Análise da produção de biofilme por cepas de Pseudomonas aeruginosa carreando o gene aac(6’)-Ib7

Abstract

In recent years, the problem of antimicrobial resistance in Pseudomonas aeruginosa has become more complicated. In previous work, our team evidenced a high frequency of the plasmid gene variant aac(6’)-Ib7 in clinical samples of extensively drug-resistant P. aeruginosa. In addition to resistance genes, the virulence of these strains, particularly their ability to produce biofilm, contributes to their persistence and dissemination in hospitals. This work evaluated the biofilm production capacity of seven strains of P. aeruginosa carrying the aac(6’)-Ib7 gene. For this evaluation, isolated samples of clinical material were selected, positive for the aac(6’)-Ib7 gene, recovered from patients treated at the Clinical Hospital belonging to the Federal University of Uberlandia, during 2014. The seven strains evaluated adhered to the unmodified polystyrene surface within two hours, however, in significantly smaller amounts (P<0.001) than the positive control. All P. aeruginosa strains showed a higher number of viable cells after 24 hours of incubation when compared to the adhesion assay. When compared with the control in the viable cell enumeration assay, none of the strains showed a significant difference. Additionally, of the seven strains analyzed, four (57%) had biomass values higher than the cut-off used, being considered strong biofilm producers, one isolate (14%) was classified as moderate producer and two (29%) were characterized as weak biofilm producers. Our results demonstrate that all strains could produce biofilm, despite this ability being presented differently among them.