Penetration of tobramycin into infected extravascular fluids and its therapeutic effectiveness.

The aminoglycoside antibiotic tobramycin was given intramuscularly to 15 patients with infected body fluids (empyema in five patients, peritonitis in five, peritonitis and empyema in one, tracheobronchitis in three, and infection of the pacemaker pocket in one). The infecting bacteria included Pseudomonas aeruginosa, Klebsiella, Enterobacter, Serratia, Escherichia coli, Proteus species, and Staphylococcus aureus. The mean dose of tobramycin was 1.7 mg/kg given intramuscularly every 8 hr for nine to 10 days. Levels of tobramycin in specimens of serum and infected body fluid obtained simultaneously were measured at various intervals after a dose of the antibiotic. Comparison was made between levels of tobramycin and minimal inhibitory concentrations (MICs) of the infecting bacteria. Bacteriological and clinical failures were common if the level in body fluid did not exceed the MIC. In patients with levels of tobramycin in body fluid that were higher than the MIC, cures were frequent. Drainage of infected body fluids is a necessary part of successful therapy of these infections.