Infective endocarditis: the role of cloxacillin alone for right-sided endocarditis was unclear.

Clinical bottom line (level 1b-)

  1. 70% of patients with right-sided endocarditis were cured following two weeks of iv cloxacillin and gentamicin.
  2. Cloxacillin alone was not clearly better than combination therapy.
Ribera et al: Annals of Internal Medicine 1996; 125: 969-974
Expires July 2003

The study

Unblinded concealed randomised trial with intention-to-treat
Setting: tertiary care hospital, Spain, 1988 to 1993

90 patients (aged mean 27 years, 75% male) intravenous drug users with isolated tricuspid valve endocarditis caused by S. aureus

Excluded if
  • infected with methicillin-resistant S. aureus
  • allergy to study medications
  • systemic infectious complications that required prolonged therapy (osteomyelitis, abscesses that could not be drained surgically)
  • confirmed or suspected left-sided endocarditis shown by clinical examination (characteristic regurgitant murmur or systemic embolisation) or echocardiography (vegetation or valvular insufficiency)
  • antibiotic therapy given for longer than 48 hours before hospitalisation


    • Control Group: (n = 45, 45 analysed): cloxacillin 2 g iv every 4 hours for 14 days combined with gentamicin 1 mg/kg of body weight iv every 8 hours for 7 days
    Experimental Group: (n = 45, 45 analysed): cloxacillin 2 g iv every 4 hours for 14 days alone

    100% followed for 6 months
    Outcome notes:
    • unsuccessful therapy : successful therapy- clinical and bacteriologic recovery without subsequent relapse

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    unsuccessful therapy 6 months 14
    (31.1%)    		 11
    (24.4%)    		 21%
    (-54% to 60%)    		 6.67%
    (-11.8% to 25.1%)    		 15
    (NNT = 4 to infinity;
    NNH = 8 to infinity)
    death 6 months 2
    (4.44%)    		 1
    (2.22%)    		 50%
    (-432% to 95%)    		 2.22%
    (-5.18% to 9.63%)    		 45
    (NNT = 10 to infinity;
    NNH = 19 to infinity)

  • 5/71 (7%) patients required prolonged treatment.

    • Comments

    1. Patients were randomised in sets of ten.
    2. The study was far too small to show small increases in harm for patients on cloxacillin alone.

    Citation

    1. Ribera E, et al: Effectiveness of cloxacillin with and without gentamicin in short-term therapy for right-sided staphylococcus aureus endocarditis. A randomized controlled trial. Annals of Internal Medicine 1996; 125: 969-974
    Search Terms: endocarditis in Cochrane
    Contributor: Carl Heneghan, Sumit Dhingra and Chris Ball, July 2000
    Reviewer:

    Clinical Question.
    Patient infective endocarditis
    Intervention or Exposure cloxacillin and gentamicin
    Outcome cured