Sprouts: FDA Investigation Summary - Multistate Outbreak of Salmonella Cubana Infections Associated with Sprouts From an Arizona Sprouter
What was the Problem and What was Done?
The U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC) and state and local public health officials investigated a multi-state outbreak of Salmonella Cubana infections linked to alfalfa sprouts from Arizona Hydroponic Farming LLC located in Eloy, AZ.
During a routine surveillance inspection at Arizona Hydroponic Farming LLC, conducted September 18-20, 2012, the FDA collected several samples of alfalfa sprouts as well as spent irrigation water. On September 27, 2012, the FDA notified the firm that both the alfalfa sprout samples and the spent irrigation water collected were confirmed positive for the bacterium Salmonella Cubana. The positive lot of alfalfa sprouts was destroyed by the firm and never distributed into commerce.
Subsequent to the inspection and sampling, FDA began working with states and CDC on limited epidemiological and traceback investigations following up on reports of Salmonella Cubana illnesses. Public health investigators used DNA “fingerprints” of Salmonella bacteria (obtained through diagnostic testing with pulsed-field gel electrophoresis, or PFGE) to identify cases of illness that may have been part of this outbreak. Using data from PulseNet , the national subtyping network made up of state and local public health laboratories and federal food regulatory laboratories that perform molecular surveillance of foodborne infections, investigators did identify cases of illness.
According to the CDC, a total of 19 people from three states were infected with the same strain of Salmonella Cubana as the one found in the sampled alfalfa sprouts from Arizona Hydroponic Farming LLC. The illnesses, reported from Arizona, Nevada and New Mexico, occurred in July and August 2012. This PFGE pattern had rarely been seen before in PulseNet, and had only been reported three times previously.
Through limited traceback investigations, alfalfa sprouts sourced from Arizona Hydroponic Farming LLC were identified as the vehicle in this outbreak. Four out of five ill persons with available food histories reported consuming sprouts in the 7 days before illness onset. One case-patient purchased alfalfa sprouts from a grocer that stated they only purchased sprouts sourced from Arizona Hydroponic Farming LLC.
The FDA conducted additional inspections at the sprout growing facility from September 28 to October 3, and from October 23-26, 2012.
The observations from the inspection that ended on October 3, 2012, included:
- Standing water 2 to 3 inches deep was present on the floor in the sprout growing room, immediately under the bottom racks of growing sprouts. It was noted that standing water may serve as a reservoir for pathogens as well as be a route of contamination if splashed onto the sprouts by employees walking by these racks.
The observations from the inspection that ended on October 26, 2012, included:
- Water for the firm’s evaporative coolers comes from a tub located at ground level, outside the building. At the time of the inspection, the tub was found to be uncovered, the water appeared dirty and green, and there were birds around the tub. This water enters the building in the form of a mist and is likely to have come in contact with uncovered sprouts and sprouting equipment.
- Two large dogs were observed roaming the property unrestrained.
- Animal excrement was observed on an area sloping towards the well head that is the source of the water used to irrigate the sprouts.
- A pipe approximately 10 inches from the well head was open and unprotected and stuck up several inches from the ground, and there was no cement apron around the well head to protect it from contamination.
- Water from the hand washing sink drain was observed splashing on the drain trough near the area where cleaned trays and panels for holding sprouts are stored.
- Floor drains were open to the outside of the building and the openings were not tightly sealed.
- Drums and tubs used for sprouting had heavy residue, and the drums could not be adequately cleaned and sanitized because they were gouged and rough.
Additionally, the investigation found that Arizona Hydroponic Farming LLC had purchased seed from a company that supplies seed for feed and lawn use rather than for human consumption. This seed firm has subsequently committed to labeling each bag of seeds it distributes with a tag that says “Not for Human Consumption.”
FDA issued a Warning Letter to Arizona Hydroponic Farming LLC on February 11, 2013 (an amendment was issued on July 22, 2013) as a result of the sampling, the outbreak investigation, and the inspection findings.
From June 18-20 2013, FDA conducted a re-inspection at the sprout growing firm. This inspection did not warrant additional actions by FDA.
The information in this release reflects the FDA’s best efforts to communicate what it has learned from the manufacturer and the state and local public health agencies involved in the investigation. The agency will update this page as more information becomes available.
Additional Information for Consumers:
Consumers can find more information on sprout safety at the following links:
Foodsafety.gov: Sprouts: What You Should Know
Additional Information for Industry:
Within the fresh produce category, sprouts present a special challenge because the conditions that promote sprouting of the seed (e.g., temperature, humidity, available nutrients) also promote the growth of pathogens if pathogens are present. FDA believes that the seed is the source of contamination in most of the foodborne illness outbreaks associated with sprout consumption. However, insanitary conditions at the sprouting facility can exacerbate any problems.
Because the seeds used in sprout production are the likely source of contamination in most outbreaks, FDA strongly encourages firms, from the farm level (seed production) through the distribution of finished product (sprouted seed), to review their current operations in light of the agency's existing guidance for reducing microbial food safety hazards for sprouted seeds.
In 1999, FDA released guidance to address potential public health concerns related to the consumption of raw sprouts including Guidance for Industry: Reducing Microbial Food Safety Hazards for Sprouted Seeds, and Guidance for Industry: Sampling and Microbial Testing of Spent Irrigation Water During Sprout Production. These documents are considered guidance and are designed to assist in complying with the Federal Food, Drug, and Cosmetic Act.
In addition, the California Department of Public Health, in cooperation with FDA also developed a series of videos related to sprout safety.
Recently, FDA, in cooperation with the Illinois Institute of Technology’s Institute for Food Safety and Health (IIT IFSH), created the Sprouts Safety Alliance (SSA) to help sprout producers and other stakeholders identify and implement best practices related to producing safer sprouts.
Another resource is the FDA web page “Food Safety Information Concerning Sprouts.”