Detection of biofilm formation and correlation with antibiotic resistance in Acinetobacter baumannii

Abstract

Acinetobacter baumannii is a major cause of hospital acquired infections worldwide and is associated with resistance to routinely used antibiotics. Many clinical isolates of Acinetobacter baumannii are found to be biofilm producers. Hence there is difficulty in treating patients with Multi Drug Resistant Acinetobacter baumannii (MDRAB). This present study aimed to study antibiotic resistance of A. baumannii isolates and to evaluate the biofilm formation of Acinetobacter baumannii by Tube Method (TM) and Microtiter Plate Method(MTPM).In this study, 73 A. baumannii isolates of various clinical specimens were evaluated. Confirmation was done through conventional methods. Testing for antimicrobial susceptibility was done by Kirby Bauer disc diffusion method. Biofilm formation was studied by TM and MTPM. Of the 73 isolates, 26(36%) were from urine, 19 (26%) from pus, 17 (23%) from sputum and 11 (15%) from other miscellaneous(body fluids excluding blood), out of which 81%(59/73) isolates were Multi Drug Resistant (MDR). 63% and 84% of isolates showed biofilm production in TM and MTPM, respectively. When comparing these two methods, MTPM assay was better than TM. Presence of a strong relationship between biofilm formation and MDRAB has been confirmed by the present study. Both methods used for detection  of biofilm formation were found to be statistically significant. Sensitivity of MTPM was more than TM, which is supported by higher Positive Predictive Value of 87.5%. Therefore MTPM is a better method than TM and can be used as a screening method to detect biofilm production.