Nosocomial enterococcal blood stream infections in the SCOPE program: Antimicrobial resistance, species occurrence, molecular testing results, and laboratory testing accuracy

Jones, Ronald N.; Marshall, Steven A.; Pfaller, Michael A.; Wilke, Werner W.; Hollis, Richard J.; Erwin, Meridith E.; Edmond, Michael B.; Wenzel, Richard P.

doi:10.1016/s0732-8893(97)00115-6

Cited by 138 publications

(77 citation statements)

References 21 publications

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“…They can readily be isolated from a range of food sources, including raw milk, and are often a constituent of some mixed starter strains used commercially. However, many strains can act as opportunistic pathogens, causing a variety of infections such as urinary tract infections, bacteremia and infective endocarditis (Murray, 1990;Jett et al, 1994), and are of major importance in community-acquired and in hospital-acquired (nosocomial) infections (Jett et al, 1994;Low et al, 1994;Jones et al, 1997;Simjee & Gill, 1997). A contributing factor to their pathogenesis is their evolving resistance to antibiotics.…”

Section: Introductionmentioning

confidence: 99%

Production of enterolysin A by a raw milk enterococcal isolate exhibiting multiple virulence factors

et al. 2003

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Even though enterococci are a common cause of human infection they can readily be isolated from a range of food sources, including various meat and dairy products. An enterococcal strain, DPC5280, which exhibits a broad spectrum of inhibition against many Gram-positive bacteria was recently isolated from an Irish raw milk sample. Characterization of the inhibition revealed that the strain exhibits haemolytic activity characteristic of the two-component lantibiotic cytolysin and also produces a heat-labile antimicrobial protein of 34 kDa. The latter protein displayed cell wall hydrolytic activity, as evidenced by zymogram gels containing autoclaved lactococcal cells. N-terminal sequencing of the purified protein yielded the sequence ASNEWS which is 100 % identical to enterolysin A (accession no. AF249740), a protein which shares 28 and 29 % identity to the Gly-Gly endopeptidases, lysostaphin and zoocin A, respectively. Indeed, amplification of entL from DPC5280 and sequencing revealed that the protein is 100 % identical to enterolysin A. The DPC5280 strain also contained the determinants associated with multiple virulence factors, including gelatinase, aggregation substance and multiple antibiotic resistance. The linkage of this cell-wall-degrading enzyme to other virulence factors in enterococci may contribute to the competitiveness of pathogenic enterococci when found in complex microbial environments such as food and the gastrointestinal tract. INTRODUCTIONDespite the fact that foods containing enterococci have a long history of safe use, these organisms are not considered as GRAS (generally recognized as safe) organisms. They can readily be isolated from a range of food sources, including raw milk, and are often a constituent of some mixed starter strains used commercially. However, many strains can act as opportunistic pathogens, causing a variety of infections such as urinary tract infections, bacteremia and infective endocarditis (Murray, 1990;Jett et al., 1994), and are of major importance in community-acquired and in hospital-acquired (nosocomial) infections (Jett et al., 1994;Low et al., 1994;Jones et al., 1997;Simjee & Gill, 1997). A contributing factor to their pathogenesis is their evolving resistance to antibiotics. For example, resistance to the antibiotic vancomycin is now widespread among members of the genus, which leaves few options for disease management (Aguirre & Collins, 1993;Knudtson & Hartman, 1993;Facklam & Sahm, 1995;Klein et al., 1998). Considerable progress has recently been made in determining the traits responsible for pathogenesis of enterococci.For example, studies have shown that phenotypes such as production of cytolysin, which has both haemolytic activity (by lysing a broad spectrum of cells, including human, horse and rabbit erythrocytes) and bactericidal activity (against Gram-positive bacteria) play a role in the progression of enterococcal infection (Ike et al., 1984;Jett et al., 1992). Cytolysin enhances the virulence of Enterococcus faecalis in animal models, such as muri...

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Section: Introductionmentioning

confidence: 99%

Production of enterolysin A by a raw milk enterococcal isolate exhibiting multiple virulence factors

et al. 2003

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“…They are now recognized as the third most prevalent cause of nosocomial bacteremias (10). The increase in the incidence of enterococcal infections is partly a result of the increasing numbers of immunocompromised patients but is also a result of the spread of multiresistant enterococci.…”

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Rapid Detection of vanA and vanB Genes Directly from Clinical Specimens and Enrichment Broths by Real-Time Multiplex PCR Assay

et al. 2003

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A real-time PCR assay previously developed for use on the Roche LightCycler platform was investigated as an alternative to culture for the direct detection of vancomycin-resistant enterococci (VRE) in clinical specimens. PCR primers and fluorescence resonance energy transfer hybridization probes specific for the vanA and vanB genes were combined in a multiplex real-time PCR assay performed directly with fecal material obtained by rectal swabbing and with enrichment broth samples. DNA was prepared from the rectal swabs and enrichment broths with a commercially available DNA preparation column designed specifically for use with fecal specimens. One hundred eighty duplicate rectal swabs were obtained from 42 patients who were previously found to be positive for VRE and who were being monitored for carriage of VRE. Direct and enrichment broth cultures were performed with one swab, while PCR was performed with the other swab as well as any corresponding presumptive positive enrichment broth. In total, 100 specimens from 30 patients remained positive for VRE by at least one method. The multiplex real-time PCR was positive for 88 enrichment broths of rectal swabs from 27 patients but for only 45 rectal swabs from 15 patients. Direct culture was positive for VRE for only 43 specimens from 11 patients, while enrichment broth culture was positive for VRE for 75 specimens from 22 patients. Inhibition studies for the multiplex real-time PCR assay, performed by spiking the DNA extracts from 50 negative rectal swabs and the corresponding enrichment broths with between 1 and 10 CFU of a VanB Enterococcus faecium strain, detected inhibition rates of 55.1 and 10%, respectively. PCR performed directly with enrichment broths was found to be significantly more sensitive than enrichment broth culture (P < 0.025). Negative samples were identified significantly earlier by PCR than by culture alone.

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“…This method is currently the only automated fingerprinting method (5). Ribotyping, or rRNA gene restriction fragment analysis (10, 23), has been used on a manual basis with the genus Enterococcus both for identification to the species level (16, 21) and for strain characterization, mainly for the species E. faecium (2,6,11,14,15,(18)(19)(20)22).To our knowledge, the interlaboratory reproducibility of automated ribotyping has never been reported in the scientific literature. Although ribotyping has been shown to be slightly less discriminatory than PFGE for typing E. faecium (12), the ease, speed, and standardization of automated ribotyping represent attractive advantages.…”

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Automated Ribotyping of Vancomycin-Resistant Enterococcus faecium Isolates

et al. 2002

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Vancomycin-resistant Enterococcus faecium (VREF) strains represent an important threat in hospital infections in the United States and are found at high frequencies in both the community and farm animals in Europe. We evaluated automated ribotyping for interlaboratory reproducibility by using the restriction enzymes EcoRI and BamHI and compared ribotyping to both amplification of fragment length polymorphism (AFLP) analysis and multilocus sequence typing (MLST) to assess its discriminatory power and capacity for the identification of epidemiologically important strains. Of 19 (EcoRI) and 16 (BamHI) isolates tested in duplicate in two laboratories, 18 (95%) and 16 (100%), respectively, showed reproducible ribotypes. These high reproducibility rates were obtained only after manual refinement of the automated fingerprint analysis. A group of 49 VREF strains initially selected to represent 32 distinct AFLP types were separated into 28 EcoRI ribotypes, 25 BamHI ribotypes, and 28 sequence types. Ribotyping with EcoRI and BamHI was able to discern the host-specific genogroups recently disclosed by AFLP typing and MLST and to distinguish most strains containing the esp gene, a marker specific for strains causing hospital outbreaks. An expandable ribotype identification library was created. We recommend EcoRI as the enzyme of choice for automated ribotyping of VREF strains. Given the high level of discrimination of VREF strains, the high rate of interlaboratory reproducibility, and the potential for the identification of epidemiologically important genotypes, automated ribotyping appears to be a very valuable approach for characterizing VREF strains.Vancomycin-resistant Enterococcus faecium (VREF) strains represent an important threat in hospital infections in the United States and are found at high frequencies in both the community and farm animals in Europe (13,29). VREF strains are often multidrug resistant, a fact which makes infections with VREF strains difficult to treat. As VREF strains often cause outbreaks in hospitals, genetic characterization techniques are needed to track their dissemination.Numerous genetic typing methods are currently used to type E. faecium isolates, including the "gold standard" pulsed-field gel electrophoresis (PFGE) (17) and the recently developed amplified fragment length polymorphism (AFLP) analysis (1, 28) and multilocus sequence typing (MLST) (12a). Interestingly, by AFLP typing, four major genogroups were distinguished and VREF strains present in the different genogroups exhibited host specificity (28). Importantly, VREF strains causing colonization and infections in hospitalized patients (genogroup C) are distinct from strains causing colonization in nonhospitalized persons (genogroup A). The ability to efficiently distinguish these two genogroups has important practical consequences with respect to screening for VREF strains upon hospitalization and implementation of infection control measures. Moreover, VREF strains causing hospital outbreaks appear to represent a distinct genet...

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Nosocomial enterococcal blood stream infections in the SCOPE program: Antimicrobial resistance, species occurrence, molecular testing results, and laboratory testing accuracy

Cited by 138 publications

References 21 publications

Production of enterolysin A by a raw milk enterococcal isolate exhibiting multiple virulence factors

Production of enterolysin A by a raw milk enterococcal isolate exhibiting multiple virulence factors

Rapid Detection of vanA and vanB Genes Directly from Clinical Specimens and Enrichment Broths by Real-Time Multiplex PCR Assay

Automated Ribotyping of Vancomycin-Resistant Enterococcus faecium Isolates

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