Description and Interrelationship Analysis of the Phenotypic and Genotypic Characteristics of MSSA and MRSA Strains Isolated From Healthcare Workers in North-eastern Brazil

Abstract

Purpose: This study therefore sought to analyse the interrelationship between the phenotypic and genotypic characteristics of methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA strains isolated from healthcare workers in north-eastern Brazil.Patients and methods: Staphylococcus aureus strains were isolated from nasal mucosa of nursing professionals. They are identified by biochemical analysis and the sensibility drug test were carried out by agar diffusion method. Biofilm formation was detected on the polystyrene plastic surface. Molecular characterization was conducted by polymerase chain reaction (PCR). The Chi-squared or Fisher's exact tests were applied for the analysis of associations between phenotypic and genotypic characteristics.Results: A total of 118 workers were involved, 49.15% of whom presented S. aureus. The most frequently observed strain was resistance to penicillin (86.21%), while the inducible clindamycin resistance (iMLSB) phenotype was detected in 48.84% of isolates. MRSA was found in 41.37% of isolates, while SCCmec type I was seen in 75%. A strain with intermediate resistance to vancomycin was also found. In terms of virulence genes, eta, tst, pvl, spa, clfA, icaA, icaC and icaD genes were detected at least once. Biofilm formation was detected in 89.65% of the strains - 18.97% of these were classified as strongly adherent. No associations with ica genes were detected. Multivariate analyses of clusters demonstrated variability between the strains, with the notable formation of three main clusters, according to phenotypic and genotypic characteristics.Conclusion: High prevalence, multidrug resistance and presence of MRSA strains were all observed. Most isolates had significant virulence genes and the ability to form biofilms, increasing the severity of potential infections. It is therefore necessary to monitor the strains circulating in this hospital and to intensify precautionary measures in order to prevent their spread.