Multistate outbreaks of salmonellosis linked to contact with backyard poultry-United States, 2015-2022.

AIMS: Contact with backyard poultry (i.e., privately-owned, non-commercial poultry) was first associated with a multistate outbreak of salmonellosis in 1955. In recent years, backyard poultry-associated salmonellosis outbreaks have caused more illnesses in the United States than salmonellosis outbreaks linked to any other type of animal. Here, we describe the epidemiology of outbreaks from 2015-2022 to inform prevention efforts. METHODS AND RESULTS: During 2015-2022, there were 88 multistate backyard poultry-associated salmonellosis outbreaks and 7866 outbreak-associated illnesses caused by 21 different Salmonella serotypes. Salmonella Enteritidis accounted for the most outbreaks (n = 21) and illnesses (n = 2400) of any serotype. Twenty-four percent (1840/7727) of patients with available information were <5 years of age. In total, 30% (1710/5644) of patients were hospitalized, and nine deaths were attributed to Salmonella infection. Throughout this period, patients reported behaviours that have a higher risk of Salmonella transmission, including kissing or snuggling poultry or allowing poultry inside their home. CONCLUSIONS: Despite ongoing efforts to reduce the burden of salmonellosis associated with backyard poultry, outbreak-associated illnesses have nearly tripled and hospitalizations more than quadrupled compared with those in 1990-2014. Because this public health problem is largely preventable, government officials, human and veterinary healthcare providers, hatcheries, and retailers might improve the prevention of illnesses by widely disseminating health and safety recommendations to the public and by continuing to develop and implement prevention measures to reduce zoonotic transmission of Salmonella by backyard poultry.

Genome Sequences of 18 Salmonella enterica Serotype Hadar Strains Collected from Patients in the United States.

Despite being linked to a number of recent poultry-associated outbreaks in the United States, few reference genomes are available for Salmonella enterica serotype Hadar. Here, we address this need by reporting 18 Salmonella Hadar genomes from samples collected from patients in the United States between 2014 and 2020.

Multistate outbreak of Salmonella Mbandaka infections linked to sweetened puffed wheat cereal - United States, 2018.

In May of 2018, PulseNet, the national molecular subtyping network for enteric pathogens, detected a multistate cluster of illnesses caused by an uncommon molecular subtype of Salmonella serovar Mbandaka. A case was defined as an illness in a person infected with the outbreak strain of Salmonella Mbandaka with illness onset on or after 3 March 2018 and before 1 September 2018. One-hundred thirty-six cases from 36 states were identified; 35 hospitalisations and no deaths were reported. Ill people ranged in age from <1 year to 95 years (median: 57 years). When standardised questionnaires did not generate a strong hypothesis, opened-ended interviews were performed. Sixty-three of 84 (75%) ultimately reported consuming or possibly consuming a specific sweetened puffed wheat cereal in the week before illness onset. Environmental sampling performed at the cereal manufacturing facility yielded the outbreak strain. The outbreak strain was also isolated from open cereal samples from ill people's homes and from a sealed retail sample. Due to these findings, the brand owner of the product issued a voluntary recall of the cereal on 14 June 2018. Additional investigation of the manufacturing facility identified persistent environmental contamination with Salmonella Mbandaka that was closely genetically related to other isolates in the outbreak. This investigation highlights the ability of Salmonella to survive in low-moisture environments, and the potential for prolonged outbreaks linked to products with long shelf lives and large distribution areas.

Analysis of Salmonella enterica Isolated from a Mixed-Use Watershed in Georgia, USA: Antimicrobial Resistance, Serotype Diversity, and Genetic Relatedness to Human Isolates.

As the cases of Salmonella enterica infections associated with contaminated water are increasing, this study was conducted to address the role of surface water as a reservoir of S. enterica serotypes. We sampled rivers and streams (n = 688) over a 3-year period (2015 to 2017) in a mixed-use watershed in Georgia, USA, and 70.2% of the total stream samples tested positive for Salmonella. A total of 1,190 isolates were recovered and characterized by serotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). A wide range of serotypes was identified, including those commonly associated with humans and animals, with S. enterica serotype Muenchen being predominant (22.7%) and each serotype exhibiting a high degree of strain diversity by PFGE. About half (46.1%) of the isolates had PFGE patterns indistinguishable from those of human clinical isolates in the CDC PulseNet database. A total of 52 isolates (4.4%) were resistant to antimicrobials, out of which 43 isolates were multidrug resistant (MDR; resistance to two or more classes of antimicrobials). These 52 resistant Salmonella isolates were screened for the presence of antimicrobial resistance genes, plasmid replicons, and class 1 integrons, out of which four representative MDR isolates were selected for whole-genome sequencing analysis. The results showed that 28 MDR isolates resistant to 10 antimicrobials had blacmy-2 on an A/C plasmid. Persistent contamination of surface water with a high diversity of Salmonella strains, some of which are drug resistant and genetically indistinguishable from human isolates, supports a role of environmental surface water as a reservoir for and transmission route of this pathogen. IMPORTANCE Salmonella has been traditionally considered a foodborne pathogen, as it is one of the most common etiologies of foodborne illnesses worldwide; however, recent Salmonella outbreaks attributed to fresh produce and water suggest a potential environmental source of Salmonella that causes some human illnesses. Here, we investigated the prevalence, diversity, and antimicrobial resistance of Salmonella isolated from a mixed-use watershed in Georgia, USA, in order to enhance the overall understanding of waterborne Salmonella. The persistence and widespread distribution of Salmonella in surface water confirm environmental sources of the pathogen. A high proportion of waterborne Salmonella with clinically significant serotypes and genetic similarity to strains of human origin supports the role of environmental water as a significant reservoir of Salmonella and indicates a potential waterborne transmission of Salmonella to humans. The presence of antimicrobial-resistant and MDR Salmonella demonstrates additional risks associated with exposure to contaminated environmental water.

Salmonella illness outbreaks linked to backyard poultry purchasing during the COVID-19 pandemic: United States, 2020.

Poultry contact is a risk factor for zoonotic transmission of non-typhoidal Salmonella spp. Salmonella illness outbreaks in the United States are identified by PulseNet, the national laboratory network for enteric disease surveillance. During 2020, PulseNet observed a 25% decline in the number of Salmonella clinical isolates uploaded by state and local health departments. However, 1722 outbreak-associated Salmonella illnesses resulting from 12 Salmonella serotypes were linked to contact with privately owned poultry, an increase from all previous years. This report highlights the need for continued efforts to prevent backyard poultry-associated outbreaks of Salmonella as ownership increases in the United States.

Onsite investigation at a mail-order hatchery following a multistate Salmonella illness outbreak linked to live poultry-United States, 2018.

Centers for Disease Control and Prevention (CDC), health departments, and other state and federal partners have linked contact with live poultry to 70 human Salmonella outbreaks in the United States from 2000 to 2017, which resulted in a total of 4,794 illnesses, 894 hospitalizations, and 7 deaths. During human salmonellosis outbreaks environmental sampling is rarely conducted as part of the outbreak investigation. CDC was contacted by state health officials on June 12, 2018, to provide support during an investigation of risk factors for Salmonella infections linked to live poultry originating at a mail-order hatchery. From January 1, 2018, to June 15, 2018, 13 human Salmonella infections in multiple states were attributed to exposure to live poultry from a single hatchery. Two serotypes of Salmonella were associated with these infections, Salmonella Enteritidis and Salmonella Litchfield. Molecular subtyping of the S. Enteritidis clinical isolates revealed they were closely related genetically (within 0 to 9 alleles) by core genome multi-locus sequence typing (cgMLST) to isolates obtained from environmental samples taken from hatchery shipping containers received at retail outlets. Environmental sampling and onsite investigation of practices was conducted at the mail-order hatchery during an investigation on June 19, 2018. A total of 45 environmental samples were collected, and 4 (9%) grew Salmonella. A chick box liner from a box in the pre-shipping area yielded an isolate closely related to the S. Enteritidis outbreak strain (within 1 to 9 alleles by cgMLST). The onsite investigation revealed lapses in biosecurity, sanitation, quality assurance, and education of consumers. Review of Salmonella serotype testing performed by the hatchery revealed that the number of samples and type of samples collected monthly varied. Also, S. Enteritidis was identified at the hatchery every year since testing began in 2016. Recommendations to the hatchery for biosecurity, testing, and sanitation measures were made to help reduce burden of Salmonella in the hatchery and breeding flocks, thereby reducing the occurrence of human illness.

Outbreak of Salmonella Newport Infections with Decreased Susceptibility to Azithromycin Linked to Beef Obtained in the United States and Soft Cheese Obtained in Mexico - United States, 2018-2019.

In September 2018, CDC identified Salmonella enterica serotype Newport (Newport) infections that were multidrug resistant (MDR), with decreased susceptibility to azithromycin, a recommended oral treatment agent. Until 2017, decreased susceptibility to azithromycin had occurred in fewer than 0.5% of Salmonella isolates from U.S. residents. This report summarizes the investigation of a multistate MDR Salmonella outbreak conducted by CDC, state and local health departments, and the U.S. Department of Agriculture's Food Safety and Inspection Service. During June 2018-March 2019, 255 cases of infection with the outbreak strain were identified in 32 states; 43% of patients (89 of 206 with information on travel) reported recent travel to Mexico. Infections were linked to consumption of soft cheese obtained in Mexico and beef obtained in the United States. Consumers should avoid eating soft cheese that could be made from unpasteurized milk, regardless of the source of the cheese. When preparing beef, a food thermometer should be used to ensure that appropriate cooking temperatures are reached. When antibiotic treatment is needed for a patient, clinicians should choose antibiotics based on susceptibility testing wherever possible.