The culprit behind the latest romaine-fueled E. coli outbreak may sound familiar.
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The Food and Drug Administration says it has located the source of the latest E. coli outbreak fueled by tainted romaine lettuce—investigators say that they've traced the bacteria back to Adam Bros. Farm in Santa Maria, California, with more sources possibly to be determined.

The strain responsible for this viral outbreak, known as E. coli O157H:7, was found in the sediment in banks of an irrigation pond on the family-owned farm, according to the latest statement from the FDA. While reports of sickness have plateaued at 59 cases in 15 different states, officials are also reminding shoppers that the outbreak isn't officially over.

Federal agents are continuing to investigate how the outbreak began—and how E. coli bacteria made its way into the irrigation pond used to water some romaine crops. The FDA report says that every case can't be traced back to the farm in Santa Maria, so investigators are continuing to test samples from other possible sources.   

“As of Dec. 13, our investigation yielded records from five restaurants in four different states that have identified 11 different distributors, nine different growers, and eight different farms as potential sources of contaminated romaine lettuce,” FDA Commissioner Scott Gottlieb said in a statement. “Currently, no single establishment is in common across the investigated supply chains. This indicates that although we have identified a positive sample from one farm to date, the outbreak may not be explained by a single farm, grower, harvester, or distributor.”

Investigators collected samples from the Adam Bros. Farm back on November 27—but researchers weren't able to confirm test results until this week.

More on this E. coli outbreak:

Federal agencies issued a blanket ban on romaine lettuce on November 20, just before the Thanksgiving holiday. This announcement comes just a few weeks after the initial announcement, unlike an earlier outbreak where months transpired before farmers in Yuma, Arizona, were identified. You may recall that contaminated water in a canal used for irrigation, tainted by the waste of nearby cattle, was also found to be the source of the widespread E. coli outbreak over the summer.  

The agencies are reminding consumers to continue to avoid romaine if its origin is unclear, given that more research and investigation has to be done before they can officially close this case. Officials say that Adams Bros. Farm is in full cooperation with the investigation and hasn't shipped any lettuce since November 20.

The FDA has shortened its list of California regions on an official romaine blacklist to just three: Monterey, San Benito, and Santa Barbara. Read the latest FDA update for more information.