Trends in antimicrobial resistance among urinary tract infection isolates of Escherichia coli from female outpatients in the United States.
The Infectious Diseases Society of America advocates trimethoprim-sulfamethoxazole (SXT) as initial therapy for females with acute uncomplicated bacterial cystitis in settings where the prevalence of SXT resistance does not exceed 10 to 20%. To determine trends in the activities of SXT, ampicillin, ciprofloxacin, and nitrofurantoin among urine isolates of Escherichia coli from female outpatients, susceptibility testing data from The Surveillance Network (TSN) Database-USA (n = 286,187) from 1995 to 2001 were analyzed. Resistance rates among E. coli isolates to ampicillin (range, 36.0 to 37.4% per year), SXT (range, 14.8 to 17.0%), ciprofloxacin (range, 0.7 to 2.5%), and nitrofurantoin (range, 0.4 to 0.8%) varied only slightly over this 7-year period. Ciprofloxacin was the only agent studied that demonstrated a consistent stepwise increase in resistance from 1995 (0.7%) to 2001 (2.5%). In 2001, SXT resistance among E. coli isolates was >10% in all nine U.S. Bureau of the Census regions. At institutions testing > or =100 urinary isolates of E. coli (n = 126) in 2001, ampicillin (range, 27.3 to 98.8%) and SXT (range, 7.5 to 47.1%) resistance rates varied widely while ciprofloxacin (range, 0 to 12.9%) and nitrofurantoin (range, 0 to 2.8%) resistance rates were more consistent. In 2001, the most frequent coresistant phenotypes were resistance to ampicillin and SXT (12.0% of all isolates; 82.3% of coresistant isolates) and resistance to ampicillin, ciprofloxacin, and SXT (1.4% of all isolates; 9.9% of coresistant isolates). Coresistance less frequently included resistance to nitrofurantoin (3.5% of coresistant isolates) than resistance to ciprofloxacin (15.8%), SXT (95.7%), and ampicillin (98.1%). In conclusion, among urinary isolates of E. coli from female outpatients in the United States, national resistance rates to SXT were relatively consistent (14.8 to 17.0%) from 1995 to 2001 but demonstrated considerable regional and institutional variation in 2001. Therapies other than SXT may need to be considered in some locations.
Karlowsky
James A
JA
Focus Technologies, Inc., 13665 Dulles Technology Drive, Suite 200, Herndon, VA 20171-4603, USA. jkarlowsky@focusanswers.com
Kelly
Laurie J
LJ
Thornsberry
Clyde
C
Jones
Mark E
ME
Sahm
Daniel F
DF
D000667:Ampicillin / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology; D000892:Anti-Infective Agents, Urinary / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D016208:Databases, Factual; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D005843:Geography; D006801:Humans; D008826:Microbial Sensitivity Tests; D009582:Nitrofurantoin / Q000494:pharmacology; D010045:Outpatients; D010406:Penicillins / Q000494:pharmacology; D010641:Phenotype; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology; D014481:United States / Q000453:epidemiology; D014552:Urinary Tract Infections / Q000453:epidemiology / Q000382:microbiology*
D000890:Anti-Infective Agents; D000892:Anti-Infective Agents, Urinary; D010406:Penicillins; D002939:Ciprofloxacin; D000667:Ampicillin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D009582:Nitrofurantoin