A case-control study of 788 nonpregnant women aged 18-49 years found that acute pyelonephritis was associated with several risk factors, including frequent sexual intercourse (odds ratio, 5.6), recent urinary tract infection (UTI) (odds ratio, 4.4), diabetes (odds ratio, 4.1), recent incontinence (odds ratio, 3.9), new sexual partner in the previous year (odds ratio, 2.2), recent spermicide use (odds ratio, 1.7), and a mother's history of UTI (odds ratio, 1.6). Escherichia coli was the most common pathogen (85% of cases). Risk factors varied by subgroup, with incontinence being strongly associated with pyelonephritis in women under 30 years of age. The study also found that diabetes and incontinence independently increased the risk for pyelonephritis. The estimated annual incidence of pyelonephritis was 27.6 cases per 10,000 women. The study highlights the importance of sexual behaviors and family history of UTI in pyelonephritis risk, and suggests that these factors may be modifiable to prevent the condition. The study also notes that the majority of pyelonephritis cases occur in otherwise healthy women, and that the condition is often asymptomatic or mild. The findings support the idea that pyelonephritis is usually caused by the ascent of organisms from the bladder to the kidneys. The study also found that the use of spermicides and sexual activity were associated with increased risk of pyelonephritis. The study's limitations include potential recall bias and reliance on automated case definitions. The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases.A case-control study of 788 nonpregnant women aged 18-49 years found that acute pyelonephritis was associated with several risk factors, including frequent sexual intercourse (odds ratio, 5.6), recent urinary tract infection (UTI) (odds ratio, 4.4), diabetes (odds ratio, 4.1), recent incontinence (odds ratio, 3.9), new sexual partner in the previous year (odds ratio, 2.2), recent spermicide use (odds ratio, 1.7), and a mother's history of UTI (odds ratio, 1.6). Escherichia coli was the most common pathogen (85% of cases). Risk factors varied by subgroup, with incontinence being strongly associated with pyelonephritis in women under 30 years of age. The study also found that diabetes and incontinence independently increased the risk for pyelonephritis. The estimated annual incidence of pyelonephritis was 27.6 cases per 10,000 women. The study highlights the importance of sexual behaviors and family history of UTI in pyelonephritis risk, and suggests that these factors may be modifiable to prevent the condition. The study also notes that the majority of pyelonephritis cases occur in otherwise healthy women, and that the condition is often asymptomatic or mild. The findings support the idea that pyelonephritis is usually caused by the ascent of organisms from the bladder to the kidneys. The study also found that the use of spermicides and sexual activity were associated with increased risk of pyelonephritis. The study's limitations include potential recall bias and reliance on automated case definitions. The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases.