Escherichia coli antimicrobial resistance increased faster among geriatric outpatients compared with adult outpatients in the USA, 2000-10.

OBJECTIVES: Few studies have examined Escherichia coli antimicrobial resistance across age groups over time. The objective of this study was to compare urinary E. coli antimicrobial resistance trends among adult and geriatric outpatients from 2000 to 2010. METHODS: Antimicrobial susceptibility results for E. coli urine isolates from adult (aged 16-64 years) and geriatric (aged ≥65 years) outpatients were analysed using data from The Surveillance Network Database-USA. RESULTS: Susceptibility test results from adult (n = 6 412 025) and geriatric (n = 3 395 297) outpatients showed that E. coli antimicrobial resistance increased faster among geriatric outpatients for all agents studied. The greatest increases in resistance over the study time period were for ciprofloxacin (9.4% and 23.5% increases among adult and geriatric individuals, respectively), trimethoprim/sulfamethoxazole (4.3% and 10.5%) and ampicillin (2.0% and 13.6%). CONCLUSIONS: Urinary E. coli antimicrobial resistance increased faster among geriatric outpatients than adult outpatients in the USA. Rising antimicrobial resistance disproportionately affects geriatric populations and presents a threat to public health.

In vitro antimicrobial resistance of urinary Escherichia coli isolates among U.S. outpatients from 2000 to 2010.

This study examines in vitro antimicrobial resistance data from Escherichia coli isolates obtained from urine samples of U.S. outpatients between 2000 and 2010 using The Surveillance Network (TSN). Antimicrobial susceptibility results (n = 12,253,679) showed the greatest increases in E. coli resistance from 2000 to 2010 for ciprofloxacin (3% to 17.1%) and trimethoprim-sulfamethoxazole (TMP-SMX) (17.9% to 24.2%), whereas nitrofurantoin (0.8% to 1.6%) and ceftriaxone (0.2% to 2.3%) showed minimal change. From 2000 to 2010, the antimicrobial resistance of urinary E. coli isolates to ciprofloxacin and TMP-SMX among outpatients increased substantially.

Analysis of resistance, cross-resistance and antimicrobial combinations for Pseudomonas aeruginosa isolates from 1997 to 2009.

Pseudomonas aeruginosa is a nosocomial and community-acquired pathogen associated with considerable patient morbidity and mortality. Multidrug resistance in P. aeruginosa is a concern owing to the limited therapeutic options available to treat infections due to this organism. In this study, rates of antimicrobial resistance of P. aeruginosa isolates collected by The Surveillance Network Database-USA (Eurofins Medinet, Chantilly, VA) from 1997 to 2009 were examined. The patient population and specimens were stratified according to patient setting and age as well as specimen source. Multidrug resistance was defined as resistance to three or more of the following antimicrobial agents: aztreonam; cefepime; ciprofloxacin; imipenem; gentamicin; and piperacillin/tazobactam (TZP). A total of 924740 P. aeruginosa isolates were examined in this study. Changes in resistance rates to individual antimicrobial agents were <5% for all agents except ciprofloxacin. There was a statistically significant decreasing rate of multidrug-resistant P. aeruginosa to four, five and six antimicrobial agents. For isolates resistant to imipenem, aztreonam and gentamicin, ciprofloxacin had the highest cross-resistance rates. The greatest coverage against P. aeruginosa was by the combination of TZP plus amikacin (94%) followed by aztreonam plus amikacin (90%). Pseudomonas aeruginosa resistance rates remained steady or minimally declined to all antimicrobials from 1997 to 2009. Amongst the ß-lactams, TZP has the greatest activity against P. aeruginosa.