Phenotypic Determination of Biofilm Formation and Acquired Resistance Profile of Clinically-Derived Bacterial Isolates

Abstract

Infections caused by biofilm forming bacteria is of major public health concern because of its association with multi-resistance to antimicrobial drugs and host defenses, leading to chronic and recurrent infections. Here, using Congo red agar method, Kirby-bauer disk diffusion technique and the consensus criteria of the European Centre for Disease Control (ECDC) and Centre for Disease Control (CDC), we determined the acquired resistance profile of biofilm producing phenotypes of clinically derived bacteria, classified as Multidrug resistant (MDR), extensively drug resistant (XDR) and Pandrug resistant (PDR). Fifty (50) de-identified bacterial isolates, comprising of five different species (Staphylococcus aureus, Escherichia coli, Proteus spp, Klebsiella pneumoniae and Pseudomonas aeruginosa) were sampled for the study. 64.0% of these isolates were observed to produce biofilms. Isolates recovered from urine samples (50.0%) were the most significant biofilm producers, chief among which was Staphylococcus aureus (15.6%) (X2=0.52; p<.05; P=0.9714). 78.0% of the biofilm producing phenotypes were atleast multidrug resistant (31.4% MDR; 31.4% XDR; 15.7% PDR) (f= 0.40678; df=3; p<.05; P=0.7502). Extreme forms of acquired resistance (XDR and PDR) was more pronounced among biofilm producing strains than the non-biofilm producing strains, and was statistically significant (f=5.0; p=.026336; df=14; p<.05). All Staphylococcus aureus and Pseudomonas aeruginosa isolates were atleast multidrug resistant, with the biofilm producing strains of the latter being completely resistant to Gentamicin and Ciprofloxacin. As such, it can be deduced that resistance to multiple antimicrobial drugs is more pronounced among biofilm producing phenotypes of clinically derived bacterial isolates.