Sampling many more food items has not yet produced a source for the E. coli O157:H7 outbreak in the St. Louis area, the Missouri Department of Health and Senior Services (DHSS) acknowledged late Thursday.
The agency leading the growing team of local, state and federal health officials reported that it was zero for 55 tries in testing food samples for the bacteria connected to some two dozen illnesses.
Missouri health officials said 17 food samples came back negative for E. coli in final results, and another 38 were negative in preliminary screening results that await final results.
And a net of two cases reduced the size of the St. Louis outbreak Thursday, putting the total at 24. Here’s how those numbers worked:
“Since (the Nov. 2) update, two cases based on samples previously received at the State Public Health Laboratory have been confirmed and added; however, four cases previously through to be connected have been determined upon further interviews and analysis to be not connected to the St. Louis outbreak,” DHSS said in a statement.
Update: Twenty-two (22) Missourians have been hospitalized since the St. Louis outbreak of E. coli O157:H7 began, and 19 of those are confirmed as having the outbreak strain. Of the five other confirmed cases, two did require hospitalization and the hospital status of three others is listed as “unknown,” according to DHSS spokesperson Jacqueline Lapine.
Lapine also told Food Safety News there is one case of hemolytic uremic syndrome (HUS) , which can occur when E.coli infection enters the digestive system producing toxic substances that destroy red blood cells causing kidney injury.
The mystery surrounding the St. Louis outbreak has brought federal experts to the city to help in the investigation. Both CDC and FDA have personnel on the ground in Missouri to work on the investigation. According to DHSS, that assistance includes:
— The federal Centers for Disease Control and Prevention (CDC) is contacting people in the neighborhoods where E. coli victims live for a case control study.
— The U.S. Food and Drug Administration (FDA) is inspecting food distribution businesses in the St. Louis area.
Meanwhile, Missouri’s Boone County, in the interior of the state, has three E. coli cases that DHSS does not believe are connected to the St. Louis outbreak. The state lab has tested four specimens from Boone County, finding three were positive for E. coli. Results from the fourth sample are still pending.
With nothing but negative results for the first group of foods, the Missouri State Public Health Laboratory returned to five Schnucks’ stores in the middle of the week to collect more food samples for testing.
Schnucks is a 90-unit St. Louis-based grocery store chain with some outlets operating popular salad bars that many of the E. coli victims have mentioned in the “food diaries” that are filled out to help the investigation.
For the second round of tests, the health department collected salad dressings, broccoli florets, deviled eggs, diced hard boiled eggs, pineapple chunks, shred carrots, radishes, shredded zucchini, slice red onions and various other salads. All of these items, however, came back negative in the preliminary tests.
Along with the earlier negative tests on lettuce, strawberries and Caesar dressing, the state lab is working its way through the entire lineup of food items that the big salad bars in Schnucks stores are known for in St. Louis.
Further testing is being done for confirmation, but so far all the testing has come up negative for E. coli.