Characterization of Enterococci isolated from intensive care unit (ICU); Distribution of virulence markers, virulence genes and antibiotic resistance pattern

Abstract

Background: Enterococci are considered as the third most common cause of nosocomial infections. Enterococci acquire antibiotic resistance by gene transfer. Virulence factors facilitate colonization and evasion from the immune system. Our objectives were to evaluate the distribution of virulence markers and genes among enterococci isolated from intensive care unit (ICU) in Sohag University Hospital and to determine the antibiotic resistance pattern of enterococci.

Methods: Virulence markers were detected by gelatinase test, caseinase test, slime layer production and modified micro titer plate method. Polymerase chain reaction is used for identification of enterococcal species and detection of virulence genes as gel E, asa 1, esp, hyl and cyl A. Antibiotic sensitivity tests were performed by disc diffusion method by using ampicillin, vancomycin, tetracycline, erythromycin and teichoplanin. Vancomycin minimum inhibitory concentrations (MICs) were measured by E-test.

Results: Vancomycin resistant enterococci (VRE) was detected in 38.4 % of isolates. There was no significant difference in the distribution of all virulence markers between Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium). The hyl gene was more commonly detected in E. faecalis (p-value= 0.01). Enterococci isolated from cases of surgical site infection (SSI) ,pneumonia and sepsis contain multiple virulence genes with the highest percentage. Vancomycin resistance was higher in gel E positive and asa1 positive E. faecalis than negative E. faecalis.

Conclusion: Multi-drug resistance (MDR) was detected in 57.6% of enterococci. Enterococcus faecalis and E. faecium have the same degree of virulence. An association was noted between the esp & asa 1 genes and biofilm formation.