The strain of Salmonella that sickened 94 people in 16 states and the District of Columbia last November and December does appear to have originated at a sprouts farm in Urbana, IL.

Tiny Greens Organic Farm was hit with a May 5 warning letter from the U.S. Food and Drug Administration that discloses results of the environmental sampling that public health authorities completed during the Nov. 1, 2010 to Feb. 9, 2011 outbreak. FDA said it linked a Salmonella enteric serotype from the outbreak “to sprouts grown in your facility.”

FDA said one sample collected from a compost pile outside Tiny Greens was found to have a Pulse Field Gel Electrophoresis (PFGE) result (DNA “fingerprinting”) indistinguishable from the outbreak strain.

Also implicated in the outbreak was Jimmy John’s fast food restaurant chain, which was a large purchaser of Tiny Greens sprouts. The multistage outbreak led Tiny Greens to recall its Alfalfa and Spicy Sprouts, although owner Bill Bagby said at the time there was nothing more than a “statistical association” to his product.

In its warning letter, FDA documented “conditions and practices” that inspectors said likely led to the sprouts being contaminated with the Salmonella outbreak strain.

Some of these problems included:

— Run-off water from the compost pile pooled into a drain along the walkway, 11 feet from the entrance to the greenhouse. The subsample that yielded the Salmonella outbreak strain was taken from this site. 

— An employee was observed dumping production waste onto the compost pile.

— After walking through the compost pile and pooled water along the walkway, the employee returned to the production area wearing the same clothing and boots that he had worn outside.  

— In addition, two employees pushed a cart containing trays of alfalfa sprouts from the sprouting area out through the greenhouse exit. 

— After walking and wheeling the cart through the compost pile, the employees returned to the production area with the cart, wearing the same clothing and boots that they had worn outside.  

–The employees did not clean or disinfect their boots or the cart at any time between these two activities.

— The sink employees used to wash their hands in the lunch room before entering the production area had a hose with a valve on its end that was leaking water onto a floor where there was a substantial amount of foot traffic. FDA noted that organic matter, in conjunction with wet conditions, such as those observed in the facility, foster the growth of Salmonella and other pathogens. 

— An employee placed a screen from a shaker table on the floor and rinsed it with a hose. This operation was performed within 2 inches of open trays of germinated sprouts. Aerosolized water droplets from the water streaming onto the floor were splashing into the trays of germinated sprouts.

— Germination drum plexiglass doors were stored on drum frames less than 12 inches from the floor. The drum closest to the greenhouse door had all four doors stored in this manner. Water and debris from the floor was observed splashed onto the doors. The doors were not cleaned prior to installation on the germination drum.

— Sprouts were unloaded from the germination drums into white perforated pails on dollies. When the dollies were rolled to the table so that the sprouts could be placed in trays, water from the dollies’ rotating wheels was splashing up and into the perforated pails containing sprouts.

In the warning letter, FDA says Tiny Greens responded to the agency in a Feb. 6 letter detailing some of the corrective actions it had taken, including a promise that production-area boots and galoshes were no longer being worn outside. FDA said the company did not address the leaky valve under the lunch room sink.

Finally, FDA also outlined procedures for storage of composted materials as well as seed treatment it wants Tiny Greens to consider using.

For Jimmy Johns, after being involved in four outbreaks in two years involving alfalfa sprouts, the restaurant chain’s founder opted to switch to clover sprouts.