Multistate Outbreak of Salmonella Braenderup Infections Linked to Nut Butter Manufactured by nSpired Natural Foods, Inc. (Final Update)

Introduction

CDC collaborated with public health officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Salmonella Braenderup infections. Results from the investigation indicated that almond and peanut butter manufactured by nSpired Natural Foods, Inc. was the likely source of this outbreak.   

Public health investigators used the PulseNet system to identify cases of illness that were part of this outbreak. PulseNet, the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC, receives DNA “fingerprints” of Salmonella bacteria obtained through diagnostic testing using pulsed-field gel electrophoresis, or PFGE. Whole genome sequencing, a highly discriminatory subtyping method, was also used to define the outbreak strain. Whole genome sequencing helped clarify which illnesses were related to the outbreak.

A total of six ill persons infected with the outbreak strain of Salmonella Braenderup were reported from five states since January 1, 2014. The number of ill persons identified in each state was as follows: Connecticut (1), Iowa (1), New Mexico (1), Tennessee (1), and Texas (2).

Illness onset dates ranged from January 20, 2014, to May 16, 2014. Ill persons ranged in age from 2 years to 83 years, with a median age of 35 years. Sixty-six percent of ill persons were female. Among five ill persons with available information, one (20%) was hospitalized. No deaths were reported.

This outbreak investigation is over. However, the recalled nut butter products have a long shelf life and may still be in people’s homes. Consumers unaware of the recall could continue to eat the products and potentially get sick. FDA’s investigation is ongoing.

Investigation of the Outbreak

During routine inspections at an nSpired Natural Foods facility in Ashland, Oregon, in February and July 2014, FDA isolated Salmonella Braenderup from environmental samples. PFGE and whole genome sequencing were performed on the environmental isolates by FDA to further characterize the bacteria.

A subsequent search of the PulseNet database identified ill persons with the same PFGE “fingerprint” of Salmonella Braenderup. Whole genome sequencing was performed on these clinical isolates, and the bacteria from six of the ill persons were found to be related to the environmental isolates taken from the firm.

Five of the six ill persons were interviewed and answered questions about foods eaten and other exposures during the week before becoming ill. Four (80%) of them reported eating peanut or almond butter, and all four (100%) reported eating a brand of peanut or almond butter produced by nSpired Natural Foods, Inc.

Between July 15 and August 29, 2014, FDA conducted an inspection at nSpired Natural Foods. FDA issued a Form 483 Inspection Report documenting eight observations made during the inspection.

On August 19, 2014, nSpired Natural Foods, Inc. voluntarily recalled certain lots of almond and peanut butters because of potential contamination with Salmonella. The recalled brands included Arrowhead Mills, MaraNatha, and specific grocery store brand almond and peanut butters.

Isolates also were tested to determine if they were resistant to any antibiotics. The National Antimicrobial Resistance Monitoring System (NARMS) is a U.S. public health surveillance system that tracks antibiotic resistance in foodborne and other enteric bacteria found in people, retail meats and poultry, and food-producing animals. NARMS is an interagency partnership among CDC, the U.S. Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA), and state and local health departments.

The NARMS human surveillance program at CDC monitors antibiotic resistance in Salmonella and other bacteria isolated from clinical specimens submitted to NARMS by public health laboratories. CDC’s NARMS laboratory conducted antibiotic resistance testing on four isolates collected from ill persons infected with the outbreak strain of Salmonella Braenderup. All isolates were susceptible to all antibiotics tested on the NARMS panel.

Final Case Count Update

A total of 6 ill persons infected with the outbreak strain of Salmonella Braenderup were reported from 5 states since January 1, 2014. Since the initial announcement on August 21, 2014, 2 additional ill persons were reported from New Mexico (1) and Texas (1).

Illness onset dates ranged from January 20, 2014, to May 16, 2014. Ill persons ranged in age from 2 years to 83 years, with a median age of 35 years. Sixty-six percent of ill persons were female. Among five ill persons with available information, one (20%) was hospitalized. No deaths were reported.

This outbreak investigation is over. However, the recalled nut butter products have a long shelf life and may still be in people’s homes. Consumers unaware of the recall could continue to eat the products and potentially get sick. FDA’s investigation is ongoing.

Initial Announcement

CDC is collaborating with public health officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Salmonella Braenderup infections. Results from this ongoing investigation indicate that almond and peanut butter manufactured by nSpired Natural Foods, Inc. is the likely source of this outbreak.

Public health investigators are using the PulseNet system to identify cases of illness that may be part of this outbreak. PulseNet, the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC, receives DNA “fingerprints” of Salmonella bacteria obtained through diagnostic testing using pulsed-field gel electrophoresis, or PFGE. Whole genome sequencing, a highly discriminatory subtyping method, was also used to define the outbreak strain. Whole genome sequencing helped clarify which illnesses were related to the outbreak.

As of August 20, 2014, a total of four ill persons infected with the outbreak strain of Salmonella Braenderup have been reported from four states since January 1, 2014. The number of ill persons identified in each state is as follows: Connecticut (1), Iowa (1), Tennessee (1), and Texas (1).

Illness onset dates range from January 22, 2014, to May 16, 2014. Ill persons range in age from 3 years to 83 years, with a median age of 36 years. Seventy-five percent of ill persons are female. Among three ill persons with available information, one (33%) reported being hospitalized. No deaths have been reported.

This outbreak can be visually described with a chart showing the number of persons who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after July 30, 2014 might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. The recalled peanut and almond butter products have a long shelf life and may still be in people’s homes, and illnesses may continue to be reported. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

Investigation of the Outbreak

During routine inspections at an nSpired Natural Foods facility in Ashland, Oregon, in January and July 2014, FDA isolated Salmonella Braenderup from environmental samples. PFGE and whole genome sequencing were performed on the environmental isolates by FDA to further characterize the bacteria.

A subsequent search of the PulseNet database identified ill persons with the same PFGE “fingerprint” of Salmonella Braenderup. CDC performed whole genome sequencing on these clinical isolates and determined that the bacteria from the ill persons were related to the environmental isolates taken from the firm.

To date, three of the four ill persons were interviewed and answered questions about foods eaten and other exposures during the week before becoming ill. All three (100%) of them reported eating peanut or almond butter, and all three (100%) reported eating a brand of peanut or almond butter produced by nSpired Natural Foods, Inc.

On August 19, 2014, nSpired Natural Foods, Inc. voluntarily recalled certain lots of almond and peanut butters because of potential contamination with Salmonella. The recalled brands include Arrowhead Mills, MaraNatha, and specific private label almond and peanut butters.

CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview ill persons about foods eaten before becoming ill. FDA is continuing to work closely with CDC and state partners in this investigation.