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FDA Investigation Summary - Multistate Outbreak of Salmonella Senftenberg Infections Associated with Pistachios from a California Roaster

Posted:  February 19, 2014

On this page:

What is the Problem and What was Done?
Additional Information for Consumers
Additional Information for Industry

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 Senftenberg illnesses linked to pistachios from ARO Pistachios, Inc., in Terra Bella, Calif.

According to the CDC, a total of 8 persons from 6 states were infected with Salmonella Senftenberg; illnesses were reported from California, Kansas, Massachusetts, Maryland, Pennsylvania, and Wisconsin and occurred from January to May 2013.  The same strain of Salmonella was also found in Arya variety pistachios associated with a report filed by Hoop Nuts LLC, a nut distributor, on January 29, 2013 through FDA’s Reportable Food Registry (RFR), which is an electronic system through which industry reports to FDA when there is a reasonable probability that an article of food will cause serious adverse health consequences.  This strain, or pulsed-field gel electrophoresis (PFGE) pattern, of Salmonella Senftenberg had rarely been seen before in the PulseNet database, 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.  Before this outbreak, this strain had only been reported two times.

Based on the RFR reports and FDA’s process and inspectional findings at ARO Pistachios, Arya pistachios manufactured by ARO Pistachios were identified as the likely vehicle in this outbreak.  Four out of six ill persons with available food histories reported consuming pistachios in the 7 days before illness onset.  The strain of Salmonella found in clinical samples taken from case patients matched the Salmonella strain found in 17 of 90 environmental samples taken from ARO Pistachios, Inc.  In addition, an import sample of pistachios initially sourced from ARO Pistachios and returned to the U.S., was also positive for Salmonella Senftenberg.  The PFGE pattern of these test results was confirmed by PulseNet to be indistinguishable from the outbreak strain.

The sample that prompted the RFR was based on a request from a customer of Hoop Nuts LLC that required testing of pistachios prior to shipping to that customer.  Roasted pistachios that had already been shipped by ARO Pistachios to Hoop Nuts were tested and found positive for Salmonella Senftenberg.

The FDA and the California Department of Public Health (CDPH) conducted several inspections, which focused on Good Manufacturing Practices (GMPs) both at ARO Pistachios, Inc., the pistachio manufacturer, and Hoop Nuts LLC, an independent distributor, between February and May 2013.  The FDA investigators made numerous observations about deficiencies which were shared with the respective firms.

During the inspections carried out from February 12 – 20, 2013 at ARO Pistachios, FDA investigators observed that ARO Pistachios did not take effective measures to protect food from pest contamination, had obstructed aisles and working spaces, failed to properly store equipment that could attract or harbor pests, and allowed equipment to lie in areas where it could adulterate food with contaminants.  The FDA also found evidence of rodent excrement and possible rodent urine stains on the premises.  The FDA collected samples of pistachios for filth analysis and environmental testing.  The pistachio samples collected from ARO Pistachio’s storage rooms tested as “positive adverse findings” for filth, while the environmental sample collected from the roasting room was negative for Salmonella Senftenberg.

In response to the ARO Pistachios facility inspection, FDA followed up in March 2013 with an inspection at Hoop Nuts, the independent distributor in Van Nuys, Calif., which had purchased pistachios from ARO Pistachios.  Hoop Nuts had originally filed the RFR report on January 29, 2013 regarding Salmonella detection in pistachios from ARO Pistachios.

During a series of four visits to Hoop Nuts between March 25 and April 1, 2013, FDA collected two environmental samples including a total of 131 swabs; all tested negative for Salmonella.  But investigators made nine observations about Hoop Nuts procedures to include gloves used in food handling were not maintained in an intact, clean, and sanitary condition; suitable outer garments that would protect against contamination of food were not worn; and the company failed to conduct cleaning and sanitizing operations for utensils and equipment in a manner that protected against food contamination.

During the visits to Hoop Nuts, the investigators also observed that the company did not take reasonable precautions to ensure that production procedures did not contribute to contamination from any source, the company failed to maintain equipment in an acceptable condition through appropriate cleaning and sanitizing, systems that discharged water or sewage were cross-connected to systems that carried water for food or food manufacturing, the company failed to store raw materials in a manner that protected against contamination, plumbing was a source of contamination to equipment and utensils, and there was a lack of adequate drainage of areas that contributed to contamination of food by seepage and foot-borne filth.

On May 15, 2013 FDA re-visited ARO Pistachios to collect a sample of pistachios, which tested negative for Salmonella.  During this visit, FDA investigators learned that ARO Pistachios had begun processing comingled pistachios and planned to distribute them.  As a result of this, FDA re-inspected ARO Pistachios on May 21-24, 2013.  During this visit, the FDA investigators observed that the firm failed to provide hand-washing facilities at each location in the plant where needed; employees did not wash or sanitize their hands thoroughly in an adequate hand-washing facility before starting work, after each absence from their work stations, and at any time their hands may have become soiled or contaminated; the company did not take all reasonable precautions to ensure that production procedures did not contribute contamination from any source; the company failed to handle work-in-progress in a manner that protects against contamination; it failed to provide adequate lighting in areas where food was examined, stored, or processed; and it failed to provide adequate screening or other protection against pests.

On June 5, 2013, ARO Pistachios issued a voluntary recall of many pistachio products from the 2012 crop year because the products may be contaminated with Salmonella

In a Warning Letter to ARO Pistachios dated January 13, 2014, the FDA, referring to the May 21 through May 24, 2013 inspection, said the ARO Pistachios facility had “serious violations of the Current Good Manufacturing Practice (CGMP) regulations for foods, Title 21, Code of Federal Regulations, Part 110 (21 CFR 110),” which rendered the pistachios “adulterated” according to section 402(a)(4) of the Federal Food, Drug, and Cosmetic Act (FFD&C Act), 21 U.S.C. § 342(a)(4) because they had been “prepared, packed, or held under insanitary conditions whereby they may have become contaminated with filth, or whereby they may have been rendered injurious to health.”

The letter noted that an analysis of environmental samples collected from different locations in the processing facility “revealed the presence of Salmonella enterica serotype Senftenberg”in 17 subsamples, and that the presence in multiple locations was a “significant concern because it indicates that the pathogen is a potential resident organism in your facility.”  The letter further noted that the presence of Salmonella on product contact surfaces and other locations close to where food is exposed indicated a “high risk of product contamination.” 

The letter stated that FDA investigators had observed an employee repeatedly touching the bottom of shipping boxes resting on the floor and then touching roasted, ready-to-eat pistachios “without washing or sanitizing hands."  The letter also said that maintenance personnel entered and exited the hand sorting room through a door that opened directly to the outside of the facility and that “[a]pparent bird droppings were observed on the floor of the outside areas where maintenance personnel were observed working and entering the hand sorting room,” and that inside the sorting room “buckets containing floor sweepings of pistachios, dust, and debris” were observed and that company officials “stated that the buckets of floor swept pistachios will be reworked into finished product.”

The letter called on ARO Pistachios to correct the violations and prevent them from recurring.

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 pistachio, and specifically tree nut, safety at the following links:

University of California (UC) Food Safety: disclaimer icon

Recall Notice for ARO pistachios, July 12, 2013:  Torn and Glasser Inc. Announces Voluntary Recall of Pistachios Due to Possible Health Risk

Recall Notice for ARO pistachios, July 10, 2013:  Western Mixers Produce & Nuts, Inc. Recalls Pistachios Because of Possible Health Risk

Additional Information for Industry: 

Within the raw produce category, tree nuts present a special challenge because the harvest conditions vary and some varieties of nuts may be more vulnerable to contamination. 

In 2011, FDA released guidance for industry to address the risk for contamination by Salmonella species in food containing a pistachio-derived product as an ingredient. 

Recently, FDA requested comments, scientific data and other information for use in an assessment of the risk of human salmonellosis associated with the consumption of tree nuts.  The need for this assessment is underscored by outbreaks of human salmonellosis linked to tree nuts over the past decade, by product recalls, and by Salmonella isolation from tree nuts during surveys.  The assessment will be used to evaluate current practices and to evaluate policies related to risk-based preventive controls.  For additional information on this effort, please see:!documentDetail;D=FDA-2013-N-0747-0001.  A recent webinar that discussed the proposed risk assessment was presented on July 22, 2013.

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