New Tests Diagnose Food Poisoning Faster, But Hurts Ability to Spot Outbreaks

A medical breakthrough may make it faster and easier to diagnose food poisoning, but it comes with a downside: It could also hurt the nation’s ability to spot and solve dangerous outbreaks.

According to Centers for Disease Control and Prevention (CDC) experts, the new tests can’t detect crucial differences between subtypes of bacteria and they warn those fingerprints are what states and federal government use to match sick people to a contaminated food.

“It’s like a forensics lab. If somebody says a shot was fired, without the bullet you don’t know where it came from,” explained E. coli expert Dr. Phillip Tarr of Washington University School of Medicine in St. Louis.

The CDC warns losing the ability to literally take a germ’s fingerprint could hamper efforts to keep food safe, and the agency is searching for solutions. According to CDC estimates, 1 in 6 Americans get sick for foodborne illnesses each year, and 3,000 die.

“These improved tests for diagnosing patients could have the unintended consequence of reducing our ability to detect and investigate outbreaks, ultimately causing more people to become sick,” said Dr. John Besser of the CDC.

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That means outbreaks like the salmonella illnesses linked this fall to a variety of Trader
Joe’s peanut butter might not be identified that quickly–or at all.

Here's the way it works now: Someone with serious diarrhea visits the doctor, who gets a stool sample and sends it to a private testing laboratory. The lab cultures the sample, growing larger batches of any lurking bacteria to identify what's there. If disease-causing germs such as E. coli O157 or salmonella are found, they may be sent on to a public health laboratory for more sophisticated analysis to uncover their unique DNA patterns–their fingerprints.

Those fingerprints are posted to a national database, called PulseNet, which the CDC and state health officials use to look for food poisoning trends.

There are lots of garden-variety cases of salmonella every year, from runny eggs to a picnic lunch that sat out too long. But if a few people in, say, Baltimore have salmonella with the same molecular signature as some sick people in Cleveland, it's time to investigate, because scientists might be able narrow the outbreak to a particular food or company.

But culture-based testing takes time–as long as two to four days after the sample reaches the lab, which makes for a long wait if you're a sick patient.

PulseNet has greatly improved the ability of regulators and the food industry to solve those mysteries since it was launched in the mid-1990s, helping to spot major outbreaks in ground beef, spinach, eggs and cantaloupe in recent years. Just this fall, PulseNet matched 42 different salmonella illnesses in 20 different states that were eventually traced to a variety of Trader Joe's peanut butter.

To ensure that kind of crucial detective work isn't lost, the CDC is asking the medical community to send samples to labs to be cultured even when they perform a new, non-culture test.

Research is beginning to look for solutions that one day might allow rapid and in-depth looks at food poisoning causes in the same test.

Based on reporting by The Associated Press.

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