Determining risk factors for methicillin-resistant Staphylococcus aureus carriage after discharge from hospital

At the University Medical Center, Utrecht, methicillin-resistant Staphyloco ccus aureus (MRSA) patients are considered lifelong MRSA carriers and poten tially contagious when readmitted. The purpose of this study was to determi ne whether patients who become MRSA carriers while in hospital remain colon ized after discharge, and whether risk factors for prolonged carriage exist . Thirty-six patients colonized with MRSA during three outbreaks at Univers ity Medical Center, Utrecht (group I: 1986-1989), and twenty patients alrea dy colonized with MRSA on, or during, admission to the hospital (group II: 1990-1995) were screened for MRSA in two studies. The patients had been dis charged from the hospital for periods varying from 15 days to 4.6 years. MR SA was found in five (9%). Four of these patients had skin lesions (wounds) , one with an external fixture. The presence of skin- and underlying diseas es differed significantly between carriers and non-carriers, supporting the hypothesis that wounds are a major risk factor for long-term MRSA carriage . This study led us to revise our policy concerning readmission of former M RSA patients. We now consider that patients who contracted MRSA in the past no longer need isolation if the following two criteria are met. Absence fo r at least six months of open wounds, skin lesions, tracheostomy, infection s and sources of infection such as abscesses and furuncles, orthopaedic imp lants, drains, catheters, or tubes. Three MRSA-negative sets of swabs from nose, throat, perineum, urine, and sputum taken at least one hour apart aft er this six-month period.