Virulence determinants in vancomycin-resistant Enterococcus faecium vanB: clonal distribution, prevalence and significance of esp and hyl in Australian patients with haematological disorders

• Published in: The Journal of hospital infection 2008-02, Vol.68 (2), p.137-144
• Main Authors: Worth, L.J, Slavin, M.A, Vankerckhoven, V, Goossens, H, Grabsch, E.A, Thursky, K.A
• Format: Article
• Language: English
• Subjects: Adult; Aged; Australia - epidemiology; Bacterial diseases; Bacterial diseases of the digestive system and abdomen; Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Biological and medical sciences; Clone Cells; Cylas; Electrophoresis, Gel, Pulsed-Field; Enterococcus faecium; Enterococcus faecium - drug effects; Enterococcus faecium - genetics; Enterococcus faecium - pathogenicity; Female; Gram-Positive Bacterial Infections - microbiology; Gram-Positive Bacterial Infections - mortality; Hematologic Diseases - epidemiology; Hematologic Diseases - microbiology; Human bacterial diseases; Humans; Immunocompromised Host; Infectious Disease; Infectious diseases; Male; Medical sciences; Membrane Proteins - genetics; Membrane Proteins - isolation & purification; Middle Aged; Polymerase Chain Reaction; Prevalence; Proto-Oncogene Proteins pp60(c-src) - genetics; Proto-Oncogene Proteins pp60(c-src) - isolation & purification; Vancomycin Resistance - genetics; Vancomycin-resistant Enterococcus faecium; Virulence - genetics; Virulence factors
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2007.10.017

SummaryEuropean studies have suggested that the esp gene and other virulence factors have roles in vancomycin-resistant Enterococcus faecium (VREfm) infections. The aim of this study was to examine the relationship between the spectrum of clinical disease and putative virulence factors in vanB VREfm isolates. A multiplex polymerase chain reaction was used to amplify potential virulence genes ( asa1, gel E, cylA, esp and hyl) in VREfm isolates obtained from an Australian population of haematology patients. Clonality was assessed by pulsed-field gel electrophoresis (PFGE) and automated ribotyping. Infection, requirement for intensive care unit (ICU) admission and all-cause 30-day mortality were used as clinical indicators of organism virulence. Forty-one VREfm vanB isolates (41 patients; 14 infected and 27 colonised only) were analysed. Thirty-five of these isolates were typed by PFGE, 31 of which were represented by three clusters. The esp gene was identified in 22 of 27 (81.5%) screening and 11 of 14 (78.6%) infection-associated isolates. One isolate was hyl gene positive, and no isolate contained asa1, gel E or cylA genes. VREfm infection was independently associated with host factors (underlying diagnosis of acute myeloid leukaemia, age ≤60 years) but not with presence of the esp gene. ICU admission was negatively associated with presence of the e sp gene (OR: 0.05; 95% CI: 0.01–0.61; P= 0.02). There was no association between 30-day mortality and host factors or the presence of the esp gene. When compared to European and US reports, a high esp gene prevalence and low hyl gene prevalence was observed in polyclonal VRE isolates obtained from this immunocompromised population.