CDC details chicken-linked Salmonella outbreak probe

The US Centers for Disease Control and Prevention (CDC) yesterday released new details about a multistate Salmonella Heidelberg outbreak that has so far sickened people in 17 states, including news that the DNA fingerprints of the bacteria match those of a similar outbreak earlier this year and that some isolates from chicken products and patients are multidrug-resistant.

The CDC's initial report on the outbreak came just a day after the US Department of Agriculture issued a public health alert about the chicken in the wake of the outbreak and as the CDC called some employees back from federal-government shutdown furloughs to help track the outbreak. So far 278 illnesses have been reported, 213 of them in California. Most of the affected states are in the West.

Health officials say the likely source is chicken products produced by three Foster Farms facilities in California. Chicken products from two of the company's other poultry processing facilities were linked to another Salmonella Heidelberg outbreak earlier this year that sickened 134 people in 13 states.

Illness onsets range from Mar 1 to Sep 24, and patient ages range from younger than 1 year to 93 years. Of 183 patients with available information, 76 (42%) have been hospitalized. No deaths have been reported.

CDC's PulseNet investigation revealed that seven strains of Salmonella Heidelberg are involved in the outbreak, including four that are rarely reported. Antibiotic-resistant strains may boost the risk of hospitalization or treatment failure in infected patients, the CDC said.

A CDC official said yesterday that the government shutdown has suspended routine monitoring for antimicrobial resistance but that labs are still testing samples on an urgent basis, including those related to the Salmonella Heidelberg outbreak.

The National Antimicrobial Resistance Monitoring System (NARMS), a collaboration between the CDC and the Food and Drug Administration (FDA), monitors antibiotic resistance in certain organisms isolated from raw retail meat, including chicken. NARMS labs detected four of the seven outbreak strains on five retail samples of Foster Farms chicken breasts and wings collected in California. Two were multidrug-resistant, according to the CDC update.

Investigations by local, state, and federal public health officials point to Foster Farms brand chicken as the source of the outbreak. Studies that compared what sick and healthy people ate found that 80% of sick patients reported eating chicken the week before their illness, compared with 65% of healthy respondents. Of sick people who had brand information available, 48 of 61 reported eating Foster Farms chicken or another brand that was likely produced by the company.

The Washington State Public Health Laboratories found one of the Salmonella Heidelberg outbreak strains in a leftover intact sample of raw Foster Farms chicken collected from a sick patient's home, according to the CDC report.

Preliminary lab tests have detected four of the seven outbreak strains in "multiple" chicken product samples from the three Foster Farms production facilities in California, the CDC said. However, so far the USDA's Food Safety and Inspection Service (FSIS) hasn't been able to link the outbreak to a specific product or production period. There hasn't been a product recall yet, but in its public health alert the FSIS said raw products from the three plants bear the following USDA inspection marks: P6137, P6137A, and P7632.

Salmonella isn't uncommon in chicken and isn't considered an adulterant. Health officials often remind consumers to avoid cross-contamination when preparing chicken and to take other food safety steps.

Foster Farms said in an Oct 7 statement that it was working with the USDA and CDC to reduce the incidence of Salmonella Heidelberg in raw chicken at its California plants and has taken extra safety steps that were successful in curbing contamination at its Pacific Northwest facilities.

See also:

Oct 8 CDC outbreak announcement

Oct 8 CIDRAP News story "Chicken-linked Salmonella outbreak tests federal response amid furloughs"

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