Laboratory and clinical studies on cephalexin and its suspension were conducted to obtain the following results:
1. The MIC of cephalexin against various organisms showed that it was 0.4-6.3mcg/ml against staphylococci and that 40% of the tested strains were resistant to ampicillin and penicillin G at more than 25mcg/ml and that all the strains were sensitive to oxacillin. The MIC against
E. coli was 3.1-12.5mcg/ml, and it was 1.6-3.1mcg/ml against most of
Klebsiella and 6.3mcg/ml against
Proteus mirabilis, but resistance was found in
enterococci.
2. Antibacterial susceptibility of cephalexin was less than those of cephaloridine and cephalothinagainst gram-positive cocci, but with little difference against gram-negative bacilli, and it was almostsame with cephalothin.
3. In the sensitivity test with disc containing cephalexin 30 mcg, most of the tested strains of over15mm inhibitory diameter were inhibited at MIC lower than 6.3mcg/ml.
4. Blood levels of cephalexin suspension on 250mg (12-26mg/kg) were assayed in 5 children. Peakblood level was at 60 minutes after administration with the average of 13.0mcg/ml (8.4-23.0), and 7.0 mcg/ml (4.6-12.0) at 2 hours, 1.3mcg/ml (0.8-3.2) at 4 hours and 0.14mcg/ml (undetermined, to 0.4) at 6 hours respectively.
5. Clinical studies were made with 76 children cases of acute infection: 22 cases of tonsillitis, 16.
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