Evaluation and cluster analysis of inflammatory reactions of dairy cattle mastitis pathogens in milk samples submitted for microbiological examination

• Diaz-Cao, Jose M. ^[1] ; Barreal, María L. ^[2] ; Pombo, Belén ^[2] ; Prieto, Alberto ^[1] ; Alonso, José M. ; Iglesias, Antonio ^[3] ; Lorenzana, Roberto ^[2] ; López-Novo, Cynthia ^[1] ; Díez-Baños, Pablo ^[1] ; Fernández, Gonzalo ^[1]
  1. [1] Universidade de Santiago de Compostela

     Universidade de Santiago de Compostela

     Santiago de Compostela, España

     
  2. [2] Laboratorio Interprofesional Gallego de Análisis de la Leche (LIGAL), Edificio de Laboratorios Agrarios. 15318 Abegondo, A Coruña
  3. [3] niversidade de Santiago de Compostela, Faculty of Veterinary Sciences, Dept. Anatomy, Animal Production and Clinical Veterinary Sciences. 27002 Lugo

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• Localización: Spanish journal of agricultural research, ISSN-e 2171-9292, ISSN 1695-971X, Vol. 17, Nº. 4, 2019
• Idioma: inglés
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  • Aim of study: We have classified into homogenous groups a wide spectrum of mammary pathogens according to their frequency of isolation in clinical mastitis and their somatic cell counts in non-clinical mastitis.Area of study: The study was conducted in Galicia (NW Spain)Material and methods: 163,741 dairy cattle quarter milk samples were analyzed. We identified mastitis pathogens to the species level and performed a cluster analysis to classify these microorganisms by their median of Linear Score (mLS), percentage of isolation in clinical mastitis samples (%ICS) and percentage of isolation in samples with somatic cell counts under 100,000 cells/mL (%ISU100).Main results: Forty-three different species were isolated. Cluster analysis identified 4 groups of pathogens; mLS and %ICS progressively increased from Group I to Group IV and %ISU100 decreased. However, several pathogens included in groups II and III showed %ISU100 values higher than 2% and 3%. Minor pathogens were mainly clustered in Group I (e.g., Corynebacterium spp. and most of Staphylococcus spp.), while known major pathogens were included in Groups II, III y IV. Species of the same family, genus or microbiological group like Enterobacteriaceae or Enterococcus spp. were frequently separated into different groups, thus showing heterogeneity among the members of these groups.Research highlights: Results obtained here may aid in assessing the pathogenicity of sporadic pathogens in relation to more well-known pathogens and suggest that the traditional classification between minor and major pathogens is an oversimplification of the reality, especially for the latter category.