Prevalence of subclinical mastitis and antimicrobial resistance profiles in dairy cows from a milk collection centre in Tahualag, Ecuador: Subclinical mastitis in dairy cows in Ecuador

Oscar Patricio Nuñez; Hirma Quinzo-Padilla; Roberto Almeida; Orlando  Quinteros; Gabriela  Ordóñez; Byron Borja

doi:10.62310/liab.v6i1.324

Authors

Oscar Patricio Nuñez Facultad de Ciencias Agropecuarias, Universidad Técnica de Ambato, Cevallos, Ecuador https://orcid.org/0000-0001-9593-5850
Hirma Quinzo-Padilla Facultad de Ciencias Agropecuarias, Universidad Técnica de Ambato
Roberto Almeida Facultad de Ciencias Agropecuarias, Universidad Técnica de Ambato, Cevallos, Ecuador https://orcid.org/0000-0002-4893-959X
Orlando Quinteros Facultad de Ciencias Agrarias, Universidad Estatal de la Península de Santa Elena, La Libertad, Ecuador https://orcid.org/0000-0002-3808-257X
Gabriela Ordóñez Facultad de Ciencias Agrarias, Universidad Estatal de la Península de Santa Elena, La Libertad, Ecuador https://orcid.org/0000-0003-3084-1997
Byron Borja Facultad de Ciencias Agropecuarias, Universidad Técnica de Ambato, Cevallos, Ecuador https://orcid.org/0000-0002-6659-8557

DOI:

https://doi.org/10.62310/liab.v6i1.324

Keywords:

Antimicrobial resistance, Subclinical mastitis, California mastitis test, Dairy cattle, Ecuador

Abstract

Subclinical mastitis remains a major constraint to dairy productivity in smallholder systems, however, Ecuador-specific evidence describing pathogen profiles and antimicrobial susceptibility patterns is still limited. This cross-sectional study estimated cow-level prevalence of subclinical mastitis using the California Mastitis Test (CMT) and characterised bacterial isolates and their antimicrobial susceptibility among dairy cows supplying a milk collection centre in Tahualag, Ecuador. Seventy clinically healthy lactating cows were screened at the quarter level using CMT, and cows with at least one CMT-positive quarter were classified as positive. Milk samples from CMT-positive cows (n = 13) were cultured using standard bacteriological techniques, and antimicrobial susceptibility was assessed using the Kirby-Bauer disk diffusion method. Results were classified as susceptible, intermediate, or resistant. Thirteen of 70 cows tested CMT-positive, corresponding to a cow-level prevalence of 18.6% (95% CI: 11.2–29.2). No significant differences were observed in the distribution of CMT-positive quarters or among cow age groups. Staphylococcus aureus was identified as the most common pathogen (38.5%), followed by other Staphylococcus spp. and coagulase-positive staphylococci (23.1% each). Streptococcus uberis and S. dysgalactiae were each detected in 7.7% of samples. Antimicrobial susceptibility profiles varied, particularly among staphylococcal isolates, with resistance observed to selected antimicrobial compounds. These findings confirm the presence of subclinical mastitis in Ecuadorian smallholder dairy systems and indicate that infections are predominantly associated with staphylococcal pathogens, underscoring the importance of improved milking hygiene and locally informed antimicrobial management.

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