February 21, 2019

CDC and public health and regulatory officials in several states investigated a multistate outbreak of Salmonella Infantis infections linked to raw chicken products. The U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS) monitored the outbreak.

Public health investigators used the PulseNet system to identify illnesses that may have been part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting was performed on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS gives a more detailed DNA fingerprint than PFGE. WGS performed on Salmonella bacteria from ill people in this outbreak showed that they were closely related genetically. This means that the ill people were more likely to share a common source of infection.

As of February 19, 2019, 129 people infected with the outbreak strain of Salmonella Infantis were reported from 32 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started from January 8, 2018, to January 27, 2019. Ill people ranged in age from less than 1 year to 105, with a median age of 42. Sixty-nine percent of ill people were female. Of 85 people with information available, 25 (29%) were hospitalized. One death was reported from New York.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Of 69 people interviewed, 60 people (87%) reported preparing or eating chicken products that were purchased raw, including ground chicken, chicken pieces, and whole chicken. Ill people reported buying many different brands of raw chicken products from multiple stores. One person got sick after pets in their home ate raw ground chicken pet foodExternal. Two ill people lived with someone who works in a facility that raises or processes chickens.

The outbreak strain of Salmonella Infantis has been identified in samples from raw chicken products from 76 slaughter and/or processing establishments, from raw chicken pet food, and from live chickens. Samples collected at slaughter and processing establishments were collected as part of FSIS’s routine testing under the Salmonella performance standards. WGS showed that the Salmonella strain from these samples was closely related genetically to the Salmonella from ill people.  This result provided more evidence that people in this outbreak got sick from handling or eating raw or undercooked chicken.

WGS analysis of Salmonella bacteria isolated from 97 ill people and 139 food or environmental samples predicted resistance to some or all of the following antibiotics: ampicillin, ceftriaxone, chloramphenicol, ciprofloxacin, fosfomycin, gentamicin, hygromycin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim-sulfamethoxazole. Four non-clinical isolates had no predicted resistance. Testing of seven isolates using standard antibiotic susceptibility testing by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory confirmed these results (fosfomycin, hygromycin, and kanamycin were not tested by this method). These antibiotic-resistant infections may be difficult to treat with commonly recommended antibiotics, and may require a different antibiotic choice. Advice to clinicians is available.

Available data indicate that this strain of Salmonella Infantis appears to be present in live chickens and in raw chicken products. A single, common supplier of raw chicken products or of live chickens was not identified.

CDC and USDA-FSIS are actively engaging with representatives from the chicken industry to explore ways to reduce Salmonella Infantis in chicken products. Because investigation results suggest this strain of Salmonella Infantis is present in both live chickens and in raw chicken products, further investigation and interventions to reduce the prevalence of this strain should target both the live chicken industry and chicken processing facilities. Consumers should be aware that raw chicken may be contaminated with harmful germs. Always follow food safety steps to prevent foodborne infection from these products.

As of February 21, 2019, this investigation is over.