Attempts to utilize bacteriophage to combat Salmonella enterica serovar Enteritidis infection in chickens

Bacteriophage capable of lysing a nalidixic acid-resistant Salmonella enter ica serovar Enteritidis strain (SeE Nal(r)) were tested for the ability to reduce cecal Salmonella counts in young chickens infected with the bacteriu m. Qualitative analysis of cloacal swabs suggested that phage treatment can possibly reduce shedding of SeE Nal(r), but average SeE Nal(r) counts of b etween 10(5) and 10(7) cfu of SeE Nal(r) per g of cecum were obtained even from phage-treated 14-day old birds and even when more than 10(7) plaque fo rming units of phage were present per gram of cecal content The average cec al SeE Nal(r) counts were generally between 0.3 and 1.3 orders of magnitude lower in phage-treated chickens than in untreated controls birds. The diff erence in counts was statistically not significant in three animal trials, but significant in two trials using feed particles as delivery vehicles for the phage. Although some of the SeE Nal(r) in the cecae of phage-treated c hickens had developed resistance to some of the phage used factors other th an phage resistance must have contributed to the failure of the phage to su bstantially reduce SeE Nal(r) counts.