Ms. Smith’s tragic demise was more dramatic than many cases of hospital-acquired infection (HAI). Necrotizing fasciitis is a frightening, but rare, complication. Still, about 8,000 Canadians a year die from bugs they contract in facilities meant to make them better, while many more see their hospital stay prolonged by such illness. Yet after years of well-intentioned work and millions of dollars spent on combatting the scourge, the details and extent of the problem remain murky. No national statistics, for instance, document the number of surgical-wound infections like Ms. Smith’s, one of the most common types of hospital-acquired pathogens. A federal...