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This study is aimed at determining the occurrence of campylobacters in waste water, sewage sludge and in a river system. The selective medium for the isolation of campylobacter consists of blood agar supplemented with the antibiotics vancomycin (10 µg/ml), cephalexin (15 µg/ml), trimethoprim (5 µg/ml), polymycin B (2.5 µg/ml) and rifampicin (5 µg/ml). Raw sewage samples contained about 103 Campylobacter/100 ml while the effluent showed an average concentration of 1.3 × 102/100 ml. Raw sewage from an oxidation pond treatment plant contained an average of 51 Campylobacter/100 ml while none were found in the effluent. No Campylobacter could be found in digested, conditioned sludge. The organism could be detected in 82.1% of river waters examined with the majority showing <10/100 ml. The presence of waterfowl and the faecal contamination from a poultry farm resulted in higher Campylobacter levels. About 50 % of the isolates typed as C. coli were really confirmed as C. jejuni by electrophoretic pattern (whole cell protein profiles).

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We previously demonstrated that a spontaneous smooth small-colony variant of Brucella abortus S19 is characterized by increased in vivo persistence and the differential expression of a gene predicted to encode a galactoside transport ATP binding protein (mglA). In order to further investigate the role of this gene in the context of its flanking regions, we analyzed the respective DNA sequences from the formerly described B. abortus S19 as well as from avirulent B. neotomae 5K33 and compared these with published data from other Brucella species. Deletion mutagenesis of mglA in the large-colony variant of B. abortus S19 resulted in increased tolerance of the deletion mutant to a hyperosmotic (toxic), galactose-containing medium as well as to oxidative stress (H 2 O 2 ). Whilst the deletion mutant is characterized by reduced growth on solid Fe 3+ -containing minimal medium (small-colony morphology), in vivo studies in mice demonstrated statistical significant differences in the bacterial load of spleens in the pre-immune, but not in the late phase of the infection.