Molecular Epidemiology of Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus in Wild, Captive and Laboratory Rats: Effect of Habitat on the Nasal S. aureus Population.

Dina Raafat,Karsten Becker,Bernd Walther,Stefan Monecke,Sarah Van Alen,Silva Holtfreter,Rainer G Ulrich,Birgit Strommenger,Werner Nicklas,Uta Westerhüs,Elisa Heuser,Jens Jacob,Kathleen R Pritchett-Corning,Fawaz Al’Sholui,Daniel M Mrochen,Jens Van Den Brandt,René Ryll,Franz‐Rainer Matuschka ,Jiří Pikula ,D Richter

doi:10.3390/toxins12020080

Abstract

Rats are a reservoir of human- and livestock-associated methicillin-resistant Staphylococcus aureus (MRSA). However, the composition of the natural S. aureus population in wild and laboratory rats is largely unknown. Here, 144 nasal S. aureus isolates from free-living wild rats, captive wild rats and laboratory rats were genotyped and profiled for antibiotic resistances and human-specific virulence genes. The nasal S. aureus carriage rate was higher among wild rats (23.4%) than laboratory rats (12.3%). Free-living wild rats were primarily colonized with isolates of clonal complex (CC) 49 and CC130 and maintained these strains even in husbandry. Moreover, upon livestock contact, CC398 isolates were acquired. In contrast, laboratory rats were colonized with many different S. aureus lineages—many of which are commonly found in humans. Five captive wild rats were colonized with CC398-MRSA. Moreover, a single CC30-MRSA and two CC130-MRSA were detected in free-living or captive wild rats. Rat-derived S. aureus isolates rarely harbored the phage-carried immune evasion gene cluster or superantigen genes, suggesting long-term adaptation to their host. Taken together, our study revealed a natural S. aureus population in wild rats, as well as a colonization pressure on wild and laboratory rats by exposure to livestock- and human-associated S. aureus, respectively.

Highlights

Staphylococcus aureus (S. aureus) is a major opportunistic pathogen in human medicine and it is increasingly recognized as a zoonotic pathogen
A total of 188 captive wild rats originating from three German federal states and held in laboratory housing or large enclosures for several years were investigated for S. aureus nasal carriage (Tables S3 and S4)
S. aureus isolates from 52 laboratory rats held in Germany, USA, Japan and Canada were analyzed (Table S5)

Summary

Introduction

Staphylococcus aureus (S. aureus) is a major opportunistic pathogen in human medicine and it is increasingly recognized as a zoonotic pathogen. The nasal cavity of approximately 20% of adult humans is persistently and asymptomatically colonized with S. aureus [1,2,3] These bacteria can cause a wide variety of illnesses, ranging from skin and soft tissue infections (e.g., abscesses) to life-threatening diseases (e.g., endocarditis and sepsis) [4]. MRSA, CA-MRSA) strains makes S. aureus a prominent example of the antibiotic resistance crisis and a major public health concern worldwide [5,6,7]. This medical predicament is especially heightened by the fact that to date, no S. aureus vaccine is available [8]. Transmission of MRSA occurs primarily upon person-to-person contact, but MRSA can spread between domestic animals and people [14,15]

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