**13. Oral infections**

Enterococci are inhabitants of the oral cavity and as opportunistic pathogen cause oral diseases like caries, endodontic infections, periodontitis and peri-implantitis. In endodontic infections the failure of root canal treatment by endodontic infections is now well evidenced. Enterococci have high resistance to endodontic medicaments and forms resistant biofilms. This is implicated in root canal treatment failure [43, 44]. Enterococci prevalence is also seen in gingivitis and periodontitis (3.7–35%) [45]. Oral Enterococci constitute the highest percentage of virulent genes and ability to form resistant biofilms. The oral cavity may hence be an important reservoir of virulent antibiotic resistant enterococci strains. VRE colonization occurs mainly in GI tract, skin, genitourinary tract and oral cavity. Enterococci can persist from months to years. The hands of health care workers are the most common source of transmission in nosocomial infections [46]. The need of oral care is particularly important in nosocomial settings. The spread of the nosocomial VRE occurs and when the immunity is lowered VRE multiply to cause disease. Few studies have shown that antibiotic resistant enterococci is transmitted by food [47–49] but recently Vidana et al. [50] have said there is no food related transmission of enterococci. Enterococci are now showing a high degree of resistance to tetracycline, chloramphenicol, erythromycin besides vancomycin pose a threat for spread of nosocomial infection particularly in patients of ICUs and on mechanical ventilators [51]. Vancomycin resistance is an independent predictor for the overall increase of hospital costs for the patient but also for the individual hospital [52].
