ATLANTA – The Centers for Disease Control and public health officials closed an investigation into Salmonella infections linked to backyard poultry and spanned 48 states, Puerto Rico and the District of Columbia.

A total of 1,135 people infected with one of five outbreak strains — Enteritidis, Hadar, Indiana, Infantis, Mbandaka, and Muenchen, according to the agency.  Of 829 people with information available, 273 (33%) were hospitalized. Two deaths were reported, one from Indiana and one from Virginia. However, CDC noted that because many people recover without medical care and are not tested for Salmonella, the true number of sick people in these outbreaks was likely much higher than the number reported, and these outbreaks may not have been limited to the states with known illnesses.

The common factor behind the infections was backyard poultry, such as chickens and ducks. Of the 677 people that state and local public health officials interviewed, 449 (66%) reported contact with backyard poultry before getting sick.

“Backyard poultry, like chicken and ducks, can carry Salmonella germs even if they look healthy and clean,” CDC said in its report on the outbreak. “These germs can easily spread to anything in the areas where the poultry live and roam.

“You can get sick from touching your backyard poultry or anything in their environment and then touching your mouth or food and swallowing Salmonella germs.”

Investigators used whole genome sequencing (WGS) to identify any predicted antibiotic resistance for bacteria from 1,101 case patient’s samples, four animal samples, and seven environmental samples. Of the 1,112 samples, 394 (35%) were predicted to be resistant to one or more antibiotics, including amoxicillin-clavulanic acid, ampicillin, chloramphenicol (0.3%), cefoxitin, ceftriaxone, ciprofloxacin, gentamicin, kanamycin, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim-sulfamethoxazole.

CDC confirmed these results by the testing of 11 sick people’s samples using standard antibiotic susceptibility testing methods by the agency’s National Antimicrobial Resistance Monitoring System. However, streptomycin and kanamycin were not tested by this method.

CDC encouraged backyard flock owners to practice regular hand washing, supervise children around flocks and handle eggs safely among other preventative measures.

The agency advised stores that sell poultry to clean and sanitize poultry display areas between shipments of new poultry, use hatcheries that take steps to reduce Salmonella on-farm and keep customers healthy by providing handwashing stations or hand sanitizers next to poultry display areas in addition to keeping those displays out of reach, especially of children.