Ventilatörle İlişkili Pnömoni (VİP) Etkeni Acinetobacter baumannii İzolatlarında Biyofilm Oluşumu ve Virülans Genlerinin Araştırılması

Abstract

Objective: This study aimed to investigate phenotypic biofilm formation and the presence of biofilm-associated and virulence genes in multidrug-resistant (MDR) Acinetobacter baumannii isolates causing ventilator-associated pneumonia (VAP). Methods: Twenty-three MDR A. baumannii isolates were collected from tracheal aspirate samples of mechanically ventilated patients in the intensive care unit between 2022 and 2023. Biofilm formation was assessed using the micro-titer plate crystal violet assay. The presence of biofilm-associated and virulence genes (bap, csuE, ompA, pgaB, csgA, abaI, adeG, traT, cpaA, cnf-1, cnf-2, kpsMII, epsA, ptk, fimH, pilA, basD, bauA, and omp33-36) was determined by polymerase chain reaction (PCR). Results: All isolates demonstrated strong biofilm formation. The genes bap, csuE, ompA, and pgaB were present in all isolates, while fimH, csgA, adeG, traT, cpaA, cnf-1, cnf-2, kpsMII, pilA, bauA, and omp33-36 were absent in all samples. The quorum-sensing gene abaI and the siderophore-related gene basD were detected in all isolates. Capsule-associated genes epsA and ptk were identified in 16.6% and 54.2% of isolates, respectively. Conclusion: The consistent detection of strong biofilm formation and presence of bap, csuE, ompA, and pgaB genes in VAP-associated MDR A. baumannii isolates suggests a potential association between biofilm formation and viru-lence. The absence of fimH and csgA genes indicates that these genes may not be the determining factors for biofilm formation in these isolates. Furthermore, the presence of abaI, basD, epsA, and ptk genes is consistent with a possible involvement in biofilm formation and antibiotic resistance mechanisms.