Last fall’s multistate outbreak of E. coli O157:H7 infection linked to romaine lettuce served mostly at Schnucks salad bars sickened 58 people, the Centers for Disease Control and Prevention reported in an update on the investigation Friday.

Two people were removed from the case count, last reported on Dec. 7, 2011,  after advanced molecular testing determined their illnesses were not related to the outbreak strain, the CDC said.

Identified by the CDC as “grocery store Chain A,” Schnucks, a popular St. Louis supermarket chain with an excellent food-safety history, has already acknowledged that something from its salad bars was the likely source of the outbreak and its cooperation with outbreak investigators has been widely reported.

According to the CDC report, the ill people were from nine states: 38 in Missouri; 9 in Illinois; 2 each in Arkansas, Indiana, Kansas and Minnesota; and 1 each in Arizona, Kentucky and Nebraska.  The two cases removed from the outbreak count had been reported earlier from Georgia and Kansas.

Those sickened ranged in age from 1 to 94 years old; the median age was 28. Of 49 patients the CDC had information on, 33 (67 percent) required hospitalization and three developed hemolytic uremic syndrome (HUS).

The epidemiologic investigation compared foods eaten by 22 ill people and 82 healthy people, including 45 well people who shopped at Schnuck’s during the week of October 17, 2011.  

The ill people  (85 percent) were significantly more likely than the well people (46 percent) to tell investigators they had eaten romaine lettuce in the week before they became ill.

Among those who specifically shopped at Schnuck’s grocery stores, the ill people (89 percent) were far more likely than the well people (9 percent) to report eating a salad from the salad bar.

Outbreak investigators found that of 18 ill people, 94 percent said they had eaten romaine lettuce from the salad bar. No other lettuce variety or food item from the salad bar was reported by more than 55 percent of the ill persons, the CDC noted.

The traceback investigation, conducted by the Food and Drug Administration and several state public health agencies, pointed to a single lot of romaine lettuce from one farm, the CDC said. “This indicates that contamination of romaine lettuce likely occurred before the product reached grocery store Chain A locations,” the report states.

The CDC report also did not identify what company distributed the romaine lettuce or where it came from.  

The CDC report says the suspect lettuce was supplied to a university campus in Minnesota and also to a distributor that supplied lettuce to a campus in Missouri, but records were insufficient to determine if the suspect lot went to the latter university.

The grower is referred to as “Farm A” in the CDC report, which notes that by the time investigators figured out where the lettuce originated, “Farm A was no longer in production” so it was not possible to determine how the lettuce became contaminated.

Marler Clark, the law firm that sponsors Food Safety News, has filed lawsuits on behalf of two people sickened in this outbreak. Vaughan Foods, an Oklahoma-based distributor, was added to both complaints when, through the law firm’s own investigation, it learned the company supplied the romaine lettuce to Schnucks.

On Friday Bill Marler said public health is not served when the CDC declines to name the source of contaminated food. 

“At this point it is public knowledge that Schnucks and Vaughan Foods had a role in this outbreak,” said Marler in a prepared statement.  “The CDC states that it saves lives, protects people, and saves money through prevention.  How does trying to keep the public in the dark accomplish any of these objectives?

“By keeping these companies’ names secret, the CDC may be trying to protect businesses, but is ultimately doing the public a disservice by quashing important data that could otherwise help consumers make informed decisions about what to eat and where to shop.”

CDC Outbreak Map: