Razi Journal of Medical Sciences

  Background and Aim: There are increasing concerns regarding antimicrobial resistance in Iran. Data are limited on the prevalence and risk factors associated with resistant organisms, including Escherichia coli (E.coli) which is the most common cause of urinary tract infection (UTI). The aim of this study was to evaluate the prevalence of resistance and risk factors for resistance to gentamycin (GEN) , ceftriaxone (CFX) and a combination of both of them in E. coli strains isolated from hospitalized patients with acute UTIs in Tehran,Iran.

  Materials and Methods: We performed a prospective descriptive case –control study from March 2005 to March 2008 among all cases of UTI in children from 1 month up to 12 years of age who were admitted to Ali Asghar Childrens Hospital (a referral pediatric center in Iran). Positive urine cultures with E.coli were further classified to sensitive, intermediate and resistant strains according to standard NCCLS method. Evaluated risk factors were checked within case control groups and the results were analyzed first by Chi square and then Logistic regression tests using SSPS V.15 software.

  Results: A total of 125 E. coli were isolated. Resistance rates were 38.4% for CFX , 24% for GEN and 20% for CFX+GEN. Univariate analyses selected the following factors as being significantly associated with E. coli resistance: I) for resistance to GEN: prophylactic antibiotic (OR=3.5, p=0.006), urologic disorder (OR=2.4 , p=0.04), resistance to CFX (OR=15.7 , p=0.000), Vesicourethral reflux (VUR)
(OR=2.7 , p=0.021) , with a trend toward significance for prior (1 year) urinary catheter (OR=2.5,
p=0.052), and prior (6 months) hospitalization (OR=2.2 , p=0.055) II) for resistance to CFX: prior
(1 year) UTI (OR=2.6 , p=0.012) , prophylactic antibiotic (OR=4.2 , p=0.001), urinary catheter (at present) (OR=4.8 , p=0.007) , prior (1 year) urinary catheter (OR=3.3 , p=0.006), urologic disorder (OR=2.7 , p=0.007) , prior (1 month) surgery (OR=8.8 , p=0.03) , prior (6 months) hospitalization
(OR=4.2 , p=0.000) , resistance to GEN (OR=15.7 , p=0.000) , VUR (OR=2.2 , p=0.04) and NB
(OR=3.9 , p=0.003) III) for resistance to CFX+GEN: age < 4 years (OR=3.9 , p=0.025) , prior (1 year) UTI(OR=2.5 , p=0.038) , prophylactic antibiotic (OR=4.1 , p=0.002) , prior (1 year) urinary catheter (OR=2.7 , p=0.036) , urologic disorder (OR=2.9 , p=0.02) , prior (6 months) hospitalization (OR=2.5 ,

  p=0.037) , and VUR (OR=2.8 , p=0.022).

  We also used Logistic regression analyses for risk factors which had p<0.05 in univariate analyses. The results were: I) for resistance to GEN: resistance to CFX (Sig. = 0.000, EXP (B) = 13.5) II) for resistance to CFX: Prior (6 months) hospitalization (Sig.= 0.047, EXP (B) = 2.9) , resistance to GEN (Sig. = 0.000 , EXP (B) = 15.6) III) for resistance to CFX + GEN: age (<4 years) (Sig. = 0.040 , EXP (B) = 4.3)

  Conclusion: Recognized risk factors must be considered when deciding for empiric therapy in children especially in referral centers. We hope that our results will contribute to the development of strategies aimed at limiting the evolution of antimicrobial resistance in Iran.