Colonization of Skilled-Care Facility Residents with Antimicrobial-Resistant Pathogens


  • Presented at the Ninth Annual Meeting of the Society for Healthcare Epidemiology of America.

Address correspondence to William E. Trick, MD, Galter Carriage House, Suite 701B, 215 E. Chicago St., Chicago, L. 60611.


OBJECTIVES: To determine the frequency of and risk factors for colonization of skilled-care unit residents by several antimicrobial-resistant bacterial species, methicillin-resistant Stuphylococcus aweus (MRSA), vancomycin-resistant enterococcus (VRE), or extended-spectrum-B-lactamase-producing (ESBL-producing) (ceftazidime resistant) Klebsiella pneumoniae or Escherichia coli.

DESIGN: Point-prevalence survey and medical record review.

SETTING: The skilled-care units in one healthcare facility.

PARTICIPANTS: 120 skilled-care unit residents.

MEASUREMENTS: Colonization by each of the four antimicrobial-resistant pathogens during a point-prevalence survey, using rectal, nasal, gastrostomy-tube site, wound, and axillary cultures, June 1–3, 1998; 117 (98%) had at least one swab collected and 1 14 (95%) had a rectal swab collected. Demographic and clinical characteristics were evaluated as risk factors for colonization. All isolates were strain typed by pulsed-field gel electrophoresis of total genomic deoxyribonucleic acid.

RESULTS: Of 117 participants, 50 (43%) were culture positive for ≥1 antimicrobial-resistant pathogen: MRSA (24%), ESBL-producing K. pneumoniae (18%) or E. coli (15%), and VRE (3.5%). Of 50 residents culture positive for any of these four antimicrobial-resistant species, 13 (26%) were colonized by more than one resistant species; only three (6%) were on contact-isolation precautions at the time of the prevalence survey. Risk factors for colonization varied by pathogen: total dependence on healthcare workers (HCWs) for activities of daily living (ADLs) and antimicrobial receipt for MRSA, total dependence on HCWs for ADLs for ESBL-producing K. pneumoniae, and antimicrobial receipt for VRE. No significant risk factors were identified for colonization by ESBL-producing E. coli. Among colonized patients, there was a limited number of strain types for MRSA (24 patients, 4 strain types) and ESBL-producing K. pneumoniae (21 patients, 3 strain types), and a high proportion of unique strain types for VRE (4 patients, 4 strain types) and ESBL-producing E. coli (17 patients, 10 strain types).

CONCLUSION: A large unrecognized reservoir of skilledcare-unit residents was colonized by antimicrobial-resistant pathogens, and co-colonization by more than one target species was common. To prevent transmission of antimicrobial-resistant pathogens in long-term care facilities in which residents have high rates of colonization, infection-control strategies may need to he modified. Potential modifications include enhanced infection-control strategies, such as universal gloving for all or high-risk residents, or screening of high-risk residents, such as those with total dependence on HCWs for ADLs or recent antimicrobial receipt, and initiation of contact-isolation precautions for colonized residents.