The U.S. Centers for Disease Control & Prevention (CDC), public health and regulatory officials in several states and the U.S. Food & Drug Administration are investigating a multi-state outbreak of multi-drug-resistant salmonella infections linked to contact with pig ear dog treats.

As of July 2, 2019, CDC reported that a total of 45 infected people from 13 states have been reported. The illnesses started on dates ranging from Nov. 18, 2018, to June 13, 2019. Ill people range in age from less than one year to 81 years, with a median age of 23. Half (50%) of ill people were female. Of 39 ill people with information available, 12 (31%) have been hospitalized. However, no deaths have been reported.

Epidemiologic evidence indicates that contact with pig ear dog treats is the likely source of this outbreak. In interviews, 34 (89%) of 38 ill people reported contact with a dog before getting sick.

Of 24 people with available information, 17 (71%) reported contact with pig ear dog treats or with dogs who were fed pig ear dog treats.

According to CDC, officials from the Michigan Department of Agriculture & Rural Development gathered pig ear dog treats at retail locations where ill people reported buying the products. They sampled pig ears for salmonella, and although the outbreak strain was not identified, other strains of salmonella were.

“Investigators are checking to see if any human illnesses are linked to those strains. Retail locations where sampling occurred have removed pig ears from shelves,” CDC reported.

According to CDC, whole-genome sequencing analysis of salmonella isolates from 30 ill people predicted antibiotic resistance or decreased susceptibility to ampicillin, ciprofloxacin, gentamicin, nalidixic acid, streptomycin, sulfisoxazole, tetracycline and trimethoprim-sulfamethoxazole. Testing of one clinical isolate using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) provided comparable results.

“These antibiotic-resistant infections may be difficult to treat with commonly recommended antibiotics and may require a different antibiotic choice,” the agency reported.

On July 3, 2019, Pet Supplies Plus recalled bulk pig ears stocked in open bins because they might be contaminated with salmonella.

CDC added that the investigation is ongoing and that it will provide updates when more information is available.