Diversity of Staphylococcus aureus isolated from nares of ruminants

Staphylococcus aureus plays a central role in infections occurring in humans and animals worldwide and depending on the present and expressed virulence factors, various clinical manifestations can appear in both of them. These manifestations can range from a mild infection to septicaemia. Particularly in ruminants, Staphylococcus aureus is primarily known and feared as a mastitis pathogen. Due to the proximity of cattle to humans and the importance of dairy as a food product, mastitis poses a health threat to humans, in addition to severe economic problems. This is of particular interest in countries where animal husbandry plays a major role, such as in the Sub-Saharan African countries. In addition, many countries within this region lack biosecurity measures, medical care is generally inferior, and food products undergo much less monitoring and quality control, which represent further risk factors for foodborne infections. The aim of this study was to analyse the diversity of Staphylococcus aureus from nasal swab samples from ruminants in Rwanda in order to understand its zoonotic potential, enhance food safety, and address public health risks in a region with limited biosecurity and a strong reliance on livestock. In this study 30 S. aureus isolates were detected, which were assigned to eight different spa types. This spa types further belonged to six different clonal complexes. Resistance to penicillin and tetracycline was detected and the presence of the Panton-Valentine leukocidin (PVL) genes (lukF-PV/lukS-PV), the bovine leukocidin genes (luk-F-P83/lukM) and the human and bovine variants of the toxic shock syndrome toxin gene (tst-1) was observed. Further investigation is needed to determine whether there is an association between the presence of the same Staphylococcus aureus strain in the milk of mastitis-affected animals and in humans living in the same region of Rwanda. This is especially crucial for a better understanding of the risk it can pose to consumers, especially in relation to antibiotic resistance. Finally, it is important to consider the nasal mucosa of ruminants as a reservoir for mastitis associated Staphylococcus aureus isolates.