Use of GenoType® Enterococcus test to improve enterococci detection correctness

Abstract number: R2379

Liduma I., Rudzite D., Skenders G., Paberza R.

Objectives: Enterococci as cause for bacteraemia, wound infections, endocarditis, urinary tract infections and infections of CNS are associated with intra-hospital infections. In some cases infections are caused by enterococci with multi drug resistance (MDR). Vancomycin is important to treat MDR enterococci patients. Some enterococci species exhibit natural resistance to vancomycin. Therefore it is highly important to identify enterococci species correctly and to interpret results from drug susceptibility testing. Our aim was to compare molecular biology method for identification of enterococci species with phenotypical detection methods.

Methods: This study was performed on 40 enterococci cultures obtained in 2 Latvian hospitals: clinical hospital "Gailezers" and State Agency of TB and Lung Diseases. We used a DNA strip assay (GenoType® Enterococcus; Hain Lifescience GmbH) designed for the simultaneous detection of the most frequent enterococcal species, Enterococcus faecium, E. faecalis, E. gallinarum, E. casseliflavus, and E. flavescens, and of the vancomycin resistance genotypes vanA, -B, -C1, and -C2/3. The assay is based on the specific amplification step followed by reverse hybridisation on nitrocellulose strip. Mini Api® rapid ID 32 Strep (bioMerieux) and BBL Crystal™ GP ID Kit (Becton Dickinson) were used as phenotypical methods for culture identification. Susceptibility to vancomycin was tested by disc diffusion and E-test.

Results: Of the 40 tested enterococci species, 26 (16 E. faecalis, 10 E. faecium) were identified as same species with the phenotypical and genotypical methods, 2 E. faecium identified by molecular method and by BBL Crystal™ but as E. casseliflavus by Mini Api®, 1 E. faecium was identified by molecular method and by Mini Api® but was identified as E. gallinarum by BBL Crystal™. 2 E. faecium identified by molecular method but as E. gallinarum by Mini Api® and as E. casseliflavus or E. casseliflavus/ E. gallinarum by BBL Crystal™. Other species represented E. avium or E. raffinosus. Phenotipicaly identified E. casseliflavus/ E. gallinarum showed susceptibility to vancomycin. 1 vancomycin resistant E. faecalis isolate was having vanA by the GenoType® and was conformed by disc diffusion and E-test.

Conclusion: Our results shows that correctness of enterococci identification only by phenotypical testing methods can lead to wrong diagnosis and genotypical methods should be used when drug susceptibility testing mismatch with species identified.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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