The long-term dynamics of Campylobacter colonizing a free-range broiler breeder flock: an observational study.
Bottom Line: Despite being free range, no newly colonizing STs were detected over a 6-week period in autumn and a 10-week period in winter, towards the end of the study.There was limited evidence that those STs identified among broiler chicken flocks on the same farm site were likely to colonize the breeder flock earlier (R(2) 0.16, P 0.01).These results suggest that there is natural control of Campylobacter dynamics within a flock which could potentially be exploited in designing new intervention strategies, and that the two different species should perhaps be considered separately.
Affiliation: The Department of Zoology, University of Oxford, South Parks Road, South Parks Road, Oxford, OX1 3PS, UK.Show MeSH
Mentions: A total of 1738 Campylobacter isolates were obtained from 4105 samples giving an average prevalence rate of 42.3% over the course of the study. Of these, 887 (51.0%) were C. jejuni and 851 (49.0%) were C. coli (Table 1 and Supporting Information Table S1). The C. jejuni isolates comprised 25 sequence types (STs) of which 17 were assigned to 12 clonal complexes, and eight STs remained unassigned. The C. coli isolates comprised 14 STs with 11 assigned to two clonal complexes and three unassigned. Eight of the 39 (20.5%) STs accounted for 66.8% of the isolates, with the remainder accounting for less than 5% of isolates each. The STs that were most commonly isolated were the C. coli ST-1487 (14.3% of isolates) and the C. jejuni ST-958 (11.7% of isolates). Ninety-two ST-flaA short variable region (SVR) combinations were identified in total, with individual STs being associated with between one and eight (and a mean of two) flaA SVR types over the course of the study (Supporting Information Table S1). Between one and nine clonal complexes, and one (week 5) and 14 STs (week 52) were isolated from the flock in any given week (Fig. 1). A 5-week rolling average frequency analysis (Fig. 2) demonstrated that the number of C. jejuni STs isolated from the flock showed a general increase over time, while the number of C. coli STs isolated from the flock each week rose quickly and was then relatively stable at a level of between three and five STs. Interrogation of the PubMLST database (http://pubmlst.org/campylobacter/, campylobacter (accessed on 03.01.2013) recording over 6000 allelic profiles and more than 22 000 isolates, revealed that many of the STs isolated from the free-range broiler breeder flock have previously been isolated from chicken sources, are distributed on a worldwide basis and have been isolated over at least a decade (Table 1). Six of the 39 (15.4%) STs were unique to the study, all of which were isolated four times or fewer.
Affiliation: The Department of Zoology, University of Oxford, South Parks Road, South Parks Road, Oxford, OX1 3PS, UK.