Risk factors for second urinary tract infection among college women

Prevalence and predictors of trimethoprim-sulfamethoxazole resistance among uropathogenic Escherichia coli isolates in Michigan

Resistance among uropathogenic Escherichia coli to trimethoprim-sulfamethoxazole (TMP-SMX) has increased. Risk factors for resistance and the impact on clinical failure have been poorly described. We performed a retrospective cohort study of women with acute uncomplicated cystitis seen at a university health center and at primary care clinics in southeastern Michigan from 1992 to 1999. The prevalence of TMP-SMX resistance increased from 8.1% to 15.8% (P=.01). Women who had taken TMP-SMX recently were >16 times as likely as women who had not taken antibiotics recently to be infected with an isolate resistant to this agent; those who had taken any other antibiotic were more than twice as likely to be infected with a resistant isolate. Women infected with a TMP-SMX-resistant isolate who were treated with TMP-SMX were >17 times as likely to have treatment failure. Recent antibiotic use is a risk factor for infection with a TMP-SMX-resistant isolate; patients who are infected with a TMP-SMX-resistant isolate and who are treated with this agent are at a higher risk for clinical failure.

Widespread distribution of urinary tract infections caused by a multidrug-resistant Escherichia coli clonal group

BACKGROUND

The management of urinary tract infections is complicated by the increasing prevalence of antibiotic-resistant strains of Escherichia coli. We studied the clonal composition of E. coli isolates that were resistant to trimethoprim-sulfamethoxazole from women with community-acquired urinary tract infections.

METHODS

Prospectively collected E. coli isolates from women with urinary tract infections in a university community in California were evaluated for antibiotic susceptibility, O:H serotype, DNA fingerprinting, pulsed-field gel electrophoretic pattern, and virulence factors. The prevalence and characteristics of an antibiotic-resistant clone were evaluated in this group of isolates and in those from comparison cohorts in Michigan and Minnesota.

RESULTS

Fifty-five of the 255 E. coli isolates (22 percent) from the California cohort were resistant to trimethoprim-sulfamethoxazole as well as other antibiotics. There was a common pattern of DNA fingerprinting, suggesting that the isolates belonged to the same clonal group (clonal group A), in 28 of 55 isolates with trimethoprim-sulfamethoxazole resistance (51 percent) and in 2 of 50 randomly selected isolates that were susceptible to trimethoprim-sulfamethoxazole (4 percent, P<0.001). In addition, 11 of 29 resistant isolates (38 percent) from the Michigan cohort and 7 of 18 (39 percent) from the Minnesota cohort belonged to clonal group A. Most of the clonal group A isolates were serotype O11:H(nt) or O77:H(nt), with similar patterns of virulence factors, antibiotic susceptibility, and electrophoretic features.

CONCLUSIONS

In three geographically diverse communities, a single clonal group accounted for nearly half of community-acquired urinary tract infections in women that were caused by E. coli strains with resistance to trimethoprim-sulfamethoxazole. The widespread distribution and high prevalence of E. coli clonal group A has major public health implications.

Urinary tract infection among women aged 40 to 65: behavioral and sexual risk factors

We conducted a case-control study to explore the role of health behavior and sexual and medical history on urinary tract infection (UTI) risk among otherwise healthy women aged 40-65. Cases and controls were recruited from nine practices and clinics in Michigan and a single clinic in Israel. In both countries, several factors were reported significantly more frequently among UTI cases than controls: a previous UTI within 12 months, incontinence symptoms, a recent episode of 30-plus minutes of cold hands, feet, back or buttocks, and recent antibiotic use. Cases were less likely than controls to report recent estrogen use, but the results were only statistically significant in Michigan. Sexual activity during the previous 2 weeks and having ceased menses were modestly, but not statistically significantly, protective at both study sites. Risk factors for UTI among women 40-65 differ from those for younger women and these differences cannot be attributed solely to changes in menopausal status.

Establishment of a persistent Escherichia coli reservoir during the acute phase of a bladder infection

The vast majority of urinary tract infections are caused by strains of uropathogenic Escherichia coli that encode filamentous adhesive organelles called type 1 pili. These structures mediate both bacterial attachment to and invasion of bladder epithelial cells. However, the mechanism by which type 1 pilus-mediated bacterial invasion contributes to the pathogenesis of a urinary tract infection is unknown. Here we show that type 1-piliated uropathogens can invade the superficial epithelial cells that line the lumenal surface of the bladder and subsequently replicate, forming massive foci of intracellular E. coli termed bacterial factories. In response to infection, superficial bladder cells exfoliate and are removed with the flow of urine. To avoid clearance by exfoliation, intracellular uropathogens can reemerge and eventually establish a persistent, quiescent bacterial reservoir within the bladder mucosa that may serve as a source for recurrent acute infections. These observations suggest that urinary tract infections are more chronic and invasive than generally assumed.

Pathogenesis of Urinary Tract Infection: the Role of Sexual Behavior and Sexual Transmission

Acute urinary tract infection (UTI) is an extremely common clinical entity that affects almost half of all women in the United States, and accounts for more than 7 million physician visits, annually, in this country. Sexual behavior and UTI history are the most important predictors of UTI risk among sexually active young women. Whether sexual behavior has similar impact on UTI risk in older women is unknown. Postcoital prophylaxis has been investigated as a strategy for the prevention of recurrent UTI in sexually active women. There are conflicting data regarding the role of voiding habits in relation to sexual intercourse and the risk of UTI. Finally, there are interesting epidemiologic studies suggesting that uropathogenic Escherichia coli may be transmitted between sex partners. We review the recent literature regarding these different areas, and comment on the potential role of sexual transmission in UTI.