Virulence Factors Found in Nasal Colonization and Infection of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates and Their Ability to Form a Biofilm

Thamiris Santana Machado,Renata Freire Alves Pereira,Lialyz Soares Pereira Andre,Felipe Ramos Pinheiro,Gabriela Coutinho De Mello,Daniela Sachs,Reginaldo Fernandes Correa,Fábio Aguiar-Alves,Bruno Penna,Tainara Aparecida Nunes Ribeiro

doi:10.3390/toxins13010014

Thamiris Santana Machado, Renata Freire Alves Pereira + Show 8 more

Open Access

https://doi.org/10.3390/toxins13010014

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Abstract

Hospitalizations related to Methicillin-resistant Staphylococcus aureus (MRSA) are frequent, increasing mortality and health costs. In this way, this study aimed to compare the genotypic and phenotypic characteristics of MRSA isolates that colonize and infect patients seen at two hospitals in the city of Niterói—Rio de Janeiro, Brazil. A total of 147 samples collected between March 2013 and December 2015 were phenotyped and genotyped to identify the protein A (SPA) gene, the mec staphylococcal chromosomal cassette (SCCmec), mecA, Panton-Valentine Leucocidin (PVL), icaC, icaR, ACME, and hla virulence genes. The strength of biofilm formation has also been exploited. The prevalence of SCCmec type IV (77.1%) was observed in the colonization group; however, in the invasive infection group, SCCmec type II was prevalent (62.9%). The Multilocus Sequence Typing (MLST), ST5/ST30, and ST5/ST239 analyses were the most frequent clones in colonization, and invasive infection isolates, respectively. Among the isolates selected to assess the ability to form a biofilm, 51.06% were classified as strong biofilm builders. Surprisingly, we observed that isolates other than the Brazilian Epidemic Clone (BEC) have appeared in Brazilian hospitals. The virulence profile has changed among these isolates since the ACME type I and II genes were also identified in this collection.

Highlights

More than 30% of the healthy population is colonized by Staphylococcus aureus, making these subjects vehicles of dissemination of this pathogen [1]
The largest number of samples has been collected from the Intensive Care Unit (ICU), followed by the infection ward and Neonatal
A recent study showed that the prevalence of high-income children colonized by Methicillin-resistant Staphylococcus aureus (MRSA) in Brazil is similar to the rates found worldwide

Summary

Introduction

More than 30% of the healthy population is colonized by Staphylococcus aureus, making these subjects vehicles of dissemination of this pathogen [1]. A high degree of similarity between nasal colonization and invasive infection isolates collected from the same patient has already been demonstrated [7,8,9], reinforcing the importance of detecting the presence of the nasal colonization and particular characteristics that could be responsible for this pathogen success and future infection development. Besides these observations, invasive nosocomial infections caused by multidrug-resistant microorganisms have been growing in recent years and account for approximately 15.5% of cases recorded worldwide [10]. It occurs due to modifications of its binding site for the altered Penicillin

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