From farm to fork follow-up of thermotolerant campylobacters throughout the broiler production chain and in human cases in a Hungarian county during a ten-months period.

A study tracking thermotolerant campylobacters from the setting of the broilers throughout the whole rearing period, slaughter and sale of chicken products in five consecutive broiler rotations of the same henhouse as well as in two different other farms was conducted in a well-defined geographic area (Hajdú-Bihar county, Hungary) between March 2006 and Feb 2007. All notified cases of human campylobacteriosis in this area during the study period were also included. One hundred and one, 44, 23 and 282 Campylobacter jejuni and 13, 15, 20 and 60C. coli were isolated from broiler houses, slaughterhouses, retail shops and human samples, respectively. Sixty-two isolates collected from broilers or their environment selected from different flocks (57C. jejuni, 5C. coli), 92 isolates collected from abattoirs and retail shops (72C. jejuni, 20C. coli), as well as 85 randomly selected human isolates (74C. jejuni, 11C. coli) were subjected to PFGE analysis using restriction enzymes KpnI and SmaI. Sixty-six of the isolates produced unique Sma-Kpn profiles; the majority (46) of these were of human origin. The remaining isolates formed PFGE clusters of between 2-25 isolates with 14 (12C. jejuni and 2C. coli) main clusters comprised of five or more isolates with identical KpnI-SmaI patterns. Two genetic clones of C. jejuni (clone A, n=25; clone B, n=20) included 18% of isolates from different sources. Generally, isolates from one cluster were found in 1-3 different flocks, notably, clone B was present in three rotations including those from the two independent farms. Six of the seven investigated flocks had one or two characteristic prevalent clones. Transmission of clones between consecutive flocks was frequently seen. Spread of both C. jejuni and C. coli was traced multiple times along the food chain; eight C. jejuni, but no C. coli clones were detected both in broilers and humans. These data suggest that broilers were the major source for C. jejuni but not for C. coli in the studied area and period. For C. jejuni the carryover of strains between consecutive flocks may be a common event, but the strain is eventually replaced by another and consecutive carryover events seem to be infrequent. The majority of the human disease was due to nonepidemic strains; some clones were transmitted from more than one broiler flocks (including epidemiologically unrelated flocks) to humans multiple times.