Dr. Walter E. Stamm, 64, whose discoveries on the diagnosis and treatment of urinary tract infections and of the relationship between chlamydia and pelvic inflammatory disease saved thousands of women from infertility, died Dec. 14 at his home in Seattle. He had been battling melanoma.

The Philadelphia-born Dr. Stamm "was one of the giants . . . who really transformed diagnosis and treatment of genitourinary infections, particularly those that result in pelvic inflammatory diseases," said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which funded much of his work. "There are a lot of happy mothers out there now because of the work of Walt Stamm."

Pelvic inflammatory disease, or PID, is particularly insidious because it can lead to infertility or other problems even in the absence of overt symptoms. Dr. Stamm demonstrated that many cases of PID are caused by the bacterium Chlamydia trachomatis. He developed a test for the organism and, in a 1996 paper, demonstrated that screening women for the bacterium could sharply reduce the incidence of PID.

Such screening programs were subsequently widely introduced in the United States and Europe.

Dr. Stamm was raised in Portland, Ore. He earned his bachelor's degree from Stanford University in 1967 and his medical degree, cum laude, from Harvard Medical School in 1971. He spent the bulk of his career at the University of Washington. - Los Angeles Times