Análise de aspectos de virulência, resistência aos antimicrobianos e diversidade genética de Staphylococcus aureus isolados de colonização nasal em puérperas
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Data
2024-06-22
Autores
Nilo, Ana Paula Marques Caldeira
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Universidade Federal do Espírito Santo
Resumo
Nasal colonization by Staphylococcus aureus in postpartum women is relevant due to the risk of colonization of newborns and of infections in both groups. This study aimed to evaluate the colonization rate, resistance, virulence, and genetic diversity of S. aureus isolated from nasal colonization in postpartum women. Nasal swabs were collected (n = 306) within 48h after birth in the maternity ward of a hospital in Brazil, between March/2018 and March/2019. Demographic data were obtained from medical records. Antimicrobial susceptibility was determined by the disk diffusion test and Minimum Inhibitory Concentrations (MICs) were obtained by broth microdilution. Biofilm production was evaluated using a polystyrene microplate test. Polymerase Chain Reaction (PCR) was used to perform SCCmec typing and detect the following adhesin and toxin genes: fnbB, clfA, clfB, cna, bbp, hla, hld, hlg, hlg-2, lukSF-PV, lukED, eta, etb, sea, seb, sec, sed, see and tsst-1. Genetic diversity was assessed by Random Amplified Polymorphic DNA (RAPD). The rate of S. aureus nasal colonization was 14.7% (45/306), with seven (15.6%) MRSA. The overall MRSA rate was 2.3% (7/306). Demographic data demonstrated an average age of 30 years, and high rates of unemployment (66.7%), multiparity (83.3%), and comorbidities (85.7%). High resistance rates to penicillin (88.9%) and erythromycin (53.3%) were observed. All MRSA isolates carried SCCmec type IVa and one was characterized as oxacilin-susceptible methicilin-resistant S. aureus (OS-MRSA). Most isolates (84.4%) were classified as strong biofilm producers. Several virulence genes were detected and the most prevalent were hld (93.3%), hla and eta (48.9%), and sea (42.2%). RAPD analysis identified 14 profiles. Profile J grouped 11 isolates (among them, five MRSA, one OS-MRSA, and one MSSA-MDR) and was the second with the greatest diversity of virulence genes (n = 14). The study highlights the high rates of toxin genes among nasal isolates of S. aureus in postpartum women, with emphasis on the genes for exfoliative toxin A and enterotoxin A. These toxins are relevant in puerperal mastitis and severe neonatal infections. This is the first report of an OS-MRSA isolate colonizing the anterior nares of postpartum women
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Staphylococcus aureus , Colonização nasal , Virulência , Toxinas esfoliativas , Puérperas