Relationship Between Pathogenic and Colonizing Microorganisms Detected in Intensive Care Unit Patients and in Their Family Members and Visitors

Abstract

A prospective, observational, pilot study was conducted in an 8-bed, mixed medical-surgical intensive care unit (ICU) to test the hypothesis that patients' family members are healthy carriers (reservoirs) of pathogens, which are, in turn, transmitted to patients, causing colonization or nosocomial infection. Patients in this ICU were treated in one room with 4 beds and in 2 rooms with 2 beds. Routine surveillance of infections already present at the time of ICU admission as well as ICU-acquired infections was performed. From May through August 2007, patients' family members and other visitors were screened for bacterial and fungal contamination or colonization on entry to the ICU and following hand washing. Swab samples from the nares and palmar skin were obtained. Overall, 180 swab samples were obtained from 90 family members and visitors; a total of 16 nasal swab samples and 20 skin swab samples were positive for pathogens. Twenty isolates were recovered from 90 skin swab samples (13 coagulase-negative Staphylococcus isolates, 5 methicillin-susceptible Staphylococcus aureus isolates, and 2 Acinetobacter species isolates). Sixteen isolates were collected from 90 nasal swab samples (7 coagulase-negative staphylococci, 8 methicillin-susceptible S. aureus, and one Aspergillus species). During that period, 19 ICU-acquired infections and one fever of unknown origin occurred in 14 patients who stayed in the ICU for longer than 6 days. None of the microorganisms responsible for infection in patients was found on the skin or in the nares of family members or visitors. No correlation was found between isolates recovered from routine surveillance cultures done for patients and isolates found to be colonizing or contaminating patients' family members or visitors.