The minimum inhibitory concentration of antibiotics against Escherichia coli from urinary tract infection cases of the National Kidney Institute and the conjugative transferability of the resistance in these isolates

Twenty-nine Escherichia coli isolates collected from June 6 to July 17, 1992 from urinary tract infection cases at the National Kidney Institute were tested for their antibiotic resistance patterns using the modified Kirby-Bauer disc-agar diffusion method. The concentrations of the antibiotics used were the prescribed ones for the method, which were based on the peak plasma concentrations of the antibiotics. The minimum inhibitory concentrations (MIC) of the commonly used antibiotics were also determined to find out the resistance of the isolates to the antibiotics based on the peak attainable concentration of the antibiotics in the urine. The percentage of resistant isolates toward the test antibiotics at the plasma level were as follows: ampicillin, 72.41 percent tetracycline, 62.07 percent co-trimoxazole, 48.28 percent chloramphenicol, 44.83 percent tetracycline, 0 percent co-trimoxazole, 48.28 percent chloramphenicol, 37.93 percent and nalidixic acid at 6.90 percent. The conjugative transferability of the multiple antibiotic resistance of fourteen donor E. coli isolates to the recipient (SF-800) was also tested. The results showed complete transfers of the resistance in 28.57 percent of the donors, incomplete transfers in 28.57 percent, and no transfer of resistance in 42.86 percent of the donors