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Enterococcis: pathogens of the 90s
D E Low1, B M Willey, S Betschel
1Department of Microbiology, Mount Sinai Hospital, Toronto, Ontario, Canada.
Abstract:
The genus Enterococcus consists of at least 12 species, two of which account for over 95% of the clinically important strains, E faecalis (85%-90%) and E faecium (5%-10%). Despite their ubiquity and frequent isolation, they have not been thought to cause serious disease because they lack common virulence factors. Now, however, enterococci are regarded as true pathogens and are the second leading cause of nosocomial infections. This change results from their increasing antimicrobial resistance and the extensive use of antimicrobial drugs (for example-cephalosporins) that are not active against them. Serious infections should usually be treated with a beta-lactam and an aminoglycoside, but glycopeptides have been increasingly used during the last decade. Two novel resistance patterns of particular concern recently are high level aminoglycoside resistance (HLAR) and vancomycin resistance. The prevalence of HLAR is between 15% and 55%, and glycopeptide resistance has become widespread in various geographical areas. This poses a serious problem, as such resistance may spread to other Gram-positive organisms and is often associated with resistance to other antimicrobial drugs. This may theoretically result in groups of organisms for which there will be no effective antimicrobial treatment.
Insights
Enterococci, once overlooked, are now recognized as significant pathogens causing hospital infections. Their rising antimicrobial resistance, including high-level aminoglycoside resistance (HLAR) and vancomycin resistance, poses a critical threat to effective treatment.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Enterococci are common bacteria, with E. faecalis and E. faecium dominating clinical isolates.
- Historically not considered major pathogens due to lacking common virulence factors.
- Now recognized as the second leading cause of nosocomial infections.
Purpose of the Study:
- To highlight the evolving role of enterococci as true pathogens.
- To discuss the impact of increasing antimicrobial resistance on treatment strategies.
- To address emerging resistance patterns like high-level aminoglycoside resistance (HLAR) and vancomycin resistance.
Main Methods:
- Literature review and synthesis of current knowledge on enterococcal infections and resistance.
- Analysis of prevalence data for HLAR and glycopeptide resistance.
- Discussion of the clinical implications of these resistance patterns.
Main Results:
- Enterococci are increasingly implicated in serious infections, particularly healthcare-associated infections.
- High-level aminoglycoside resistance (HLAR) prevalence ranges from 15% to 55%.
- Vancomycin resistance is widespread and often co-occurs with resistance to other antibiotics.
Conclusions:
- Enterococci are significant pathogens requiring careful management.
- Antimicrobial resistance in enterococci, especially HLAR and vancomycin resistance, presents a major clinical challenge.
- The spread of resistance could lead to untreatable infections in Gram-positive organisms.