Temporal association of antimicrobial use in livestock with antimicrobial resistance in non-typhoid Salmonella human infections in the Netherlands, 2008-2019.

Background: Antimicrobial use (AMU) in livestock contributes to antimicrobial resistance (AMR) among zoonotic pathogens, such as non-typhoid Salmonella (NTS). Since 2009, the Netherlands has made substantial efforts to reduce AMU in livestock. Objectives: To assess the association between AMU in livestock and AMR in NTS human isolates. Additionally, associations between AMU in broilers/pigs and AMR in NTS broiler/pig isolates, and between AMR in broilers/pigs and in human NTS isolates were assessed. The focus was on Salmonella Enteritidis (SE) and Salmonella Typhimurium including its monophasic variant (ST/STM). Methods: A national population registry-based study was conducted in the Netherlands from 2008 to 2019. Multivariable logistic regression models were used to assess the associations between livestock AMU and NTS resistance proportion in humans and broilers/pigs, overall as well as per class-specific antimicrobials. Correlation analysis was performed to relate AMR proportions between human and broiler/pig NTS isolates. Results: For SE, only a positive association between penicillins use in broilers and resistance to ampicillin among human isolates was significant. For ST/STM, most associations between AMU in livestock and AMR among human isolates were significantly positive, overall and per class-specific antimicrobials, namely for penicillins-ampicillin, tetracyclines-tetracycline and sulfonamides/trimethoprim-sulfamethoxazole/trimethoprim. Significantly positive associations between AMU in broilers/pigs and AMR in broiler/pig ST/STM isolates were also observed, but not between broiler/pig and human AMR levels. Conclusions: Significant associations were generally found between livestock AMU and AMR in human and broiler/pig ST/STM isolates. However, confounding factors, such as imported meat and travel are of concern. To fully comprehend the impact of livestock AMU on resistance in human NTS isolates, it is imperative to enhance AMR surveillance of NTS.

Evolution of Salmonella spp. isolated compared to those of Campylobacter spp. in faecal samples for 12 years.

OBJECTIVE: The Autonomous Community of Galicia has adopted DECREE 216/2011 on health standards for poultry production, in addition to the Spanish national programs. However, no program has yet been implemented to eradicate campylobacteriosis, which shares the same reservoir. The aim of this study was to compare the evolution of Salmonella spp. isolates with respect to those of Campylobacter spp. in faecal samples received by the Microbiology Department. METHODS: A retrospective descriptive comparative study was conducted through the Laboratory Information System (SIL) of Salmonella spp. isolated against Campylobacter spp. in faeces between 2011 and 2022 at the Lucus Augusti University Hospital (HULA), Lugo, Spain. RESULTS: A total of 35,704 stool samples were analysed, of which 3,045 were positive. 751 Salmonella spp. were isolated. Statistical differences were observed in the annual distribution (p<0.01), with a clear turning point in 2018. Five hundred and five patients required hospital care, especially in 2014 with 72 patients (69%). On the other hand, 1,587 Campylobacter spp. were isolated. Required hospital care 1,002 patients during the study, with a peak in 2019 with 111 cases (62%). CONCLUSIONS: The reduction of salmonellosis cases and the maintenance of campylobacteriosis cases are directly related to the implementation of DECREE 216/2011. This, in turn, has reduced the pressure on hospitals in the HULA health area. Therefore, we believe that the ONE Health concept is being strengthened in the area studied.

Tackling salmonellosis: A comprehensive exploration of risks factors, impacts, and solutions.

Salmonellosis, caused by Salmonella species, is one of the most common foodborne illnesses worldwide with an estimated 93.8 million cases and about 155,00 fatalities. In both industrialized and developing nations, Salmonellosis has been reported to be one of the most prevalent foodborne zoonoses and is linked with arrays of illness syndromes such as acute and chronic enteritis, and septicaemia. The two major and most common Salmonella species implicated in both warm-blooded and cold-blooded animals are Salmonella bongori and Salmonella enterica. To date, more than 2400 S. enterica serovars which affect both humans and animals have been identified. Salmonella is further classified into serotypes based on three primary antigenic determinants: somatic (O), flagella (H), and capsular (K). The capacity of nearly all Salmonella species to infect, multiply, and survive in human host cells with the aid of their pathogenic and virulence arsenals makes them deadly and important public health pathogens. Primarily, food-producing animals such as poultry, swine, cattle, and their products have been identified as important sources of salmonellosis. Additionally, raw fruits and vegetables are among other food types that have been linked to the spread of Salmonella spp. Based on the clinical manifestation of human salmonellosis, Salmonella strains can be categorized as either non-typhoidal Salmonella (NTS) and typhoidal Salmonella. The detection of aseptically collected Salmonella in necropsies, environmental samples, feedstuffs, rectal swabs, and food products serves as the basis for diagnosis. In developing nations, typhoid fever due to Salmonella Typhi typically results in the death of 5%-30% of those affected. The World Health Organization (WHO) calculated that there are between 16 and 17 million typhoid cases worldwide each year, with scaring 600,000 deaths as a result. The contagiousness of a Salmonella outbreak depends on the bacterial strain, serovar, growth environment, and host susceptibility. Risk factors for Salmonella infection include a variety of foods; for example, contaminated chicken, beef, and pork. Globally, there is a growing incidence and emergence of life-threatening clinical cases, especially due to multidrug-resistant (MDR) Salmonella spp, including strains exhibiting resistance to important antimicrobials such as beta-lactams, fluoroquinolones, and third-generation cephalosporins. In extreme cases, especially in situations involving very difficult-to-treat strains, death usually results. The severity of the infections resulting from Salmonella pathogens is dependent on the serovar type, host susceptibility, the type of bacterial strains, and growth environment. This review therefore aims to detail the nomenclature, etiology, history, pathogenesis, reservoir, clinical manifestations, diagnosis, epidemiology, transmission, risk factors, antimicrobial resistance, public health importance, economic impact, treatment, and control of salmonellosis.

Detection and Phenotypic Antimicrobial Susceptibility of Salmonella enterica Serotypes in Dairy Cattle Farms in the Po Valley, Northern Italy.

The presence of Salmonella spp. in dairy cattle farms poses a major risk to animal health and welfare. This study focused on Salmonella detection in dairy farms located in the Cremona and Mantua provinces (northern Italy) in samples collected and submitted to laboratories in 2021-2022. A total of 2710 samples from different sources, including calf carcasses/organs (n = 128), rectal swabs (n = 1937), feces (n = 390), bulk milk (n = 93), and overshoes/swabs (n = 127) for environmental sampling, were analyzed for the presence of Salmonella spp. and were included in the present study. Our results indicate that Salmonella was most commonly firstly identified from calf carcasses and organs (61.67%) and that the serotypes most frequently detected in dairies were S. Dublin (38.33%), S. Typhimurium (23.33%), and S. Typhimurium monophasic variant (14.17%). The most common pathological findings in calf carcasses were enteritis, hepatosplenomegaly, and pneumonia. The antimicrobial resistance pattern analyzed using the MIC assay of 51 Salmonella isolates revealed the presence of multi-resistant strains, which pose a major risk to public and animal health.

Modeling the growth of Salmonella in raw ground pork under dynamic conditions of temperature abuse.

Salmonella contamination of pork products is a significant public health concern. Temperature abuse scenarios, such as inadequate refrigeration or prolonged exposure to room temperature, can enhance Salmonella proliferation. This study aimed to develop and validate models for Salmonella growth considering competition with background microbiota in raw ground pork, under isothermal and dynamic conditions of temperature abuse between 10 and 40 °C. The maximum specific growth rate (µmax) and maximum population density (MPD) were estimated to quantitatively describe the growth behavior of Salmonella. To reflect more realistic microbial interactions in Salmonella-contaminated product, our model considered competition with the background microbiota, measured as mesophilic aerobic plate counts (APC). Notably, the µmax of Salmonella in low-fat samples (∼5 %) was significantly higher (p < 0.05) than that in high-fat samples (∼25 %) at 10, 20, and 30 °C. The average doubling time of Salmonella was 26, 4, 2, 1.5, 0.8, and 1.1 h at 10, 15, 20, 25, 30, and 40 °C, respectively. The initial concentration of Salmonella minimally impacted its growth in ground pork at any temperature. The MPD of APC consistently exceeded that of Salmonella, indicating the growth of APC without competition from Salmonella. The competition model exhibited excellent fit with the experimental data, as 95 % (627/660) of residual errors fell within the desired acceptable prediction zone (pAPZ >0.70). The theoretical minimum and optimum growth temperatures for Salmonella ranged from 5 to 6 °C and 35 to 36 °C, respectively. The dynamic model displayed strong predictive performance, with 90 % (57/63) of residual errors falling within the APZ. Dynamic models could be valuable tools for validating and refining simpler static or isothermal models, ultimately improving their predictive capabilities to enhance food safety.

Nationwide trends and features of human salmonellosis outbreaks in China.

Salmonellosis is one of the most common causes of diarrhea, affecting 1/10 of the global population. Salmonellosis outbreaks (SO) pose a severe threat to the healthcare systems of developing regions. To elucidate the patterns of SO in China, we conducted a systematic review and meta-analysis encompassing 1,134 reports across 74 years, involving 89,050 patients and 270 deaths. A rising trend of SO reports has been observed since the 1970s, with most outbreaks occurring east of the Hu line, especially in coastal and populated regions. It is estimated to have an overall attack rate of 36.66% (95% CI, 33.88-39.45%), and antimicrobial resistance towards quinolone (49.51%) and beta-lactam (73.76%) remains high. Furthermore, we developed an online website, the Chinese Salmonellosis Outbreak Database (CSOD), for visual presentation and data-sharing purposes. This study indicated that healthcare-associated SO required further attention, and our study served as a foundational step in pursuing outbreak intervention and prediction.

Machine learning approach as an early warning system to prevent foodborne Salmonella outbreaks in northwestern Italy.

Salmonellosis, one of the most common foodborne infections in Europe, is monitored by food safety surveillance programmes, resulting in the generation of extensive databases. By leveraging tree-based machine learning (ML) algorithms, we exploited data from food safety audits to predict spatiotemporal patterns of salmonellosis in northwestern Italy. Data on human cases confirmed in 2015-2018 (n = 1969) and food surveillance data collected in 2014-2018 were used to develop ML algorithms. We integrated the monthly municipal human incidence with 27 potential predictors, including the observed prevalence of Salmonella in food. We applied the tree regression, random forest and gradient boosting algorithms considering different scenarios and evaluated their predictivity in terms of the mean absolute percentage error (MAPE) and R2. Using a similar dataset from the year 2019, spatiotemporal predictions and their relative sensitivities and specificities were obtained. Random forest and gradient boosting (R2 = 0.55, MAPE = 7.5%) outperformed the tree regression algorithm (R2 = 0.42, MAPE = 8.8%). Salmonella prevalence in food; spatial features; and monitoring efforts in ready-to-eat milk, fruits and vegetables, and pig meat products contributed the most to the models' predictivity, reducing the variance by 90.5%. Conversely, the number of positive samples obtained for specific food matrices minimally influenced the predictions (2.9%). Spatiotemporal predictions for 2019 showed sensitivity and specificity levels of 46.5% (due to the lack of some infection hotspots) and 78.5%, respectively. This study demonstrates the added value of integrating data from human and veterinary health services to develop predictive models of human salmonellosis occurrence, providing early warnings useful for mitigating foodborne disease impacts on public health.

Genotypic and phenotypic analysis of Salmonella enterica serovar Derby, looking for clues explaining the impairment of egg isolates to cause human disease.

Salmonella enterica serovar Derby causes foodborne disease (FBD) outbreaks worldwide, mainly from contaminated pork but also from chickens. During a major epidemic of FBD in Uruguay due to S. enteritidis from poultry, we conducted a large survey of commercially available eggs, where we isolated many S. enteritidis strains but surprisingly also a much larger number (ratio 5:1) of S. Derby strains. No single case of S. Derby infection was detected in that period, suggesting that the S. Derby egg strains were impaired for human infection. We sequenced fourteen of these egg isolates, as well as fifteen isolates from pork or human infection that were isolated in Uruguay before and after that period, and all sequenced strains had the same sequence type (ST40). Phylogenomic analysis was conducted using more than 3,500 genomes from the same sequence type (ST), revealing that Uruguayan isolates clustered into four distantly related lineages. Population structure analysis (BAPS) suggested the division of the analyzed genomes into nine different BAPS1 groups, with Uruguayan strains clustering within four of them. All egg isolates clustered together as a monophyletic group and showed differences in gene content with the strains in the other clusters. Differences included variations in the composition of mobile genetic elements, such as plasmids, insertion sequences, transposons, and phages, between egg isolates and human/pork isolates. Egg isolates showed an acid susceptibility phenotype, reduced ability to reach the intestine after oral inoculation of mice, and reduced induction of SPI-2 ssaG gene, compared to human isolates from other monophyletic groups. Mice challenge experiments showed that mice infected intraperitoneally with human/pork isolates died between 1-7 days p.i., while all animals infected with the egg strain survived the challenge. Altogether, our results suggest that loss of genes functions, the insertion of phages and the absence of plasmids in egg isolates may explain why these S. Derby were not capable of producing human infection despite being at that time, the main serovar recovered from eggs countrywide.

A Case of Food-Borne Salmonellosis in a Corn Snake (Pantherophis guttatus) after a Feeder Mouse Meal.

Reptiles are usually asymptomatic carriers of Salmonella, with the manifestation of typical clinical signs of acute forms in adult and non-immunocompromised animals being considered exceptions. In the present case, an adult male corn snake (Pantherophis guttatus) was found dead due to septic shock 48 h after consuming a feeder mouse purchased online. The snake's tissue samples and faeces were cultured for bacteria isolation. Microbiological examinations of the snake and mouse livers revealed the presence of Salmonella enterica subsp. enterica serovar Midway. A whole-genome analysis of these two isolates showed a high correlation between them: they belonged to the strain type ST-357 for the classic MLST scheme and to the strain type ST 171322 for the cgMLST scheme. Also, a virulence gene analysis revealed the presence of stdB and STM3026 genes. This report conveys a case of food-borne salmonellosis in a pet snake, transmitted from a feeder mouse, likely responsible for the snake's death due to septic shock. It highlights the relevance of feeder mice as a source of Salmonella infections in snakes and the associated risks to human health.

Salmonella Typhimurium caused an unprecedentedly large foodborne outbreak in Finland in 2021.

AIMS: Salmonella infections are significant causes of foodborne outbreaks in the European Union. This study investigates a sudden increase in gastroenteritis patients in the hospital district of Central Finland in June 2021. The primary aim was to study the outbreak's magnitude and source of the outbreak. METHODS AND RESULTS: Epidemiological, microbiological, environmental and traceback investigations were conducted. Over 700 persons fell ill during the outbreak caused by Salmonella Typhimurium associated with a daycare lunch. Similar S. Typhimurium was found in the patients and a vegetable mix containing iceberg lettuce, cucumber and peas served during lunch. The traceback investigation revealed that the batch information of vegetables from the wholesaler was not complete. The wholesaler had received quality complaints about the iceberg lettuce from the central kitchen. The manufacturer did not test the suspected batch for Salmonella since the production plant had given a certificate declaring it Salmonella negative. CONCLUSIONS: The most suspect ingredient was one batch of iceberg lettuce due to quality complaints. The lettuce had not been served in two daycare centres without cases. We recommend that in order to enable thorough microbiological investigation, institutional kitchens store the food samples separately as part of the internal quality control and that food items should always be tested when Salmonella contamination in an outbreak is suspected.

Comparing Individual and Community-level Characteristics of People with Ground Beef-associated Salmonellosis and Other Ground Beef Eaters: A Case-control Analysis.

Salmonella is estimated to be the leading bacterial cause of U.S. domestically acquired foodborne illness. Large outbreaks of Salmonella attributed to ground beef have been reported in recent years. The demographic and sociodemographic characteristics of infected individuals linked to these outbreaks are poorly understood. We employed a retrospective case-control design; case-patients were people with laboratory-confirmed Salmonella infections linked to ground beef-associated outbreaks between 2012 and 2019, and controls were respondents to the 2018-2019 FoodNet Population Survey who reported eating ground beef and denied recent gastrointestinal illness. We used county-level CDC/ATSDR Social Vulnerability Index (SVI) to compare case-patient and controls. Case-patient status was regressed on county-level social vulnerability and individual-level demographic characteristics. We identified 376 case-patients and 1,321 controls in the FoodNet sites. Being a case-patient was associated with increased overall county-level social vulnerability (OR: 1.21 [95% CI: 1.07-1.36]) and socioeconomic vulnerability (OR: 1.24 [1.05-1.47]) when adjusted for individual-level demographics. Case-patient status was not strongly associated with the other SVI themes of household composition and disability, minority status and language, and housing type and transportation. Data on individual-level factors such as income, poverty, unemployment, and education could facilitate further analyses to understand this relationship.

Trends in antimicrobial susceptibility pattern of Salmonella species isolated from bacteremia patients at a tertiary care center in Northern India.

The study was done to assess the antimicrobial susceptibility pattern among Salmonella enterica serovars causing bacteremia in Northern India. In this observational study, blood samples positive for Salmonella enterica serovars from January 2021 to April 2023 were studied. Species identification was done using MALDI-ToF MS. Serotyping was done using slide agglutination method. Antimicrobial susceptibility was interpreted as per the CLSI guidelines. During the study period, 32 Salmonella enterica serovars were isolated. Salmonella enterica serovar Typhi was the predominant serovar, followed by Salmonella enterica serovar Paratyphi A. All isolates were susceptible to ceftriaxone, chloramphenicol, co-trimoxazole and cefotaxime. Pefloxacin showed 100% resistance. Resistance to nalidixic acid was found in 81.2% isolates. Of the isolates resistant to nalidixic acid, 19(73.08%) isolates were resistant to ciprofloxacin also. This changing susceptibility pattern necessitates continuous surveillance of antibiogram of Salmonella isolates to rationalize the treatment protocols for invasive salmonellosis and prevent emergence of resistant strains.

Biocompatible plasma-treated liquids: A sustainable approach for decontaminating gastrointestinal-infection causing pathogens.

Nosocomial infections are a serious threat and difficult to cure due to rising antibiotic resistance in pathogens and biofilms. Direct exposure to cold atmospheric plasma (CAP) has been widely employed in numerous biological research endeavors. Nonetheless, plasma-treated liquids (PTLs) formulated with physiological solutions may offer additional benefits such as enhanced portability, and biocompatibility. Additionally, CAP-infused long-lived reactive oxygen and nitrogen species (RONS) such as nitrite (NO2-), nitrate (NO3-), and hydrogen peroxide (H2O2) can synergistically induce their antibacterial activity. Herein, we investigated those argon-plasma jet-treated liquids, including Ringer's lactate (RL), phosphate-buffered saline (PBS), and physiological saline, have significant antibacterial activity against nosocomial/gastrointestinal-causing pathogens, which might be due to ROS-mediated lipid peroxidation. Combining the conventional culture-based method with propidium iodide monoazide quantitative PCR (PMAxx™-qPCR) indicated that PTLs induce a minimal viable but non-culturable (VBNC) state and moderately affect culturable counts. Specifically, the PTL exposure resulted in pathogenicity dysfunction via controlling T3SS-related effector genes of S. enterica. Overall, this study provides insights into the effectiveness of PTLs for inducing ROS-mediated damage, controlling the virulence of diarrheagenic bacteria, and modulating homeostatic genes.

Outbreak of multidrug-resistant Salmonella infections in people linked to pig ear pet treats, United States, 2015-2019: results of a multistate investigation.

Background: International distribution of contaminated foods can be a source of Salmonella infections in people and can contribute to the spread of antimicrobial-resistant bacteria across countries. We report an investigation led by the United States Centers for Disease Control and Prevention, the Food and Drug Administration (FDA), and state governmental officials into a multistate outbreak of salmonellosis linked to pig ear pet treats. Methods: Pig ear treats and companion dogs were tested for Salmonella by state officials and the FDA. Products were traced back to the country of origin when possible. Cases were defined as outbreak illnesses in people associated with one of seven Salmonella serotypes genetically related to samples from pig ear pet treats, with isolation dates from June 2015 to September 2019. Whole genome sequencing (WGS) of isolates was used to predict antimicrobial resistance. Findings: The outbreak included 154 human cases in 34 states. Of these, 107 of 122 (88%) patients reported dog contact, and 65 of 97 (67%) reported contact with pig ear pet treats. Salmonella was isolated from 137 pig ear treats, including some imported from Argentina, Brazil, and Colombia, and from four dogs. WGS predicted 77% (105/137) of human and 43% (58/135) of pig ear treat isolates were resistant to ≥3 antimicrobial classes. Interpretation: This was the first documented United States multistate outbreak of Salmonella infections linked to pig ear pet treats. This multidrug-resistant outbreak highlights the interconnectedness of human health and companion animal ownership and the need for zoonotic pathogen surveillance to prevent human illness resulting from internationally transported pet food products. Funding: Animal Feed Regulatory Program Standards award. Animal and product testing conducted by FDA Vet-LIRN was funded by Vet-LIRN infrastructure grants (PAR-22-063).

Salmonellosis in Poland in 2021. / Salmonelozy w Polsce w 2021 roku.

AIM: The aim of the article is to present and assess the epidemiological situation of salmonellosis in Poland in 2021, in relation to previous years. MATERIAL AND METHODS: The assessment of the epidemiological situation of salmonellosis in Poland was made on the basis of individual data on salmonellosis cases, entered by sanitary-epidemiological stations into the EpiBaza System, data on outbreaks caused by Salmonella bacilli from the Registry of Epidemic Outbreaks System (ROE), as well as on the basis of aggregated data published in the annual bulletins "Infectious Diseases and Poisoning in Poland" (NIPH NIH - NRI, GIS, Warsaw), including information sent by laboratories of sanitary-epidemiological stations, data from the article on the epidemiological situation of salmonellosis in Poland in 2020 and data from the Demographic Research Department of the Central Statistical Office. RESULTS: In 2021, in Poland sanitary-epidemiological stations registered 8,294 cases of salmonellosis - 8,014 cases of intestinal salmonellosis and 280 extra-intestinal salmonellosis, including 190 cases of salmonellosis septicemia. The incidence rate for total salmonellosis was 21.7/100,000 population, for intestinal salmonellosis 21.0, for salmonellosis septicemia 0.50, and 0.23 per 100,000 population for other extra-intestinal infections of salmonellosis etiology. The reported 7,988 cases were classified as confirmed and 306 as probable. There were 5,127 hospitalizations due to salmonellosis, mainly children and the elderly. The peak of the incidence was registered in July. The highest incidence rate of salmonellosis in 2021 was recorded in the Podkarpackie voivodeship (39.8/100,000 population), the lowest in the Swietokrzyskie voivodeship (10.7/100,000 population). The highest incidence of intestinal salmonellosis was registered in the age group 0-4 years, accounting for 44.2% of the total number of cases. Among extra-intestinal infections, almost 62% of cases occurred in people aged 60+. In 2021, sanitary-epidemiological stations were detected and reported 229 outbreaks of food poisoning caused by Salmonella bacilli, 75% of them was Enteritidis serotype. In 2021, the most frequently isolated serotypes were S. Enteritidis 72%, S. Typhimurium (2%) and S. Infantis (0.5%). The serotype was not determined in 24.3% of cases. There were 24 imported cases of salmonellosis from different regions of the world. Due to Salmonella infection 11 people died in 2021. Laboratories of sanitary-epidemiological stations performed 438,183 tests for the presence of Salmonella and Shigella bacilli among humans, 92% of these tests concerned people working in contact with food. CONCLUSIONS: In 2021, there was an increase in the number of salmonellosis cases in Poland, compared to 2020. It can therefore be concluded that the COVID-19 pandemic did not have a long-term impact on reducing the number of Salmonella infections. At the same time, despite the increase, the situation of salmonellosis in Poland has not fully returned to the state before the COVID-19 pandemic.The area where we observe a significant difference, is the percentage of hospitalizations, which is the lowest in 2021 since 1998. It can be assumed, that one of the reasons for this, could be a stricter qualification of people with milder symptoms for hospital treatment, in favour of outpatient care.

Multidrug resistance in Salmonella isolates of swine origin: mobile genetic elements and plasmids associated with cephalosporin resistance with potential transmission to humans.

The emergence of foodborne Salmonella strains carrying antimicrobial resistance (AMR) in mobile genetic elements (MGE) is a significant public health threat in a One Health context requiring continuous surveillance. Resistance to ciprofloxacin and cephalosporins is of particular concern. Since pigs are a relevant source of foodborne Salmonella for human beings, we studied transmissible AMR genes and MGE in a collection of 83 strains showing 9 different serovars and 15 patterns of multidrug resistant (MDR) previously isolated from pigs raised in the conventional breeding system of Northern Spain. All isolates were susceptible to ciprofloxacin and three isolates carried blaCMY-2 or blaCTX-M-9 genes responsible for cefotaxime resistance. Filter mating experiments showed that the two plasmids carrying blaCTX-M-9 were conjugative while that carrying blaCMY-2 was self-transmissible by transformation. Whole-genome sequencing and comparative analyses were performed on the isolates and plasmids. The IncC plasmid pSB109, carrying blaCMY-2, was similar to one found in S. Reading from cattle, indicating potential horizontal transfer between serovars and animal sources. The IncHI2 plasmids pSH102 in S. Heidelberg and pSTM45 in S. Typhimurium ST34, carrying blaCTX-M-9, shared similar backbones and two novel "complex class 1 integrons" containing different AMR and heavy metal genes. Our findings emphasize the importance of sequencing techniques to identify emerging AMR regions in conjugative and stable plasmids from livestock production. The presence of MGE carrying clinically relevant AMR genes raises public health concerns, requiring monitoring to mitigate the emergence of bacteria carrying AMR genes and subsequent spread through animals and food.IMPORTANCEThe emergence of foodborne Salmonella strains carrying antimicrobial resistance (AMR) in mobile genetic elements (MGE) is a significant public health threat in a One Health context. Since pigs are a relevant source of foodborne Salmonella for humans, in this study, we investigate different aspects of AMR in a collection of 83 Salmonella showing nine different serovars and 15 patterns of multidrug resistant (MDR) isolated from pigs raised in the conventional breeding system. Our findings emphasize the importance of sequencing techniques to identify emerging AMR regions in conjugative and stable plasmids from livestock production. The presence of MGE carrying clinically relevant AMR genes raises public health concerns, requiring monitoring to mitigate the emergence of bacteria carrying AMR genes and subsequent spread through animals and food.

Extra-intestinal salmonellosis in a tertiary care centre in South India.

Background and Objectives: Extra-intestinal salmonellosis is associated with higher case fatality and is underestimated in the developing countries like India. Here we present a case series of bacteriologically proven extra-intestinal salmonellosis managed at our institute over the past two years. Materials and Methods: Retrospective analysis of bacteriologically proven extra-intestinal salmonellosis over two years between January 2020 to December 2021 was carried out. Medical records were reviewed for site of infection, evidence of any underlying or predisposing illnesses and antimicrobial susceptibility report. Results: Eight patients were diagnosed with extra-intestinal salmonellosis. Male to female ratio was 3:1. Mean age was 44 years. Four were typhoidal and four were nontyphoidal Salmonellae. The extra-intestinal sites involved were purulent aspirates from scrotum, caecum, perianal region, intraperitoneal collection, synovium, and urine. Predisposing factors include chronic myeloid leukemia, HIV and gastric malignancy. All deep seated abscess required surgical intervention. All typhoidal Salmonella (n=4) were sensitive to cotrimoxazole, ampicillin, ceftriaxone. Among nontyphoidal Salmonella, one was resistant to cotrimoxazole; two were resistant to ampicillin, ceftriaxone and three resistant to ciprofloxacin. Conclusion: The diagnosis of extra-intestinal salmonellosis requires a high degree of clinical suspicion and should be included in the differential diagnosis in patients with deep-seated abscesses.

A live attenuated Salmonella Typhimurium vaccine dose and diluent have minimal effects on the caecal microbiota of layer chickens.

Among the Salmonella reduction strategies in poultry production, one option is to use a Salmonella vaccine. The aim of vaccinating layer flocks is to reduce the shedding of wild-type Salmonella in the poultry environment, thereby reducing the contamination of poultry products (eggs and meat). Nutritive diluent and a higher dose of vaccine may enhance its colonization potential in the gut of chickens. In this study, a commercially available live attenuated vaccine (Vaxsafe® ST) was reconstituted in different media and delivered orally to day-old chicks at three different doses (107, 108, and 109 CFU/chick). Gut colonization of the vaccine strain and the effects of vaccination on gut microbiota were assessed in commercial-layer chickens. The vaccine diluent and dosage minimally affected microbiota alpha diversity. Microbiota beta diversity was significantly different (P < 0.05) based on the vaccine diluent and dose, which indicated that the vaccinated and unvaccinated chickens had different gut microbial communities. Differences were noted in the abundance of several genera, including Blautia, Colidextribacter, Dickeya, Enterococcus, Lactobacillus, Pediococcus, and Sellimonas. The abundance of Colidextribacter was significantly lower in chickens that received vaccine reconstituted in Marek's and water diluents, while Lactobacillus abundance was significantly lower in the water group. The highest vaccine dose (109 CFU/chick) did not significantly alter (P > 0.05) the abundance of microbial genera. Chicken age affected the microbiota composition more significantly than the vaccine dose and diluent. The abundance of Lactobacillus, Blautia, Caproiciproducens, Pediococcus, and Colidextribacter was significantly higher on day 14 compared with day 7 post-vaccination. The Salmonella Typhimurium vaccine load in the caeca was not significantly affected by diluent and vaccine dose; however, it was significantly lower (P < 0.0001) on day 14 compared with day 7 post-vaccination. Overall, the S. Typhimurium vaccine minimally affected the gut microbiota structure of layer chicks, whereas changes in microbiota were more significant with chicken age.

Salmonella infections in Denmark from 2013-2022 with focus on serotype distribution, invasiveness, age, sex, and travel exposition.

PURPOSE: To analyze the nationwide incidence of Salmonella infections in Denmark from 2013 to 2022. METHODS: Confirmed cases of Salmonella enterica subsp. enterica were examined using the National Register of Enteric Pathogens during 2013-2022. Proportions, incidence rates (IR), relative risk (RR), and 95% confidence intervals (CI) were calculated to assess differences in serotypes, invasiveness, age, sex, and travel exposure. RESULTS: We identified 9,944 Danish Salmonella enterica subsp. enterica cases, with an average annual incidence rate of 16.9 per 100,000 inhabitants, declining during the COVID-19 pandemic. Typhoidal cases totaled 206, with an average annual IR of 0.35 per 100,000 inhabitants. Enteric fever patients had a median age of 24 years (IQR:17-36). Leading non-typhoid Salmonella (NTS) serotypes were S. Enteritidis (26.4%), monophasic S. Typhimurium (16.5%), and S. Typhimurium (13.5%). Median age for NTS cases was 42 (IQR: 18-62), with even sex distribution, and a third reported travel prior to onset of disease. The overall percentage of invasive NTS (iNTS) infection was 8.1% (CI: 7.6-8.7). Eleven serotypes were associated with higher invasiveness, with S. Dublin and S. Panama having the highest invasiveness with age and sex-adjusted RR of 7.31 (CI: 6.35-8.43) and 5.42 (CI: 3.42-8.60), respectively, compared to all other NTS serotypes. Increased age was associated with higher RR for iNTS infection. CONCLUSION: During the decade, there was a limited number of typhoidal cases. The dominant NTS serotypes were S. Enteritidis and monophasic S. Typhimurium, whereas S. Dublin and S. Panama exhibited the highest invasive potential.