[MICs and MBCs of cefotaxime, desacetylcefotaxime and ceftriaxone against four principal bacteria causing meningitis].

: The MICs and MBCs of cefotaxime (CTX), desacetylcefotaxime (Des-CTX) and ceftriaxone (CTRX) were determined in relation to 4 of the principal bacterial species which cause meningitis, i.e., S. pneumoniae, S. agalactiae, H. influenzae and E. coli. These tests were performed using final inocula of 10(8) cells/ml and 10(6) cells/ml. Comparison was made with the MIC and MBC values of benzylpenicillin (PCG) and ampicillin (ABPC). 1. Against 25 strains of S. pneumoniae, the MIC 90 values with inocula levels of 10(8) and 10(6) cells/ml were as follows: CTX, 0.05 and 0.024 micrograms/ml; Des-CTX, 0.39 and 0.20 micrograms/ml; CTRX, 0.10 and 0.05 micrograms/ml, respectively; and PCG, less than 0.012 micrograms/ml at both size. Similarly, the MBC 90 values were: CTX, 0.01 and 0.05 micrograms/ml; Des-CTX, 0.78 and 0.39 micrograms/ml; CTRX, 0.20 and 0.10 micrograms/ml; and PCG, 0.024 and 0.012 micrograms/ml, respectively. It is thus apparent that PCG showed the lowest values for both the MIC and MBC, followed by CTX, CTRX and then Des-CTX. Against 25 strains of S. agalactiae, the MIC 90 values with inocula of 10(8) and 10(6) cells/ml were as follows: CTX, 0.05 and 0.05 micrograms/ml; Des-CTX, 0.39 and 0.20 micrograms/ml; CTRX, 0.10 and 0.05 micrograms/ml; and PCG, 0.39 and 0.20 micrograms/ml, respectively. Similarly, the MBC 90 values of Des-CTX were 0.78 and 0.39 micrograms/ml, while the other 3 antibiotics showed the same values with both the 10(8) and 10(6) cells/ml inocula: 0.10 micrograms/ml for CTX, 0.20 micrograms/ml for CTRX and 0.39 micrograms/ml for PCG. Accordingly, CTX showed the lowest values, followed by CTRX and then PCG being about the same as Des-CTX. Against 25 strains of H. influenzae, the MIC 90 values with inocula levels of 10(8) and 10(6) cells/ml were as follows: CTX, 0.10 and 0.05 micrograms/ml; Des-CTX, 0.39 and 0.39 micrograms/ml; CTRX, 0.10 and 0.05 micrograms/ml; and ABPC, 50 and 6.25 micrograms/ml, respectively. Similarly, the MBC 90 values were: CTX, 0.20 and 0.10 micrograms/ml; Des-CTX, 1.56 and 1.56 micrograms/ml; CTRX, 0.39 and 0.20 micrograms/ml; and ABPC, greater than 100 and 50 micrograms/ml, respectively. Accordingly, in terms of the MIC 90, CTX and CTRX showed the same values, but in terms of the MBC 90 CTX was superior. (ABSTRACT TRUNCATED AT 400 WORDS)