Impact on Morbidity, Mortality, and Length of Stay of Hospital-Acquired Infections by Resistant Microorganisms

Background: Infections by multidrug-resistant organisms (MDROs) are a global threat and are particularly common in hospitals. This study was performed to assess the impact of hospital-acquired infections caused by MDROs on morbidity, mortality, and length of hospital stay.

Methods: This was a retrospective cohort study. A sample of adults aged ≥18 years with a respiratory, urinary, bloodstream, or surgical site infection caused by a multidrug-resistant (cases) or -sensitive (controls) microorganism was selected. Measurements included hospital mortality from all causes (total and 30 days after infection), length of stay (LOS), and 5 indicators of morbidity: intensive care or surgery admissions, number of diagnostic tests after infection, and hospital readmissions or visits to the emergency department within 30 days of discharge.

Results: The sample was composed of 324 cases and 676 control patients. Risk of hospital mortality from all causes (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.25-2.32) and 30 day-mortality after infection (HR, 1.77; 95% CI, 1.29-2.44) were higher in patients with an MDRO infection. Probability of readmission was also higher (odds ratio [OR], 2.17; 95% CI, 1.36-3.46) in the case group. Emergency department visits were only significantly higher in methicillin-resistant Staphylococcus aureus (OR, 2.80; 95% CI, 1.65-4.74) and in Escherichia coli-resistant infections (OR, 2.28; 95% CI, 1.32-3.96). Infections by MDRO were not associated with any other outcome.

Conclusions: Hospital infections caused by MDROs increase mortality, readmissions, and in some cases, visits to the emergency department compared with those produced by susceptible strains. They do not appear to influence LOS nor the need for hospital admission, intensive care, surgery, or diagnostic tests.