Antimicrobial resistance pattern of Escherichia coli causing urinary tract infections, and that of human fecal flora, in the southeast of Iran.

Sensitivity of 500 Escherichia coli isolates from urinary tract infections (UTIs, 311 isolate) and fecal samples (189 isolates) was tested against 12 antimicrobial agents using the standard disk diffusion method. Although the rate of resistance to antimicrobial agents was higher in the UTIs, in comparison with the fecal samples, the only significant difference was found in cases of tetracycline (p = 0.008), nalidixic acid (p = 0.038), and trimethoprim-sulfamethoxazole (Sxt,p = 0.05). The pattern of sensitivity to antimicrobial agents with respect to statistically significant difference in the number of sensitive isolates (p < or = 0.01) was: ceftizoxime (99.4%) and ceftriaxone (99.2%) > gentamicin (97.8%), ciprofloxacin (93%) and nitrofurantoin (92%) > cefazoline (85.2%) and nalidixic acid (84.6%) > chloramphenicol (71.6%), cephradine (69.6%) and tetracycline (63.2%) > Sxt (41.6%) > ampicillin (23.2%). Sensitivity of the isolates in respect to sex and age was also determined and compared during this study. Resistance to three or more antimicrobial agents (multidrug resistance, MDR) was found in 209 (41.8%) of the isolates. The high rate of resistance to Sxt and the presence of a high rate of MDR isolates in this area suggest that a reevaluation of the first-line therapeutic may be necessary for the treatment of UTIs in this area.