Nasal Carriage by Staphylococcus aureus among Healthcare Workers and Students Attending a University Hospital in Southern Brazil: Prevalence, Phenotypic, and Molecular Characteristics

Tiago Danelli; Felipe Crepaldi Duarte; Thilara Alessandra de Oliveira; Raquel Soares da Silva; Daniela Frizon Alfieri; Guilherme Bartolomeu Gonçalves; Caio Ferreira de Oliveira; Eliandro Reis Tavares; Lucy Megumi Yamauchi; Marcia Regina Eches Perugini; Sueli Fumie Yamada-Ogatta

doi:10.1155/2020/3808036

Nasal Carriage by Staphylococcus aureus among Healthcare Workers and Students Attending a University Hospital in Southern Brazil: Prevalence, Phenotypic, and Molecular Characteristics

Interdiscip Perspect Infect Dis. 2020 Dec 3:2020:3808036. doi: 10.1155/2020/3808036. eCollection 2020.

Authors

Tiago Danelli¹, Felipe Crepaldi Duarte¹, Thilara Alessandra de Oliveira¹, Raquel Soares da Silva¹, Daniela Frizon Alfieri², Guilherme Bartolomeu Gonçalves³, Caio Ferreira de Oliveira³, Eliandro Reis Tavares^{4

5}, Lucy Megumi Yamauchi^{3

4}, Marcia Regina Eches Perugini^{1

2}, Sueli Fumie Yamada-Ogatta^{1

3

4}

Affiliations

¹ Programa de Pós-graduação em Fisiopatologia Clínica e Laboratorial, Universidade Estadual de Londrina-Rodovia Celso Garcia Cid, PR 445 km 380, Campus Universitário, Londrina, Paraná, Brazil.
² Departamento de Patologia, Análises Clínicas e Toxicológicas, Centro de Ciências da Saúde, Universidade Estadual de Londrina, Londrina, Brazil.
³ Programa de Pós-graduação em Microbiologia, Universidade Estadual de Londrina, Londrina, Brazil.
⁴ Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil.
⁵ Programa Nacional de Pós-Doutorado-CAPES, Universidade Estadual de Londrina, Londrina, Brazil.

Abstract

Background: Staphylococcus aureus can asymptomatically colonize the human anterior nares and skin, and nasal colonization by this bacterium represents a potential risk for development of invasive infections. The aim of this study was to determine the prevalence of S. aureus nasal carriage among healthcare workers and students attending a university hospital and to characterize the isolates phenotypically and molecularly.

Methods: A cross-sectional study was performed with 324 volunteers. Cultures from nasal samples were obtained and S. aureus isolates were characterized according to their antimicrobial susceptibility profile and four virulence factors-encoding genes. MRSA isolates were characterized regarding their oxacillin/cefoxitin susceptibility, SCCmec, and REP-PCR types. Potential risks for S. aureus and MRSA carriage were analyzed.

Results: Of 324 nasal samples, 42.9% were identified as S. aureus, of which 28.8% were MRSA. S. aureus carriers were significantly higher in males and students (OR = 2.898, 95%CI 1.553-5.410); however, no variables were associated with MRSA carriage. All isolates were susceptible to vancomycin and the highest rate of resistance was observed for penicillin (90.6%). All isolates harbored the coa gene, and 97.8%, the icaA gene; 15.8% and 6.5% were positive for tst and lukS-PV/lukF-PV genes, respectively. Among MRSA isolates, 45% carried the mecA gene but were phenotypically susceptible to oxacillin/cefoxitin; two harbored the tst and none had lukS-PV/lukF-PV genes. All MRSAs were distributed into six SCCmec types and type I (62.5%) was the most frequent. REP-PCR typing identified four main clusters among MRSA isolates.

Conclusion: High prevalence of healthcare workers and students were identified as nasal carriers of S. aureus exhibiting different antimicrobial resistance profiles, including mecA-positive oxacillin-susceptible S. aureus (OS-MRSA) and the presence of virulence-encoding genes. Both cohorts may represent potential sources for the emergence of a successful S. aureus strain highly adapted to the hospital environment.