Bacterial pathogens associated with clinical and subclinical mastitis in a Mediterranean pasture-based dairy production system of Australia

L K Chung; S Sahibzada; H C Annandale; I D Robertson; F W Waichigo; M S Tufail; J A Aleri

doi:10.1016/j.rvsc.2021.10.005

Bacterial pathogens associated with clinical and subclinical mastitis in a Mediterranean pasture-based dairy production system of Australia

Res Vet Sci. 2021 Dec:141:103-109. doi: 10.1016/j.rvsc.2021.10.005. Epub 2021 Oct 7.

Authors

L K Chung¹, S Sahibzada², H C Annandale¹, I D Robertson³, F W Waichigo⁴, M S Tufail¹, J A Aleri⁵

Affiliations

¹ School of Veterinary Medicine, Murdoch University, 90 South Street, Murdoch 6150, WA, Australia.
² School of Veterinary Medicine, Murdoch University, 90 South Street, Murdoch 6150, WA, Australia; Antimicrobial Resistance and Infectious Diseases Research Laboratory, Murdoch University, 90 South Street, Murdoch 6150, WA, Australia.
³ School of Veterinary Medicine, Murdoch University, 90 South Street, Murdoch 6150, WA, Australia; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
⁴ Brunswick Veterinary Services, 27 Ommaney Road, Brunswick Junction, WA 6224, Australia.
⁵ College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Centre for Animal Production and Health, Future Foods Institute, Murdoch University, 90 South Street, Murdoch 6150, WA, Australia. Electronic address: J.Aleri@murdoch.edu.au.

PMID: 34710800
DOI: 10.1016/j.rvsc.2021.10.005

Abstract

Mastitis is an economically important production disease in the dairy industry worldwide. There is limited information on the aetiology of clinical mastitis (CM) and subclinical mastitis (SCM) in Australia's Mediterranean pasture-based production system. A prospective study was conducted in the south-west region of Western Australia to characterise the bacterial pathogens associated with CM and SCM cases and their associated antimicrobial susceptibility profiles. A total of 102 CM and 132 SCM milk samples were collected in twelve dairy farms between April 2020 and September 2020 recovering a total of 310 bacterial isolates. The isolates were evaluated for their antimicrobial susceptibility to twelve antibiotics using the agar disk diffusion (ADD) method. The most common pathogens associated with CM was Bacillus spp. (35.29%), followed by coagulase-negative staphylococci (CNS) (22.55%), Pseudomonas spp. (19.61%), Staphylococcus aureus (10.78%), Escherichia coli (5.88%) and Streptococcus uberis (2.94%). The most common pathogens associated with SCM was CNS (44.70%), followed by Bacillus spp. (30.30%), S. aureus (20.45%), Strep. uberis (15.91%), coliforms (Citrobacter spp., Cronobacter spp., Enterobacter spp., Klebsiella spp., Kosakonia spp., Morganella spp., Serratia spp.) (9.86%), environmental Streptococci (6.06%) and E. coli (6.06%). Beta-lactams resistance was the most common resistance observed in the Staphylococcal isolates and a high proportion of Streptococcal isolates exhibited resistance to enrofloxacin. Overall, the proportion of bacterial pathogens isolated in this study was comparable to the figures reported in other studies in Australia. Future research should focus on risk factors and the determination of resistant genetic components among the common isolates.

Keywords: Cows; Mastitis; Pasture-based production system; Staphylococcus aureus.

MeSH terms

Animals
Cattle
Cattle Diseases*
Escherichia coli
Female
Mastitis* / veterinary
Mastitis, Bovine* / epidemiology
Prospective Studies
Staphylococcus aureus