MANY CLINICIANS have had the experience of prescribing a sulfonamide drug for the treatment of a urinary tract infection with gratifying clinical results, only to receive, several days later, a bacterial sensitivity report, alleging the infecting organism to be sulfonamide-resistant. Such disparity between laboratory estimation of bacterial resistance to sulfonamides and the clinically curative action of these drugs is a source of insecurity to clinicians, for clinicians are constantly admonished to prescribe appropriate or specific chemotherapy in accordance with laboratory-determined bacterial sensitivity. A degree of fortitude, of folly, or of both, is required of the clinician who prescribes a drug that has been reported by the laboratory to be ineffective as an inhibitor of the bacteria causing the infection he wishes to control. More conservative clinicians eliminate sulfonamides from consideration and find refuge in the use of broad-spectrum antibiotics.
Possible explanations for this phenomenon of clinic-laboratory dissociation are laboratory