Synergistic Combinations of Penicillins in the Treatment of Bacteriuria

MOST bacteria that are highly resistant to benzylpenicillin produce penicillinases.1 2 3 4 Large numbers of bacterial cells of many strains, even some considered to be highly resistant to penicillins and cephalosporins, can be killed in the presence of moderate concentrations of these antibiotics, and the survivors proliferate only after most or all of the antibiotic has been destroyed by the enzymes.2 , 4 5 6 Except for a few unusual isolates,7 penicillinase-producing staphylococci owe their penicillin resistance completely to penicillinase (β-lactamase). There is considerable evidence that β-lactamases are also important for the resistance of many strains of gram-negative bacilli to penicillins4 5 6 , 8 and cephalosporins,5 , 6 but the precise . . .