Exudative epidermitis in pigs. Bacteriological studies on the causative agent

The properties of six pathogenic and six non-pathogenic strains of staphylococci from clinical cases of exudative epidermitis are described. The pathogenic strains were shown to produce typical lesions following experimental inoculation of pigs. All of the strains studied were classified among the staphylococci due to their ability to produce acid from glucose under anaerobic conditions. One of the six pathogenic strains was a slow coagulase producer. It is suggested that the species designation Staphylococcus hyicus be retained.

Mastitis in mink due to Staphylococcus aureus and Escherichia coli

An epizootic of mastitis in mink due to Staphylococcus aureus and Escherichia coli associated with food poisoning was studied on a Connecticut ranch with 3,500 mink. In the course of the epizootic, approximately 2,000 mink kits and 480 adult mink, mostly nursing females, died within 10 days. Affected females had swollen mammary glands due to acute mastitis; S. aureus was isolated in pure culture from 2 mink and E. coli in pure culture from a 3rd. Staphylococcus aureus was isolated from the organs of 1 mink kit, S. aureus and E. coli from a 2nd kit, and E. coli from a 3rd. The organs of the remaining 7 kits examined did not contain bacteria. Both isolates were pathogenic when inoculated intraperitoneally into mice and mink, causing fatal septicemia within 16 to 24 hours. The meat from a septicemic bovine carcass fed prior to the epizootic was considered a possible source of infection, since it was found to be heavily contaminated with E. coli, S. aureus, and Streptococcus spp.

The lesions in bovine udders shedding nonhemolytic coagulase-negative staphylococci

Inflammatory and atrophic lesions were found in 12 out of 13 quarters examined from 6 cows which were shedding nonhemolytic, coagulase-negative staphylococci. A few foci of neutrophils were observed in all except one quarter and this one had vacuolated alveolar epithelium. The most severe lesions were small and consisted of interstitial infiltration by fibroblasts, lymphocytes and plasma cells, and of vacuolated epithelium and neutrophils in alveoli. Milder lesions included both focal and widespread exudation of small numbers of neutrophils into alveoli and slight alveolar epithelial vacuolation.

The lesions in bovine udders shedding hemolytic coagulase-positive staphylococci

Coagulase-positive staphylococci occurred in the mammary tissue in a few sites of each infected quarter. Lesions varied from acute to chronic in a single quarter with neutrophilic infiltration and vacuolation of alveolar epithelial cells being associated with recent blocking of small collecting ducts by exudate. Chronic inflammatory changes were most prominent in the wall of small ducts, and fibrosis sometimes extended into the lumen or occluded it. Chronic abscesses originated in blocked areas of small mammary ducts. Ductal lesions probably contributed to focal atrophy duc to slowed drainage of milk.