Application of a Dot Blot Hybridization Platform to AssessStreptococcus uberisPopulation Structure in Dairy Herds.
Streptococcus uberisis considered one of the most important pathogens associated with bovine mastitis. While traditionally acknowledged as an environmental pathogen,S. uberishas been shown to adopt a contagious epidemiological pattern in several dairy herds. Since different control strategies are employed depending on the mode of transmission, in-depth studies ofS. uberispopulations are essential to determine the best practices to control this pathogen. In this work, we optimized and validated a dot blot platform, combined with automatic image analysis, to rapidly assess the population structure of infectiveS. uberis, and evaluated its efficiency when compared to multilocus sequence analysis (MLSA) genotyping. Two dairy herds with prevalentS. uberisinfections were followed in a 6 month period, in order to collect and characterize isolates from cows with persistent infections. These herds, located in Portugal (Barcelos and Maia regions), had similar management practices, with the herd from Barcelos being smaller and having a better milking parlor management, since infected cow segregation was immediate. A total of 54S. uberisisolates were obtained from 24 different cows from the two herds. To overcome operator-dependent analysis of the dot blots and increase the technique's consistency and reliability, the hybridization signals were converted into probability values, with average probabilities higher than 0.5 being considered positive results. These data allowed to confirm the isolates' identity asS. uberisusing taxa-specific markers and to determine the presence of virulence- and antibiotic resistance-related genes. In addition, MLSA allowed to disclose the most prevalentS. uberisclonal lineages in both herds. Seven different clusters were identified, with Barcelos showing a high clonal diversity and Maia a dominant lineage infecting most cows, suggesting distinct epidemiological patterns, withS. uberisdisplaying an environmental or contagious transmission pattern depending on the herd. Overall, this work showed the utility of dot blot and MLSA to characterize population structure and epidemiological patterns of mastitis-causingS. uberis. This approach allowed to disclose prevalent virulence patterns and clonal lineages ofS. uberisin two distinct herds, and gain insights on the impact of herd management practices on pathogen population structure.
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto Vairão, Portugal.
Pedro
P
Albuquerque
Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal; Estudos de Populações, Instituto de Saúde Pública da Universidade do PortoPorto, Portugal.
Niza
N
Ribeiro
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do PortoVairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do PortoPorto, Portugal.
Alexandre
A
Almeida
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do PortoVairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do PortoPorto, Portugal.
Irena
I
Panschin
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do PortoVairão, Portugal; Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal.
Afonso
A
Porfirio
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do PortoVairão, Portugal; Instituto de Ciências Biomédicas de Abel Salazar, Universidade do PortoPorto, Portugal.
Marta
M
Vales
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do PortoVairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do PortoPorto, Portugal.
Francisca
F
Diniz
Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto Porto, Portugal.
Helena
H
Madeira
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do PortoVairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do PortoPorto, Portugal.
Fernando
F
Tavares
Streptococcus uberis; bovine mastitis; dot blot; multilocus sequence analysis; population structure