Comparison of Campylobacter carriage rates in diarrheic and healthy pet animals

To explore the clinical significance of campylobacter infections for dogs and cats we compared intestinal carriage rates for Campylobacter sp. between animals with gastroenteritis and healthy controls. We cultured fecal specimens of 405 diarrheic dogs and 203 cats as well as 71 asymptomatic dogs and 35 cats using a selective medium in addition to filtration on a non-selective blood agar plate. We identified 224 campylobacter isolates using conventional phenotypic tests and DNA hybridization. There were 112 isolates, of C. upsaliensis, 43 C. jejuni and 69 other Campylobacter sp. For cats, there was no association between campylobacter carriage and disease, irrespective of the animals age. For dogs older than 12 months there was also no difference in campylobacter carriage rates between diarrheic and healthy animals. However, in younger dogs 44% of animals with diarrhea shed campylobacters in their feces, more than twice the rate in asymptomatic controls (21%), a significant difference. C. jejuni and C. upsaliensis contributed equally to this association between diarrhea and campylobacter prevalence. The parallel use of two culture methods enabled us to show that the recovery of Campylobacter sp. by filtration may be less than optimal and that filtering is probably unsuitable as a reference method for culturing C. upsaliensis. Finally we found that almost half of the campylobacter isolates from cats belong to a phenotypically homogeneous group of strains closely resembling C. upsaliensis but hybridizing only weakly with C. upsaliensis DNA.