Table 2.
Baseline characteristics and clinical outcomes of patients with methicillin-susceptible S. aureus bacteremia. Patients received either empiric combination therapy with β-lactam plus vancomycin or empiric β-lactam monotherapy
| Patient characteristics | β-lactam plus vancomycina (n=153) | β-lactam monotherapya (n=47) | P-value |
|---|---|---|---|
| Ageb | 51.3 ± 16.9 | 58.7 ± 16.1 | < 0.01 |
| Males | 92 (60.1) | 34 (72.3) | 0.17 |
| Community-onset | 137 (89.5) | 36 (76.6) | 0.03 |
| Hospital-onset | 16 (10.5) | 11 (23.4) | 0.03 |
| HIV infection | 18 (11.8) | 2 (4.26) | 0.17 |
| Hepatitis C infection | 50 (32.7) | 11 (23.4) | 0.28 |
| Immunocompromised | 12 (7.84) | 6 (12.8) | 0.38 |
| Alcohol or illicit drug abuse | 68 (44.4) | 14 (29.8) | 0.09 |
| Intravenous drug use | 54 (35.3) | 10 (21.3) | 0.08 |
| Charlson comorbidity indexc | 3 (1–6) | 3 (1–5) | 0.30 |
| Pitt bacteremia scorec | 1 (0–2) | 0 (0–1) | < 0.01 |
| Infectious diseases consultation | 120 (78.4) | 30 (63.8) | 0.05 |
| Source of bacteremia | |||
| Central or peripheral line | 15 (9.80) | 9 (19.1) | 0.12 |
| Skin and soft tissue | 25 (16.3) | 11 (23.4) | 0.28 |
| Intravenous drug use | 43 (28.1) | 5 (10.6) | 0.02 |
| Bone or joint infection | 15 (9.80) | 8 (17.0) | 0.19 |
| Lung | 4 (2.61) | 2 (4.26) | 0.63 |
| Other | 14 (9.15) | 5 (10.6) | 0.78 |
| Unknown | 37 (24.2) | 7 (14.9) | 0.23 |
| Infective endocarditis | 40 (26.1) | 5 (10.6) | 0.03 |
| Metastatic complications | 66 (43.1) | 7 (14.9) | < 0.001 |
| Surgical source control | 31 (20.3) | 12 (25.5) | 0.43 |
| Empiric antimicrobials | |||
| Cloxacillin or cefazolin | 95 (62.1) | 43 (91.5) | < 0.0001 |
| 3rd generation cephalosporin | 73 (47.7) | 7 (14.9) | < 0.0001 |
| Piperacillin-tazobactam | 65 (42.5) | 4 (8.51) | < 0.0001 |
| Ticarcillin-clavulanic acid | 2 (1.31) | 1 (2.13) | 0.55 |
| Carbapenem | 7 (4.58) | 1 (2.13) | 0.68 |
| Daptomycin | 0 | 2 (4.26) | 0.05 |
| Linezolid | 1 (0.65) | 1 (2.13) | 0.42 |
| Otherd | 60 (39.2) | 22 (46.8) | 1.00 |
| Blood culture time to positivitye | 20.3 (16.3–25.3) | 19.8 (18.0–27) | 0.36 |
| Duration of empiric therapye | 55.5 (44.9–73.8) | 54.3 (38.8–64.5) | 0.08 |
| Duration of definitive therapyf | 31 (14–43) | 26 (12–40) | 0.18 |
| Time to receipt of empiric therapye | 1.6 (0.03–6.17) | 3.95 (0.58–15.5) | 0.08 |
| Time to receipt of β-lactame | 2.77 (0.25–13.7) | 3.95 (0.58–16.6) | 0.74 |
| Time to receipt of cloxacillin or cefazoline | 34.8 (21.2–58.4) | 13.0 (1.83–23.8) | 0.00 |
| Empiric β-lactam exposuree | 52.3 (39.8–73.8) | 51.7 (38.8–64.5) | 0.42 |
| Proportional empiric β-lactam exposureg | 100 (86.1–100) | 100 (95.2–100) | 0.01 |
| Primary outcome | |||
| 28-day mortality | 14 (9.15) | 2 (4.26) | 0.37 |
| Secondary outcomes | |||
| 90-day mortality | 21 (13.7) | 4 (8.51) | 0.45 |
| Recurrent infection at 6 months | 5 (3.27) | 2 (4.26) | 0.67 |
| Duration of bacteremiae,h | 84.8 (52.5–136) | 63.4 (30.5–114) | 0.03 |
| ≥ 3 daysh | 81 (56.3) | 17 (44.7) | 0.27 |
| Hospital length of stayf | 26 (13–45) | 15 (10–30) | < 0.01 |
aVariables are displayed as counts and percentages in parentheses unless otherwise specified
bAge is represented as a mean ± standard deviation in years
cVariables are expressed as a median with interquartile range in parentheses
dOther antimicrobials used during empiric and definitive therapy included rifampin, aminoglycosides, fluoroquinolones, macrolides, trimethoprim-sulfamethoxazole, and clindamycin
eVariables are expressed as median hours with interquartile range in parentheses
fVariables are expressed as median days with interquartile range in parentheses
gVariables are expressed as median percentages with interquartile range in parentheses
hData missing for 9 patients in each subgroup