Trends in Antimicrobial Resistance among Urinary Tract Infection Isolates of Escherichia coli from Female Outpatients in the United States

Abstract

There are an estimated 150 million urinary tract infections per annum worldwide (26). In the United States, urinary tract infections result in approximately 8 million physician visits per year (30). Urinary tract infections are the most common bacterial infections in women and account for significant morbidity and health care costs (4, 26). A limited and predictable spectrum of organisms cause urinary tract infections in young, otherwise healthy females. Among both outpatients and inpatients, Escherichia coli is the primary urinary tract pathogen, accounting for 75 to 90% of uncomplicated urinary tract infection isolates (4, 21). Staphylococcus saprophyticus, Klebsiella spp., Proteus spp., Enterococcus spp., and Enterobacter spp. are pathogens less commonly isolated from outpatients.The currently recommended empirical antimicrobial regimen for treating acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females is a 3-day course of double-strength trimethoprim-sulfamethoxazole (SXT) in settings where the prevalence of SXT resistance is Ͻ10 to 20% (1, 30). Investigators studying the economic impact of SXT and ciprofloxacin therapies have presented data supporting the empirical use of SXT when the local rate of resistance to SXT does not exceed 22% (14). Alternative therapy for uncomplicated urinary tract infections in settings with Ͼ10 to 20% SXT resistance may include a fluoroquinolone, nitrofurantoin, or fosfomycin (30).The Infectious Diseases Society of America also recommends that physicians obtain information on local resistance rates and that ongoing surveillance be conducted to monitor changes in susceptibility of uropathogens (30). Surveillance at the institutional and regional level is particularly important given that previous studies have reported that the activity of SXT against urinary isolates of E. coli can vary considerably by geographic region (6,25). The prevalence of SXT resistance among urinary pathogens appears considerable in the United States, and it seems inevitable that SXT will eventually need to be replaced by alternative therapies, at least in some areas (5-7, 11, 26).In vitro studies specifically describing the antimicrobial susceptibilities of urinary isolates of E. coli from female outpatients are limited (5-7, 9, 12, 18). In these studies, SXT resistance increased from 7 to 9% in 1989 to 1992 (5, 7, 18, 28) to 17 to 18% in 1995 to 1999 (5-7, 12). Fluoroquinolone resistance was Յ1% in each of the aforementioned studies, and nitrofurantoin resistance was reported to be Յ2% on national and regional levels in the United States. The 1998 SENTRY surveillance program, reporting on isolates of E. coli collected from 26 U.S. centers, found the overall prevalence of SXT

Secular Trend and Risk Factors for Antimicrobial Resistance in Escherichia coli Isolates in Switzerland 1997–2007

“…Clinical information is lacking in most of the large epidemiological studies that have been published on the susceptibility rates of E. coli [7,14,15,19]. In contrast to other studies [8,30], we did not find differences in the resistance pattern of E. coli isolates from patients presenting with a UTI compared to those with colonization.…”

“…In contrast to other pathogens, fluoroquinolone resistance has not been reported to be higher in in-hospital isolates [7,29], which may be explained by the widespread use of fluoroquinolones in the out-patient settings. Nosocomial E. coli UTIs are mainly due to factors associated with the hospital setting, such as the placement of urinary catheters during elective surgery.…”

“…Most of the relevant studies carried out to date refer to hospitalized patients, and the susceptibility of E. coli varies considerably in different parts of the world [5][6][7][8][9]. Trimethoprim/sulfamethoxazole (TMP/SMX) is the empiric treatment of choice for UTIs, if the local resistance rate is less than 10-20% [10].…”

Antimicrobial Resistance in Uropathogen Isolates from Patients with Urinary Tract Infections

“…In the third world, considering resource constraints, it is a matter of regret that routine analysis of antibiotic resistance is impractical. Resistance of uropathogens to antibiotics is now a global concern (Gupta, 2001;Karlowsky et al, 2002;Kurutepe et al, 2005). Variations in resistance pattern of different antibiotics are known to occur in different geographical area as well as in the same country (Schito et al, 2009).…”

Choice of antibiotic for empirical therapy of acute cystitis in a setting of high antimicrobial resistance

“…For example, in the United States, the empiric regimen for acute, uncomplicated cystitis is a 3-day course of double strength Trimethoprim/Sulphamethoxazole (TMP/ SMX) in areas where the prevalence of TMP/ SMX-resistant pathogens is <10%. [2] But as this prevalence has exceeded 10-20% in many regions of USA, [3,4,5] the current empirical regimen is likely to be replaced by alternative therapies, such as Fluoroquinolones or Nitrofurantoin. [6] Since empirical therapy should be guided by the proportion of pathogens resistant to the chosen antibiotic, the present study was undertaken to determine the sensitivity profiles of urinary isolates in the Garhwal region of Uttaranchal, which would expectedly indicate the most appropriate antibiotic for empirical treatment of this condition.…”