Epidemiology of intramammary infections with Staphylococcus aureus and mastitis streptococci in a dairy cattle herd with a history of recurrent clinical mastitis.

The aim of the present work was to examine a dairy herd with an anamnesis of recurrent clinical mastitis and decreased milk production. A total of 239 individual cow milk samples originating from asymptomatic cows were collected at four-month intervals and examined mainly for the presence of Staphylococcus aureus and mastitis streptococci using standard cultivation methods. In total, 29.

In vivo spread of macrolide-lincosamide-streptogramin B (MLSB) resistance--a model study in chickens.

The influence of specific and non-specific antibiotic pressure on in vivo spread of macrolide-lincosamide-streptogramin B (MLSB) resistance was evaluated in this study. Chickens repeatedly inoculated with Enterococcus faecalis harbouring the plasmid pAMβ1 carrying the erm(B) gene were perorally treated for one week with tylosin, lincomycin (both specific antibiotic pressure) and chlortetracycline (non-specific antibiotic pressure). Antibiotic non-treated but E.

The role of the qacA gene in mediating resistance to quaternary ammonium compounds.

Conditions facilitating resistance to quaternary ammonium compounds (QACs) were investigated in Staphylococcus aureus SK982 exposed to benzalkonium chloride (BAC; a member of QACs) under various circumstances. S. aureus SK982 carrying the qacA gene encoding for resistance to QACs was grown in the presence of stable or gradually increasing concentrations of BAC, or it was exposed to this antiseptic in the exponential phase of growth.

Distribution, characterization and genetic bases of erythromycin resistance in staphylococci and enterococci originating from livestock.

The occurrence of staphylococci and enterococci expressing increased resistance to erythromycin (ERY) and, in particular, to macrolide-lincosamide-streptogramin B (MLS(B) ) antibiotics was investigated in dairy cattle, pigs and turkeys. Three hundred rectal (cloacal) swabs of each animal species were examined. A total of 120 and 71 staphylococci and enterococci, respectively, with increased resistance to ERY were identified.