Table 2.
Characteristics of Household Contacts at Enrollment (Non–Index Subjects)
| Variable | 3 mo, No. (%) (n = 588) | 6 mo, No. (%) (n = 510) |
|---|---|---|
| Demographics | ||
| Los Angeles site | 303 (52) | 245 (48) |
| Female sex | 368 (63) | 334 (66) |
| Age | ||
| Younger child (<5 y) | 79 (13) | 56 (11) |
| Child (5–18 y) | 129 (22) | 104 (20) |
| Adult (19–65 y) | 353 (60) | 324 (64) |
| Older adult (>65 y) | 27 (5) | 26 (5) |
| Ethnicity | ||
| African American | 282 (48) | 261 (51) |
| White | 35 (6) | 34 (7) |
| Hispanic | 232 (40) | 186 (37) |
| Other/mixed/unknown | 39 (7) | 29 (6) |
| Clinical factors | ||
| Comorbidities | ||
| Charlson comorbidity score | ||
| Mean ± SD | 0.4 ± 0.9 | 0.4 ± 0.9 |
| Median (range) | 0 (0–7) | 0 (0–7) |
| Diabetes | 56 (10) | 48 (10) |
| HIV infection | 4 (1) | 4 (1) |
| In the past 3 mo | ||
| Underwent major surgery | 39 (7) | 10 (2) |
| Received dialysis | 1 (0) | 2 (0) |
| Hospitalized | 66 (11) | 14 (3) |
| Skin infection | 57 (10) | 40 (9) |
| In the past 12 mo | ||
| Any antibiotic exposure | 181 (32) | 158 (32) |
| Use of clindamycin | 7 (1) | 9 (2) |
| Use of TMP-SMX | 8 (1) | 9 (2) |
| Use of cephalexin | 14 (2) | 12 (2) |
| Use of immunosuppressant medications | 57 (10) | 58 (12) |
| Spent time living in a skilled nursing facility, rehabilitation center, or other type of group facility | 18 (3) | 15 (3) |
| Epidemiologic factors | ||
| Homelessness in the past 12 mo | 30 (5) | 24 (5) |
| In the past 3 mo | ||
| Illicit drug use | 34 (8) | 20 (6) |
| Showered at least once a day | 432 (74) | 338 (75) |
| Shared makeup with others | 63 (12) | 40 (10) |
| Shared clothes with others with washing | 29 (5) | 17 (4) |
| Shared any towels with others | 297 (51) | 149 (34) |
| Wore clothes more than once without washing | 283 (49) | 209 (47) |
| Hand-washing frequency after using the bathroom | ||
| Mean ± SD | 2.7 ± 0.61 | 2.8 ± 0.56 |
| Median (range) | 3 (0–3) | 3 (0–3) |
| Participated in contact sports | 147 (25) | 94 (21) |
| Went to daycare | 10 (11) | 13 (14) |
| Colonization | ||
| Any colonization with S. aureus | 282 (48) | 207 (42) |
| Any colonization with MRSA | 125 (21) | 85 (17) |
| Any colonization with index subject's infection isolate | 95 (16) | 62 (13) |
| Nasal colonization with index subject's infection isolate | 41 (7) | 32 (7) |
| Oropharyngeal colonization with index subject's infection isolate | 44 (7) | 28 (6) |
| Inguinal colonization with index subject's infection isolate | 47 (8) | 26 (5) |
Abbreviations: HIV, human immunodeficiency virus; MRSA, methicillin-resistant Staphylococcus aureus; S. aureus, Staphylococcus aureus; SD, standard deviation; TMP-SMX, trimethoprim-sulfamethoxazole.