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Table 2 Comparison of baseline characteristics and clinical outcomes of patients with methicillin-susceptible S. aureus bacteremia who received empiric combination therapy with β-lactam plus vancomycin or empiric β-lactam monotherapy

From: Comparative effectiveness of β-lactam versus vancomycin empiric therapy in patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia

Patient characteristics β-lactam plus vancomycina (n = 88) β-lactam monotherapya (n = 43) p value
Age (mean ± standard deviation in years) 50.5 ± 16.4 58.9 ± 16.6 0.006
Males 53 (60.2) 30 (69.8) 0.34
Community-onset 74 (84.1) 31 (72.1) 0.16
Hospital-onset 14 (15.9) 12 (27.9) 0.16
HIV infection 9 (10.2) 2 (4.7) 0.34
Hepatitis C infection 19 (21.6) 10 (23.3) 0.83
Immunocompromised 8 (9.1) 6 (14.0) 0.39
Alcohol or illicit drug abuse 29 (33.0) 12 (27.9) 0.69
Intravenous drug use 21 (23.9) 8 (18.6) 0.65
Charlson comorbidity index (median with IQR) 2 (1–4) 3 (1–5) 0.07
Pitt bacteremia score (median with IQR) 1 (0–2) 0 (0–1) 0.01
Infectious diseases consultation 71 (80.7) 27 (62.8) 0.03
Source of bacteremia
 Central or peripheral line 12 (13.6) 8 (18.6) 0.45
 Skin and soft tissue 20 (22.7) 11 (25.6) 0.83
 Intravenous drug use 16 (18.2) 5 (11.6) 0.45
 Bone or joint infection 10 (11.4) 8 (18.6) 0.29
 Lung 2 (2.3) 2 (4.7) 0.60
 Other 9 (10.2) 3 (7.0) 0.75
 Unknown 19 (21.6) 6 (14.0) 0.35
Infective endocarditis 19 (21.6) 5 (11.6) 0.23
Metastatic complications 33 (37.5) 7 (16.3) 0.02
Surgical source control 22 (25) 11 (25.6) 1.00
Recurrent infection at 6 months 2 (2.3) 2 (4.7) 0.60
Empiric antimicrobials    
 Daptomycin 0 2 (4.7) 0.11
 Linezolid 1 (1.1) 1 (2.3) 0.55
 Cloxacillin or cefazolin 88 (100) 43 (100) 1.00
 3rd generation cephalosporin 35 (39.8) 5 (11.6) 0.001
 Piperacillin–tazobactam 30 (34.1) 3 (7.0) <0.001
 Ticarcillin–clavulanic acid 2 (2.3) 1 (2.3) 1.00
 Carbapenem 1 (1.1) 1 (2.3) 0.55
 Otherb 27 (30.7) 20 (46.5) 0.08
Blood culture time to positivity (median hours with IQR) 20 (16.0–24.0) 20.7 (18–27.3) 0.07
Duration of empiric therapy (median hours with IQR) 54.1 (43.0–71.7) 51.7 (38–64.5) 0.18
Duration of definitive therapy (median days with IQR) 38 (16–43) 23 (12–40) 0.08
Time to receipt of empiric therapy (median hours with IQR) 1.91 (0–6.17) 3.42 (0.58–17.2) 0.19
Time to receipt of β-lactam (median hours with IQR) 2.88 (0.21–15.1) 3.42 (0.58–17.2) 0.87
Time to receipt of cloxacillin or cefazolin (median hours with IQR) 23.1 (13.0–31.7) 6.5 (1.5–22.1) 0.001
Primary outcome    
 28-day mortality 5 (5.7) 2 (4.7) 1.00
Secondary outcomes    
 90-day mortality 10 (11.4) 4 (9.3) 1.00
 Duration of bacteremia (median hours with IQR)c 71.4 (50.3–126.9) 68.5 (36.4–115.8) 0.35
 ≥3 days 41 (46.6) 17 (39.5) 0.46
 Hospital length of stay (median days with IQR)d 22 (12–44) 14 (10–22.8) 0.02
  1. IQR interquartile range
  2. aVariables are displayed as counts and percentages in parentheses unless otherwise specified
  3. bOther antimicrobials used during empiric and definitive therapy included rifampin, aminoglycosides, fluoroquinolones, macrolides, trimethoprim-sulfamethoxazole, and clindamycin
  4. c6 and 9 patients from the β-lactam plus vancomycin and β-lactam monotherapy subgroup respectively were excluded from the analysis due to lack of follow-up blood cultures
  5. d9 and 3 patients from the β-lactam plus vancomycin and β-lactam monotherapy subgroup respectively were excluded from the analysis due to death during hospital admission