In the bacteriological studies on cephalexin, the following results were obtained.
1. Both gram-positive and gram-negative bacteria were almost equally sensitive to cephalexin. This result appeared to differ from those of cephalothin and cephaloridine which were more sensitive to gram-positive than to gram-negative bacteria.
2. The sensitivities of the clinical isolates of
Staph. aureue (64 strains) and
E. coli (41 strains) were almost same as those of standard strains, though some strains of
E. coli were observed to be resistant to cephalexin.
3. Antibacterial activity of cephalexin
in vitro was not influenced by pH of medium and serum, though it was increased to some extent at pH5. Inoculum size had some influence on the antibacterial activity.
4. Cephalexin showed bactericidal action to
Staph. aureus and
E. coli at the concentrations of more than 3.5mcg/ml and 12.5mcg/ml.
5. The stability in solution, artincial development of resistance,inactivation by β-lactamase and
in vivo activity in experimental infections in mice were also studied.
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