| Congresso Brasileiro de Microbiologia 2023 | Resumo: 635-1 | ||||
Resumo:A. baumannii (Ab), being an opportunistic pathogen, gained advert importance due to its emerging multidrug-resistant (MDR) characteristics and the presence of virulence attributes, including biofilm formation. The superior capability of Ab strains to produce biofilms significantly facilitates its colonization on biotic and abiotic surfaces and, consequently, its persistence in the hospital-environment, which increases the probability of healthcare-associated infections. Furthermore, the biofilm formation has led to an improved resistance mechanism against antimicrobial stressors, disinfectants and antibiotics, which makes biofilm infections persistent and challenging to treat. Thus, biofilm is represented as one of the potent virulence factors. This study was undertaken to characterize the biofilm production under different conditions and cell-surface properties of Ab clinical strains with MDR and carbapenem-resistant profile. The reference strain NCTC 12156 and 26 nonclonal related Ab clinical strains have been investigated. The genetic profile and the antimicrobial susceptibility pattern of all clinical strains have been previously established. Biofilm formation was determined in LB broth using the microplate crystal violet assay on the following substrates: polystyrene (PS), PS coated with 10% fetal bovine serum (FBS) and PS coated with poly-L-lysine (PLL). Cell-surface hydrophobicity (CSH) was measured by the water-octane two-phase assay and the Zeta potential (ζ) was evaluated with a bacterial cell suspension (1.5 mL containing 108 bacterial cells) in ultrapure water. Out of 27 strains studied, 100% showed ability to biofilm formation, although at different levels. On uncoated PS substrate, 3.7%, 29.63% and 66,67% of strains were strong, moderate, and weak biofilm-producer, respectively. FBS coating did not interfere significantly with biofilm formation, while PLL coating significantly reduced the amount of biofilm formed (P < 0.05). On PLL-coated PS substrate, 96.3% of strains were weak biofilm-producers, while none was strong producers. No correlation was found between CSH and biofilm formation, with 19 (70.37%) strains exhibiting low CSH, and the remaining eight isolates (29.63%) exhibiting low CSH. Regarding the ζ, except for one sample, all the remaining strains exhibited electronegative charge, with values ranging from -57.71 to -21.56 mV. Here we demonstrated the high frequency of biofilm-forming Ab strains and the effects of different substrates on this. The present findings may offer insights for developing novel therapies aimed at preventing and treating biofilm-associated Ab infections.
Financial support: FAPES, CAPES and CNPq.
Palavras-chave: Acinetobacter baumannii infections, MDR strains, Carbapenem-resistance, Biofilm formation, Virulence Agência de fomento:Fundação de Amparo à Pesquisa e Inovação do Espírito Santo (FAPES) | |||||