Within recent months antimicrobial agents capable of suppressing the multiplication of almost all of the pathogenic bacteria have been given widespread clinical trial. None of these agents has been effective against all strains of the Pseudomonas (Pyocyaneus)1 and Proteus group of organisms. As the result of the suppression of other more pathogenic bacteria in the prophylactic or therapeutic use of the antibiotics, these relatively nonpathogenic organisms have frequently been allowed to multiply and have played an active part in the pathogenesis of infectious processes.
It is the purpose of this paper to present examples of infections due to Proteus or Pseudomonas that developed during or following therapy with the commonly used antimicrobial agents. During the past two years 56 patients have been observed with such infections. Their diagnoses are presented in the table and eight illustrative cases are described. The pathogenesis, diagnosis, and treatment of these infections are also