CRISPR- cas system in the acquisition of virulence genes in dental-root canal and hospital-acquired isolates of Enterococcus faecalis

摘要

Enterococcus faecalis is one of the important causative agents of nosocomial and life-threatening?infections in human. Several studies have demonstrated that the presence of CRISPR-cas?is associated with antibiotic susceptibility and lack of virulence traits. In this study, we aimed to assess the phenotypic and genotypic virulence determinants in relation to CRISPR elements from the dental-root?canals and hospital-acquired?isolates of?E.?faecalis.?Eighty-eight?hospital-acquired?and 73 dental-root?canal isolates of?E.?faecalis?were assessed in this study. Phenotypic screening of the isolates included biofilm formation, and gelatinase and hemolysis activities. Genotypical screening using PCR was further used to evaluate the presence of CRISPR elements and different virulence-associated?genes such as?efaA, esp, cylA, hyl, gelE, ace, ebpR, and?asa1.?Biofilm formation, gelatinase, and hemolysis activities were detected in 93.8%, 29.2%, and 19.2% of the isolates, respectively. The most prevalent virulence-associated?gene was?ace, which was followed by?efaA, whereas?cylA?was the least identified. The presence of CRISPR1-cas,?orphan CRISPR2, and CRISPR3-cas?was determined in 13%, 55.3%, and 17.4% of the isolates, respectively. CRISPR elements were significantly more prevalent in the dental-root?canal isolates. An inverse significant correlation was found between CRISPR-cas?loci,?esp,?and?gelE, while direct correlations were observed in the case of?cylA, hyl, gelE?(among CRISPR-loci?1 and?3),?asa1, ace, biofilm formation, and hemolysis activity.?Findings, therefore, indicate that CRISPR-cas?might prevent the acquisition of some respective pathogenicity factors in some isolates, though not all; so selective forces could not influence pathogenic traits.