Identification of Enterococcus spp. by MALDI-TOF mass spectrometry isolated from clinical mastitis and bulk tank milk samples

• Published in: BMC veterinary research 2024-08, Vol.20 (1), p.378-7
• Main Authors: Guimarães, Felipe Freitas, Moraes, G N, Joaquim, S F, Guerra, S T, Dalanezi, F M, Mioni, M S R, Medeiros, F M H, Lucheis, S B, Possebon, F S, Pantoja, J C F, Ribeiro, M G, Rall, V L M, Hernandes, R T, Leite, D S, Langoni, H
• Format: Article
• Language: English
• Subjects: Animals; Bacteria; Brazil; Cattle; Causes of; Contamination; Dairy farm; Dairy industry; Diseases; E. Faecalis; E. Saccharolyticus; Enterococcus; Enterococcus - isolation & purification; Equipment and supplies; Female; Gram-Positive Bacterial Infections - diagnosis; Gram-Positive Bacterial Infections - microbiology; Gram-Positive Bacterial Infections - veterinary; Health aspects; Identification and classification; Infections; Mass spectrometry; Mass spectroscopy; Mastitis; Mastitis, Bovine - diagnosis; Mastitis, Bovine - microbiology; Matrix-assisted laser desorption/Ionization; Methods; Milk; Milk - chemistry; Milk - microbiology; Pathogens; Scientific imaging; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - veterinary; Time-of-flight mass spectrometry
• ISSN: 1746-6148; 1746-6148
• DOI: 10.1186/s12917-024-04217-2

Throughout a three-year study period, 1,577 bovine clinical mastitis samples and 302 bulk tank samples were analyzed from ten Brazilian dairy herds. Enterococcus spp. was isolated and identified in 93 (5.9%) clinical mastitis samples. In addition, 258 Enterococcus spp. were isolated from the bulk tank samples of the same herds. The identification of Enterococcus spp. isolated from bulk tanks and milk samples of clinical mastitis were accomplished by phenotypic characteristics and confirmed by MALDI-TOF Mass Spectrometry (MS). Fisher test was performed to verify the difference between bulk tanks and mastitis samples. The following species were identified from clinical mastitis: E. saccharolyticus (62.4%), E. faecalis (19.4%), E. faecium (15.1%), E. hirae (1.1%), E. mundtii (1.1%), E. durans (1.1%). Furthermore, from 258 bulk tank milk samples, eight enterococci species were isolated: E. faecalis (67.8%), E. hirae (15.1%), E. faecium (4.6%), E. saccharolyticus (4.6%), E. mundtii (3.1%), E. caseliflavus ( 2.7%), E. durans (1.2%), E. galinarum (0.8%). The difference in species predominance in bulk tank samples (67.8% of E. faecalis) and clinical mastitis (62.4% of E. saccharolyticus) was unexpected and caught our attention. Although Enterococcus spp. are traditionally classified as an environmental mastitis agent, in the present study, E. saccharolyticus behaved as a contagious agent of mastitis, which consequently changed the control patterns to be implemented.