Acute vancomycin-resistant enterococcal bacteraemia outbreak analysis in haematology patients: a case-control study

Introduction: We report a retrospective case-control series of a vancomycin-resistant Enterococcus faecium (VRE) bacteraemia outbreak at a tertiary metropolitan hospital in Queensland, Australia. The outbreak occurred on a haematology ward between 8 and 14 February 2014, 6 weeks after a ward relocation. The aim was to determine risk factors related to progression from colonisation with VRE to bacteraemia. Methods: The cases were patients with haematological malignancy and proven catheter-related VRE bacteraemia. Matched controls were selected from the same ward with similar underlying haematological diagnoses and proven gastrointestinal VRE colonisation without invasive infection. Results: This study suggests that female sex, recent administration of total parenteral nutrition, right-sided catheter placement with odds ratios (OR) 1.99, gastrointestinal disruption (OR: 1.91), and dexamethasone administration (OR: 2.37) are potential risk factors for progression from colonisation to infection. Notably, given the small sample size, the 95% confidence intervals are wide ranging from 0.02 to 222. Conclusion: While progression from colonisation with VRE to invasive disease is likely to be a complex multifactorial process, the results of this study suggest certain clinical variables that warrant enhanced vigilance to reduce this occurrence. Interestingly, recent relocation of the haematology ward may play a significant role in this outbreak. This study highlights the importance of good infection control practice and the need for additional studies to further delineate risk factors for invasive VRE infection.