Caracterização molecular de estirpes de Staphylococcus aureus resistentes à meticilina isoladas em amostras de pus e sangue de pacientes atendidos no Hospital Central de Maputo

Abstract

Enterotoxin-producing and resistant strains of S. aureus constitute a threat to public health, especially in low- and middle-income countries, where second-line antibiotics are scarce, self-medication rates are high and there is a lack of monitoring and regulations that prohibit access to medicines without a prescription, contributing to the occurrence of high rates of morbidity and mortality due to S. aureus infection. Objective: To analyze resistance and virulence factors in S. aureus strains isolated from pus and blood samples from patients treated at the Maputo Central Hospital. Methodology: This is a retrospective cross-sectional descriptive study, carried out between February and July 2023, in which 53 strains of S. aureus were included (with a previously known antibiotic susceptibility profile) isolated from pus and blood samples of patients treated at the hospital Central Maputo, and preserved in the Biobank of the Faculty of Medicine. The resistance genes (mecA, femA) and virulence (spa, sei) were identified using the Polymerase Chain Reaction and the data were analyzed using frequencies made using the SPSS-21 statistical program and represented in tables made using the Microsoft Excel program. Results: In the 53 S. aureus isolates (22 sensitive and 31 resistant to methicillin) included in the study, mecA and femA resistance genes were detected in 20.8% (11/53) and 58.5% (31/53 ), respectively, and the virulence genes, spa and sei, were in turn detected in 92.5% (49/53) and in 11.3% (6/53), respectively. The coexistence of resistance and virulence genes was observed in 64.2% (34/53) of the isolates, where the femA+spa+ combination was observed in 50.0%, the mecA+femA+spa+ combination was observed in 32.0 % and the combination femA+spa+sei+ and spa+sei+ in 9.0% of the isolates. Conclusion: S. aureus strains isolated from patients treated at the Maputo Central Hospital contain mecA and femA genes associated with methicillin resistance and the sei and spa genes associated with virulence. Among these strains, some present different combinations of resistance and virulence genes, which suggests their high pathogenicity. The study proposes continued surveillance and molecular characterization of S. aureus infections, including the application of prevention and control measures (TRADUÇÃO NOSSA)