Enterococcal infections & antimicrobial resistance

Enterococci have traditionally regarded as low grade pathogens, have emerged as an increasingly important cause of nosocomial infections in the last decade. Although about a dozen enterococcus species have been identified, only two are responsible for the majority of human infections, i.e., Enterococcus faecalis and E. faecium. The most common nosocomial infections produced by these organisms are urinary tract infections (associated with instrumentation and antimicrobial resistance), followed by intra-abdominal and pelvic infections. They also cause surgical wound infections, bacteraemia, endocarditis, neonatal sepsis and rarely meningitis. A major reason why these organisms survive in hospital environment is the intrinsic resistance to several commonly used antibiotics and, perhaps more importantly, their ability to acquire resistance to all currently available antibiotics, either by mutation or by receipt of foreign genetic material through the transfer of plasmids and transposons. The emergence of vancomycin-resistant enterococci (VRE) is a cause of concern, as once established, it is very difficult to control. Moreover, there can be transfer of resistant gene from enterococci to Staphylococcus aureus thereby posing a threat to the patient safety and also challenges for the treating physicians. This review highlights the shifting spectrum of enterococcal infections, along with their geographical distribution and growing nosocomial importance. Emergence of antimicrobial resistance, pathogenicity and virulence factors, current preventive, control and treatment modalities of severe enterococcal infections are also dealt with.