(MALDI-TOF MS) FOR IDENTIFICATION OF COAGULASE NEGATIVE Staphylococcus

CONESA A.; BARBERIS C.; BONETTO C.; PELLEGRINO M.; DIESER S.; VAY C; PORPORATTO C.; RASPANTI C.

Capital Federal

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

Sociedades de Biociencias

Coagulase-negative Staphylococcus (CNS) are the predominant pathogens causing bovine mastitis. Correct identification is essential to understand the involvement of CNS in intramammary infections (IMI) and make appropriate management decisions. The aim of the present study was to evaluate the performances of gap or groEL genes PCR-restriction fragment length polymorphism (PCRRFLP) as reliable reference methods for Staphylococcus speciesidentification in comparison to matrix-assisted laser desorption ionization?time of flight mass spectrometry (MALDI-TOF MS), which can differentiate microorganisms based on their protein profiles. In this study, we identified 114 CNS isolates from bovine IMI at species level by MALDI-TOF MS as the definitive test. Based on previous studies, a cut-off score >1,7 was considered for species level identification. The identification obtained using this method wascompared to results from the gap and groEL PCR-RFLP analysis. The partial gap and groEL genes (approximately 931 and 550 bp, respectively) were successfully amplified by PCR from ATCC control strains and CNS isolates from IMI. The size and number of the fragments obtained by Alul digestions made possible to form distinctive gap and groEL PCR-RFLP patterns. Only 49% (56/114) of thespecies identification results obtained by groEL PCR-RFLP matched those obtained by MALDI-TOF MS, whereas 96,5% (110/114) of the species identification results obtained by the gap PCR-RFLP analysis matched those obtained by MALDI-TOF MS. Only three strains were misidentified, two S. chromogenes strains were assigned as S. haemolyticus and S. warneri, and one S. xylosus strain as S. chromogenes.In this way, the gap PCR-RFLP analysis could be a useful and reliable alternative method for the species identification of CNS isolates from bovine IMI and appears to be a more accurate method of species identification than the groEL PCR-RFLP.