Evaluation of the relative expression of genes involved in biofilm formation by Acinetobacter baumannii

Acinetobacter baumannii é um patógeno oportunista, de grande importância no ambiente hospitalar devido à sua capacidade de adquirir mecanismos de resistência, de aderir e formar biofilmes sob diferentes superfícies. Devido a relevância da infecção causadas pelo A. baumannii torna-se fundamental o conhecimento dos mecanismos envolvidos na sua patogenicidade. Sendo assim, o objetivo desse estudo foi realizar a análise transcricional dos genes envolvidos na formação e manutenção do biofilme (bap, abaI, ompA, bfmRS, csuAB, pgaA, pilZ, wspR, eal, eagg, IscRSU e csdA) de duas cepas clínicas de A. baumannii obtidas de hospitais de Porto Alegre, Brasil (AbH e AbC) e uma cepa controle ATCC 19606 (AbA) sob diferentes condições de crescimento. As cepas foram avaliadas quanto a sua capacidade de formar biofilme a 25 °C e 37 °C, crescendo em caldo Luria Bertani (LB), LB acrescido de 1% glicose (LB-G), LB acrescido de 10% sangue de carneiro (LB-SC) e urina pura (UP). A análise transcricional foi realizada por PCR quantitativo em tempo real. A cepas AbH, AbC e AbA foram fortes formadoras de biofilme em LB e LB-G a 25 e 37 °C. Em LB-SC, as cepas AbH e AbA foram fortes formadoras e AbC foi classificada fraca formadora de biofilme. Em UP, a cepa AbH foi moderadamente formadora, AbC e AbA foram fracas formadoras de biofilme. Os genes wspR, pgaA, ompA, bap, abaI de AbA, csdA de Ab He o operon IscRSU foram superexpressos em biofilme; os genes eagg de AbH, pilZ e csuAB foram inibidos e os genes bfmRS, eal, eaggde AbA, csdA de AbA e abaIde AbH não possuíram uma variação significativa na expressão durante a formação do biofilme.Acinetobacter baumannii is an opportunistic pathogen of high importance in the hospital environment due to its ability to develop resistance mechanisms as well as to adhere and form biofilms on different surface types. Due to the high relevance of infections caused by A. baumannii, knowing the mechanisms involved in its pathogenicity is of extreme importance. Thus, we aimed to perform a transcriptional analysis on genes involved in biofilm formation and maintenance (bap, abaI, ompA, bfmRS, csuAB, pgaA, pilZ, wspR, eal, eagg, IscRSU e csdA) of two clinically isolated A. baumannii strains obtained from hospitals in Porto Alegre city, Rio Grande do Sul state, southern Brazil (AbH and AbC), and of the reference strain ATCC 19606 (AbA), cultivated under different growth conditions. Biofilm formation ability was evaluated at 25 and 37 °C using LB broth (LB), LB + 1% glucose (LB-G), pure urine (PU), and LB + 10% sheep blood (LB-SB). Gene transcriptional profiling was performed by real time qPCR. Strains AbH, AbC and AbA were strong biofilm producers in LB and LB-G at 25 and 37 °C. In LB-SB, strains AbH and AbA were strong biofilm producers while AbC was a week biofilm producer. In PU, the strain AbH was a moderate biofilm producer, while strains AbC and AbA were weak biofilm producers. Genes wspR, pgaA, ompA, bap, abaI de AbA; csdA of AbH; and the operon IscRSU were all overexpressed in biofilms. On the other hand, genes eagg of AbH, pilZ and csuAB were suppressed, while genes bfmRS, eal and eagg of AbA; csdA of AbA; and abaI of AbH showed no significant variation in their expression during biofilm formation