Thermophilic campylobacters in seagulls and DNA-DNA hybridization test of isolates.

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Abstract
A total of 170 fecal samples from black-headed and black-tailed seagulls collected along the coast of Tokyo Bay and at the estuary of the Sagami River were examined for thermophilic campylobacters. Of these, 51 (30.0%) were found to contain the campylobacters by at least one of culture procedures used, which consisted of both direct plating culture on a modified Skirrow''s agar and enrichment cultures in four broths. Blaser''s, CEM, Doyle-Roman''s, and Preston, each followed by plating on the Skirrow''s agar. Eleven samples (6.5%) were positive in the direct plating procedure and 50 samples (29.4%) were positive in one or more of the enrichment procedures. No single procedure detected all the positive samples. The highest recovery rate (18.8%) was obtained by an enrichment procedure using Preston broth. The isolation rate in black-headed gulls (41.4%) was higher than that in black-tailed gulls (22.0%). Eighty-seven strains isolated were identified as Campylobacter jejuni (44 strains), C. coli (20 strains), and C. laridis (23 strains) by biochemical characteristics. Their respective recovery rates were 14.1, 7.6, and 9.4%. DNA homology indices of 2 strains of C. laridis to 4 strains of C. jejuni, 3 strains of C. coli, and 4 strains of C. laridis were 12 to 19, 10 to 17, and 75 to 99%, respectively. The seagulls strains with nalidixic acid resistance (30 .mu.g/ml) were also identified as C. laridis by DNA-DNA hybridization test.