Enterococcus faecium / faecalis

Biology

Habitat and Transmission: Enterococcus faecalis and E. faecium are both gut commensals of humans and animals; however they have more recently been associated with nosocomial infections.

Treatment and antibiotic resistance: Enterococci have high intrinsic resistance to antibiotics and penicillin, ampicillin, piperacillin, imipenem and vancomycin are among the few antibiotics that are capable of producing any sort of inhibitory (not bactericidal) response in enterococci. Enterococci are also able to acquire and transfer antibiotic resistance through exchange of resistance-encoding genes located on conjugative transposons with other gut commensals. Virulence factors have been identified in E. faecalis and to a lesser extent in E. faecium, which aid enterococci in establishing infection in the host (Fisher and Phillips, 2009; Sava et al., 2010). Nosocomial enterococcal infections are becoming increasingly difficult to treat with antimicrobials due to the increase in antibiotic resistant strains such as vancomycin resistant enterococci (VRE) (Fisher and Phillips, 2009).

Prevention and control: Enterococci are known for their ability to endure stresses such as extremes of temperature (5-60°C), pH (4.5-10) and high NaCl concentrations (Fisher and Phillips, 2009). Enterococci have been known to survive in the environment for up to 4 months, which creates a constant reservoir of infection (Kramer et al., 2006).

Industry of Interest: Healthcare

Classification: Bacteria

Microbiology: Enterococci are Gram-positive cocci that exist as chains or single cells. They are catalase negative, facultatively anaerobic lactic acid bacteria. Enterococci also exhibit haemolysis when plated out onto blood agar (Fisher and Phillips, 2009).

Symptoms/Effects

Disease and symptoms: Enterococci are emerging as significant nosocomial pathogens capable of causing a range of diseases. Infections with enterococci can range from urinary tract infections (UTIs), hepatobiliary sepsis, endocarditis, wound infections, bacteraemia and neo-natal sepsis (Fisher and Phillips, 2009). E. faecalis and E. faecium are thought to be the cause of most enterococcal infections, although infrequently other enterococci have been implicated (Huycke et al., 1998).

Technical

References:

Fisher R. And Phillips C. (2009) The ecology, epidemiology and virulence of Enterococcus. Microbiology. 155(pt 6): 1749-1757.

Huycke M.M., Sahm D.F. and Gilmore M.S. (1998) Multiple-drug resistant enterococci: The nature of the problem and an agenda for the future. Emerg Infect Dis 4(2): 239-249.

Kramer A., Schwebke I. and Kampf G. (2006) How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infect Dis. 6(130).

Sava I.G., Heikens E. and Huebner J. (2010) Pathogenesis and immunity in Enterococcal infections. Clin Microbiol Infect. 16(6): 533-540.