Promiscuity, pheromones and pathogenicity : why all Enterococci are not created equal

Pelzer, Elise S., Rathnayake, Irani, & Huygens, Flavia (2014) Promiscuity, pheromones and pathogenicity : why all Enterococci are not created equal. In Mack, Henry L. (Ed.) Enterococcus faecalis : Molecular Characteristics, Role in Nosocomial Infections and Antibacterial Effects. NOVA Science Publishers, New York, pp. 69-92.

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Abstract

Enterococcus faecalis is a Gram-positive, coccus shaped, lactic acid bacterium, with demonstrated ubiquity across multiple anatomical sites. Enterococcus faecalis isolates have been isolated from clinical samples as the etiological agent in patients with overt infections, and from body sites previously thought to be sterile but absent of signs and symptoms of infection.

E. faecalis is implicated in both human health and disease, recognized as a commensal, a probiotic and an opportunistic multiply resistant pathogen. E. faecalis has emerged as a key pathogen in nosocomial infections.

E. faecalis is well equipped to avert recognition by host cell immune mediators. Antigenic cell wall components including lipotechoic acids are concealed from immune detection by capsular polysaccharides produced by some strains. Thereby preventing complement activation, the pro-inflammatory response, opsonisation and phagocytosis. E. faecalis also produces a suite of enzymes including gelatinase and cytolysin, which aid in both virulence and host immune evasion. The ability of enterococci to form biofilms in vivo further increases virulence, whilst simultaneously preventing detection by host cells.

E. faecalis exhibits high levels of both intrinsic and acquired antimicrobial resistance. The mobility of the E. faecalis genome is a significant contributor to antimicrobial resistance, with this species also transferring resistance to other Gram-positive bacteria. Whilst E. faecalis is of increasing concern in nosocomial infections, its role as a member of the endogenous microbiota cannot be underestimated. As a commensal and probiotic, E. faecalis plays an integral role in modulating the immune response, and in providing endogenous antimicrobial activity to enhance exclusion or inhibition of opportunistic pathogens in certain anatomical niches.

In this chapter we will review possible mediators of enterococcal transition from commensal microbe to opportunistic pathogen, considering isolates obtained from patients diagnosed with pathogenic infections and those obtained from asymptomatic patients.

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ID Code: 80218
Item Type: Book Chapter
Keywords: Enterococcus faecalis, Epidemiology, Virulence, Antibiotic resistance, Immune evasion
ISBN: 9781633210493
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > MICROBIOLOGY (060500) > Infectious Agents (060502)
Divisions: Current > Schools > School of Biomedical Sciences
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2014 NOVA Science Publishers
Deposited On: 20 Jan 2015 22:45
Last Modified: 20 Jan 2016 15:13

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