Gastroenteritis Outbreak Associated with Unpasteurized Tempeh, North Carolina, USA

Stephanie E. Griese

, Aaron T. Fleischauer, Jennifer K. MacFarquhar, Zackary Moore, Cris Harrelson, Anita Valiani, Sue Ellen Morrison, David Sweat, Jean-Marie Maillard, Denise Griffin, Debra Springer, Matthew Mikoleit, Anna E. Newton, Brendan Jackson, Thai-An Nguyen, Stacey Bosch, and Megan Davies

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (S.E. Griese, A.T. Fleischauer, J.K. MacFarquhar, M. Mikoleit, A.E. Newton, B. Jackson, T.-A. Nguyen, S. Bosch); North Carolina Division of Public Health, Raleigh, North Carolina, USA (S.E. Griese, A.T. Fleischauer, J.K. MacFarquhar, Z. Moore, C. Harrelson, A. Valiani, D. Sweat, J.-M. Maillard, D. Griffin, D. Springer, M. Davies); Buncombe County Department of Health, Asheville, North Carolina, USA (S.E. Morrison)

Abstract

During an investigation of an outbreak of gastroenteritis caused by Salmonella enterica serovar Paratyphi B variant L(+) tartrate(+), we identified unpasteurized tempeh as a novel food vehicle and Rhizopus spp. starter culture as the source of the contamination. Safe handling of uncooked, unpasteurized tempeh should be emphasized for prevention of foodborne illnesses.

Infections with Salmonella spp., a leading cause of hospitalizations and death among persons with foodborne illness in the United States, are most often associated with contaminated poultry or eggs (1,2). S. enterica serovar Paratyphi B variant L(+) tartrate(+) (formerly Salmonella var. Java) accounted for 1.1% of Salmonella infections reported to the Centers for Disease Control and Prevention (CDC) in 2009 (3). We investigated an outbreak of gastroenteritis caused by S. enterica ser. Paratyphi B var. L(+) tartrate(+) in North Carolina, USA, and found that the infections were associated with contaminated Rhizopus spp. starter culture and unpasteurized tempeh, a meat substitute, as a novel food vehicle.

The Study

On March 30, 2012, a local health department notified the North Carolina Division of Public Health (NCDPH) of 5 persons who had laboratory-confirmed infection with S. enterica ser. Paratyphi B var. L(+) tartrate(+) and 3 epidemiologically linked persons who also had gastroenteritis. All 8 ill persons ate or worked at the same restaurant in Buncombe County, North Carolina; 5 (63%) were food handlers. Patient interviews did not identify a common source or vehicle for the infection. On April 24, NCDPH was notified of 10 additional persons with laboratory-confirmed S. enterica ser. Paratyphi B var. L(+) tartrate(+) infection; all had visited or resided in Buncombe County during the infection’s incubation period.
Pulsed-field gel electrophoresis (PFGE) patterns of isolates from all 15 laboratory-confirmed case-patients were indistinguishable and represented a pattern not previously reported to the national database of enteric PFGE patterns, PulseNet, coordinated by CDC (www.cdc.gov/pulsenet; outbreak strain identification Xba1 JKXX01.1228). NCDPH initiated an investigation to determine the extent of the outbreak, identify the transmission source, and implement control measures.
A confirmed case was defined as laboratory identification of the outbreak strain from a person’s clinical specimen, regardless of illness onset date or exposure location. A probable case was defined as gastroenteritis in a person epidemiologically linked to a confirmed case. Passive reporting was enhanced through media reports and provider alerts. Active case finding was performed by hospital-based public health epidemiologists. Patients were interviewed by using the standard NCDPH salmonellosis reporting form to assess clinical symptoms; travel history; and food, water, and animal exposures.