The received wisdom in British poultry circles is that campylobacter is a problem that emerges only once the birds reach a minimum of three weeks, suggesting that it is something that comes in from the external environment.
But this was challenged at the BVPA meeting by Prof Margie Lee from the College of Veterinary Medicine at the University of Georgia, USA.
Work by her research team has revealed that campylobacter can, in fact, be detected in day-old chicks, and even in the yolk of fertile eggs.
“Most scientific papers say that you can only isolate campylobacter in birds from about three weeks of age,” she told the meeting. “That certainly seems to be the case when samples are taken from the caecum or faeces.
“But we took samples from the ileum and found we could detect campy even from day-old chicks. We don’t normally look for campy in the ileum, but when we did we found it.”
Prof Lee’s research involved taking day-old chicks from a breeder flock that had been treated with the antibiotic fluoroquinolone, making sure they had had no access to food or water since hatching.
Once euthanised, yolk and intestinal contents were removed and tested for campylobacter.
While it was not possible to cultivate colonies of campylobacter from these samples using traditional culture techniques, using the polymerase chain reaction (PCR) method to amplify the DNA, the researchers were able to find campylobacter DNA in the ileal, cecal and yolk contents.
The DNA was almost identical to that of C coli, C jeuni and C lari, Prof Lee explained, indicating that campylobacter can be present in the intestines of very young chicks before they have eaten or drunk.
The implication was that, either the bacteria were present on or in the shell at time of hatching, or that there was some degree of vertical transmission involved. After all, it was known that C jeuni could colonise the oviduct of hens and could be cultured from the semen of roosters.
A further study was conducted by the University of Georgia team to see if the same strains of bacteria were present in a flock of broiler breeders and in their six-week-old progeny on separate commercial broiler farms.
The broiler breeders had been given fluoroquinolone, and the researchers sought to establish if the same fluoroquinolone-resistant campylobacter strains were found in their progeny.
This was indeed the case, suggesting that the campylobacter strain may have come from a common source in the hatchery or in the breeder flock.
Dr Lee acknowledged that vertical transmission was a controversial idea, but it was certainly possible that it played a part – and there was no doubt that campylobacter was present from a very early stage, if you knew how and where to look for it.