[Comparison of four recently introduced cephalosporins with respect to probability of resistance in multiresistant strains of Escherichia coli, Proteus mirabilis and Klebsiella spec. (author's transl)].

Strains with the same number of resistances were arranged in so-called resistance classes. Nine classes of resistance (0 to greater to or equal to 8) were formed by means of ten standard chemotherapeutics; the four new cephalosporins were excluded. For every resistance class frequency of cephalosporinresistance was described as coefficient ranging from 0 to 1 (Fig. 1). In Cephalothin the coefficients were markedly rising only in 6 (7)-fold resistant strains of the species examined. Similar but somewhat reduced rising of coefficients was also observed in Cefaclor and Cefamandole. In Cefaclor this is particularly evident for E. coli, whereas in Cefamandole, it concerns Klebsiella spec. In the other species rising of coefficients of Cefaclor and Cefamandole are less marked. The probability of restance in multiresistant strains are therefore distinguished more clearly from that of Cephalothin. Cefuroxime and Cefoxitin take a special position because the probability of resistance does not rise in multiresistant strains. The coefficients of Cefoxitin do not show any recognizable dependance on multiresistance. For clinical purpose the following conclusions can be derived: Because of their effectiveness in multiresistant strains Cefoxitin and Cefuroxime are suitable for empiric use in intensive care units where many multiresistant Klebsiella-strains are to be expected. Cefamandole on the other hand is characterized by a rising probability of resistance in multiresistant strains. Therefore it should only be given after antibiotic testing. Cefaclor, a new oral cephalosporin, will be introduced specially for outpatients where multiresistant strains are rarely found.