title: Prevalence of contagious and environmental mastitis-causing bacteria in bulk tank milk and its relationships with milking practices of dairy cattle herds in São Miguel Island (Azores).
abstract: This study aimed to assess the degree of contamination of bulk tank milk (BTM) by Staphylococcus spp. and coliform bacteria and to identify major milking practices that help perpetuate them in dairy cattle herds in São Miguel Island. In July 2014, BTM was sampled and a survey concerning local milking practices was conducted on 100 herds. Semi quantitative multiplex polymerase chain reaction detected coagulase-negative staphylococci, Escherichia coli, Staphylococcus aureus, and other coliform bacteria (Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens) in 100, 75, 59, and 35 % of BTM, respectively. According to multivariable univariate models, on herds not using hot water for cleaning the milking machine and teat liners, there was at least 3.4 more odds (P < 0.01) to have S. aureus or coliform bacteria contamination in BTM. The likelihood of finding S. aureus in BTM was higher (P < 0.001) on herds without high hygiene during milking, when milking mastitic cows at the end, on abrupt cessation of milking at dry-off, and official milk control implementation. The glove use also favored (odds ratio (OR) 5.8; P < 0.01) the detection of coliform bacteria in BTM. Poor milking practices identified in this study should be avoided in order to decrease S. aureus and coliform bacteria contamination of BTM. Other factors associated with milk quality in São Miguel Island also should be further investigated.
authors.affiliation: HIPRA, Avinguda La Selva, 135, 17170, Amer, Girona, Spain.
authors.forename: Carla
authors.initials: C
authors.lastname: Azevedo
authors.affiliation: University of Évora, Largo dos colegiais 2, 7004-516, Évora, Portugal.
authors.forename: Diana
authors.initials: D
authors.lastname: Pacheco
authors.affiliation: São Miguel Young Farmers Association, Arrifes, Ponta Delgada, São Miguel, 9500-372, Azores, Portugal.
authors.forename: Luísa
authors.initials: L
authors.lastname: Soares
authors.affiliation: University of Évora, Largo dos colegiais 2, 7004-516, Évora, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Romão
authors.affiliation: São Miguel Young Farmers Association, Arrifes, Ponta Delgada, São Miguel, 9500-372, Azores, Portugal.
authors.forename: Mónica
authors.initials: M
authors.lastname: Moitoso
authors.affiliation: HIPRA, Avinguda La Selva, 135, 17170, Amer, Girona, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Maldonado
authors.affiliation: HIPRA, Avinguda La Selva, 135, 17170, Amer, Girona, Spain.
authors.forename: Roger
authors.initials: R
authors.lastname: Guix
authors.affiliation: University of Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-811, Vila Real, Portugal. jsimoes@utad.pt.
authors.forename: João
authors.identifier: http://orcid.org/0000-0002-4997-3933
authors.initials: J
authors.lastname: Simões
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001394:Azores / Q000453:epidemiology; D002417:Cattle; D003612:Dairying; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D007709:Klebsiella / Q000302:isolation & purification; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D008892:Milk / Q000382:microbiology*; D015995:Prevalence; D012307:Risk Factors; D012706:Serratia marcescens / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000302:isolation & purification
keywords: Cattle; Coliform bacteria; Epidemiology; Mastitis; Risk factors; Staphylococcus aureus