Changes in the prevalence, genotypes and antimicrobial resistance phenotypes of non-typhoidal Salmonella recovered from mail-order hatchling poultry sold at US feed stores, 2013-2015.

Every year, multiple outbreaks of salmonellosis in humans are linked to contact with mail-order chicks and ducks. The objective of this study was to describe the temporal changes in the prevalence of serovars, genotypes and antimicrobial resistance (AMR) phenotypes of non-typhoidal Salmonella (NTS) recovered from shipped boxes of mail-order hatchling poultry in the United States during 2013 to 2015. In each year, a sample of feed stores belonging to a single national chain participated in the study. The store employees submitted swabs or hatchling pads from hatchling boxes and shipment tracking information of the arriving boxes to the investigators. NTS was cultured from the samples and isolates were sent to the National Veterinary Services Laboratories (Ames, IA) for serotyping, pulsed-field gel electrophoresis (PFGE) and AMR phenotyping. The PFGE patterns of Salmonella serovars isolated from hatchling boxes were compared with those from human outbreaks of salmonellosis linked to live poultry contact. The box-level prevalence of NTS was significantly higher in 2015 compared to 2014. Also, the population of Salmonella serovars recovered in 2015 was more diverse and substantially different from those recovered in the previous two years. Of PFGE patterns recovered from hatchling boxes, seven distinct patterns in 2015, three in 2014 and four in 2013 were indistinguishable from the PFGE patterns of human outbreaks-associated strains in the respective years. Importantly, a significant positive correlation was found between the box-level prevalence of PFGE patterns and the number of human illnesses associated with the same patterns. Also, the proportion of multidrug-resistant isolates was higher in 2014 and 2015 compared to that in 2013. The results demonstrate that shipments of mail-order hatchling poultry are frequently contaminated with Salmonella genotypes indistinguishable from human outbreaks-associated strains each year, and control efforts at hatchery level are likely to have an important public health impact.

Genotypic and epidemiologic characterization of extended-spectrum cephalosporin resistant Salmonella enterica from US beef feedlots.

In the US, nontyphoidal Salmonellae are a common foodborne zoonotic pathogen causing gastroenteritis. Invasive Salmonella infections caused by extended-spectrum cephalosporin resistant (ESCR) phenotypes are more likely to result in treatment failure and adverse health outcomes, especially in severe pediatric Salmonella infections where the extended-spectrum ß-lactams are the therapy of choice. To examine the genetic and epidemiologic characteristics of ESCR Salmonellae which may enter the food chain, we characterized 44 ceftiofur-resistant Salmonella isolates from the National Animal Health Monitoring System (NAHMS) 2011 beef cattle feedlot health and management study. As part of the NAHMS Feedlot 2011 study, 5050 individual fecal samples from 68 large (1000+ head capacity) feedlots were cultured for Salmonella spp. The resulting 460 positive samples yielded 571 Salmonella isolates with 44 (8%) expressing an AmpC ß-lactamase phenotype. These phenotypic blaCMY-2Salmonella isolates represented 8 serotypes, most commonly S. Newport (n=14, 32%), S. Typhimurium (n=13, 30%), and S. Reading (n=5, 11%), followed by S. Dublin, S. Infantis, S. Montevideo, S. Rough O:i;v:1;7, and S. Uganda. Carriage of the blaCMY-2 gene was confirmed for all isolates expressing an AmpC ß-lactamase phenotype by PCR. Additionally, all 44 isolates were shown to carry the blaCMY-2 gene on a large IncA/C plasmid, a gene/plasmid combination which has been previously reported in multiple species. Other plasmids, including IncN, FIC, and FIIA, were also detected in some isolates. Cattle fed chlortetracycline were less likely to be positive for a blaCMY-2Salmonella isolate in their enteric flora compared to those not receiving chlortetracycline during the feeding period. Carriage of blaCMY-2 was more prevalent in Salmonella isolates originating from lighter weight cattle, cattle fed tylosin and dairy breeds. Our characterization of the NAHMS Feedlot 2011 study Salmonella isolates with ESCR phenotype shows that while other cephalosporin resistance mechanisms have been reported in US cattle, specific serotypes harboring blaCMY-2 on IncA/C plasmids may be the dominant resistance genotype.

Multistate Outbreak of Human Salmonella Typhimurium Infections Linked to Pet Hedgehogs - United States, 2011-2013.

Zoonotic Salmonella infections cause approximately 130 000 illnesses annually in the United States. Of 72.9 million US households owning at least one pet, five million own small mammals; 3000 hedgehogs were documented by USDA in USDA-licensed breeding facilities and pet stores in 2012. State health department collaborators and PulseNet, the national bacterial subtyping network, identified human infections of a Salmonella Typhimurium outbreak strain, which were investigated by CDC, USDA-APHIS and state public and animal health officials. A case was defined as an illness in a person infected with the outbreak strain identified between 1 December 2011 and 3 June 2013. Investigators collected information on patient exposures, cultured animal and environmental specimens for Salmonella, and conducted traceback investigations of USDA-licensed hedgehog facilities. There were 26 cases in 12 states. Illness onset dates ranged from 26 December 2011 to 8 April 2013. The median patient age was 15 years (range = <1-91 years); 58% were female. Among 23 persons with available information, 8 (35%) were hospitalized and one outbreak strain-associated death was reported. Of 25 patients with available information, 20 (80%) reported pet hedgehog contact in the week before illness onset. The outbreak strain was isolated from animal and environmental samples collected from three ill persons' homes in three states. Hedgehogs were purchased in geographically distant states from USDA-licensed breeders (10/17, 59%); a USDA-licensed pet store (1/17, 6%); unlicensed or unknown status breeders (3/17, 18%); and private individuals (3/17, 18%). Traceback investigations of USDA-licensed facilities did not reveal a single source of infection. Public and animal health collaboration linked pet hedgehog contact to human infections of Salmonella Typhimurium, highlighting the importance of a One Health investigative approach to zoonotic salmonellosis outbreaks. More efforts are needed to increase awareness among multiple stakeholders on the risk of illness associated with pet hedgehogs.

Distribution and Diversity of Salmonella Strains in Shipments of Hatchling Poultry, United States, 2013.

Multistate outbreaks of salmonellosis associated with live poultry contact have been occurring with increasing frequency. In 2013, multistate outbreaks of salmonellosis were traced back to exposure to live poultry, some of which were purchased at a national chain of farm stores (Farm store chain Y). This study was conducted at 36 stores of Farm store chain Y and was concurrent with the timing of exposure for the human outbreaks of salmonellosis in 2013. We used environmental swabs of arriving shipment boxes of hatchling poultry and shipment tracking information to examine the distribution, diversity and anti-microbial resistance of non-typhoidal Salmonella (NTS) across farm stores and hatcheries. Isolates recovered from shipment boxes underwent serotyping, anti-microbial resistance (AMR) testing and pulsed-field gel electrophoresis (PFGE). Postal service tracking codes from the shipment boxes were used to determine the hatchery of origin. The PFGE patterns were compared with the PFGE patterns of NTS causing outbreaks of salmonellosis in 2013. A total of 219 hatchling boxes from 36 stores in 13 states were swabbed between 15 March 2013 and 18 April 2013. NTS were recovered from 59 (27%) of 219 hatchling boxes. Recovery was not significantly associated with species of hatchlings, number of birds in the shipment box, or the presence of dead, injured or sick birds. Four of the 23 PFGE patterns and 23 of 50 isolates were indistinguishable from strains causing human outbreaks in 2013. For serotypes associated with human illnesses, PFGE patterns most frequently recovered from shipment boxes were also more frequent causes of human illness. Boxes positive for the same PFGE pattern most frequently originated from the same mail-order hatchery. Only one of 59 isolates was resistant to anti-microbials used to treat Salmonella infections in people. This study provides critical information to address recurrent human outbreaks of salmonellosis associated with mail-order hatchling poultry.

Environmental Salmonella in agricultural fair poultry exhibits in Colorado.

Salmonella enterica is a common zoonotic pathogen in humans. Transmission typically occurs through consumption of contaminated food products or contact with infected animals, including poultry or their environment. The objective of this study was to estimate the frequency of Salmonella contamination in the environment in poultry exhibits at agricultural fairs. Samples were collected from cages, feed, floors and tables in the exhibit and cultured for Salmonella. At least one environmental sample was positive for Salmonella in 10 of 11 fairs (91%), and Salmonella was isolated from 28 of 55 environmental samples (50.9%). Eleven different serotypes were detected. Results of this study demonstrate that environmental surfaces at agricultural fairs can be contaminated with Salmonella and could potentially serve as a route of transmission to bird owners and the general public. Poultry owners and the general public should be educated about the risks of Salmonella infection from the poultry exhibit environment. Agricultural fairs should consider instituting policies and practices to improve hygiene and mitigate the risk of zoonotic salmonellosis.

Comparison of individual, pooled, and composite fecal sampling methods for detection of Salmonella on U.S. dairy operations.

The objectives of this study were to estimate the prevalence of Salmonella for individual, pooled, and composite fecal samples and to compare culture results from each sample type for determining herd Salmonella infection status and identifying Salmonella serovar(s). During the U.S. Department of Agriculture National Animal Health Monitoring System Dairy 2007 study, data and samples were collected from dairy operations in 17 major dairy states. As part of the study, composite fecal samples (six per operation) were collected from cow areas, such as holding pens, alleyways, and lagoons, where manure accumulates. Fecal samples also were collected from individual cows (35 per operation), and fecal sample pools were created by combining samples from 5 cows (7 per operation). A total of 1,541 composite fecal samples were collected from 260 operations in 17 states, and 406 (26.3%) of these samples were culture positive for Salmonella. Among the 116 operations for which all three sample types were obtained, 41.4% (48 operations) were Salmonella culture positive based on individual samples, 39.7% (46 operations) were positive based on pooled samples, and 49.1% (57 operations) were positive based on composite fecal samples. Relative to individual samples, the sensitivity of composite fecal samples for determining herd infection status was 85.4% and the sensitivity of pooled fecal samples was 91.7%. On 33.6% of operations (39 of 116), Salmonella was cultured from all three fecal sample types (individual, pooled, and composite), and 20 (51.3%) of these operations had exactly the same serovar in all three sample types. Use of composite fecal samples is less costly and time-consuming than use of individual or pooled samples and provides similar results for detecting the presence and identifying serovars of Salmonella in dairy herds. Therefore, composite sampling may be an appropriate alternative to culture of individual samples when assessing Salmonella status in dairy herds.

Salmonella prevalence and antimicrobial susceptibility from the National Animal Health Monitoring System Swine 2000 and 2006 studies.

Concern about Salmonella contamination of food is compounded by fear that antimicrobials traditionally used to combat the infection will become useless due to rising antibiotic resistance. Livestock, in particular swine, often are blamed for illnesses caused by Salmonella and for increasing antibiotic resistance due to use of antibiotics in pigs. As part of the National Animal Health Monitoring System Swine 2000 and 2006 studies, swine fecal samples were cultured for Salmonella. These samples were collected from 123 operations in 17 states in 2000 and from 135 operations in 17 states in 2006. At each operation, 50 and 60 fecal samples were collected from late finisher pig pens in 2000 and 2006, respectively. Salmonella isolates were characterized to determine serogroup and serotype and were tested for susceptibility to a panel of 17 and 15 antimicrobial drugs in 2000 and 2006, respectively. A total of 5,470 and 7,788 samples were cultured for Salmonella in 2000 and 2006, respectively. Overall, 6.2% of the samples and 34.2% of the farms were positive for Salmonella in 2000. In 2006, 7.2% of the samples and 52.6% of the farms were positive. Salmonella Derby, Salmonella Typhimurium var. 5- (formerly Salmonella Typhimurium var. Copenhagen), and Salmonella Agona were the three serotypes most often recovered in both study years. The most common antimicrobial resistance pattern for Salmonella Derby in the two study years was resistance to streptomycin, sulfisoxazole, and tetracycline. Most isolates were resistant to tetracycline, sulfisoxazole, and streptomycin in both study years. The proportion of Salmonella isolates that were susceptible to all antimicrobials (pansusceptible) was 38.1% in 2000 and 20.4% in 2006. The proportion of Salmonella isolates that were resistant to three or more antimicrobials (multidrug resistant) was similar in 2000 and in 2006 (52.8 and 57.7%, respectively).

Four multistate outbreaks of human Salmonella infections associated with live poultry contact, United States, 2009.

Outbreaks of human salmonellosis associated with live poultry contact have been reported since 1955. Multiple Salmonella serotypes have been associated with these outbreaks, and specific outbreak strains have been repeatedly linked to single hatcheries over multiple years. During 2009, four multistate outbreaks of human Salmonella infections associated with direct and indirect exposure to live poultry purchased from mail-order hatcheries and agricultural feed stores were identified, resulting in 165 culture-confirmed cases in 30 states. This report describes the epidemiologic, environmental and laboratory investigations conducted by state and local health departments, state departments of agriculture, the U.S. Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), National Poultry Improvement Plan (NPIP) and National Veterinary Services Laboratories (NVSL), and the Centers for Disease Control and Prevention (CDC). Case-patients were identified through PulseNet, the national molecular subtyping network for foodborne disease surveillance, and interviewed using the CDC standard live poultry contact questionnaire that asks about poultry-related exposures during the 7 days before illness onset. These outbreaks highlight the need to focus efforts on strategies to decrease and prevent human illness associated with live poultry contact through comprehensive interventions at the mail-order hatchery, agricultural feed store and consumer levels. Additional consumer education and interventions at mail-order hatcheries and venues where live poultry are sold, including agricultural feed stores, are necessary to prevent transmission of Salmonella from poultry to humans.

Replicon particle vaccine protects swine against influenza.

An alphavirus derived replicon particle (RP) vaccine expressing the cluster IV H3N2 swine influenza virus (SIV) hemagglutinin (HA) gene induced protective immunity against homologous influenza virus challenge. However, pigs with maternal antibody had no protective immunity against challenge after vaccination with RP vaccines expressing HA gene alone or in combination with nucleoprotein gene.

Alphavirus replicon particle vaccines developed for use in humans induce high levels of antibodies to influenza virus hemagglutinin in swine: proof of concept.

A propagation-defective, single-cycle, alphavirus replicon particle (RP) system was used to produce two vaccines against human influenza virus A/Wyoming/03/2003 (H3N2). One vaccine was prepared from Venezeulan equine encephalitis virus (VEEV) strain 3014 and the other from VEEV strain TC-83. Both vaccines induced high antibody titers to the influenza hemagglutinin (HA) protein and illustrated the potential of using alphavirus RP influenza vaccines in swine.

Acute infection of swine by various Salmonella serovars.

The objective of this study was to evaluate the ability of various serovars of Salmonella enterica subsp. enterica to infect alimentary and nonalimentary tissues of swine within 3 h of inoculation. Fourteen wild-type S. enterica serovars (4,12:imonophasic, 6,7 nonmotile, Agona, Brandenburg, Bredeney, Derby, Heidelberg, Infantis, Muenchen, Thompson, Typhimurium, Typhimurium variant Copenhagen, untypeable, and Worthington), two known virulent S. enterica serovars (Choleraesuis strain SC-38 and Typhimurium strain chi4232), and two avirulent S. enterica Choleraesuis vaccine strains (Argus and SC-54) were inoculated intranasally (approximately 5 x 10(9) cells) into swine (four animals per Salmonella isolate). Three hours after inoculation, animals were euthanized, and both alimentary tissues (tonsil, colon contents, and cecum contents) and nonalimentary tissues (mandibular lymph node, thymus, lung, liver, spleen, ileocecal lymph node, and blood) were collected for Salmonella isolation. All Salmonella serovars evaluated except Salmonella Choleraesuis SC-54 acutely infected both alimentary and nonalimentary tissues. These results indicate that Salmonella isolates commonly found in swine are capable of acutely infecting both alimentary and nonalimentary tissues in a time frame consistent with that in which animals are transported and held in lairage prior to slaughter.

Evaluation of the 1-2 test for detecting Salmonella in swine feces.

The 1-2 Test is a rapid culture test for the detection of motile Salmonella. The aim of this study was to evaluate the 1-2 Test for its ability to detect Salmonella in swine feces following preenrichment and selective enrichment. Pooled pen fecal samples (n = 118) and pig rectal swabs (n = 51) were cultured for Salmonella by the 1-2 Test, which was compared with the standard isolation protocol currently used in our laboratory. In addition, pen fecal samples known to be free of Salmonella were spiked with various concentrations of Salmonella enterica subsp. enterica serovar Typhimurium and cultured by both methods to determine the minimum number of organisms needed to produce a positive result. When naturally contaminated pen feces and rectal swabs were used, results obtained with the standard culture method were similar to those obtained with the 1-2 Test. However, the 1-2 Test did outperform the standard culture method when the spiked feces samples were tested (chi2 = 4.00). The test kit reduced the time and materials required for the detection of Salmonella in swine feces. The results of this study indicate that the 1-2 Test is an accurate method for monitoring Salmonella in swine feces.