Antimicrobial Resistance Patterns of Escherichia coli Isolated from Urinary Tract Infections in the Midwestern United States

Abstract

Aims: To determine the antimicrobial resistance of urinary tract infection isolates in a major metropolitan area for the purposes of tracking increases in resistance and to provide information that will help drive improved therapy. Study Design: Antimicrobial resistance data on Escherichia coli isolated from urinary tract infections was collected and analyzed. Place and Duration of Study: Data was collected from several large healthcare centers in the Detroit, Michigan area. Data collected was from January to July of 2008. Methodology: Data on the antimicrobial susceptibility of 960 Escherichia coli isolated from urinary tract infections was collected and analyzed to determine resistance to typical drugs used in urinary tract infection susceptibility testing. Results: The percentage of isolates that were resistant to one or more of the drugs tested was 47%. The most common drug resistance was to ampicillin (41%); with 11.6% of the isolates being only resistant to ampicillin. As to total resistance, 22.4% of the isolates were resistant to only one drug class, 14.4% were resistant to two classes, 7.2% to three classes, and 4.4% to more than three classes. Resistance as to antimicrobial effects were: 87.9% were resistant to drugs that interfere with cell wall synthesis, 40.3% were resistant to drugs that inhibit protein synthesis, 38.3% to anti-metabolites, and 38.1% to drugs that inhibit nuclei acid synthesis. Conclusion: The data indicate that E. coli isolated from urinary tract infections are manifesting disturbing resistance patterns. Not only is resistance to many drugs increasing, but the bacteria are becoming increasingly multi-drug resistant. This is not only true in this region, but seen worldwide as well.