The microflora of downgraded Danish bulk tank milk was examined to identify the main causes of increased microbial counts. Seventy-five representative samples with a microbial count exceeding 3.0 x 10(4) cfu/mL were selected for a more detailed microbial examination. A total of 1237 isolates from these samples were identified. Gram-negative, oxidase-positive bacteria were found in 72% of the samples. Coliforms were found in 20% of the samples, and non-coliforms were found in 49% of the samples. Coryneforms, other gram-positive rods, Lactococcus spp., Micrococcus spp., and coagulase-negative Staphylococcus spp. were found in 28 to 53% of the samples. Bacillus spp., Enterococcus spp., Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus uberis, and yeasts were found in <25% of the samples. Additionally, the isolates were divided into 3 groups, based on the main cause of an elevated microbial count. Microorganisms primarily associated with poor hygiene dominated the microflora in 64% of the samples; bacteria also related to poor hygiene, but in addition associated with growth at low temperatures (psychrotrophic bacteria) dominated the microflora in 28% of the samples; and bacteria mainly associated with mastitis dominated the microflora in 8% of the samples. A bulk tank milk storage period of 48 h instead of 24 h did not affect the proportion of downgraded milk samples and could not be associated with a specific group of microorganisms. Further, no relationship was found between somatic cell counts and the presence of mastitis bacteria.

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The port of entrance in the fish for the pathogenic bacterium Vibrio anguillarum remains an enigma. Chemotactic motility has previously been shown to be a virulence factor, and chemotactic responses to mucus from different parts of the body might differ depending on the preferred port. In the present study, V. anguillarum was highly chemotactic to fish mucus from gills, skin and intestine of rainbow trout (Oncorhynchus mykiss L.) and significantly more chemotactic to skin and intestinal mucus than gill mucus. Strains of V. anguillarum show some degree of host preference. However, serogroup O1 strains (most commonly isolated from salmonids) and serogroup O2 strains (commonly isolated from cod) were all chemotactic to mucus from the skin of rainbow trout, cod, common bream, and flounder. An avirulent strain of V. anguillarum was as chemotactic as the virulent strains. ß