[In vitro susceptibility of Escherichia coli and Klebsiella sp. to antibiotics].

A nationwide susceptibility survey of clinical isolates of Escherichia coli and Klebsiella pneumoniae initiated in 1980 was continued for the 8th consecutive year. A total of 4,421 strains of E. coli and 2,825 strains of K. pneumoniae isolated mainly from urine, sputum and pus, were obtained from 69 hospitals throughout Japan during the 2 years (1986-1987). MICs were determined using the agar plate dilution method (Mueller-Hinton agar, BBL) with inoculation of 10(8)CFU/ml bacteria. Antibiotics tested in this survey were 2 penicillins, 7 cephems and 2 aminoglycosides. Most of the strains of the two species of bacteria were susceptible to ceftizoxime (CZX), cefotetan (CTT), latamoxef (LMOX), cefotiam (CTM) and cefmetazole (CMZ) and also gentamicin (GM) and netilmicin (NTL) were active against both species of bacteria. About 90% of the E. coli strains were inhibited at a concentration of 0.20 micrograms/ml of CZX, 0.39 micrograms/ml of LMOX, 0.78 micrograms/ml of CTT, 1.56 micrograms/ml of CTM or NTL, or 3.13 micrograms/ml of CMZ or GM. Most of the strains were resistant to ampicillin (ABPC) and piperacillin. For the strains of K. pneumoniae, similar results were obtained. Yearly changes in susceptibility of E. coli and K. pneumoniae were not obvious with ABPC, cefazolin, CMZ or GM. No significant differences were observed during 1986-1987 in susceptibilities of the isolates of both species of bacteria due to different clinical specimens. These results suggest that the 2nd and the 3rd generation cephems and aminoglycosides, alone or in combination, may be efficacious in treating infections due to E. coli and K. pneumoniae.