Enterococcus faecium, Infections and Bio Film Formation
Enterococcus faecium, a major cause of nosocomial infections, is often isolated from conditions where biofilm is considered to be important in the establishment of infections. We investigated biofilm formation among E. faecium isolates from diverse sources and found that the occurrence and amount of biofilm formation was significantly greater in clinical isolates than fecal isolates from community volunteers. We also found that the presence of the empfm (E. faecium pilus) operon was associated with the amount of biofilm formation. Furthermore, we analyzed the possible association between the distribution of 16 putative virulence genes and the occurrence of biofilm production. Even though the prevalence of these virulence genes was significantly higher in clinical isolates, we did not observe any correlation with the occurrence of biofilm formation.
Key words
Enterococcus faecium, biofilm, virulence
Introduction
Enterococci, found naturally as part of the digestive tract flora in humans and animals, have evolved into major opportunistic pathogens causing nosocomial infections including bacteremia in neutropenic patients, endocarditis and device infections (Arias & Murray, 2012). In the USA, there has been a rapid increase in Enterococcus faecium infections associated with hospital outbreaks since the 1980s, often attributed to the emergence of resistance to ampicillin, the increased use of advanced generation cephalosporins and vancomycin and the subsequent development of resistance to vancomycin (Murray, 2000, Somarajan & Murray, 2013). Also, a recent CDC survey reported that about 38% of hospital-associated enterococcal isolates identified to the species level were E. faecium (Hidron, et al., 2008). Over the last two decades, i...
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...on. Even though our study does not find a correlation between the presence of genes and the occurrence of biofilm formation, we recognize the possibility that recent isolates with substantial genomic diversity might yield different results.
In conclusion, our study finds that biofilm formation as measured in a microtiter plate assay occurs at a higher frequency and amount in clinical E. faecium isolates compared to isolates from healthy volunteers, thus suggesting a potential connection between biofilm formation and virulence potential. Our study also suggests that enrichment of emp (pilus) genes may account for the higher amount of biofilm formation associated with clinical isolates, which in turn could enhance their ability to cause infection through increased resistance to antibiotics and innate host defenses (Donelli & Guaglianone, 2004, Fedtke, et al., 2004).
In this essay, the author
- Explains that enterococcus faecium, a major cause of nosocomial infections, is often isolated from conditions where biofilm is considered important in the establishment of infections.
- Explains that enterococci have evolved into opportunistic pathogens causing nosocomial infections, including bacteremia in neutropenic patients, endocarditis and device infections.
- Explains that e. faecium's clinical impact may be enhanced by biofilm formation, which makes it more difficult to treat with antibiotics.
- Explains that enterococcus faecium, a major cause of nosocomial infections, is often isolated from conditions where biofilm is considered important in the establishment of infections.
- Explains that enterococci have evolved into opportunistic pathogens causing nosocomial infections, including bacteremia in neutropenic patients, endocarditis and device infections.
- Explains that e. faecium's clinical impact may be enhanced by biofilm formation, which makes it more difficult to treat with antibiotics.
- Explains that the present study assessed the ability of e. faecium isolates from diverse sources to form biofilm.
- Explains how biofilm formation was quantitated by measuring od570 of crystal violet stained wells. each strain was assessed on at least two occasions.
- Explains that the prevalence of various genes was evaluated using dna colony hybridizations, as described previously. genomic dna probes were prepared by pcr amplification of intragenic regions of diverse genes using specific primers.
- Analyzes the association between biofilm formation and the distribution of the 16 genes in e. faecium strains belonging to different clinical or non-clinical subgroups using fisher’s exact test and binary logistic regression.
- Analyzes the biofilm formation capacity of e. faecium isolates from diverse sources.
- Analyzes whether the presence of putative virulence genes was associated with the amount of biofilm formation, and finds that the empfm operon showed a significant association, as shown by the higher median od570 values for e. faecium isolates.
- Concludes that the presence of virulence traits is not always associated with increased biofilm formation capacity.
- Analyzes the association between the presence of putative virulence determinants and the occurrence of biofilm formation among isolates of different origin.
- Analyzes whether there was an association between gene distribution and the occurrence of biofilm formation in e. faecium isolates.
- Concludes that biofilm formation occurs at a higher frequency and amount in clinical e. faecium isolates compared to healthy volunteers.
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