Comparison of standard and on-plate extraction protocols for identification of mastitis-causing bacteria by MALDI-TOF MS

Autor(es)

Barcelos, M. M. ^[1] ; Martins, L. ^[1] ; Grenfell, R. C. ^[2] ; Juliano, L. ^[2] ; Anderson, K. L. ^[3] ; dos Santos, M. V. ^[1] ; Goncalves, J. L. ^{[3, 1]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Anim Sci, 225 Duque Caxias Norte Ave, BR-13635900 Pirassununga, SP - Brazil

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

^[3] North Carolina State Univ, Coll Vet Med, Dept Populat Hlth & Pathobiol, Raleigh, NC 27695 - USA

• Tipo de documento: Artigo Científico
• Fonte: Brazilian Journal of Microbiology; v. 50, n. 3, p. 849-857, JUL 2019.
• Citações Web of Science: 0

Resumo

The objective was to compare standard versus on-plate sample preparation protocols for identification of mastitis bacteria by MALDI-TOF MS. A total of 186 bacterial isolates from cows with subclinical mastitis were identified by MALDI-TOF MS after preparation using two extraction protocols. On-plate protocol was performed by applying the bacterial colony directly from the culture plate onto the plate spot. For the standard protocol, lysis of bacterial colonies using reagents was performed in a cryotube, and the resulting extract was applied onto the plate spot for analysis. The on-plate protocol showed a similar bacteria identification rate (91.4%, n = 170/186) in comparison to the standard (94.6%, n = 176/186). Identification was higher for both protocols when scores used for species-level identification (>= 2.0) was reduced to genus-level (>= 1.7); genus-level identification score rate increased from 94.6 to 100% when using the standard protocol, and from 91.4 to 94.6% when using the on-plate protocol. However, when compared standard (as gold standard) versus on-plate protocol, genus-level identification score rate ranged from 87.1 to 89.8%. Therefore, when the on-plate protocol fails to identify any specie, the standard extraction may be more suitable as a reference protocol for use. Strategy for increasing identification with the on-plate protocol may include upgrading the reference database library. Choice of protocol for preparation may be influenced by the bacterial type to be identified. Standard and on-plate extraction protocols of bacterial ribosomal proteins associated with MALDI-TOF MS might be alternatives to conventional microbiology methods for identification of subclinical mastitis pathogens. (AU)

• Processo FAPESP: 13/23613-8 - Impacto da mastite subclínica sobre custo de produção e qualidade do leite em rebanhos leiteiros
• Beneficiário: Juliano Leonel Gonçalves
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 14/22076-1 - Identificação de patógenos primários isolados de infecção intramamária subclínica pela técnica de espectrometria de massas por ionização e dessorção à laser assistida por matriz
• Beneficiário: Melina Melo Barcelos
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 14/17411-6 - Impacto econômico e perfil de agentes etiológicos da mastite bovina
• Beneficiário: Marcos Veiga dos Santos
• Modalidade de apoio: Auxílio à Pesquisa - Regular