into 10 flaA-based RFLP types. Identical RFLP types were found in isolates obtained from chickens originating from multiple hatcheries and reared in different chicken houses on individual farms. Flocks were colonized by strains with 1 or 2 RFLP types in each production cycle, sometimes differing between cycles. Identical RFLP types were found in isolates obtained from the environment around the chicken houses. Using multilocus sequence typing, strains with different RFLP types could be distinguished from each other. Identical RFLP and multilocus sequence typing profiles were found in isolates obtained from farms 1 and 4, and from farms 1 and 2. These results suggest that C. jejuni in these farms comes from common sources external to the farms, even if the farms belong to different companies and obtain chicks from different suppliers.

Effects of climatic elements on Campylobacter-contaminated chicken products in Japan

Japanese weather data for areas that produced Campylobacter spp.-positive chicken products were compared with those for areas producing negative samples. Regarding samples produced during the period of rising temperature (spring and summer), the mean weekly air temperatures for Campylobacter-positive samples were higher than those for negative samples for the period of the week in which the samples were purchased (18·7°C vs. 13·1°C, P=0·006) to a 12-week lag (12 weeks before purchasing samples; 7·9°C vs. 3·4°C, P=0·009). Significant differences in weekly mean minimum humidity and sunshine duration per day were also observed for 1- and 2-week lag periods. We postulated that the high air temperature, high humidity and short duration of sunshine for the chicken-rearing period increased Campylobacter colonization in chickens during the period of rising temperature. Consequently, the number of Campylobacter-contaminated chicken products on the market in Japan may fluctuate because of the climatic conditions to which reared chickens are exposed.

Role of antimicrobial selective pressure and secondary factors on antimicrobial resistance prevalence in Escherichia coli from food-producing animals in Japan

The use of antimicrobial agents in the veterinary field affects the emergence, prevalence, and dissemination of antimicrobial resistance in bacteria isolated from food-producing animals. To control the emergence, prevalence, and dissemination of antimicrobial resistance, it is necessary to implement appropriate actions based on scientific evidence. In Japan, the Japanese Veterinary Antimicrobial Resistance Monitoring System (JVARM) was established in 1999 to monitor the antimicrobial susceptibility of foodborne and commensal bacteria from food-producing animals. The JVARM showed that the emergence and prevalence of resistant Escherichia coli were likely linked to the therapeutic antimicrobial use in food-producing animals through not only direct selection of the corresponding resistance but also indirect selections via cross-resistance and coresistance. In addition, relevant factors such as host animals and bacterial properties might affect the occurrence and prevalence of antimicrobial-resistant E. coli under the selective pressure from antimicrobial usage. This paper reviews the trends in antimicrobial resistance in E. coli and consumption of antimicrobials agents in Japan and introduces the relationship between antimicrobial usage and prevalence of antimicrobial-resistant bacteria, from food-producing animals under the JVARM program. In this paper, we will provide the underlying information about the significant factors that can help control antimicrobial resistance in bacteria in veterinary medicine.