Absence of Staphylococcus aureus in Wild Populations of Fish Supports a Spillover Hypothesis
Marta Matuszewska, Alicja Dabrowska, Gemma G. R. Murray, Steve M. Kett, Andy J. A. Vick, Sofie C. Banister, Leonardo Pantoja Muñoz, Peter S. Cunningham, John J. Welch, Mark A. Holmes, Lucy A. Weinert
Abstract
Staphylococcus aureus is a human and livestock commensal but also an important pathogen responsible for high human mortality rates and economic losses in farming. Recent studies show that S. aureus is common in wild animals, including fish. However, we do not know whether these animals are part of the normal host range of S. aureus or whether infection is due to repeated spillover events from true S. aureus hosts. Answering this question has implications for public health and conservation. We find support for the spillover hypothesis by combining genome sequencing of S. aureus isolates from farmed fish and screens for S. aureus in isolated wild populations. The results imply that fish are unlikely to be a source of novel emergent S. aureus strains but highlight the prominence of the spillover of antibiotic-resistant bacteria from humans and livestock. This may affect both future fish disease potential and the risk of human food poisoning.