A cost-effective study of VRE surveillance in a Greek university hospital

Abstract number: 1733_1329

Charalambakis N., Pantelaki M., Chatzigeorgiou K., Kapi M., Siafakas N., Galani L., Zerva L.

Objectives: Enterococci with acquired resistance to the glycopeptides (VRE) have emerged in European hospitals necessitating prompt identification. Enterococcal speciation and susceptibility determination by automated systems (including Phoenix by Becton Dickinson) remains problematic. While performing a VRE surveillance study, a cost-effective approach of rapid and accurate pathogen identification was developed.

Methods: A rectal swab was collected from all consenting hospitalised patients (n = 132) and was inoculated into vancomycin (6 mg/mL) containing Enterococcosel Agar and Broth (BD). Phoenix was used for speciation and susceptibility testing supplemented by PYR, motility and pigment production. When indicated, vanco and teico E-tests were performed (Biodisk). A PCR assay confirmed speciation and glycopeptide resistance of VRE strains. Reagent cost and number of performed tests were recorded; test results were analysed in order to develop the most cost-effective approach for performing a VRE surveillance study.

Results: A total of 99 isolates were obtained but only 57 were Enterococci (44.4% colonisation rate). They were speciated as E. faecalis (n = 4), E. faecium (n = 11) and E. cass.//gallinarum (n = 42) by Phoenix. All E. faecium strains demonstrated high level glycopeptide resistance and were confirmed as E. faecium vanA by E-test and PCR. VRE carriage rate corresponded to 8.3%. The majority of strains (81%, including all VRE strains) were isolated from both agar and broth cultures. Among E. cass./gallinarum strains 78% were motile and 21% produced pigment. All E. faecalis isolates were vanco-S and teico-S by Phoenix, however, one dilution lower vanco MICs were obtained by the E-test. Non-motile E. cass./gallinarum strains demonstrated vanco-S, I or R and teico-S MICs by Phoenix, while vanco E-testing showed lower MICs. Three E. cass./gallinarum isolates revealing high level glycopeptide resistance by Phoenix were vanco-I and teico-S MICs by the E-test. Total reagent cost for ``extended testing'' corresponded to 2,760 Euros, but the analysis of obtained results allowed the development of a ``minimally required testing'' approach reducing costs by 29%.

Conclusion: These results show high rates of enterococcal and non-enterococcal strain isolation on selective media, an overestimation of vanco MICs by Phoenix, while solid media inoculation suffices for VRE strain isolation. Significantly, cost reduction for performing a VRE surveillance study is possible.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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