The Genomic Context for the Evolution and Transmission of Community-Associated Staphylococcus aureus ST59 Through the Food Chain

Rui Pang,Moutong Chen,Shi Wu,Youxiong Zhang,Haoming Wu,Qihui Gu,Zhenwen Zhou,Wenzhi Li,Qingping Wu,Junhui Zhang,Jumei Zhang,Feng Zhang,Yu Ding,Bingshao Liang,Jiahui Huang,Yanping Li,Xianhu Wei

doi:10.3389/fmicb.2020.00422

Abstract

Sequence type 59 (ST59) is a predominant clonal lineage of community-acquired, methicillin-resistant Staphylococcus aureus (CA-MRSA) in Asia. Despite its increasing clinical relevance in China, the evolution and geographic expansion of ST59 has been relatively uncared for. Previous study has shown that ST59 was the predominant clone in food-related MRSA in China. This study compared the genomes of 87 clonal complex (CC) 59 S. aureus isolates sourced from food chain and infection cases to reconstruct the molecular evolution and geographical spread of ST59. Accordingly, three major sub-clades of ST59 were identified and these did not correlate with isolation source or location. Phylogenetic analysis estimated that ST59 in mainland China diverged from a most common recent ancestor around 1974, and most of the cases of cross-country transmission occurred between 1987 and 2000. Notably, two recent events of cross-country transmission through the food chain were observed, the isolates from these events diverged within relatively short time intervals. These isolates also showed high similarity in terms of their core genome, accessory genes, and antibiotic resistance patterns. These findings provide a valuable insight into the potential route of ST59 expansion in China and indicate a need for robust food chain surveillance to prevent the spread of this pathogen.

Highlights

Staphylococcus aureus is an opportunistic pathogen that causes serious community- and hospitalacquired disease; it accounts for the majority of skin and soft tissue infections in humans, and is a causative agent of infective endocarditis, necrotizing pneumonia, septicemia, and toxic shock syndrome (Lowy, 1998; Diep et al, 2006)
CA-methicillin-resistant Staphylococcus aureus (MRSA) isolates primarily belong to a subset of clonal lineages and possess specific staphylococcal cassette chromosome mec (SCCmec) elements, which confer methicillin resistance, and the phage-encoded toxin, PantonValentine leukocidin (PVL), which contributes to skin and soft tissue infections (Otto, 2013)
Most of these transmission pathways lack regularity, making it difficult to determine the origin of the MRSA clone, especially when clones have spread across the country

Summary

Introduction

Staphylococcus aureus is an opportunistic pathogen that causes serious community- and hospitalacquired disease; it accounts for the majority of skin and soft tissue infections in humans, and is a causative agent of infective endocarditis, necrotizing pneumonia, septicemia, and toxic shock syndrome (Lowy, 1998; Diep et al, 2006). Staphylococcus aureus ST59 Food Chain-Transmission of methicillin-resistant Staphylococcus aureus (MRSA) infections, which have emerged as a major public health concern. CA-MRSA isolates primarily belong to a subset of clonal lineages and possess specific staphylococcal cassette chromosome mec (SCCmec) elements, which confer methicillin resistance, and the phage-encoded toxin, PantonValentine leukocidin (PVL), which contributes to skin and soft tissue infections (Otto, 2013). The evolution and expansion of S. aureus ST59 in this region has been relatively understudied

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