Strain of Multidrug-Resistant Salmonella Newport Remains Linked to Travel to Mexico and U.S. Beef Products - United States, 2021-2022.

In 2016, CDC identified a multidrug-resistant (MDR) strain of Salmonella enterica serotype Newport that is now monitored as a persisting strain (REPJJP01). Isolates have been obtained from U.S. residents in all 50 states and the District of Columbia, linked to travel to Mexico, consumption of beef products obtained in the United States, or cheese obtained in Mexico. In 2021, the number of isolates of this strain approximately doubled compared with the 2018-2020 baseline and remained high in 2022. During January 1, 2021- December 31, 2022, a total of 1,308 isolates were obtained from patients, cattle, and sheep; 86% were MDR, most with decreased susceptibility to azithromycin. Approximately one half of patients were Hispanic or Latino; nearly one half reported travel to Mexico during the month preceding illness, and one third were hospitalized. Two multistate outbreak investigations implicated beef products obtained in the United States. This highly resistant strain might spread through travelers, animals, imported foods, domestic foods, or other sources. Isolates from domestic and imported cattle slaughtered in the United States suggests a possible source of contamination. Safe food and drink consumption practices while traveling and interventions across the food production chain to ensure beef safety are necessary in preventing illness.

Human Salmonellosis Outbreak Linked to Salmonella Typhimurium Epidemic in Wild Songbirds, United States, 2020-2021.

Salmonella infection causes epidemic death in wild songbirds, with potential to spread to humans. In February 2021, public health officials in Oregon and Washington, USA, isolated a strain of Salmonella enterica serovar Typhimurium from humans and a wild songbird. Investigation by public health partners ultimately identified 30 illnesses in 12 states linked to an epidemic of Salmonella Typhimurium in songbirds. We report a multistate outbreak of human salmonellosis associated with songbirds, resulting from direct handling of sick and dead birds or indirect contact with contaminated birdfeeders. Companion animals might have contributed to the spread of Salmonella between songbirds and patients; the outbreak strain was detected in 1 ill dog, and a cat became ill after contact with a wild bird. This outbreak highlights a One Health issue where actions like regular cleaning of birdfeeders might reduce the health risk to wildlife, companion animals, and humans.

Lessons Learned from a Decade of Investigations of Shiga Toxin-Producing Escherichia coli Outbreaks Linked to Leafy Greens, United States and Canada.

Shiga toxin-producing Escherichia coli (STEC) cause substantial and costly illnesses. Leafy greens are the second most common source of foodborne STEC O157 outbreaks. We examined STEC outbreaks linked to leafy greens during 2009-2018 in the United States and Canada. We identified 40 outbreaks, 1,212 illnesses, 77 cases of hemolytic uremic syndrome, and 8 deaths. More outbreaks were linked to romaine lettuce (54%) than to any other type of leafy green. More outbreaks occurred in the fall (45%) and spring (28%) than in other seasons. Barriers in epidemiologic and traceback investigations complicated identification of the ultimate outbreak source. Research on the seasonality of leafy green outbreaks and vulnerability to STEC contamination and bacterial survival dynamics by leafy green type are warranted. Improvements in traceability of leafy greens are also needed. Federal and state health partners, researchers, the leafy green industry, and retailers can work together on interventions to reduce STEC contamination.

Shiga Toxin-Producing Escherichia coli Infections Associated With Romaine Lettuce-United States, 2018.

BACKGROUND: Produce-associated outbreaks of Shiga toxin-producing Escherichia coli (STEC) were first identified in 1991. In April 2018, New Jersey and Pennsylvania officials reported a cluster of STEC O157 infections associated with multiple locations of a restaurant chain. The Centers for Disease Control and Prevention (CDC) queried PulseNet, the national laboratory network for foodborne disease surveillance, for additional cases and began a national investigation. METHODS: A case was defined as an infection between 13 March and 22 August 2018 with 1 of the 22 identified outbreak-associated E. coli O157:H7 or E. coli O61 pulsed-field gel electrophoresis pattern combinations, or with a strain STEC O157 that was closely related to the main outbreak strain by whole-genome sequencing. We conducted epidemiologic and traceback investigations to identify illness subclusters and common sources. A US Food and Drug Administration-led environmental assessment, which tested water, soil, manure, compost, and scat samples, was conducted to evaluate potential sources of STEC contamination. RESULTS: We identified 240 case-patients from 37 states; 104 were hospitalized, 28 developed hemolytic uremic syndrome, and 5 died. Of 179 people who were interviewed, 152 (85%) reported consuming romaine lettuce in the week before illness onset. Twenty subclusters were identified. Product traceback from subcluster restaurants identified numerous romaine lettuce distributors and growers; all lettuce originated from the Yuma growing region. Water samples collected from an irrigation canal in the region yielded the outbreak strain of STEC O157. CONCLUSIONS: We report on the largest multistate leafy greens-linked STEC O157 outbreak in several decades. The investigation highlights the complexities associated with investigating outbreaks involving widespread environmental contamination.

Laboratory Investigation of Salmonella enterica serovar Poona Outbreak in California: Comparison of Pulsed-Field Gel Electrophoresis (PFGE) and Whole Genome Sequencing (WGS) Results.

INTRODUCTION: Recently, Salmonella enterica serovar Poona caused a multistate outbreak, with 245 out of 907 cases occurring in California. We report a comparison of pulsed-field gel electrophoresis (PFGE) results with whole genome sequencing (WGS) for genotyping of Salmonella Poona isolates. METHODS: CA Salmonella Poona isolates, collected from July to August 2015, were genotyped by PFGE using XbaI restriction enzyme. WGS was done using Nextera XT library kit with 2x300 bp or 2x250 bp sequencing chemistry on the Illumina MiSeq Sequencer.  Reads were mapped to the de novo assembled serovar Poona draft genome (48 contigs, N50= 223,917) from the outbreak using CLCbio GW 8.0.2. The phylogenetic tree was generated based on hqSNPs calling. Genomes were annotated with CGE and PHAST online tools. In silico MLST was performed using the CGE online tool. RESULTS: Human (14) and cucumber (2) Salmonella Poona isolates exhibited 3 possibly related PFGE patterns (JL6X01.0018 [predominant], JL6X01.0375, JL6X01.0778).  All isolates that were related by PFGE also clustered together according to the WGS. One isolate with a divergent PFGE pattern (JL6X01.0776) served as an outlier in the phylogenetic analysis and substantially differed from the outbreak clade by WGS. All outbreak isolates were assigned to MLST sequence type 447. The majority of the outbreak-related isolates possessed the same set of Salmonella Pathogenicity Islands with few variations. One outbreak isolate was sequenced and analyzed independently by CDC and CDPH laboratories; there was 0 SNP difference in results. Additional two isolates were sequenced by CDC and the raw data was processed through CDPH and CDC analysis pipelines. Both data analysis pipelines also generated concordant results.  Discussion: PFGE and WGS results for the recent CA Salmonella enterica serovar Poona outbreak provided concordant assignment of the isolates to the outbreak cluster. WGS allowed more robust determination of genetic relatedness, provided information regarding MLST-type, pathogenicity genes, and bacteriophage content. WGS data obtained independently at two laboratories showed complete agreement.

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.

Multistate Outbreak of Human Salmonella Poona Infections Associated with Pet Turtle Exposure--United States, 2014.

In May 2014, a cluster of human Salmonella Poona infections was identified through PulseNet, the national molecular subtyping network for foodborne disease surveillance. Historically, this rare serotype has been identified in multiple Salmonella outbreaks associated with pet turtle exposure and has posed a particular risk to small children. Although the sale and distribution of small turtles (those with carapace [upper shell] lengths <4 inches [<10.2 cm]) is prohibited by federal law, they are still available for legal purchase online for "bona-fide" scientific, educational, or exhibition purposes, other than use as pets. In addition, small turtles are still available for illegal purchase through transient street vendors, at flea markets, and at fairs.

Outbreak of Salmonella Wandsworth and Typhimurium infections in infants and toddlers traced to a commercial vegetable-coated snack food.

OBJECTIVE: Human outbreaks of Salmonella infection have been attributed to a variety of food vehicles. Processed snack foods are increasingly consumed by children. In May 2007, state and local health departments and the Centers for Disease Control and Prevention investigated human infections from Salmonella Wandsworth, an extremely rare serotype. MATERIALS AND METHODS: Serotyping and pulsed-field gel electrophoresis were used to identify outbreak-associated illnesses. Food history questionnaires and open-ended interviews were used to generate exposure hypotheses. A nationwide case-control study was conducted to epidemiologically implicate a source. Public health laboratories cultured implicated product from patient homes and retail stores. RESULTS: Sixty-nine patients from 23 states were identified; 93% were aged 10 months to 3 years. Eighty-one percent of child patients had bloody diarrhea; 6 were hospitalized. No deaths were reported. The case-control study strongly associated illness with a commercial puffed vegetable-coated ready-to-eat snack food (mOR = 23.3, P = 0.0001), leading to a nationwide recall. Parents of 92% of interviewed case-children reported that children consumed the food during the week before their illness began; 43% reported daily consumption. Salmonella Wandsworth, 3 additional Salmonella serotypes and Chronobacter (formerly Enterobacter) sakazaki were all cultured from this product, leading to the identification of 18 human outbreak-related Salmonella Typhimurium illnesses. CONCLUSIONS: This report documents a nationwide outbreak associated with a commercial processed ready-to-eat snack food. Cases occurred primarily in infants and toddlers, many of whom frequently consumed the food. Measures are needed to ensure that ingredients added to ready-to-eat foods after the final lethal processing step are free of pathogens.

The effectiveness of vaccine day and educational interventions on influenza vaccine coverage among health care workers at long-term care facilities.

OBJECTIVES: We examined barriers to influenza vaccination among long-term care facility (LTCF) health care workers in Southern California and developed simple, effective interventions to improve influenza vaccine coverage of these workers. METHODS: In 2002, health care workers at LTCFs were surveyed regarding their knowledge and attitudes about influenza and the influenza vaccine. Results were used to develop 2 interventions, an educational campaign and Vaccine Day (a well-publicized day for free influenza vaccination of all employees at the worksite). Seventy facilities were recruited to participate in an intervention trial and randomly assigned to 4 study groups. RESULTS: The combination of Vaccine Day and an educational campaign was most effective in increasing vaccine coverage (53% coverage; prevalence ratio [PR]=1.45; 95% confidence interval [CI]=1.24, 1.71, compared with 27% coverage in the control group). Vaccine Day alone was also effective (46% coverage; PR= 1.41; 95% CI=1.17, 1.71). The educational campaign alone was not effective in improving coverage levels (34% coverage; PR=1.18; 95% CI=0.93, 1.50). CONCLUSION: Influenza vaccine coverage of LTCF health care workers can be improved by providing free vaccinations at the worksite with a well-publicized Vaccine Day.

Outbreak of Ralstonia pickettii bacteremia in a neonatal intensive care unit.

BACKGROUND: Ralstonia pickettii is a Gram-negative bacillus commonly found in soil and moist environments; however, R. pickettii is rarely isolated from clinical specimens. In August 2001, a cluster of R. pickettii bacteremia occurred among neonatal intensive care unit (NICU) infants at a California hospital. METHODS: A case-control study was conducted to determine risk factors for infection. A case was a NICU patient with R. pickettii bacteremia. Controls were NICU infants with negative blood cultures drawn during the same time period. A detailed environmental investigation was also conducted. RESULTS: We identified 18 patients with 19 distinct episodes of R. pickettii bacteremia from July 30 through August 30, 2001. All cases had intravascular access at the time of bacteremia. Although the case-control study did not implicate any statistically significant risk factors, the most likely source of the outbreak was the heparin flush prepared in the hospital pharmacy. This is supported by the following: (1) the heparin flush was the only substance introduced directly into the bloodstream of all case infants; (2) the heparin flush was used exclusively by the NICU; and (3) no further cases were identified after the heparin flush was discontinued. Cultures of remaining heparin flush and environmental cultures from the NICU were negative for R. pickettii. CONCLUSIONS: This unusual outbreak of R. pickettii bacteremia was most likely caused by contaminated heparin flush and ended after the heparin flush was discontinued.

Outbreak of necrotizing fasciitis due to Clostridium sordellii among black-tar heroin users.

In California, black tar heroin (BTH) use among injection drug users (IDUs) has resulted in an increased number of cases of wound botulism due to Clostridium botulinum, tetanus due to Clostridium tetani, and necrotizing soft-tissue infections due to a variety of clostridia. From December 1999 to April 2000, nine IDUs in Ventura County, California, developed necrotizing fasciitis; 4 died. Cultures of wound specimens from 6 case patients yielded Clostridium sordellii. Some of the patients appeared to have the toxic shock syndrome previously reported to be characteristic of toxin-mediated C. sordellii infection, which is characterized by hypotension, marked leukocytosis, and hemoconcentration. The suspected source of this outbreak was contaminated BTH that was injected subcutaneously or intramuscularly ("skin popped"). This outbreak of C. sordellii infection serves as another example of how BTH can potentially serve as a vehicle for transmitting severe and often deadly clostridial infections, and reinforces the need to educate IDUs and clinicians about the risks associated with skin popping of BTH.

The effectiveness of assessment and referral on immunization coverage in the special supplemental nutrition program for women, infants, and children.

BACKGROUND: The use of immunization assessment and referral (A/R) in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) has been shown to produce dramatic improvements in vaccination coverage when coupled with parental incentive; however, data are lacking to support the use of A/R alone. OBJECTIVE: To determine the effectiveness of A/R in increasing immunization coverage among WIC participants. DESIGN: Participating WIC centers were assigned to1 of 3 interventions that delivered A/R of varying frequency or a control group. SETTING: Twenty of the largest Public Health Foundation Enterprises-WIC centers in Los Angeles County. PARTICIPANTS: Children continuously enrolled in participating WIC centers from 6 to 24 months of age. INTERVENTION: Assessment of child's vaccination status followed by referral to a health care provider for those lacking indicated vaccinations. MAIN OUTCOME MEASURE: Up-to-date (UTD) status at 24 months of age for all recommended vaccines. RESULTS: Baseline coverage rates were similar among all study sites (overall, 77% UTD). After the study period, compared with the controls (88% UTD), we found no differences in immunization coverage among WIC centers that administered A/R at every visit (every 2 months) to all children (90% UTD; adjusted odds ratio [OR], 1.02; 95% confidence interval [CI], 0.54-1.94), every 6 months to all children (89% UTD; OR, 0.98; 95% CI, 0.62-1.56), or every visit to children found to be behind at 8 months of age (89% UTD; OR, 0.89; 95% CI, 0.48-1.68). CONCLUSION: In this urban population of WIC children with high baseline immunization coverage, A/R was not effective in increasing immunization coverage.