Multiple multistate Salmonella outbreaks with multiple serotypes due to backyard flocks
By Dan Flynn on July 25, 2019
The July report for backyard poultry was bleak for the adults and children who care for them.
The federal Centers for Disease Control and Prevention in Atlanta reports that since June 13 it added 489 patients and eight states to the Salmonella outbreaks associated with backyard chicken flocks.
With the July totals added in, the backyard poultry flocks are responsible for multiple national outbreaks totaling 768 confirmed Salmonella cases across 48 of the 50 states. CDC also reports the ongoing continuing outbreaks are responsible for two deaths and have seen at least 122 people admitted to hospitals. Texas and Ohio each recorded one death associated with the outbreak.
CDC added five additional bugs to the list of involved pathogens. The Salmonella serotypes involved include Agona, Alachua, Anatum, Braenderup, Enteritidis, Infantis, Manhattan, Montevideo, Muenchen, Newport, and Oranienburg.
Epidemiologic and laboratory evidence indicate that contact with backyard poultry, such as chicks and ducklings, from multiple hatcheries, are the likely source of these outbreaks.
In interviews, CDC found 237, or 75 percent, of 315 ill people reported contact with chicks or ducklings. People reported getting chicks and ducklings from several sources, including agricultural stores, websites, and hatcheries.
Five of the outbreak strains making people sick were in samples collected from backyard poultry environments in four states. The sampling was from backyard poultry environments in ill people’s homes in California and Ohio and from retail poultry environments in Michigan and Oregon.
The nation’s premiere disease laboratory reports that regardless of where poultry is purchased, they can carry Salmonella germs that can make people sick. It says backyard poultry owners should always follow steps to stay healthy around their poultry.
Meanwhile, it is clear the multiple multistate outbreaks of Salmonella from backyard flocks is not over. Public health investigators are using the PulseNet system to identify illnesses that may be part of these outbreaks.
PulseNet is the national subtyping network of public health laboratories coordinated by CDC. DNA fingerprinting is performed on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS).
CDC’s 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 from ill people in this outbreak showed that they are closely related genetically. This means that the ill people are more likely to share a common source of infection.
WGS analysis of 117 isolates from ill people predicted antibiotic resistance to one or more of the following drugs: amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftriaxone, chloramphenicol, ciprofloxacin, fosfomycin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole.
Testing of 5 isolates using standard antibiotic susceptibility testing by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory confirmed these results (fosfomycin and kanamycin were not tested by this method). If antibiotics are needed, this resistance profile may affect the choice of antibiotic.
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