The Prevalence of Virulence Determinants and Antibiotic Resistance Patterns in Methicillin-Resistant Staphylococcus aureus in a Nursing Home in Poland.

Martyna Kasela,Anna Malm,Bożena Nowakowicz-Dębek,Agnieszka Grzegorczyk

doi:10.3390/pathogens10040427

Abstract

Nursing homes (NH) contribute to the regional spread of methicillin-resistant Staphylococcus aureus (MRSA). Moreover, residents are vulnerable to the colonization and subsequent infection of MRSA etiology. We aimed at investigating the molecular and phenotypic characteristics of 21 MRSA collected from the residents and personnel in an NH (Lublin, Poland) during 2018. All MRSA were screened for 20 genes encoding virulence determinants (sea-see, eta, etb, tst, lukS-F-PV, eno, cna, ebpS, fib, bbp, fnbA, fnbB, icaADBC) and for resistance to 18 antimicrobials. To establish the relatedness and clonal complexes of MRSA in NH we applied multiple-locus variable-number tandem-repeat fingerprinting (MLVF), pulse field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing. We identified four sequence types (ST) among two clonal complexes (CC): ST (CC22) known as EMRSA-15 as well as three novel STs—ST6295 (CC8), ST6293 (CC8) and ST6294. All tested MRSA were negative for sec, eta, etb, lukS-F-PV, bbp and ebpS genes. The most prevalent gene encoding toxin was sed (52.4%; n = 11/21), and adhesins were eno and fnbA (100%). Only 9.5% (n = 2/21) of MRSA were classified as multidrug-resistant. The emergence of novel MRSA with a unique virulence and the presence of epidemic clone EMRSA-15 creates challenges for controlling the spread of MRSA in NH.

Highlights

Published: 3 April 2021Staphylococcus aureus is a major human opportunistic pathogen causing a wide variety of infections both in hospital settings and in the community [1]
Among all S. aureus strains collected from the participants, 8.2% were identified as methicillin-resistant Staphylococcus aureus (MRSA) (21/256)
We found that none of the MRSA isolated in our study were resistant to fusidic acid and mupirocin, which implies good chances for successful eradication therapy when needed

Summary

Introduction

Published: 3 April 2021Staphylococcus aureus is a major human opportunistic pathogen causing a wide variety of infections both in hospital settings and in the community [1]. Two main MRSA subpopulations are listed, i.e., hospital-associated (HA-MRSA) and community-associated (CA-MRSA) While the former are mainly isolated from hospitalized patients, the latter are usually characterized by a higher virulence but lower antimicrobial resistance and often infect people without significant risk factors for the infection development [3,4]. Infections of MRSA etiology cause multiple therapeutic issues, because of resistance to β-lactam antibiotics and growing resistance to other classes of antimicrobial agents currently used [5]. Another feature enhancing MRSA pathogenicity is the production of toxins and adhesion factors. Adhesins mediate the effective attachment to host tissues, colonization and biofilm formation but are responsible for escaping the host’s immune

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Discussion

Conclusion