Table 1.
Clinical Factors of Community-Associated Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus
| Clinical Factors | CA-MSSA (N = 313) No. (Weighted %)a |
CA-MRSA (N = 270) No. (Weighted %)a |
P Value |
|---|---|---|---|
| Days of symptoms prior to presentationb | |||
| Median, 95% CI | 4.3 (3.1–5.5) | 1.9 (1.3–2.5) | — |
| Clinical course | |||
| Hospitalized | 70 (29.7%) | 86 (36.8%) | .11 |
| Median length of stay, days (95% CI) | 3.3 (2.5–4.0) | 2.2 (1.8–2.5) | — |
| Deaths | 0 | 0 | — |
| Clinical diagnosisc | |||
| Invasive disease | 16 (6.2%) | 3 (1.1%) | .004 |
| Bacteremia | 5 (1.5%) | 2 (1.0%) | .59 |
| Pneumonia | 4 (1.4%) | 0 | — |
| Osteomyelitis | 10 (3.8%) | 0 | — |
| Abscess–not skin | 4 (1.4%) | 3 (1.1%) | .82 |
| Septic arthritis | 4 (1.4%) | 0 | — |
| Skin infection | 151 (49.1) | 215 (79.2%) | <.0001 |
| Abscess–skin | 39 (13.2%) | 115 (43.5%) | <.0001 |
| Cellulitis | 65 (23.8%) | 131 (47.6%) | <.0001 |
| Folliculitis | 4 (1.0%) | 4 (1.6%) | .56 |
| Impetigo | 21 (7.4%) | 9 (2.4%) | .008 |
| Superinfected eczema | 21 (5.0%) | 3 (0.5%) | <.0001 |
| Other skin infectionsd | 40 (9.3%) | 12 (3.7%) | .06 |
| Othere | 54 (18.8%) | 16 (7.1%) | .003 |
| Unknown clinical diagnosis | 84 (24.3%) | 36 (13.2%) | .002 |
| Culture site | |||
| Sterile | |||
| Blood | 10 (4.1%) | 3 (1.5%) | .10 |
| Bone | 1 (0.2%) | 0 | — |
| Nonsterile | |||
| Wound or pustule | 220 (70.1%) | 182 (75.5%) | .17 |
| Abscess | 34 (8.2%) | 77 (19.8%) | <.0001 |
| Respiratoryf | 13 (6.0%) | 0 | — |
| Other | 30 (9.5%) | 8 (3.5%) | .008 |
| Unknown site | 5 (0.5%) | 3 (0.9%) | .63 |
| Body site for wound, pustule or abscess culturesg | |||
| Extremity | 106 (38.0%) | 84 (32.6%) | .25 |
| Groin/buttock | 22 (11.0%) | 79 (33.1%) | <.0001 |
| Face/head/neck | 73 (28.9%) | 40 (15.4%) | .0010 |
| Trunk | 24 (11.5%) | 38 (13.7%) | .50 |
| Other | 13 (6.0%) | 17 (8.1%) | .43 |
| Polymicrobial culturesh | 129 (41.5%) | 48 (17.5%) | <.0001 |
| Underlying conditionsc | |||
| Eczema | 106 (24.3%) | 48 (13.5%) | .001 |
| Asthma | 40 (10.6%) | 31 (10.5%) | .97 |
| Diabetes | 1 (0.5%) | 0 | — |
| Immunosuppressed | 1 (0.2%) | 0 | — |
| Influenza (last 10 days) | 1 (0.5%) | 0 | — |
| Lupus | 9 (1.9%) | 3 (1.5%) | .70 |
| Malignancy | 0 | 1 (0.5%) | — |
| Obesity | 4 (1.0%) | 7 (1.8%) | .44 |
| Premature birth | 2 (0.3%) | 4 (1.9%) | .02 |
| Substance abuse | 3 (0.6%) | 3 (1.2%) | .26 |
| Other conditions | 38 (8.9%) | 23 (5.9%) | .17 |
Abbreviations: CA-MRSA, community-associated methicillin-resistant Staphylococcus aureus; CA-MSSA, community-associated methicillin-sensitive S aureus; CI, confidence interval.
aPercentages calculated based on weighted data (weight of 3 for Children's Hospital Oakland subjects, 1 for all other subjects).
bObtained from chart abstractions, CA-MSSA n = 95, CA-MRSA n = 58.
cMore than 1 may apply.
dIncludes traumatic wound, surgical incision (2 infections after pilomatricoma removal), nail, carbuncle/furuncle, sebaceous gland, hair, and skin infections not otherwise specified.
eIncludes kidney, eye, urinary tract, lymph node, ear (internal or external), and other infections.
fIncludes nasopharyngeal, throat, sputum, tracheal/endotracheal tube aspirate, and bronchoalveolar lavage.
gSome episodes involved multiple body sites; the total number of body sites is greater than the total number of cultures.
hData based on isolates not episodes, CA-MSSA n = 317, CA-MRSA n = 272.