TABLE 2.
Characteristics of patients with USA 300 and non-USA 300 MRSA bacteremiaa
| Characteristicsb | Strain type
|
Pc | |
|---|---|---|---|
| USA 300 (n = 23) | Non-USA 300 (n = 65) | ||
| Median age in yr (range) | 43 (25-58) | 62 (22-91) | <0.001†d |
| No. female (%) | 7 (30) | 34 (52) | 0.09 |
| No. of patients (%)* of race or ethnic group | 0.002‡† | ||
| Caucasian | 9 (39) | 51 (78) | |
| Black | 10 (43) | 9 (14) | |
| Hispanic | 3 (13) | 2 (3) | |
| Other | 1 (4) | 3 (5) | |
| No. of patients (%)* in: | 0.018† | ||
| North America | 23 (100) | 52 (80) | |
| Europe | 0 | 13 (20) | |
| No. of patients (%)* with risk factor | |||
| Diabetes mellitus | 6 (26) | 29 (45) | 0.14 |
| Systemic inflammatory response syndrome | 20 (87) | 47 (72) | 0.25 |
| Injection drug use | 14 (61) | 10 (15) | <0.001† |
| Surgery in prior 30 days | 7 (30) | 29 (45) | 0.33 |
| Human immunodeficiency virus positive | 1 (4) | 1 (2) | 0.46 |
| Intravascular devices | 1 (4) | 13 (20) | 0.10 |
| Extravascular foreign material | 4 (17) | 24 (37) | 0.12 |
| Creatinine clearance < 50 ml/min | 2 (9) | 15 (23) | 0.22 |
| Prior history of endocarditis | 3 (13) | 3 (5) | 0.18 |
| Presumed skin source | 7 (30) | 20 (31) | >0.99 |
| No. of patients (%)* undergoing therapy | 0.27‡ | ||
| Daptomycin | 10 (44) | 34 (52) | |
| Vancomycin | 12 (52) | 31 (48) | |
| Semisynthetic penicillin ± vancomycin | 1 (4) | 0 | |
| No. of patients (%)* with persistent bacteremiae | 2 (9) | 18 (28) | 0.08 |
| No. of patients/total no. (%)* with success at test of curef | |||
| Uncomplicated bacteremia | 3/4 (75) | 15/17 (88) | 0.49 |
| Complicated bacteremia | 3/8 (38) | 22/35 (63) | 0.25 |
| Right-sided endocarditis | 9/9 (100) | 2/6 (33) | 0.01† |
| Left-sided endocarditis | 1/2 (50) | 1/7 (14) | 0.42 |
| No. of patients (%)* with bacterial characteristics | |||
| pvl | 23 (100) | 18 (28) | <0.001† |
| arcA (for arginine mobile catabolic element) | 23 (100) | 2 (3) | <0.001† |
One MRSA isolate was nontypeable and was excluded from the analysis.
*, percentage of patients within each diagnostic category with the indicated characteristic.
Calculated using the Fisher exact test unless otherwise noted. †, statistically significant result with an FDR of <20%; ‡, comparison of USA 300 and non-USA 300 distributions across all levels of this characteristic.
This value was calculated using the Wilcoxon rank-sum test.
Persistent bacteremia was defined as persisting or relapsing S. aureus bacteremia as determined by the adjudication committee.
Failures due to persisting or relapsing S. aureus infection, clinical failure, or death were used to calculate success rates.