Acute Uncomplicated Cystitis And Pyelonephritis In Women

Acute uncomplicated cystitis and pyelonephritis in women
Author
Thomas M Hooton, MD
Section Editor
Stephen B Calderwood, MD
Deputy Editor
Elinor L Baron, MD, DTMH
Disclosures
Last literature review version 19.3: enero 2012 | This topic last updated: agosto 10, 2011 (More)
INTRODUCTION — Acute cystitis refers to infection of the bladder (lower urinary tract); it can occur alone or inconjunction with pyelonephritis (infection of the kidney – the upper urinary tract) [1].
Most episodes of cystitis and pyelonephritis are generally considered to be uncomplicated in otherwise healthy nonpregnant adult women. A complicated urinary tract infection, whether localized to the lower or upper tract, is associated with an underlying condition that increases the risk of failing therapy (suchas obstruction, anatomic abnormality, urologic dysfunction, or a multiply-resistant uropathogen).
Issues related to acute uncomplicated cystitis and pyelonephritis in women will be reviewed here. Issues related to urinary tract infections in men and acute complicated urinary tract infections are discussed separately. (See "Acute complicated cystitis and pyelonephritis" and "Acute uncomplicatedcystitis, pyelonephritis, and asymptomatic bacteriuria in men".)
EPIDEMIOLOGY — Among sexually active young women, the incidence of symptomatic urinary tract infection (UTI) is high; in one university cohort of 796 women, the incidence was 0.5 to 0.7 UTIs per person-year [2]. Risk factors include recent sexual intercourse, recent spermicide use, and a history of urinary tract infection [2,3].Cystitis also occurs in postmenopausal women. In a prospective cohort study of 1017 postmenopausal women followed for two years, the estimated incidence of culture-confirmed acute cystitis was 0.07 episodes per person per year [4].
Acute pyelonephritis is less common than acute cystitis; in one review including over 3200 patients with a first episode of acute pyelonephritis, the annual incidence ofacute pyelonephritis was 12 to 13 cases per 10,000 women [5].
PATHOGENESIS — The pathogenesis of urinary tract infection in women begins with colonization of the vaginal introitus by uropathogens from the fecal flora, followed by ascension via the urethra into the bladder. Pyelonephritis develops when pathogens ascend to the kidneys via the ureters. Host and microbial factors that underlieprogression from bladder to kidney infection require further investigation.
Pyelonephritis can also be caused by seeding of the kidneys from bacteremia. It is possible that some cases of pyelonephritis are associated with seeding of the kidneys from bacteria in the lymphatics.
MICROBIOLOGY — The microbial spectrum of uncomplicated cystitis and pyelonephritis in women consists mainly of Escherichia coli(75 to 95 percent), with occasional other species of Enterobacteriaceae, such as Proteus mirabilis and Klebsiella pneumoniae, and other bacteria such as Staphylococcus saprophyticus [5,6]. Other gram-negative and gram-positive species are rarely isolated in uncomplicated UTIs. Therefore, local antimicrobial susceptibility patterns of E. coli in particular should be considered in empiricantimicrobial selection for uncomplicated UTIs.
Antimicrobial resistance — There is considerable geographic variability among E. coli for in vitro susceptibility. In four large studies, resistance rates were higher in US medical centers than in Canadian medical centers, and higher in Portugal and Spain than other European countries [7-10]. In general, resistance rates >20 percent were reported in allregions for ampicillin, and in many regions fortrimethoprim (with or without sulfamethoxazole). Fluoroquinolone resistance rates were <10 percent in most parts of North America and Europe, but there was a clear trend for increasing resistance over time. Resistance rates for first and second generation oral cephalosporins and amoxicillin-clavulanic acid are regionally variable but generally...