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

Outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 associated with romaine lettuce consumption, 2011.

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) O157:H7 is the causal agent for more than 96,000 cases of diarrheal illness and 3,200 infection-attributable hospitalizations annually in the United States. MATERIALS AND METHODS: We defined a confirmed case as a compatible illness in a person with the outbreak strain during 10/07/2011-11/30/2011. Investigation included hypothesis generation, a case-control study utilizing geographically-matched controls, and a case series investigation. Environmental inspections and tracebacks were conducted. RESULTS: We identified 58 cases in 10 states; 67% were hospitalized and 6.4% developed hemolytic uremic syndrome. Any romaine consumption was significantly associated with illness (matched Odds Ratio (mOR) = 10.0, 95% Confidence Interval (CI) = 2.1-97.0). Grocery Store Chain A salad bar was significantly associated with illness (mOR = 18.9, 95% CI = 4.5-176.8). Two separate traceback investigations for romaine lettuce converged on Farm A. Case series results indicate that cases (64.9%) were more likely than the FoodNet population (47%) to eat romaine lettuce (p-value = 0.013); 61.3% of cases reported consuming romaine lettuce from the Grocery Store Chain A salad bar. CONCLUSIONS: This multistate outbreak of STEC O157:H7 infections was associated with consumption of romaine lettuce. Traceback analysis determined that a single common lot of romaine lettuce harvested from Farm A was used to supply Grocery Store Chain A and a university campus linked to a case with the outbreak strain. An investigation at Farm A did not identify the source of contamination. Improved ability to trace produce from the growing fields to the point of consumption will allow more timely prevention and control measures to be implemented

National Outbreak of Multidrug Resistant Salmonella Heidelberg Infections Linked to a Single Poultry Company.

IMPORTANCE:This large outbreak of foodborne salmonellosis demonstrated the complexity of investigating outbreaks linked to poultry products. The outbreak also highlighted the importance of efforts to strengthen food safety policies related to Salmonella in chicken parts and has implications for future changes within the poultry industry. OBJECTIVE:To investigate a large multistate outbreak of multidrug resistant Salmonella Heidelberg infections. DESIGN:Epidemiologic and laboratory investigations of patients infected with the outbreak strains of Salmonella Heidelberg and traceback of possible food exposures. SETTING:United States. Outbreak period was March 1, 2013 through July 11, 2014. PATIENTS:A case was defined as illness in a person infected with a laboratory-confirmed Salmonella Heidelberg with 1 of 7 outbreak pulsed-field gel electrophoresis (PFGE) XbaI patterns with illness onset from March 1, 2013 through July 11, 2014. A total of 634 case-patients were identified through passive surveillance; 200/528 (38%) were hospitalized, none died. RESULTS:Interviews were conducted with 435 case-patients: 371 (85%) reported eating any chicken in the 7 days before becoming ill. Of 273 case-patients interviewed with a focused questionnaire, 201 (74%) reported eating chicken prepared at home. Among case-patients with available brand information, 152 (87%) of 175 patients reported consuming Company A brand chicken. Antimicrobial susceptibility testing was completed on 69 clinical isolates collected from case-patients; 67% were drug resistant, including 24 isolates (35%) that were multidrug resistant. The source of Company A brand chicken consumed by case-patients was traced back to 3 California production establishments from which 6 of 7 outbreak strains were isolated. CONCLUSIONS:Epidemiologic, laboratory, traceback, and environmental investigations conducted by local, state, and federal public health and regulatory officials indicated that consumption of Company A chicken was the cause of this outbreak. The outbreak involved multiple PFGE patterns, a variety of chicken products, and 3 production establishments, suggesting a reservoir for contamination upstream from the production establishments. Sources of bacteria and genes responsible for resistance, such as farms providing birds for slaughter or environmental reservoir on farms that raise chickens, might explain how multiple PFGE patterns were linked to chicken from 3 separate production establishments and many different poultry products

Frequency of selected case-series exposures in case patients vs. FoodNet population survey exposure.

†<p>Any consumption in the seven days prior to illness onset.</p>‡<p>Foodborne Diseases Active Surveillance Network (FoodNet) Population Survey Atlas of Exposures, 2006–2007 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055300#pone.0055300-Centers1" target="_blank">[6]</a>.</p

Epidemic curve of infections with the outbreak strain of STEC O157, by date of onset.

<p>Epidemic curve of infections with the outbreak strain of STEC O157, by date of onset.</p

Persons Infected with the Outbreak Strains of <i>Salmonella</i> Heidelberg by State, n = 634, 2013–2014.

<p>Persons Infected with the Outbreak Strains of <i>Salmonella</i> Heidelberg by State, n = 634, 2013–2014.</p

Age category-adjusted matched odds ratios of selected exposures in case patients vs. controls.

†<p>Any exposure in the seven days before illness onset.</p

Leftover Chicken Products Collected from Case-Patient Homes, Multistate Outbreak of Multidrug-Resistant <i>Salmonella</i> Heidelberg Infections Linked to a Single Poultry Company, 2013–2014.

<p>Leftover Chicken Products Collected from Case-Patient Homes, Multistate Outbreak of Multidrug-Resistant <i>Salmonella</i> Heidelberg Infections Linked to a Single Poultry Company, 2013–2014.</p

Persons Infected with the Outbreak Strains of <i>Salmonella</i> Heidelberg, by Week of Illness Onset, March 2013-July 2014.

<p>Persons Infected with the Outbreak Strains of <i>Salmonella</i> Heidelberg, by Week of Illness Onset, March 2013-July 2014.</p

Case-patient Characteristics in Multistate Outbreak of Multidrug-Resistant <i>Salmonella</i> Heidelberg Infections Linked to a Single Poultry Company, by Pulsed-Field Gel Electrophoresis Pattern, 2013–2014.

<p>Case-patient Characteristics in Multistate Outbreak of Multidrug-Resistant <i>Salmonella</i> Heidelberg Infections Linked to a Single Poultry Company, by Pulsed-Field Gel Electrophoresis Pattern, 2013–2014.</p