Chemotherapy plays the most important role in the treatment of urinary tract infections. It is necessary for the effective treatment to classify causative microorganisms and to determine drug sensitivity of the bacteria. It is a purpose of this paper to study 1) the yearly change of the incidence of causative microorganisms of bacteriuria, 2) the antimicrobial susceptivility patterns of the clinical isolates of the main gram-negative microorganisms, and 3) the antimicrobial effect of ampicillin, sulbenicillin and cephalothin on
Escherichia coli, Klebsiella and
Pseudomonas aeruginosa, which are moderately resistant to the above antibiotics, in urine.
1) Annual change of the incidence of causative microorganisms of bacteriuria in Juntendo University Hospital over the past 11 years (January 1964 to December 1974) shows that there has been a gradual decrease in the incidence of E. coli, especially since 1972, and a gradual and persistent increase in that of the gram-negative microorganisms:
Klebsiella, Proteus and
Ps. aeruginosa.
2) In order to investigate antimicrobial susceptibility patterns of the clinical isolates of
E. coli, Klebsiella, Enterobacter, Serratia, Pr. morganii, Pr. mirabilis and
Ps. aeruginosa, the minimum inhibitory concentrations (MIC) of ampicillin, carbenicillin, sulbenicillin and cephalothin for the isolates were studied by agar dilution method.
For ampicillin 65% of the strains of
E. coli and 85% or more of those of
Enterobacter, Serratia, Pr. morganii and
Ps. aeruginosa had MICs of 200μg/ml or greater and most of these strains were not inhibited at a concentration of 1,600μg/ml. About 70% of the strains of
Klebsiella and
Pr. mirabilis had MICs of 100μg/ml or less. For carbenicillin and sulbenicillin 60% or more of the strains of
E. coli, Klebsiella, Enterobacter, Serratia and
Pr. morganii had MICs of 200μg/ml or greater and a large number of these strains were not inhibited at a concentration of 1,600μg/ml. Seventy percent of
Pr. mirabilis, 80% of mucoid type of
Ps. aeruginosa and 50% of non-mucoid type of
Ps. aeruginosa had MICs of 100μg/ml or less. For cephalothin 80% or more of the strains of
Enterobacter, Serratia, Pr. morganii and
Pseudomonas had MICs of 1,600μg/ml or greater. About 70% of the strains of
Klebsiella and
Pr. mirabilis had MICs of 100 μg/ml or less.
3) From the results of the
in-vitro experimental study of the inhibitory effect of the antibiotics on the microorganisms studied, the effect of ampicillin on the strain of
E. coli with MIC 800μg/ml and on the strain of
Klebsiella with 200μg/ml was demonstrated at concentrations of the MIC or greater during 4 to 10 hours in culture. The effect of sulbenicillin on the strain of
E. coli with MIC 200μg/ml, of
Klebsiella with MIC 400μg/ml and of
Ps. aeruginosa with 200μg/ml was shown at concentrations of the MIC or greater during 6 to 10 hours in culture. For cephalothin against
E. coli with MIC 400μg/ml and
Klebsiella with 800μg/ml, the
E. coli and the
Klebsiella were inhibited at the 4-fold concentration of the MIC and 2-fold concentration of the MIC during 2 to 10 hours in culture respectively.
View full abstract