Molecular Characterization of Rifampicin-Resistant Staphylococcus aureus Isolates from Retail Foods in China.

Qihui Gu,Yu Ding,Jiahui Huang,Jingsha Dai,Jumei Zhang,Shi Wu,Liang Xue,Miao Zhao,Juan Wang,Moutong Chen,Dongli Rong,Feng Zhang,Qingping Wu

doi:10.3390/antibiotics10121487

Abstract

This study investigated the molecular characteristics of rifampin-resistant (RIF-R) Staphylococcus aureus isolates recovered from 4300 retail food samples covering most provincial capitals in China, from 2011 to 2016. Of the 1463 S. aureus enrolled, 149 isolates (142 MSSA and 7 MRSA) were identified as rifampicin-resistant, including 20 high-level (MICs ≥ 8 μg/mL) and 129 low-level (MICs between 2 and 4 μg/mL) rifampicin-resistant strains. Most of the RIF-R S. aureus isolates were resistant to more than three antibiotics. The mutations in the rifampicin resistance-determining region of the rpoB gene were studied in all RIF-R strains. All of the strains presented the mutational change 481 His/Asn and five isolates presented an additional mutation, including 477 Asp/Tyr, 527 Ile/Met, and 466 Leu/Ser, respectively. Thirteen STs and twenty-one spa types were represented, in which five MRSA showed non-type SCCmec and the remaining MRSA belonged to SCCmec type IV—where, ST1-t127 was the predominant type from all of the isolates, while ST398-t034 was the predominant type for the MRSA isolates. In this study, we found that the food-related RIF-R S. aureus may have a unique genetic background selection. However, the scenario regarding the presence of RIF-R S. aureus, especially MRSA, in retail food in China is not favorable and warrants public attention.

Highlights

Staphylococcus aureus is a versatile pathogens capable of causing nosocomial and community-acquired infections [1]
The prevalence rate of RIF-R S. aureus isolates in food the food we examined in China was not low, which should be brought to public attention
RIF-R S. aureus isolates were observed in most animalderived types of food samples and rare in other types of food

Summary

Introduction

Staphylococcus aureus is a versatile pathogens capable of causing nosocomial and community-acquired infections [1]. It is one of the most important foodborne microorganisms, for which its pathogenicity affects human’s health through staphylococcal enterotoxins (SEs). The first food poisoning event caused by staphylococci occurred in 1884 [2]. It has been found in food producing chains, for example the equipment used for the production of food and in contaminated ingredients and so on [3,4]. In China, the prevalence of S. aureus-contaminated retail food increased over time [8]

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