Impact of colonisation with multidrug-resistant gram-negative bacteria in a low endemicity setting: a population-based observational study.

PURPOSE: The health impact of multidrug-resistant gram-negative bacilli (MDR-GNB) colonisation in low-endemic settings remains insufficiently characterised. We aimed to evaluate mortality and healthcare utilisation associated with MDR-GNB colonisation in a Swedish population identified through targeted screening following universal risk assessment.

METHODS

All patients screened for MDR-GNB in Skåne, Sweden, between 2013 and 2022, were included, with one year of follow-up. Data on mortality (primary outcome), and secondary outcomes, including emergency department (ED) visits and hospital admissions, outpatient visits and antibiotic prescriptions, were extracted from health records. Logistic regression and Cox proportional hazards models were applied to compare patients with and without MDR-GNB colonisation, with odds ratio (OR) and hazard ratios (HR) quantifying associations.

RESULTS

Among 12,901 screened patients, 2,485 (19%) had colonisation with extended-spectrum β-lactamase-producing Enterobacterales, 83 (0.6%) with carbapenemase-producing Enterobacterales, 50 (0.4%) with carbapenem-resistant Acinetobacter spp. and 21 (0.2%) with carbapenem-resistant Pseudomonas aeruginosa. The overall one-year mortality was 6.6%, with no association between MDR-GNB colonisation and mortality (HR 0.96, 95% CI 0.80-1.14). MDR-GNB colonisation was, however, associated with increased risk of ED visits and hospital admissions, longer hospital stays, ICU-admissions, increased use of ambulatory and primary care, and higher antibiotic prescribing. These associations were most pronounced within the first three months post-screening and declined thereafter.

CONCLUSIONS

Although MDR-GNB colonisation did not increase one-year mortality risk, patients with colonisation experienced significantly increased healthcare use. Further research is warranted to optimise patient outcomes, including preventive measures, and healthcare resource utilisation in this population.