Direct identification of bovine mastitis pathogens by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in pre-incubated milk

Autor(es)

Barreiro, Juliana R. ^[1] ; Goncalves, Juliano L. ^[1] ; Grenfell, Rafaella ^[2] ; Leite, Renata F. ^[1] ; Juliano, Luiz ^[2] ; Santos, V, Marcos

Afiliação do(s) autor(es)

^[1] V, Univ Sao Paulo, Fac Med Vet & Zootecnia, Dept Nutr & Prod Anim, Pirassununga, SP - Brazil

^[2] Univ Fed Sao Paulo, Dept Biofis, Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Brazilian Journal of Microbiology; v. 49, n. 4, p. 801-807, OCT-DEC 2018.
• Citações Web of Science: 2

Resumo

ABSTRACT The present study aimed to compare two MALDI-TOF identification methods [(a) direct sample identification after pre-incubation; or (b) use of bacteria isolated on pre-culture)] to standard, traditional bench microbiology. A total of 120 quarter milk samples from 40 Holstein lactating cows were screened based on culture-positive results obtained by microbiological culture (reference method) with the following numbers of quarters positive per cow: 4 cows with 1, 8 cows with 2, 12 cows with 3 and 16 cows with 4 infected quarters per cow. For direct identification method, quarter milk samples (n = 120) were skimmed by centrifugation (10,000 × g/10 min) and pre-incubated at 37 ºC for 12 h. After pre-incubation, quarter milk samples were submitted to total bacterial count by flow cytometry and for a preparation protocol for bacterial ribosomal protein extraction followed by MALDI-TOF MS analysis. The direct MALDI-TOF MS identification method compared to microbiological culture correctly identified isolates of coagulase-negative Staphylococci (27.2%), Streptococcus agalactiae (21.8%), Staphylococcus aureus (14.2%), and Streptococcus uberis (5.2%). The pre-incubation protocol of milk samples, associated to the direct identification method by MALDI-TOF MS, did not increase the identification at species level (score >2.0) of pathogens causing subclinical mastitis in comparison to the method without previous incubation. (AU)

• Processo FAPESP: 11/15815-4 - Identificação rápida de microrganismos causadores de mastite por espectrometria de massas
• Beneficiário: Marcos Veiga dos Santos
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 11/14456-0 - Identificação rápida de microrganismos causadores de mastite por espectrometria de massas
• Beneficiário: Juliana Regina Barreiro
• Modalidade de apoio: Bolsas no Brasil - Doutorado