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.

Salmonella Vitkin Outbreak Associated with Bearded Dragons, Canada and United States, 2020-2022

We identified 2 cases of Salmonella enterica serovar Vitkin infection linked by whole-genome sequencing in infants in Ontario, Canada, during 2022. Both households of the infants reported having bearded dragons as pets. The outbreak strain was also isolated from an environmental sample collected from a patient's bearded dragon enclosure. Twelve cases were detected in the United States, and onset dates occurred during March 2021-September 2022 (isolates related to isolates from Canada within 0-9 allele differences by core-genome multilocus sequence typing). Most US patients (66.7%) were <1 year of age, and most (72.7%) had reported bearded dragon exposure. Hospitalization was reported for 5 (38.5%) of 13 patients. Traceback of bearded dragons identified at least 1 potential common supplier in Southeast Asia. Sharing rare serovar information and whole-genome sequencing data between Canada and the United States can assist in timely identification of outbreaks, including those that might not be detected through routine surveillance.

Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018

Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates.

Multistate nontyphoidal Salmonella and Shiga toxin-producing Escherichia coli outbreaks linked to international travel-United States, 2017-2020

Enteric bacterial infections are common among people who travel internationally. During 2017-2020, the Centers for Disease Control and Prevention investigated 41 multistate outbreaks of nontyphoidal Salmonella and Shiga toxin-producing Escherichia coli linked to international travel. Resistance to one or more antimicrobial agents was detected in at least 10% of isolates in 16 of 30 (53%) nontyphoidal Salmonella outbreaks and 8 of 11 (73%) Shiga toxin-producing E. coli outbreaks evaluated by the National Antimicrobial Resistance Monitoring System. At least 10% of the isolates in 14 nontyphoidal Salmonella outbreaks conferred resistance to one or more of the clinically significant antimicrobials used in human medicine. This report describes the epidemiology and antimicrobial resistance patterns of these travel-associated multistate outbreaks. Investigating illnesses among returned travellers and collaboration with international partners could result in the implementation of public health interventions to improve hygiene practices and food safety standards and to prevent illness and spread of multidrug-resistant organisms domestically and internationally.

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.

Increased Multidrug-Resistant Salmonella enterica I Serotype 4,[5],12:i:- Infections Associated with Pork, United States, 2009-2018

Reports of Salmonella enterica I serotype 4,[5],12:i:- infections resistant to ampicillin, streptomycin, sulphamethoxazole, and tetracycline (ASSuT) have been increasing. We analyzed data from 5 national surveillance systems to describe the epidemiology, resistance traits, and genetics of infections with this Salmonella strain in the United States. We found ASSuT-resistant Salmonella 4,[5],12:i:- increased from 1.1% of Salmonella infections during 2009-2013 to 2.6% during 2014-2018; the proportion of Salmonella 4,[5],12:i:- isolates without this resistance pattern declined from 3.1% to 2.4% during the same timeframe. Among isolates sequenced during 2015-2018, a total of 69% were in the same phylogenetic clade. Within that clade, 77% of isolates had genetic determinants of ASSuT resistance, and 16% had genetic determinants of decreased susceptibility to ciprofloxacin, ceftriaxone, or azithromycin. Among outbreaks related to the multidrug-resistant clade, 63% were associated with pork consumption or contact with swine. Preventing Salmonella 4,[5],12:i:- carriage in swine would likely avert human infections with this strain.

Multistate reptile- and amphibian-associated salmonellosis outbreaks in humans, United States, 2009-2018

Non-typhoidal Salmonella cause an estimated 1.4 million human illnesses, 26,000 hospitalizations and 400 deaths annually in the United States. Approximately 11% of these infections are attributed to animal contact. Reptiles and amphibians are known sources of salmonellosis; young children (aged <5 years) are disproportionately affected by reptile- and amphibian-associated salmonellosis (RAAS) outbreaks. We describe multistate RAAS outbreaks to characterize illnesses and inform prevention efforts. RAAS outbreaks were defined as ≥2 culture-confirmed human Salmonella infections with similar pulsed-field gel electrophoresis patterns and epidemiologic, laboratory or traceback evidence linking them to a common reptile/amphibian exposure. Data sources included the Animal Contact Outbreak Surveillance System; CDC Outbreak Response and Prevention Branch's outbreak management database; PulseNet, the national molecular subtyping network for foodborne disease surveillance in the United States; and the National Antimicrobial Resistance Monitoring System. Twenty-six RAAS outbreaks were reported during 2009-2018, resulting in 1465 illnesses and 306 hospitalizations. The outbreaks were associated with turtles (19), lizards (5), snakes (1) and frogs (1). Sixteen (61.5%) outbreaks were linked to small turtles (<4 inches), resulting in 914 illnesses. Forty-nine percent of outbreak-associated patients were aged <5 years. Of 362 patients/caregivers interviewed, 111 (30.7%) were aware that reptiles/amphibians can carry Salmonella. Among 267 patient isolates with antimicrobial susceptibility information, 20 (7.5%) were non-susceptible to ≥1 antibiotic used to treat human salmonellosis. RAAS outbreaks result in considerable morbidity, particularly among young children. Illnesses linked to small turtles are preventable through education, targeted outreach to caregivers and paediatricians, and when appropriate, enforcement. Historically, individual states and jurisdictions have enforced existing or promulgated new authorities to address outbreaks. Preventing future RAAS outbreaks requires addressing challenges related to the illegal sale/distribution of small turtles; and for legal reptile sales, providing information on RAAS risk to consumers at point of sale to support informed pet ownership decisions.

714. Increase in Multidrug-resistant Salmonella Serotype I 4,[5],12:i:- Infections Linked to Pork—United States, 2009–2018

Background

Salmonella enterica I 4,[5],12:i:- is the 5^th most common serotype causing clinical Salmonella infections in the United States. A strain with resistance to ampicillin, streptomycin, sulfamethoxazole, and tetracycline (ASSuT) has been linked to swine production in Europe and the United States. We reviewed U.S. surveillance data to describe clinical infections with antibiotic-resistant I 4,[5],12:i:-.

Methods

We reviewed data from CDC’s National Antimicrobial Resistance Monitoring System (NARMS) from 2009–2018 to describe trends. We analyzed whole-genome sequence data in PulseNet, the molecular surveillance network for foodborne illness in the United States, from 2015–2018 to distinguish between strains of I 4,[5],12:i:- using core-genome multilocus sequence typing, and identified antibiotic resistance determinants (ARDs). We reviewed data from the Foodborne Disease Outbreak Surveillance System to identify foods associated with outbreaks during 2009–2018.

Results

From 2009–2013 to 2014–2018, I 4,[5],12:i:- increased as a proportion of nontyphoidal Salmonella isolates in NARMS from 4.3% to 5.0% (P=0.006), while I 4,[5],12:i:- resistant to ASSuT increased from 1.1% to 2.6% (P< 0.001). Of the 3,056 sequenced I 4,[5],12:i:- isolates in PulseNet, 2,105 (69%) were in a clade within 0–108 alleles of each other (ASSuT clade). Within this clade, 77% of isolates had ARDs conferring resistance to ASSuT, compared with 3% outside the clade. Isolates in the clade were also more likely than those outside the clade to have ARDs conferring decreased susceptibility to ciprofloxacin (13.1% vs. 5.2%, P< 0.001) and resistance to ceftriaxone (5.4% vs. 2.3%, P< 0.001). Among I 4,[5],12:i:- outbreaks with a single food source, those related to the ASSuT clade were more often linked to pork (10/15 [67%] vs. 1/5 [20%], P=0.07).

Conclusion

The increase in I 4,[5],12:i:- infections during 2009–2018 was likely driven by a clade of which most members had resistance to ASSuT, and many had decreased susceptibility to antibiotics used for empiric treatment. The association of this strain with outbreaks linked to pork suggests that measures to decrease carriage of Salmonella and selection for this strain in swine could prevent clinical infections with multidrug resistant Salmonella I 4,[5],12:i-.

Disclosures

All Authors: No reported disclosures

Detecting national human enteric disease outbreaks linked to animal contact in the United States of America

Enteric pathogens, such as non-typhoidal Salmonella, Campylobacter and Escherichia coli, can reside in the intestinal tract of many animals, including livestock, companion animals, small mammals and reptiles. Often, these animals can appear healthy; nonetheless, humans can become infected after direct or indirect contact, resulting in a substantial illness burden. An estimated 14% of the 3.2 million illnesses that occur in the United States of America (USA) each year from such enteric pathogens are attributable to animal contact. Surveillance for enteric pathogens in the USA includes the compilation and interpretation of both laboratory and epidemiologic data. However, the authors feel that a collaborative, multisectoral and transdisciplinary - or One Health - approach is needed for data collection and analysis, at every level. In addition, they suggest that the future of enteric illness surveillance lies in the development of improved technologies for pathogen detection and characterisation, such as genomic sequencing and metagenomics. In particular, using whole-genome sequencing to compare genetic sequences of enteric pathogens from humans, food, animals and the environment, can help to predict antimicrobial resistance among these pathogens, determine their genetic relatedness and identify outbreaks linked to a common source. In this paper, the authors describe three recent, multi-state human enteric illness outbreaks linked to animal contact in the USA and discuss how integrated disease surveillance was essential to outbreak detection and response. Additional datasharing between public health and animal health laboratories and epidemiologists at the local, national, regional and international level may help to improve surveillance for emerging animal and human health threats and lead to new opportunities for prevention.

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.

Multistate Outbreak of Salmonella Virchow Infections Linked to a Powdered Meal Replacement Product-United States, 2015-2016

Background

Nontyphoidal Salmonella is the leading cause of bacterial gastroenteritis in the United States. Meal replacement products containing raw and "superfood" ingredients have gained increasing popularity among consumers in recent years. In January 2016, we investigated a multistate outbreak of infections with a novel strain of Salmonella Virchow.

Methods

Cases were defined using molecular subtyping procedures. Commonly reported exposures were compared with responses from healthy people interviewed in the 2006-2007 FoodNet Population Survey. Firm inspections and product traceback and testing were performed.

Results

Thirty-five cases from 24 states were identified; 6 hospitalizations and no deaths were reported. Thirty-one of 33 (94%) ill people interviewed reported consuming a powdered supplement in the week before illness; of these, 30 (97%) reported consuming product A, a raw organic powdered shake product consumed as a meal replacement. Laboratory testing isolated the outbreak strain of Salmonella Virchow from leftover product A collected from ill people's homes, organic moringa leaf powder (an ingredient in product A), and finished product retained by the firm. Firm inspections at 3 facilities linked to product A production did not reveal contamination at the facilities. Traceback investigation identified that the contaminated moringa leaf powder was imported from South Africa.

Conclusions

This investigation identified a novel outbreak vehicle and highlighted the potential risk with similar products not intended to be cooked by consumers before consuming. The company issued a voluntary recall of all implicated products. As this product has a long shelf life, the recall likely prevented additional illnesses.

Whole Genome Sequencing: Bridging One-Health Surveillance of Foodborne Diseases

Infections caused by pathogens commonly acquired from consumption of food are not always transmitted by that route. They may also be transmitted through contact to animals, other humans or the environment. Additionally, many outbreaks are associated with food contaminated from these non-food sources. For this reason, such presumed foodborne outbreaks are best investigated through a One Health approach working across human, animal and environmental sectors and disciplines. Outbreak strains or clones that have propagated and continue to evolve in non-human sources and environments often show more sequence variation than observed in typical monoclonal point-source outbreaks. This represents a challenge when using whole genome sequencing (WGS), the new gold standard for molecular surveillance of foodborne pathogens, for outbreak detection and investigation. In this review, using recent examples from outbreaks investigated in the United States (US) some aspects of One Health approaches that have been used successfully to solve such outbreaks are presented. These include using different combinations of flexible WGS based case definition, efficient epidemiological follow-up, traceback, surveillance, and testing of potential food and environmental sources and animal hosts.

An Overview of PulseNet USA Databases

PulseNet USA is the molecular surveillance network for foodborne disease in the United States. The network consists of state and local public health laboratories, as well as food regulatory agencies, that follow PulseNet's standardized protocols to perform pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) and analyze the results using standardized software. The raw sequences are uploaded to the GenomeTrakr or PulseNet bioprojects at the National Center for Biotechnology Information. The PFGE patterns and analyzed sequence data are uploaded in real time with associated demographic data to the PulseNet national databases managed at the Centers for Disease Control and Prevention. The PulseNet databases are organism specific and provide a central storage location for molecular and demographic data related to an isolate. Sequences are compared in the databases, thereby facilitating the rapid detection of clusters of foodborne diseases that may represent widespread outbreaks. WGS genotyping data, for example, antibiotic resistance and virulence profiles, are also uploaded in real time to the PulseNet databases to improve food safety surveillance activities.

Epidemiology of Salmonella enterica Serotype Dublin Infections among Humans, United States, 1968-2013

Infection incidence and antimicrobial drug resistance are increasing.

Salmonella enterica serotype Dublin is a cattle-adapted bacterium that typically causes bloodstream infections in humans. To summarize demographic, clinical, and antimicrobial drug resistance characteristics of human infections with this organism in the United States, we analyzed data for 1968–2013 from 5 US surveillance systems. During this period, the incidence rate for infection with Salmonella Dublin increased more than that for infection with other Salmonella. Data from 1 system (FoodNet) showed that a higher percentage of persons with Salmonella Dublin infection were hospitalized and died during 2005−2013 (78% hospitalized, 4.2% died) than during 1996–2004 (68% hospitalized, 2.7% died). Susceptibility data showed that a higher percentage of isolates were resistant to >7 classes of antimicrobial drugs during 2005–2013 (50.8%) than during 1996–2004 (2.4%).

Utility of Combining Whole Genome Sequencing with Traditional Investigational Methods To Solve Foodborne Outbreaks of Salmonella Infections Associated with Chicken: A New Tool for Tackling This Challenging Food Vehicle

High consumption rates and a multitude of brands make multistate foodborne outbreaks of Salmonella infections associated with chicken challenging to investigate, but whole genome sequencing is a powerful tool that can be used to assist investigators. Whole genome sequencing of pathogens isolated from clinical, environmental, and food samples is increasingly being used in multistate foodborne outbreak investigations to determine with unprecedented resolution how closely related these isolates are to one another genetically. In 2014, federal and state health officials investigated an outbreak of 146 Salmonella Heidelberg infections in 24 states. A follow-up analysis was conducted after the conclusion of the investigation in which 27 clinical and 24 food isolates from the outbreak underwent whole genome sequencing. These isolates formed seven clades, the largest of which contained clinical isolates from a subcluster of case patients who attended a catered party. One isolate from a chicken processed by a large producer was closely related genetically (zero to three single-nucleotide polymorphism differences) to the clinical isolates from these subcluster case patients. Chicken from this large producer was also present in the kitchen of the caterer on the day before the event, thus providing additional evidence that the chicken from this producer was the outbreak source. This investigation highlights how whole genome sequencing can be used with epidemiologic and traceback evidence to identify chicken sources of foodborne outbreaks.

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.

Outbreaks of Salmonellosis From Small Turtles

OBJECTIVE

Turtle-associated salmonellosis (TAS), especially in children, is a reemerging public health issue. In 1975, small pet turtles (shell length <4 inches) sales were banned by federal law; reductions in pediatric TAS followed. Since 2006, the number of multistate TAS outbreaks has increased. We describe 8 multistate outbreaks with illness-onset dates occurring in 2011-2013.

METHODS

We conducted epidemiologic, environmental, and traceback investigations. Cases were defined as infection with ≥ 1 of 10 molecular subtypes of Salmonella Sandiego, Pomona, Poona, Typhimurium, and I 4,[5],12:i:-. Water samples from turtle habitats linked to human illnesses were cultured for Salmonella.

RESULTS

We identified 8 outbreaks totaling 473 cases from 41 states, Washington DC, and Puerto Rico with illness onsets during May 2011-September 2013. The median patient age was 4 years (range: 1 month-94 years); 45% percent were Hispanic; and 28% were hospitalized. In the week preceding illness, 68% (187 of 273) of case-patients reported turtle exposure; among these, 88% (124 of 141) described small turtles. Outbreak strains were isolated from turtle habitats linked to human illnesses in seven outbreaks. Traceback investigations identified 2 Louisiana turtle farms as the source of small turtles linked to 1 outbreak; 1 outbreak strain was isolated from turtle pond water from 1 turtle farm.

CONCLUSIONS

Eight multistate outbreaks associated with small turtles were investigated during 2011-2013. Children <5 years and Hispanics were disproportionately affected. Prevention efforts should focus on patient education targeting families with young children and Hispanics and enactment of state and local regulations to complement federal sales restrictions.

Genomic epidemiology of Salmonella enterica serotype Enteritidis based on population structure of prevalent lineages

Major lineages emerged during the 17th–18th centuries and diversified during the 1920s and 1950s.

Salmonella enterica serotype Enteritidis is one of the most commonly reported causes of human salmonellosis. Its low genetic diversity, measured by fingerprinting methods, has made subtyping a challenge. We used whole-genome sequencing to characterize 125 S. enterica Enteritidis and 3 S. enterica serotype Nitra strains. Single-nucleotide polymorphisms were filtered to identify 4,887 reliable loci that distinguished all isolates from each other. Our whole-genome single-nucleotide polymorphism typing approach was robust for S. enterica Enteritidis subtyping with combined data for different strains from 2 different sequencing platforms. Five major genetic lineages were recognized, which revealed possible patterns of geographic and epidemiologic distribution. Analyses on the population dynamics and evolutionary history estimated that major lineages emerged during the 17th–18th centuries and diversified during the 1920s and 1950s.

Characterization of blaCMY plasmids and their possible role in source attribution of Salmonella enterica serotype Typhimurium infections

Salmonella is an important cause of foodborne illness; however, identifying the source of these infections can be difficult. This is especially true for Salmonella serotype Typhimurium, which is found in diverse agricultural niches. Extended-spectrum cephalosporins (ESC) are one of the primary treatment choices for complicated Salmonella infections. In Salmonella, ESC resistance in the United States is mainly mediated by blaCMY genes carried on various plasmids. In this study, we examined whether the characterization of blaCMY plasmids, along with additional information, can help us identify potential sources of infection by Salmonella, and used serotype Typhimurium as a model. In the United States, monitoring of retail meat, food animals, and ill persons for antimicrobial-resistant Salmonella is conducted by the National Antimicrobial Resistance Monitoring System. In 2008, 70 isolates (70/581; 12.0%) (34 isolates from retail meat, 23 food animal, and 13 human) were resistant to ceftriaxone and amoxicillin/clavulanic acid. All were polymerase chain reaction (PCR)-positive for blaCMY and 59/70 (84.3%) of these genes were plasmid encoded. PCR-based replicon typing identified 42/59 (71.2%) IncI1-blaCMY plasmids and 17/59 (28.8%) IncA/C-blaCMY plasmids. Isolates from chickens or chicken products with blaCMY plasmids primarily had IncI1-blaCMY plasmids (37/40; 92.5%), while all isolates from cattle had IncA/C-blaCMY plasmids. Isolates from humans had either IncA/C- blaCMY (n=8/12; [66.7%]) or IncI1- blaCMY (n=4/12 [33.3%]) plasmids. All of the IncI1-blaCMY plasmids were ST12 or were closely related to ST12. Antimicrobial susceptibility patterns (AST) and pulsed-field gel electrophoresis (PFGE) patterns of the isolates were also compared and differences were identified between isolate sources. When the source of a Typhimurium outbreak or sporadic illness is unknown, characterizing the outbreak isolate's blaCMY plasmids, AST, and PFGE patterns may help identify it.

The timing and sequence of multiple device-related complications in patients with long-term indwelling Groshong catheters

BACKGROUND

The function of long term indwelling venous access devices is commonly perturbed by postinsertion catheter-related complications (CRC). In an effort to assess the patterns of CRC in our community accurately, a prospective analysis of Groshong catheters in adult cancer patients was undertaken.

METHODS

Three hundred and twenty-four consecutive adult oncology patients in whom a Groshong catheter was utilized for long-term central venous access were observed for the development of a CRC. A subset analysis was undertaken of those catheters that developed one or more complications.

RESULTS

Among the 221 catheters with a primary complication, 176 additional complications were subsequently identified (109 2nd, 50 3rd, and 17 4th complicating events). Ball-valve effect (BVE), the most frequent complication, was found to occur disproportionately as a primary event (85 of 119 catheters, P < 0.01), whereas catheter-related venous thrombosis (CR-VT) was more likely to occur as a later, subsequent complication (46 of 66 catheters, P < 0.01). Although risk analysis affirmed a paucity of clinical predictors for developing a primary complication, patients with BVE as a first complication were at increased risk for developing a later episode of CR-VT.

CONCLUSIONS

Multiple sequential complications are common in patients with Groshong catheters, occurring in a rather predictable sequence. The increased risk of CR-VT in patients with catheters with an early complication suggests a cause-effect relationship. An awareness of this sequencing may lead to improved strategies for the prevention of primary and subsequent complications.

The prognostic significance of the ball-valve effect in Groshong catheters

The aim of the work was to determine the prognostic significance of the ball-valve effect (BVE) in a population of adult cancer patients with long-term indwelling Groshong catheters. A prospective longitudinal study of 356 Groshong catheters utilized for long-term central venous access was carried out in adult oncology patients. A subset analysis was undertaken of those catheters that developed BVE. BVE was the most commonly identified impediment to normal catheter function, comprising 30% of all identified complications (119/397). BVE was also the most frequent de, novo (primary) complication (85 of 221, 38.5%), as well as the complication that occurred soonest in the life of the catheter (average = 61.2 days after insertion). Patients with BVE were likely to develop subsequent catheter-related venous thrombosis (20 of 30 compared to 65 of 191, P 0.01), but no other significant catheter-related complication. Patients more than 65 years old had an increased incidence of BVE as the primary complication (46 of 85 compared to 49 of 136, P = 0.01). while patients with breast cancer had a lower incidence (12 of 85 compared to 36 of 136, P = 0.04). No catheter was removed as a result of the development of BVE. The onset of BVE represents an elemental perturbation of catheter function which portends the development of other, more significant vascular occlusive complications. Phenomenologically, BVE has been overshadowed in significance by the clinically more dramatic venous thrombosis and catheter-related infections. The true significance of BVE can not be determined until the impact of preventing this early complication on the incidence of secondary complications is analyzed prospectively.