Evaluation of virulence factors and detection of vanA, vanB and esp genes from clinical isolates of vancomycin-resistant enterococcus faecalis

Abstract

The great attention of scientific researches about vancomycin-resistant Enterococcus faecalis due to the great healthy problems in the world. Evaluation of E. faecalis virulence factors showed that all isolates (100%) were hemolysin, protease and aggregation substance producer, 30% were a gelatinase producer, and 40.7% were a lipase producer. The results of the tube method showed that all E. faecalis isolates (100%) were slime layer and biofilm producer but the amount of adherent layer were different among the isolates ranged from strong to moderate and weak. Antibiotics susceptibility test for 20 isolates was done against 11 antibiotics, eighteen E. faecalis isolates were multi drug resistance. Seventeen E. faecalis isolates were determined as Vancomycin-Resistant by the minimum inhibitory concentrations [MICs] using agar dilution method. The virulence factor Enterococcal Surface Protein (esp) which is chromosomal was amplified by Polymerase chain reaction (PCR) technique in a monoplex pattern, results of this investigation showed that 20 (100%) E. faecalis isolates gave the amplicon size 933 base pair for the esp gene. The genetic determinants of Vancomycin-Resistant vanA and vanB genes were amplified using monoplex and multiplex PCR techniques in order to identify vancomycin resistant (van+) and sensitive (lacking van) among (13) E. faecalis. The vanA, vanB genes were detected in 11 and 4 E. faecalis isolates, respectively. The results of monoplex and multiplex PCR revealed that the molecular weight of vanA and vanB genes were 550 and nearly 600 bp, respectively. The results revealed that the vanA and vanB amplicons have a genetic variation in their molecular weight during the electrophoresis of PCR product.