**6. Urinary tract infection (UTI)**

Enterococci cause both uncomplicated and complicated health care associated UTI. *E. faecalis*. Vancomycin resistant *E. faecalis* and vancomycin resistant *E. faecium* have been mainly implicated in Enterococcal UTI. VRE is fast becoming a major cause of health care associated UTI. The treatment of UTI involves the use of broad spectrum antibiotics which is a major cause of resistant strains to vancomycin (VRE). The complications range from uncomplicated cystitis, pyelonephritis, perinephric abscess, and prostatitis. These organisms are responsible for nosocomial infection of urinary tract particularly in intensive care units (ICU). Enterococci have been particularly reported in catheter associated urinary tract infections, CAUTI (28.4%). Enterococci species are capable of producing biofilms, which are a population of cells attached irreversibly on various biotic and abiotic surfaces. CAUTI are associated with multispecies biofilms. Biofilms are difficult to remove and result in many chronic infections. Bacteria in biofilms colonize medical devices such as catheters, pacemakers, prosthetic heart valves and orthopedic appliances [30]. These multispecies biofilms have synergistic or antagonistic effects of interspecies interaction. Many studies have shown the association of biofilm producing enterococci and urinary catheter [31, 32]. Enterococci biofilms which are formed on catheter in CAUTI are resistant to immune clearance, urination

force and even antibiotics. These enterococci utilize fibrinogen formed on catheter surface and form resistant biofilms*. E. faecalis* attachment in biofilm formation seen in vitro is partially inhibited by uropathogenic *E. coli* (UPEC) but biofilm formation by *K. pneumoniae* or UPEC are not affected by *E. faecalis* but *E. faecalis* increased *E. coli* biofilm mass accumulation and it has been seen that co-culture of an *E. faecium* probiotic strain with enteropathogenic *E. coli* increased the antibiotic sensitivity of *E. coli* to aminoglycosides, B-lactams and quinolones [33]. Biofilm formation confers the organism resistance to phagocytosis and antimicrobial agents. UTI by *E. faecalis* is mediated by virulence factors of the genes esp., srtC, ebp A, ebpC, ace, epaB, msrA, msr B, sigV, efbA, and grvR/etaR. *E. faecium* also displays similar genes related to virulence. Both *E. faecalis* and *E. faecium* isolated from nosocomial UTIs show kidney tropism. It is important to study factors in enterococcal causing pyelonephritis [33].
