269. The Incidence of Drug Resistant Escherichia coli Urine Isolates Varies by Age and Location of Onset:  a Population-based Study from Olmsted County, MN
Session: Poster Abstract Session: Antimicrobial Susceptibility and Resistance
Friday, October 21, 2011
Room: Poster Hall B1
  • IDSA 2011 - E coli poster FINAL.pdf (423.6 kB)
  • Background: There is increasing drug resistance among Escherichia coli (E. coli), the most common cause of urinary tract infections (UTIs). We performed a population-based study of the incidence of drug resistant E. coli urine isolates.

    Methods: All urine cultures positive for E. coli from 1/1/05 through 12/31/09 were identified by the Microbiology Laboratories at Mayo Clinic and Olmsted Medical Center, which capture over 90% of the Olmsted County population. Polymicrobial cultures, cultures that had fewer than 105 colony forming units/ml, and cultures from patients who did not reside in Olmsted County or who had not provided authorization were excluded. One isolate per patient per year was included.

    Results: We evaluated 5843 urinary isolates from 4930 unique patients, primarily female and outpatients. The incidence of drug resistant E. coli was highest and increased most significantly during the study period among adults >65 years. In this age group, incidence (per 100,000 person years) of resistance to fluoroquinolones (FQ) increased from 279 to 657 (p<0.001); trimethoprim-sulfamethoxazole (TMP-sulfa) resistance rose from 428 to 595  (p=0.004), FQ and TMP-sulfa coresistance increased from 182 to 354 (p=0.0002), and resistance to 3 or more drugs classes (MDR) rose from 78 to 157 (p=0.019).  Among adults 18 to 65 years, the incidence of isolates with resistance to TMP-sulfa, FQs and FQ plus TMP-sulfa also increased significantly.  Among children <18 years, the incidence of drug resistant isolates did not change.

    When analyzed by location of onset, the most significant increases in incidence occurred among  community onset (CA) isolates: resistance to TMP-sulfa (87 to 131; p =0.002), FQs (28 to 72; p<0.0001), TMP-sulfa plus FQ (16 to 45; p<0.0001) and MDR (8 to 24; p=0.0007).  Resistance increased less dramatically among healthcare-associated (HA) and nosocomial isolates to FQs  (30 to 44 [p=0.0004] for HA; 2 to 10 [p=0.02] for nosocomial). Resistance to all drug classes was highest in community associated (CA) isolates by 2009. 

    Conclusion: Between 2005-2009 in Olmsted County, the incidence of E. coli urine isolates resistant to FQs, TMP-sulfa, FQ plus TMP-sulfa, or >3 drug classes nearly doubled among individuals >65 years, and those with CA infections.

    Subject Category: C. Clinical studies of bacterial infections and antibacterials including sexually transmitted diseases and mycobacterial infections (surveys, epidemiology, and clinical trials)

    Sanjeev Swami, MD1, Juliette Liesinger, BA2, Barbara Yawn, MD, MSc3, Nilay Shah, PhD2 and Ritu Banerjee, MD, PhD1, (1)Division of Pediatric Infectious Diseases, Mayo Clinic, Rochester, MN, (2)Department of Health Sciences Research, Mayo Clinic, Rochester, MN, (3)Research, Olmsted Medical Center, Rochester, MN


    S. Swami, None

    J. Liesinger, None

    B. Yawn, None

    N. Shah, None

    R. Banerjee, None

    Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.