Estudo epidemiológico molecular e avaliação da produção de biofilme em cepas clínicas multirresistentes de Acinetobacter baumannii

Abstract

Introduction: The persistence and survival of biofilm-forming multidrug-resistant Acinetobacter baumannii in various hospital settings has made it one of the leading causes of Healthcare-associated Infections (HAIs) worldwide. Objectives: To investigate the determinants of virulence, resistance. and clonal profile, as well as to assess the phenotypic production of biofilm in clinical isolates of Acinetobacter baumannii from hospitalized patients in a tertiary care center located in the state of Minas Gerais, Brazil. Materials and Methods: Nine clinical strains of A. baumannii collected from December 2021 and December 2023 were examined. Demographic and clinical data, along with the patient's clinical outcomes, were obtained from the medical records. Phenotypic biofilm formation was assessed using the adhesion, crystal violet biomass production and viable cell count techniques, while the detection of virulence and resistance genes (basG, basJ, plcD, hcp, tssM, bfmS, bap, csuE, csuA, adeH, pgaA, abaI and ptk, blaOXA-51 and blaOXA-23) was performed using conventional Polymerase Chain Reaction (PCR). Molecular typing was carried out by Pulsed-Field Gel Electrophoresis (PFGE). Results: All the strains were classified as multidrug-resistant, showing resistance to carbapenems and some to colistin. Most of the patients evaluated were elderly women with comorbidities, using invasive devices and previously treated with antibiotics, and a mortality rate of 88.9% was observed. Biofilm production was observed in 44.4% of the strains, regardless of the resistance profile. All the isolates carried at least 10 virulence genes, with a predominance of the basG, basJ, plcD, bfmS, csuE, adeH and pgaA genes (100%). The blaOXA-51 gene was present in all the strains, while the blaOXA-23 gene was identified in seven of them (66.7%). Clonal diversity was evidenced by the four pulsotypes (A-D) detected, along with the identification of clones A and B. Conclusion: This study highlights the presence of A. baumannii in critically ill patients, with an important frequency of biofilm-producing multidrug-resistant strains carrying several virulence genes, as well as a diversity of identified pulsotypes. Infection prevention and control strategies are crucial to mitigate the spread of these isolates in hospital settings.