To the Editor.
—In the October 1979 issue of the Archives, (139:1094-1098), Dr Licht reported on a retrospective study on the bactericidal activity of the sera of 14 patients with staphylococcal bacteremia who were treated initially with a penicillinaseresistant penicillin (PRP) alone and later with the same drug in combination with gentamicin sulfate. In most of their patients, the addition of gentamicin to the PRP was associated with a marked increase in the bactericidal activity of the serum against the infecting organism. The only data concerning the clinical outcome of the patients can be found in the article published by Murray et al,1 studying in detail one of the patients of this series. For this patient, therapy with methicillin sodium alone gave unsatisfactory results, and addition of gentamicin resulted in clinical improvement. We have been impressed by the low bactericidal activity of the serum containing the PRP alone (1:2