Prevalence of multidrug-resistant organisms in intensive care unit patients and rate of subsequent bacteraemia: a 5-year study

Abstract

Multidrug-resistant organism (MRO) bacteraemia is associated with significant mortality. A limited number of studies have examined the relationship between MRO colonisation and subsequent bacteraemia in critically ill patients. All patients with a positive surveillance swab result and a positive blood culture result for MROs admitted to the Westmead intensive care unit (ICU) between 1 January 2014 and 31 March 2019 had their results matched with ICU data extracted from the ICU database and analysed for the risk of bacteraemia among swab positive patients. There were 3,878 (2,388 males, 1,490 females) assessable admissions during the period. The median APACHE II (Acute Physiology and Chronic Health Evaluation) score was 17. A total of 9,681 swab results were collected from 3,878 patients. Of the 3,878 patients, 818 were positive for MROs, and 3,060 were negative. Thirty-two swab positive patients (3.9%) tested positive for MROs in the blood culture, and 16 (0.52%) in the swab negative group had MROs in their blood cultures. This difference was statistically significant (adjusted [adj] OR 6.33; 95% CI: 3.40-11.76). The swab positive group was also associated with a significantly higher positive blood culture with orga-nisms other than MROs than the swab negatives (11.1% and 6.2%, respectively, adj OR 1.37; 95% CI: 1.04-1.82). The overall mortality was higher in swab positive compared to swab negative patients (20.7% vs. 13.1%, P < 0.001). The overall prevalence of MRO colonisation was 21% in our cohort. The risk of MRO bacteraemia was higher among patients with a positive surveillance swab result for the organism compared to those with a negative swab, but this was not associated with higher mortality in that group.