Patients colonized by antibiotic resistant bacteria--a potential source of infections in the medical wards.

Bacterial colonization was studied in 12 non-infected female patients admitted into one medical ward, Siriraj hospital, Bangkok, from March to June 1988. Swabs were taken on the first day of admission, then every other day until discharge, from six sites; i.e. anterior nares, vault of axilla, hands, anterior chest, abdomen and toe web. The times and total number of swabbing were 52 and 312 respectively. All patients were colonized with bacteria. S. epidermidis was found in all patients. S. aureus was found in 9 patients, 48 times (15.4%). Methicillin-resistant S. aureus (M.R.S.A.) was identified in 4 patients on 10 occasions (3.2%). Gram-negative bacilli were isolated in 11 of 12 patients, and the number of positive samples was 60 (19.2%). All bacteria were highly resistant to the commonly used antimicrobials. The study failed to show that colonization increased with the duration of hospitalization. It is concluded that the majority of patients who had been colonized with pathogenic bacteria were important sources of infections in the medical ward.