title: Identification of coagulase-negative staphylococci from bovine intramammary infection by matrix-assisted laser desorption ionization-time of flight mass spectrometry.
abstract: Coagulase-negative staphylococci (CoNS) are among the main pathogens causing bovine intramammary infection (IMI) in many countries. However, one of the limitations related to the specific diagnosis of CoNS is the lack of an accurate, rapid, and convenient method that can differentiate the bacterial species comprising this group. The aim of this study was to evaluate the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to accurately identify CoNS species in dairy cow IMI. In addition, the study aimed to determine the frequency of CoNS species causing bovine IMI. A total of 108 bacterial isolates were diagnosed as CoNS by microbiological cultures from two milk samples collected from 21 dairy herds; the first sample was collected at the cow level (i.e., 1,242 composite samples from all quarters), while the second sample was collected at the mammary quarter level (i.e., 1,140 mammary samples collected from 285 cows). After CoNS isolation was confirmed by microbiological culture for both samples, all CoNS isolates (n=108) were genotypically differentiated by PCR restriction fragment length polymorphism (RFLP) analysis of a partial groEL gene sequence and subjected to the MALDI-TOF MS identification procedure. MALDI-TOF MS correctly identified 103 (95.4%) of the CoNS isolates identified by PCR-RFLP at the species level. Eleven CoNS species isolated from bovine IMI were identified by PCR-RFLP, and the most prevalent species was Staphylococcus chromogenes (n=80; 74.1%). In conclusion, MALDI-TOF MS may be a reliable alternative method for differentiating CoNS species causing bovine IMI.
authors.affiliation: Department of Animal Nutrition and Production, School of Veterinary Medicine and Animal Science (USP), Pirassununga, Sao Paulo, Brazil.
authors.forename: Tiago
authors.initials: T
authors.lastname: Tomazi
authors.forename: Juliano Leonel
authors.initials: JL
authors.lastname: Gonçalves
authors.forename: Juliana Regina
authors.initials: JR
authors.lastname: Barreiro
authors.forename: Patrícia Aparecida
authors.initials: PA
authors.lastname: de Campos Braga
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Prada e Silva
authors.forename: Marcos Nogueira
authors.initials: MN
authors.lastname: Eberlin
authors.forename: Marcos Veiga
authors.initials: MV
authors.lastname: dos Santos
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D003030:Coagulase / Q000235:genetics*; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000235:genetics*
chemical_list: D003030:Coagulase