Comparative studies of antimicrobial agents against causative organisms isolated from urinary tract infections (1984): III. Secular changes in susceptibility

Cases with infections of urinary tracts were divided into 3 groups of the simple infections, and complicated infections without indwelling of catheter, and complicated infections with indwelling of catheter. Susceptibilities to antimicrobial agents of Escherichia coli, Klebsiella spp., Proteus spp., Citrobacter spp., Enterobacter spp., Pseudomonas aeruginosa and Serratia marcescens which were isolated from patients with these infections were determined. There was no tendency of decline in the susceptibilities of E. coli isolated from the patients with simple urinary tract infections (UTI). Susceptibilities of E. coli isolated from the patients with complicated UTI without and with indwelling of catheter to cephem antibiotics of the third generation were examined. The susceptibility of E. coli strains isolated from patients with complicated UTI without and with indwelling of catheter remained the same. More specifically, cefmenoxime (CMX) at a concentration of less than 0.10 µg/ml inhibited the growth of E. coli isolated from cases without: with catheter at 74.1%: 78.3% in 1982, 75.4%: 73.3% in 1983, and 81.3%: 84.8% in 1984. Also, ceftizoxime (CZX) at a concentration of less than 0.10 µg/ml inhibited the growth at 83.3%: 95.7% in 1982, 89.2%: 86.7% in 1983, and 91.7%: 97.0% in 1984. Latamoxef (LMOX) at less than 0.10 µg/ml inhibited the growth at 59.3%: 43.5% in 1982, 47.7%: 40.0% in 1983, and 47.9%: 42.4% in 1984. The antibacterial effect of penicillin against Klebsiella spp. was found to be poor, while those of oral cephem antibiotics, cephalexin (CEX), cefaclor (CCL), and cefazolin (CEZ)which is the cephem antibiotics of the so-called first generation and cefotiam (CTM) among other cephem antibiotics of the so-called second generation were relatively good. A study of susceptibilities of Klebsiella spp. isolated from patients with complicated UTI without and with indwelling of catheter revealed inhibition of growth by CTM at a concentration of 0.39 µ/ml at 84.0%: 75.9% in 1982, 70.6%: 75.0% in 1983, and 95.8%: 77.8% in 1984. Cefmetazole (CMZ) at a concentration of 0.39 µg/ml showed a relatively lower rate of growth inhibition of Klebsiella spp., while at 0.78 µg/ml it inhibited the growth at 88.0%: 72.4% in 1982, 52.9%: 50.0% in 1983, and 70.8%: 66.7% in 1984. The antibacterial effects of both CTM and CMZ against Klebsiella spp. isolated from patients with indwelling of catheter were found to be poor, and some of the bacterial strains showed a MIC over than 100 µg/ml. Likewise, a study of susceptibilities of the cephem antibiotics of the so-called third generation revealed that CMX at a concentration of less than 0.10 µg/ml inhibited the growth of Klebsiella spp. from cases without: with catheter at a ratio of 84.6%: 72.4% in 1982, 73.7%: 68.8% in 1983, and 83.3%: 72.2% in 1984. CZX at less than 0.10 µg/ml inhibited the growth at 92.3%: 75.9% in 1982, 78.9%: 81.3% in 1983, and 100%: 94.4% in 1984. LMOX at less than 0.10 µg/ml inhibited the growth at a ratio of 73.1%: 55.2% in 1982, 63.2%: 25.0% in 1983, 37.5%: 44.4% in 1984, indicating slight decline over the period in the susceptibility in comparison to CZX or CMX. The antibacterial effects of penicillins, oral cephem antibiotics and cephem antibiotics of the first generation were not appreciable against Proteus spp. The susceptibilities of Proteus spp. strains isolated from the patients with complicated UTI with indwelling of catheter was found to be low to the cephem antibiotics of the second generation. CMZ at a concentration of 1.56 µg/ml inhibited the growth of the strains at a frequency of 70.8%: 58.3% in 1982, 71.4%: 20.0% in 1983, and 73.1%: 45.5% in 1984. CTM at 0.78 µg/ml inhibited the growth at a ratio of 45.8%: 29.2% in 1982, 28.6%: 32.0% in 1983, and 84.6%: 38.6% in 1984. CZX, CMX, and CTX which are the cephem antibiotics of the third generation showed similar antibacterial effects against Proteus spp. Antibacterial efficacy of a comparable degree was identified against Proteus spp. strains isolated from patients with complicated UTI without and with indwelling of catheter. Antibacterial effects of most of the isolated strains of Citrobacter spp. were found to be poor, but CZX, CTX and CMX among other cephem antibiotics of the third generation demonstrated relatively good antibacterial effects. Susceptibilities of the Citrobacter spp. strains isolated from patients with complicated UTI without and with indwelling of catheter did not vary very much. Because the number of the bacterial strains of Citrobacter spp. isolated for the present study was so limited that it was deemed as necessary to review and summarize the data obtained in several years to determine the susceptibility of Citrobacter spp. unequivocally. Antibacterial effects of most of the antibiotics against Enterobacter spp. were also poor similarly to the case of Citrobacter spp. It used to be believed that the antibacterial effects of GM, TOB and AMK all of which are aminoglycosides were outstanding against P. aeruginosa. However, the result of our present study revealed that antibacterial effects of GM and AMK were so reduced that GM at a concentration of 3.13 µg/ml inhibited the growth at a ratio of 60.9%: 53.1% in 1982 against P. aeruginosa isolated from patients of complicated UTI without and with indwelling of catheter, but the extent of the growth inhibition was reduced in 1984 to 45.2%: 31.3%. A similar trend was observed with AMK also; it inhibited the growth at 3.13 µg/ml in 1982 at a ratio of 65.2%: 93.9% but the effectiveness was sharply lowered in 1984 to 29.0%: 22.9%. The above fact should be noted. TOB demonstrated potent antibacterial efficacy at a ratio of 71.0%: 64.6% in 1984 at a concentration of 1.56 µg/ml. On the other hand, the study on antibacterial effects of CPZ and CFS against P. aeruginosa revealed that CPZ at a concentration of 3.13 µg/ml showed inhibition ratios of 56.5%: 38.8% in 1982 and 59.4%: 51.0% in 1984, while CFS at 1.56 µg/ml showed ratios of 60.9%: 46.9% in 1982 and 51.6%: 50.0% in 1984, showing no decline in their antibacterial efficacies. S. marcescens showed good susceptibility to CZX and CMX, among other cephem antibiotics of the third generation. CZX at a concentration of 1.56 µg/ml inhibited the growth of the strains isolated from patients with complicated UTI without and with indwelling of catheter at a ratio of 71.4%: 64.7% in 1984, and CMX at 60.7%: 50.0%. Other antibiotics such as LMOX, CPZ, and CTX showed effectiveness slightly lower than the above. Antibacterial effects against Serratia spp. were deemed still insufficient even with CZX or CMX, both of which are the antibiotics of the third generation. Therefore, a full care should be taken for the therapeutic treatment of complicated infections of urinary tracts in compromised hosts, including bacterial alteration.