SAN FRANCISCO -- Fifty-one years ago, Edward J. Nevin checked into a San Francisco hospital, complaining of chills, fever and general malaise. Three weeks later, the 75-year-old retired pipe fitter was dead, the victim of what doctors said was an infection of the bacterium Serratia marcescens.

Decades later, Mr. Nevin's family learned what they believe was the cause of the infection, linked at the time to the hospitalizations of 10 other patients. In Senate subcommittee hearings in 1977, the U.S. Army revealed that weeks before...