Detection of biofilms and their interaction in wound infection: role of N-ACYL homoserine lacton and other virulence factors in enhancement of biofilm formation

ABSTRACT

The deleterious effect of microbial infection on wound healing has been recognized for decades and control of bioburden is considered as an important aspect of wound management. Biofilms play a role in prevention of wound healing. Biofilm-related diseases are typically persistent infections. The aim of this study involves assessment of wound infection through isolation and identification of infected wound-associated pathogens, determination of their ability for biofilm formation, study of interspecies interaction and their antimicrobial resistance pattern. A total of 52 swabs taken from different wounds revealed 80 isolates, that were identified by cultural, microscopic and biochemical tests. These isolates were examined for their biofilm forming capacity by modified microtiter plate assay. For selected culture mates, some virulence factors, which are involved in quorum sensing as well as production of N-Acyl homoserine lactone were determined. Furthermore, antibiotic susceptibility testing of all isolates was done. In total, 27% of the isolates were Pseudomonas species, 33% Staphylococcus aureus, 19% coagulase negative staphylococci, 15% Escherichia coli, 1% and 5% Klebsiella and Proteus species, respectively. All Pseudomonas and Staphylococcus isolates were biofilm formers but with different intensities. Among Pseudomonas and Staphylococcus isolates, 29% and 11% were strong biofilm formers, respectively. All the Pseudomonas isolates were N-Acyl homoserine lactone-producers but with different intensity in its production. A relation between the level of N-Acyl homoserine lactone-production and the expression of virulence factors was observed. A multidrug resistance pattern was observed throughout the different isolates. Biofilm is highly implicated in wound infections caused by either single or mixed species demonstrating a multidrug resistance pattern. Such behavior along with other virulence factors might be controlled by quorum sensing in case of Pseudomonas species and the production of N-Acyl homoserine lactones signaling molecules