Multidrug-Resistant Organisms Detected More Than 48 Hours After Hospital Admission Are Not Necessarily Hospital-Acquired

BACKGROUND. Infections and colonization with multidrug-resistant organisms (MDROs) identified >48 hours after hospital admission are considered healthcare-acquired according to the definition of the Centers for Diiease Control and Prevention (CDC). Some may originate from delayed diagnosis rather than true acquisition in the hospital, potentially diluting the impact of infection control programs. Idaddition, such infections are not necessarily reimbursed in a healthcare system based on the diagnosis-related groups (DRGs). OBJECTIVE. The goal of the study was to estimate the preventable proportion of healthcare-acquired infections in a tertiary care hospital in Switzerland by analyzing patients colonized or infected with MDROs. METHODS. All hospitalized patients with healthcare-acquired MDRO infection or colonization (HAMIC) or according to the CDC definition (CDC-HAMIC) were prospectively assessed from 2002 to 2011 to determine whether there was evidence for nosocomial transmission. We utilized an additional work-up with epidemiological, microbiological, and molecular typing data to determine the true preventable proportion of HAMICs. RESULTS. Overall, 1,190 cases with infection or colonization with MDROs were analyzed; 274 (23.0%) were classified as CDC-HAMICs. Only 51.8% of CDC-HAMICs had confirmed evidence of hospital-acquisition and were considered preventable. Specifically, 57% of MRSA infections, 83.3% of VRE infections, 43.9% of ESBL infections, and 74.1% of non-ESBL MDRO infections were preventable HAMICs. CONCLUSIONS. The CDC definition overestimates the preventable proportion of HAMICs with MDROs by more than 50%. Relying only on the CDC definition of HAMICs may lead to inaccurate measurement of the impact of infection control interventions and to inadequate reimbursement under the DRG system.