title: Independent antibiotic actions of hetacillin and ampicillin revealed by fast methods.
abstract: Fast methods for measuring inhibition of growth of Escherichia coli or Staphylococcus aureus by hetacillin or ampicillin showed that the rate of inhibition was a function of the antibiotic concentration. When ampicillin concentrations were measured rapidly, hetacillin was shown to have a half-life of 20 min at 37 C and pH 6.7. Hetacillin was much less susceptible to penicillinase (beta-lactamase) than was ampicillin. An inhibitory effect of hetacillin was shown in the presence of beta-lactamase, which destroyed ampicillin activity very rapidly.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects*; D006207:Half-Life; D008722:Methods; D010406:Penicillins / Q000494:pharmacology*; D013210:Staphylococcus / Q000187:drug effects*
chemical_list: D010406:Penicillins; D000667:Ampicillin