Porcine ear necrosis syndrome is characterized by erosive and ulcerative lesions at the margin or tip of the pinna. Three growing pigs of different ages exhibited retarded growth accompanied by reddening and necrosis of ear prior to death. Gross examination showed reddening, swelling, black discoloration, scaling, and variable-sized yellowish materials and edema in ear cross section. Microscopically, thrombosis, abscess, ulceration, epidermal hyperplasia, and dermal pyogranulomatous inflammation with an intralesional bacterial colony were observed. Staphylococcus hyicus was isolated in all pigs' ears and porcine reproductive and respiratory syndrome virus was detected by PCR and immunohistochemistry.

<p>Staphylococcus hyicus cultures, isolated from piglets with skin lesions, were investigated for their plasmid profile and their resistance to antimicrobial agents. Plasmid of different sizes could be detected in six Staphylococcus hyicus isolates. All that samples showed tetracycline resistance and presented small plasmid of 4.0 Kb. Curing and transformation experiments showed that the 4.0 Kb plasmid harboured the genetic determinant of tetracycline resistance in this strains.</p> | <p>Staphylococcus hyicus isolados de leitões com lesões de pele foram estudados no que se refere aos seus plasmídios e resistência a agentes antimicrobianos. Plasmídios de diferentes pesos moleculares foram detectados nas seis amostras de Staphylococcus hyicus. Todas as amostras mostraram resistência à tetraciclina e um pequeno plasmídio de 4.0 Kb, com uma exceção. Experimentos de cura e transformação demonstraram que este plasmídio abriga o determinante genético para resistência à tetraciclina nas amostras estudadas.</p>