Susceptibility at high inoculum of penicillin-resistant Staphylococcus aureus to six cephalosporins

Six cephalosporins (currently available for clinical use or undergoing clinical trials) were tested by tube dilution method against high inoculum (107 colony forming units) of 37 strains of penicillin resistant Staphylococcus aureus. 3.1 μg/ml of cephalothin inhibited 100% of strains while higher concentrations of cefoxitin, cephapirin, cefamandole, cephalexin and cephradine were required. The percent of strains with minimal inhibitory concentration higher than 3.1 μg/ml ranged between 10.8% (cefoxitin) and 100% (cephradine). These findings support the observation that cephalothin is less susceptible to inactivation than the other cephalosporins. Although the exact clinical implication of these findings has not been established, cephalothin might be the cephalosporin of choice for treatment of severe infections caused by penicillin resistant Staphylococcus aureus

A Clinical Trial of Tobramycin with Pharmacological and Microbiological Studies

Tobramycin, a new aminoglycoside antibiotic, was shown to be effective in vitroagainst Pseudomonas, Klebsiella, Staphylococcus aureus, Enterobacter, Proteus mirabilis, indole-positive Proteus, and Eshcherichia coli. It was shown to produce serum and urine concentrations similar to gentamicin when administered intramuscularly. Preliminary animal studies showed this agent to have nephrotoxic and ototoxic effects similar to gentamicin. In our studies, tobramycin was well tolerated and produced only two transient elevations in serum creatinine and no abnormalities in audiograms and vestibular function tests. It was effective in 10 of 12 susceptible infections, including 2 of 4 with Pseudomonas endocarditis. Tobramycin compared favorably with gentamicin and may be superior in treatment of susceptible Pseudomonas infections