Sulfonamide-resistant Staphylococci: Correlation of in Vitro Sulfonamide-resistance with Sulfonamide Therapy.

A feature of sulfonamide therapy for bacterial infections is that species of bacteria differ in their resistance to the antibacterial action of the compounds. It is also recognized that strains of microorganisms within the same species display variations in susceptibility. A disconcerting and confusing factor associated with chemotherapy, which appears to be assuming increasing clinical significance, is the ease and frequency with which some species of bacteria may develop in vtro and in vivo resistance to the bacteriostatic action of the sulfonamides. In the literature, the term "sulfonamide-fast" has been applied to those strains which become resistant to the antibacterial action of the compounds. This is particularly applicable to studies involving species of bacteria whose progenitors were known to be sensitive to the sulfonamides. Because the development of resistance is a relative phenomenon, and because, under proper experimental conditions, the growth of even the most resistant strains of bacteria may be inhibited by the drugs, the term "sulfonamide-resistant" is believed to be a more accurate description. The purpose of this report is to review briefly the problem of sulfonamide-resistant bacteria in general, and to record the results of investigations with several strains of staphylococcus isolated from patients. An attempt has been made to answer the following questions: If a standard in vitro test is used for quantitating the inhibitory effect of the sulfonamides upon the growth of staphylococci, do strains of this species vary in their susceptibility to the antistaphylococcic action of the compounds? Is there any correlation between the isolation of sulfonamide-resistant strains of staphylococci