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

IntroductionWe 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.MethodsThe 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.ResultsThis 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.ConclusionWhile 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.