ANALYSIS OF ASPECTS OF VIRULENCE, RESISTANCE TO ANTIMICROBIALS AND GENETIC DIVERSITY OF Staphylococcus aureus ISOLATED FROM NASAL COLONIZATION IN PUERPERAL WOMEN
Name: ANA PAULA MARQUES CALDEIRA NILO
Publication date: 22/05/2024
Examining board:
Name |
Role |
|---|---|
| FERNANDA SAMPAIO CAVALCANTE | Examinador Externo |
| MOISES PALACI | Examinador Interno |
| RICARDO PINTO SCHUENCK | Presidente |
Summary: Nasal colonization by Staphylococcus aureus in postpartum women is relevant due to the risk of colonization in newborns and infections in both groups. The objective of this study was 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 48 hours after birth in the maternity ward of a hospital in Vitória – ES, between March/2018 and March/2019. Demographic data were obtained from the patients' 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. The 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 nasal colonization by S. aureus was found to be 14.7% (45/306), with seven (15.6%) being resistant to methicillin (MRSA). The overall rate of MRSA was 2.3% (7/306). The average age of patients was 30 years, with high rates of unemployment (66.7%), multiparity (83.3%) and comorbidities (85.7%). The majority of isolates were resistant to penicillin (88.9%) and erythromycin (53.3%). All MRSA isolates presented SCCmec type IVa and one was characterized as OS-MRSA (oxacillin-susceptible methicillin-resistant S. aureus). The majority (84.4%) were 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 was the second with the greatest diversity of virulence genes (n = 14) and grouped 11 isolates (among them, five MRSA, one OS-MRSA and one MSSA-MDR). The study highlights the high rates of toxin genes among nasal isolates of S. aureus in postpartum women, with emphasis on the genes encoding 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.
