Biofilm Formation by Acinetobacter Species Isolated from Intensive Care Units: Unveiling the Impact on Antibiotic Resistance

Abstract

Background:The potential ability of Acinetobacter species to form biofilm could explain their remarkable antibiotic resistance in intensive care settings. Objectives: This work aimed to detect the biofilm formation by Acinetobacter species and investigate its impact on their antibiotic resistance pattern. Methodology: A total of 50 non-replicate Acinetobacter isolates, recovered from patients admitted to intensive care units (ICUs), were collected from the Clinical Laboratories of Kasr Al-Ainy University Hospitals. The isolates were subjected to antibiotic susceptibility testing against nine antibiotics of different classes using the Kirby-Bauer disk diffusion method, while the broth microdilution (BMD) method was used to determine polymyxin B susceptibility. The ability to produce biofilm was determined via the tissue culture plate (TCP) method. Results: Forty-nine (98%) isolates were biofilm formers, of which 53.1% were moderate biofilm formers that predominated over the strong and weak biofilm formers (38.8% and 8.1%, respectively). All cases with CAUTIs were infected with moderate biofilm formers (100%, p = 0.045), while the strong biofilm formers displayed a statistically significant higher resistance rate (68.4%) to cotrimoxazole (p = 0.048). Although the strong biofilm formers among multidrug-resistant (MDR) isolates were higher than that of extensively drug-resistant (XDR) isolates (62.5% and 34.1% respectively), the difference was statistically insignificant (p = 0.442). Conclusions: The high rate of biofilm-forming Acinetobacter isolates could potentially increase the colonization by MDR and XDR bacteria in intensive care settings. Isolates with a lower level of resistance exhibited more robust biofilm, which necessitates the urgent finding of effective preventive measures against biofilm formation.