Expert evaluation of different infection types in dairy cow quarters naturally infected with Staphylococcus aureus or Streptococcus agalactiae

Publication date: Available online 15 March 2019Source: Preventive Veterinary MedicineAuthor(s): Line Svennesen, Thomas B. Lund, Alice P. Skarbye, Ilka C. Klaas, Søren S. NielsenAbstractThe purpose of this study was to improve the diagnostic recommendations for Staphylococcus aureus and Streptococcus agalactiae control using bacterial culture (BC), polymerase chain reaction (PCR) and somatic cell count (SCC) as diagnostic methods. The study was carried out in three steps: firstly, diagnostic test patterns for naturally infected quarters with Staph. aureus (24 quarters) and Strep. agalactiae (16 quarters) were created by sampling the quarters each day for 21 days and analysing the daily quarter milk samples using BC, PCR and SCC. Secondly, 30 mastitis experts were asked to group and describe the diagnostic test patterns and to establish a diagnosis for each group. The experts’ statements regarding the groups they established were subsequently examined using qualitative content analysis to assign “infection types” to the statements. Lastly, the test performance was estimated for BC, PCR and SCC using generalised logistic regression models with the interpreted statements as a reference for infection.The experts mainly identified the Staph. aureus quarter-patterns as persistent infections, while some had more dynamic patterns. Strep. agalactiae quarter-patterns mainly involved persistent infection, yet some appeared hard to diagnose and were assigned to almost all differen...
Source: Preventive Veterinary Medicine - Category: Veterinary Research Source Type: research