To evaluate the prevalence of colonization among patients with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection and their household contacts.

Prospective, observational laboratory study of nasal colonization among patients and their household members from September 15, 2004, to February 20, 2006.

A 600-bed, urban, academic medical center.

Fifty-one patients who presented with CA-MRSA infections and 49 household members had cultures of nasal swab specimens performed.

Skin and soft-tissue infections were seen in 50 patients (98%) and 2 household members. Twenty-one (41%) of 51 patients and 10 (20%) of 49 household members were colonized with MRSA. An additional 5 patients (10%) and 12 household members (24%) were colonized with methicillin-susceptible Staphylococcus aureus. Most MRSA isolates (95%; infective and colonizing) carried the staphylococcal cassette chromosome mec type IV complex, and 67% represented a single clone, identical to USA 300. Of the colonized household members, 5 had isolates related to the patients' infective isolate.

The frequency of CA-MRSA colonization among household members of patients with CA-MRSA infections is higher than rates reported among the general population. Among colonized household members, only half of the MRSA strains were related to the patients' infective isolate. Within the same household, multiple strains of CA-MRSA may be present.

To determine the prevalence of stool colonization with vancomycin-resistant enterococci (VRE) among healthcare workers (HCWs) and their families.

Prospective assessment of fecal colonization with VRE.

A 603-bed, tertiary-care teaching hospital.

Healthy volunteers recruited from hospital employees and their households were screened to exclude pregnancy, diabetes mellitus, immunosuppressive disorders, and recent use of antimicrobials.

Self-obtained stool swabs were used to obtain cultures. Isolated enterococci were screened for vancomycin resistance and species were identified. Intra-household isolates were genotyped using pulsed-field gel electrophoresis (PFGE).

The participants (n = 228; age range, 28 days to 80 years) were from 137 households with and 91 without employees who had contact with patients. Enterococcus species were isolated from 127 stool specimens (55.7%). VRE were detected in 12 individuals, representing 6 E. casseliflavus, 5 E. faecium, and 1 E. gallinarum. VRE were more commonly isolated in employees who had contact with patients (5 of 52 vs 0 of 40; relative risk [RR], 1.9; 95% confidence interval [CI95], 1.5 to 2.2; P = .07) and their household members (10 of 137 vs 2 of 91; RR, 3.3; CI95, 0.7 to 14.8; P = .13). In 2 households (2 adults in a physician's household and an adult plus a child in a nurse's household) PFGE analysis demonstrated identical intra-household strains of vancomycin-resistant E. faecium.

VRE colonization was found in 5.3% of screened stools and was more prevalent in HCWs who had contact with patients and their households. Identical PFGE patterns between 2 employees who had contact with patients and their household members demonstrated probable intra-household spread. Although the mode of acquisition was uncertain, the association with employees who had contact with patients suggests possible occupational sources. These findings demonstrate the spread of VRE within the household and implicate occupational risk for its acquisition.