Original Research

Species identification and cow risks of non-aureus staphylococci from South African dairy herds

Inge-Marie Petzer, Christiaan Labuschagne, Lufuno Phophi, Joanne Karzis
Onderstepoort Journal of Veterinary Research | Vol 89, No 1 | a2021 | DOI: https://doi.org/10.4102/ojvr.v89i1.2021 | © 2022 Inge-Marie Petzer, Christiaan Labuschagne, Lufuno Phophi, Joanne Karzis | This work is licensed under CC Attribution 4.0
Submitted: 23 March 2022 | Published: 27 July 2022

About the author(s)

Inge-Marie Petzer, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
Christiaan Labuschagne, Inqaba Biotechnical Industries, Pretoria, South Africa
Lufuno Phophi, Department of Paraclinical Science, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
Joanne Karzis, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa


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Abstract

Detailed information on specific species of non-aureus staphylococci (NAS) has become a necessity for effective udder health control programs in South Africa. The main objective of this preliminary study was to identify the different NAS species and strains present in dairy herds in South Africa using a cost-effective method. A further objective was to investigate the effects of cow risk factors and farming systems on the NAS isolates identified. A total of 214 NAS, isolated from milk collected from 17 South African dairy herds, were identified using three diagnostic tests (API Staph test, MALDI-TOF and 16s rRNA). There was a good observed agreement between the MALDI-TOF and 16S rRNA sequencing (92.2%) and a poor observed agreement between the MALDI-TOF and API Staph (25.7%). The genetic relatedness within species was investigated in 128 of these isolates using random polymorphic amplified deoxyribonucleic acid (DNA) (RAPD), verified by multilocus sequence typing (MLST), and phylogenetic analysis and cow risk factors were investigated on species level. The main NAS species isolated were Staphylococcus chromogenes (75.2%), Staphylococcus epidermidis (9.4%) and Staphylococcus haemolyticus (8.9%). The RAPD test identified 34 Staphylococcus chromogenes, 13 Staphylococcus epidermidis and nine Staphylococcus haemolyticus strains, indicating genetic diversity amongst strains and herds. The presence of NAS intramammary infections was found to be significantly related to the farming systems, composite cow milk somatic cell count (SCC), parity and days in milk (DIM). Significantly more NAS were isolated from primiparous and from older cows. This knowledge could assist with the management of NAS on dairy farms.


Keywords

molecular epidemiology; NAS species identification; genetic diversity; cow risk factors; intramammary infection; dairy cows; South Africa

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