Occurrence of thermophilic campylobacters in rural and urban surface waters in central Finland

In order to clarify the occurrence of campylobacters, surface waters in rural and urban sites in Central Finland were studied in 1987–1988 using membrane filtration and enrichment techniques. The maximum isolation frequency was in autumn (24% of the sites were positive), with second peaks in spring (17–21% campylobacter-positive sites), and minima in summer and winter (5–6% of the sites were positive). The chemical and bacteriological parameters indicated higher fecal contamination in the campylobacter-positive than in the campylobacter-negative waters. Although the urban sites, based on the enumeration of fecal indicator bacteria, were as contaminated as the rural sites, the isolation frequency of campylobacters in the urban waters was lower than in the rural ones. The results showed that when prefiltration is necessary in turbid waters, the membranes of 5.0 and 1.2 μm pore size had also to be cultured to avoid underestimation. Of the isolated strains 61 were biotyped as Campylobacter jejuni and one as C. coli. Of the C. jejuni strains, 64% were biotype 1 when the FBP-H 2S test was applied. Only few of the isolated Penner serotypes and serogroup complexes are reported to be common in surface waters of England or U.S.A. Among the isolates there were serotypes common in human infections.