Open Access Research article

Case-case-control study on factors associated with vanB vancomycin-resistant and vancomycin-susceptible enterococcal bacteraemia

Agnes Loo Yee Cheah123, Trisha Peel4, Benjamin P Howden367, Denis Spelman289, M Lindsay Grayson35, Roger L Nation1 and David CM Kong1*

Author Affiliations

1 Centre for Medicine Use and Safety, Monash University, 381 Royal Parade, Parkville, Victoria, Australia

2 Department of Infectious Diseases, The Alfred, Melbourne, Victoria, Australia

3 Infectious Diseases Department, Austin Health, 145 Studley Road, Heidelberg, Victoria, Australia

4 Department of Surgery, St Vincent’s Health, University of Melbourne, Melbourne, Australia

5 Department of Medicine, University of Melbourne, Melbourne, Australia

6 Microbiology Department, Austin Health, 145 Studley Road, Heidelberg, Victoria, Australia

7 Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia

8 Microbiology Unit, The Alfred, Melbourne, Victoria, Australia

9 Monash University, Victoria, Australia

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BMC Infectious Diseases 2014, 14:353  doi:10.1186/1471-2334-14-353

Published: 28 June 2014

Abstract

Background

Enterococci are a major cause of healthcare-associated infection. In Australia, vanB vancomycin-resistant enterococci (VRE) is the predominant genotype. There are limited data on the factors linked to vanB VRE bacteraemia. This study aimed to identify factors associated with vanB VRE bacteraemia, and compare them with those for vancomycin-susceptible enterococci (VSE) bacteraemia.

Methods

A case-case-control study was performed in two tertiary public hospitals in Victoria, Australia. VRE and VSE bacteraemia cases were compared with controls without evidence of enterococcal bacteraemia, but may have had infections due to other pathogens.

Results

All VRE isolates had vanB genotype. Factors associated with vanB VRE bacteraemia were urinary catheter use within the last 30 days (OR 2.86, 95% CI 1.09-7.53), an increase in duration of metronidazole therapy (OR 1.65, 95% CI 1.17-2.33), and a higher Chronic Disease Score specific for VRE (OR 1.70, 95% CI 1.05-2.77). Factors linked to VSE bacteraemia were a history of gastrointestinal disease (OR 2.29, 95% CI 1.05-4.99) and an increase in duration of metronidazole therapy (OR 1.23, 95% CI 1.02-1.48). Admission into the haematology/oncology unit was associated with lower odds of VSE bacteraemia (OR 0.08, 95% CI 0.01-0.74).

Conclusions

This is the largest case-case-control study involving vanB VRE bacteraemia. Factors associated with the development of vanB VRE bacteraemia were different to those of VSE bacteraemia.

Keywords:
Enterococci; Vancomycin-resistant; Vancomycin-susceptible; Bacteraemia