Search Results (32)

Background/Objective: Non-typhoidal Salmonella is a leading cause of foodborne illness worldwide and presents a significant One Health concern due to zoonotic transmission. Although antibiotic therapy remains a standard approach for treating salmonellosis in severe cases in animals, the widespread misuse of antibiotics has contributed to the emergence of multidrug-resistant (MDR) Salmonella strains. This study provides insights into the genotypic and phenotypic characteristics among Salmonella isolates from necropsied cattle. Methods: A total of 1008 samples were collected from necropsied cattle. Salmonella enterica subspecies were identified by MALDI-TOF MS and subsequently confirmed by serotyping. The biofilm-forming ability of the isolated bacteria was assessed using a crystal violet assay. The motility of the isolates was assessed on soft agar plates. Additionally, the antimicrobial resistance genes (ARGs) and virulence genes were investigated. Antimicrobial resistance patterns were investigated against 19 antibiotics representing 9 different classes. Results:Salmonella species were isolated and identified in 27 necropsied cattle. Salmonella Dublin was the most prevalent serotype (29.6%). Additionally, all the isolates were biofilm producers at different levels of intensity, and 96.3% of the isolates exhibited both swarming and swimming motility. Furthermore, virulence genes, including invA, hilA, fimA, and csgA, were detected in all the isolates. The highest resistance was observed to macrolides (azithromycin and clindamycin) (100%), followed by imipenem (92.6%), and chloramphenicol (85.2%). All isolates were multidrug-resistant, with a multiple antibiotic resistance (MAR) index ranging between 0.32 and 0.74. The aminoglycoside resistance gene aac(6′)-Ib was detected in all the isolates (100%), whereas the distribution of other antimicrobial resistance genes (ARGs) varied among the isolates. Conclusions: The increasing prevalence of MDR Salmonella poses a significant public health risk. These resistant strains can reduce the effectiveness of standard treatments and elevate outbreak risks. Strengthening surveillance and regulating antibiotic use in livestock are essential to mitigating these threats. Full article

Waterborne illnesses, including those caused by Salmonella, are an increasing public health challenge, particularly in developing countries. Potential sources of salmonellosis include fruits and vegetables irrigated/treated with surface water, leading to human infections. Salmonella causes millions of gastroenteritis cases annually, but early detection through routine water quality surveillance is time-consuming, requires specialized equipment, and faces limitations, such as coverage gaps, delayed data, and poor accessibility. Climate change-driven extreme events such as floods and droughts further exacerbate variability in water quality. In this context, remote sensing offers an efficient and cost-effective alternative for environmental monitoring. This study evaluated the potential of Sentinel-2 satellite imagery to predict Salmonella occurrence in the Maipo and Mapocho river basins (Chile) by integrating spectral, microbiological, climatic, and land use variables. A total of 1851 water samples collected between 2019 and 2023, including 704 positive samples for Salmonella, were used to develop a predictive model. Predicting Salmonella in surface waters using remote sensing is challenging for several reasons. Satellite sensors capture environmental proxies (e.g., vegetation cover, surface moisture, and turbidity) but not pathogens. Our goal was to identify proxies that reliably correlate with Salmonella. Twelve spectral indices (e.g., NDVI, NDWI, and MNDWI) were used as predictors to develop a predictive model for the presence of the pathogen, which achieved 59.2% accuracy. By spatially interpolating the occurrences, it was possible to identify areas with the greatest potential for Salmonella presence. NDWI and AWEI were most strongly correlated with Salmonella presence in high-humidity areas, and spatial interpolation identified the higher-risk zones. These findings reveal the challenges of using remote sensing to identify environmental conditions conducive to the presence of pathogens in surface waters. This study highlights the methodological challenges that must be addressed to make satellite-based surveillance an accessible and effective public health tool. By integrating satellite data with environmental and microbiological analyses, this approach can potentially strengthen low-cost, proactive environmental monitoring for public health decision-making in the context of climate change. Full article

Background: Infections caused by carbapenem-resistant Enterobacterales have steadily multiplied over time, becoming a major threat to healthcare systems due to limited therapeutic options and high case-fatality rates. Case report: We studied a patient who, after being discharged from an ICU, developed salmonellosis caused by an antibiotic-susceptible S. enteritidis. After undergoing treatment with ciprofloxacin, the patient presented an episode of asymptomatic bacteriuria originated by a carbapenem and ciprofloxacin-resistant S. enteritidis. Results: Whole genome sequencing analysis revealed that both Salmonella isolates belonged to the same strain, and that isolate SEn_T2 acquired a plasmid carrying both bla_NDM-1 and qnrA1 genes (pIncCSEn) which was previously present in the patient’s gut in at least one Enterobacter cloacae isolate. Additionally, pIncCSEN was identified as a putatively new sub-lineage of IncC2 plasmids which lacked the first copy of the methyltransferase gene dcm and the rhs gene. The resistance genes bla_NDM-1 and qnrA1 were incorporated into a Tn21-derived transposon that included a complex class 1 integron whose genetic arrangement was: intI1- dfrA12- orfF- aadA2- qacEΔ1-sul1-ISCR1- trpF- ble- bla_NDM-1 (in reverse direction)- ISAba125-ISCR1- qnrA- cmlA1- qacEΔ1-sul1. Conclusions: Antimicrobial persistence and co-selection of antibiotic resistance play an important role in the dissemination of antimicrobial resistance genes; in this regard, a joint effort involving the infection control team, effective antibiotic stewardship, and genomic surveillance could help mitigate the spread of these multidrug resistant microorganisms. Full article

Salmonellosis is the second most common foodborne bacterial gastroenteritis in humans in Finland and worldwide. In Finland, a national salmonella control program covering cattle, pigs, and poultry, as well as the meat and eggs obtained from them, has been in place since the country joined the EU in 1995. To identify trends in the incidence of salmonellosis and to reflect on their causes, we analyzed Salmonella case data from the Finnish Infectious Disease Register (FIDR) from 1995 to 2022 and outbreak data from the national food and waterborne outbreak register (the FWO register) in the period 2010–2022. From 1995–1999 to 2015–2019, the incidence of salmonellosis decreased by 66% and 63% for domestic and travel-related cases, respectively. Most salmonellosis cases (72%) were travel-related, and, of them, 27% were infected in Southeast Asia. The most common serovars were S. Typhimurium and S. Enteritidis (38% and 19% of domestic cases, and 7% and 39% of travel-related cases). During 2010–2022, Salmonella sp. was reported as a cause in 31 foodborne outbreaks. In 14 of them, the source was identified at foodstuff level, and 12 sources were of foreign origin. The results of this study indicate that the national salmonella control program may have prevented domestic human infections in Finland. Full article

Salmonellosis is one of the most frequent foodborne zoonoses, and the consumption of contaminated poultry meat is considered the main source of Salmonella infections in humans. From 2021 to 2023, 384 chicken samples were collected from retailers in Apulia and Basilicata regions and analysed at the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata (IZSPB) laboratories. The Salmonella isolates were investigated to evaluate their phenotypic characteristics of antimicrobial resistance. A total of 125 (32.55%) samples tested positive for Salmonella spp. Three samples were simultaneously infected with strains of two different serotypes. Strains were classified into nine serotypes. Out of 128 strains, 112 (87.5%) isolates showed multidrug-resistant (MDR) profiles. Moreover, 16 isolates (12.5%) were ESBL producers with MDR profiles. Our data confirm that chicken products are a common source of Salmonella and highlight how S. Infantis was the most prevalent serotype (85.93%). Furthermore, Salmonella isolates showed antimicrobial resistance, which is very worrisome for animals and consumers. The high rate of antibiotic resistance along with the appearance of numerous MDR isolates is considered an actual concern and requires a robust surveillance network in a One Health concept. Full article

Salmonella remains a significant foodborne pathogen globally with S. Typhimurium presenting as a frequently occurring serovar. This study aimed to characterize 67 S. Typhimurium isolates from humans, food, farms, and slaughterhouses collected in Singapore from 2016 to 2017. Using whole-genome sequencing analysis, the isolates were found to belong to either ST19 (n = 33) or ST36 (n = 34). ST36 predominated in human intestinal and chicken isolates, while human extra-intestinal and non-chicken food isolates belonged to ST19. Plasmids were predicted in 88.1% (n = 59) of the isolates with the most common incompatibility group profiles being IncFIB(S), IncFII(S) and IncQ1. IncFIB(S) (adjusted p-value < 0.05) and IncFII(S) (adjusted p-value < 0.05) were significantly more prevalent in ST19 isolates, while Col156 (adjusted p-value < 0.05) was more significantly found in ST36 isolates. ST36 isolates exhibited higher resistance to multiple antibiotic classes such as penicillins, phenicols, folate pathway inhibitors, aminoglycosides, β-lactam/β-lactamase inhibitor combinations, tetracyclines, and fluoroquinolones. Phylogenetics analysis suggested potential shared routes of transmission among human, chicken, farm and slaughterhouse environments. Taken together, this study offers a cross-sectional epidemiological insight into the genomic epidemiology and antimicrobial landscape of S. Typhimurium isolates in Singapore, informing strategies for future public health and food safety surveillance. Full article

Salmonella Pullorum (S. Pullorum) and Salmonella Gallinarum (S. Gallinarum) are two biovars of Salmonella enterica serovar Gallinarum, responsible for pullorum disease and fowl typhoid, which are the most prevalent and pathogenic forms of salmonellosis in poultry in developing countries. Traditional differentiation methods for S. Pullorum and S. Gallinarum are based on distinct clinical manifestations and biochemical traits, given their indistinguishable nature via serological assays alone. Molecular differentiation methods such as allele-specific PCR and dual PCR combined with gel electrophoresis or enzyme digestion have also been used to discriminate S. Pullorum and S. Gallinarum, but the detection efficiency is not high. This investigation introduces a Fluorescence Resonance Energy Transfer (FRET) PCR assay targeting the pegB gene, exclusively found in specific Salmonella serovars such as S. Pullorum and S. Gallinarum, and exhibiting conserved single-nucleotide polymorphisms across these two biovars. High-resolution melting curve analysis demonstrates distinct dissolution profiles, facilitating the precise discrimination of S. Pullorum and S. Gallinarum. This FRET-PCR assay exhibits a detection limit of 10 copies per reaction and has been rigorously validated utilizing 17 reference strains and 39 clinical isolates. The innovation presented herein provides a valuable tool for the rapid differentiation of S. Pullorum and S. Gallinarum, thereby enhancing diagnostic efficiency and molecular surveillance of poultry Salmonella. The developed pegB-targeting FRET-PCR assay presents a promising alternative to current cumbersome and time-consuming diagnostic modalities, offering significant potential for expedited identification and control of Salmonella in poultry and mitigating economic losses associated with Salmonella contamination in poultry production. Full article

Salmonella enterica subsp. enterica serotype Enteritidis (S. Enteritidis) is one of the major causes of foodborne infections and is responsible for many national and multi-country foodborne outbreaks worldwide. In Greece, human salmonellosis is a mandatory notifiable disease, with laboratory surveillance being on a voluntary basis. This study aims to provide the first insights into the genetic characteristics and antimicrobial resistance profiles of 47 S. Enteritidis human isolates using whole-genome sequencing (WGS) technology. The S. Enteritidis population was mainly resistant to fluoroquinolones due to gyrA point mutations, whereas one isolate presented a multi-resistant plasmid-mediated phenotype. ST11 was the most frequent sequence type, and phylogenetic analysis through the cgMLST and SNP methods revealed considerable genetic diversity. Regarding virulence factors, 8 out of the 24 known SPIs and C63PI were detected. Due to the observed variability between countries, it is of utmost importance to record the circulating S. Enteritidis strains’ structure and genomic epidemiology at the national level. WGS is a valuable tool that is revolutionizing our approach to Salmonella by providing a deeper understanding of these pathogens and their impact on human health. Full article

Salmonella is one of the most spread foodborne pathogens worldwide, and Salmonella infections in humans still represent a global health burden. The main source of Salmonella infections in humans is represented by contaminated animal-derived foodstuffs, with pork products being one of the most important players. Salmonella infection in swine is critical not only because it is one of the main causes of economic losses in the pork industry, but also because pigs can be infected by several Salmonella serovars, potentially contaminating the pig meat production chain and thus posing a significant threat to public health globally. As of now, in Europe and in the United States, swine-related Salmonella serovars, e.g., Salmonella Typhimurium and its monophasic variant Salmonella enterica subsp. enterica 1,4,[5],12:i:-, are also frequently associated with human salmonellosis cases. Moreover, multiple outbreaks have been reported in the last few decades which were triggered by the consumption of Salmonella-contaminated pig meat. Throughout the years, changes and evolution across the pork industry may have acted as triggers for new issues and obstacles hindering Salmonella control along the food chain. Gathered evidence reinforces the importance of coordinating control measures and harmonizing monitoring programs for the efficient control of Salmonella in swine. This is necessary in order to manage outbreaks of clinical disease in pigs and also to protect pork consumers by controlling Salmonella subclinical carriage and shedding. This review provides an update on Salmonella infection in pigs, with insights on Salmonella ecology, focusing mainly on Salmonella Choleraesuis, S. Typhimurium, and S. 1,4,[5],12:i:-, and their correlation to human salmonellosis cases. An update on surveillance methods for epidemiological purposes of Salmonella infection in pigs and humans, in a “One Health” approach, will also be reported. Full article

With poultry products as one of the leading reservoirs for the pathogen, in a typical year in the United States, it is estimated that over one million individuals contract non-typhoidal Salmonella infections. Foodborne outbreaks associated with Salmonella infections in poultry, thus, continue to remain a significant risk to public health. Moreover, the further emergence of antimicrobial resistance among various serovars of Salmonella is an additional public health concern. Feeding-based strategies (such as use of prebiotics, probiotics, and/or phytobiotics as well as essential oils), non-feeding-based strategies (such as use of bacteriophages, vaccinations, and in ovo strategies), omics tools and surveillance for identifying antibiotic-resistance genes, post-harvest application of antimicrobials, and biosecurity measures at poultry facilities are practical interventions that could reduce the public health burden of salmonellosis and antibiotic resistance associated with poultry products. With the escalating consumption of poultry products around the globe, the fate, prevalence, and transmission of Salmonella in agricultural settings and various poultry-processing facilities are major public health challenges demanding integrated control measures throughout the food chain. Implementation of practical preventive measures discussed in the current study could appreciably reduce the public health burden of foodborne salmonellosis associated with poultry products. Full article

To prevent and/or control infectious diseases in animal and human health, an appropriate surveillance system based on suitable up-to-date epidemiological data is required. The systematic review protocol was designed according to the PRISMA statement to look at the available data on infectious diseases of livestock in Cameroon from 2000–2020. Data were searched through online databases. Grey literature was comprised of dissertations and theses from veterinary higher education institutions in Cameroon. A random-effects model was used to calculate pooled prevalence using Comprehensive Meta-Analysis Software. Based on disease prevalence, major infectious diseases of livestock in Cameroon were gastrointestinal parasitosis (57.4% in cattle, 67.2% in poultry, 88% in pigs), hemoparasites (21.6% in small ruminants, 19.7% in cattle), bovine pasteurellosis (55.5%), fowl salmonellosis (48.2%), small ruminant plague (39.7%), foot-and-mouth disease (34.5% in cattle), and African swine fever (18.9%). Furthermore, other important endemic zoonoses in the country included: Rift Valley fever (10.9% in cattle, 3.7% in small ruminants), brucellosis (7% in cattle, 8% in pigs), bovine tuberculosis (4.7% in cattle), hepatitis E virus (8.4% in pigs) and bovine leptospirosis (2.5%). Most of the retrieved research were carried out in the Adamawa, Northwest, and West regions of Cameroon. The evaluation of existing data as evidence, albeit publication-specific, is an important step towards the process of prioritizing animal diseases, including zoonoses. Full article

Salmonella enterica subspecies enterica is one of the most important foodborne pathogens and the causative agent of salmonellosis, which affects both humans and animals producing numerous infections every year. The study and understanding of its epidemiology are key to monitoring and controlling these bacteria. With the development of whole-genome sequencing (WGS) technologies, surveillance based on traditional serotyping and phenotypic tests of resistance is being replaced by genomic surveillance. To introduce WGS as a routine methodology for the surveillance of food-borne Salmonella in the region, we applied this technology to analyze a set of 141 S. enterica isolates obtained from various food sources between 2010 and 2017 in the Comunitat Valenciana (Spain). For this, we performed an evaluation of the most relevant Salmonella typing methods, serotyping and sequence typing, using both traditional and in silico approaches. We extended the use of WGS to detect antimicrobial resistance determinants and predicted minimum inhibitory concentrations (MICs). Finally, to understand possible contaminant sources in this region and their relationship to antimicrobial resistance (AMR), we performed cluster detection combining single-nucleotide polymorphism (SNP) pairwise distances and phylogenetic and epidemiological data. The results of in silico serotyping with WGS data were highly congruent with those of serological analyses (98.5% concordance). Multi-locus sequence typing (MLST) profiles obtained with WGS information were also highly congruent with the sequence type (ST) assignment based on Sanger sequencing (91.9% coincidence). In silico identification of antimicrobial resistance determinants and minimum inhibitory concentrations revealed a high number of resistance genes and possible resistant isolates. A combined phylogenetic and epidemiological analysis with complete genome sequences revealed relationships among isolates indicative of possible common sources for isolates with separate sampling in time and space that had not been detected from epidemiological information. As a result, we demonstrate the usefulness of WGS and in silico methods to obtain an improved characterization of S. enterica enterica isolates, allowing better surveillance of the pathogen in food products and in potential environmental and clinical samples of related interest. Full article

Non-typhoidal salmonellosis (NTS) is one of the most common foodborne diseases worldwide. In this study, we aimed to analyze trends in the epidemiology of NTS in the last decade in Israel. Laboratory-confirmed cases of NTS at eight sentinel laboratories were reported to the Israel Sentinel Laboratory-Based Surveillance Network, integrated with the serotype identification performed at the Salmonella National Reference Laboratory of the Ministry of Health. The decrease in NTS incidence since 1999 continued between 2010 and 2014 (16.1 per 100,000 in 2014) and was interrupted by a rise between 2015 and 2017 (39.1 per 100,000 in 2017) associated with outbreaks of Salmonella Enteritidis. The incidence of NTS dropped again thereafter (21.4 per 100,000 in 2021). The 0–4 age group was the most affected by NTS (55.5% of the cases) throughout the surveillance period. The age-adjusted incidence rates were consistently high in the summer months (June-September) and low in the winter months (December–February). The overall decrease in the incidence of NTS in Israel since 1999 was temporarily interrupted in the last decade by country-wide outbreaks involving emerging or re-emerging Salmonella serotypes. Control measures should be enhanced for all risk points of food chain transmission of Salmonella spp. to further reduce the NTS morbidity in Israel. Full article

Foodborne infections cause illness and death every year worldwide. The aim of this study was to describe trends in 2013–2019 in the occurrence of human cases of salmonellosis, campylobacteriosis, listeriosis, and hepatitis A in the Campania region. Human case data were provided by the National Surveillance System of disease and were grouped by year, province, age group, and sex. Moreover, the number of people hospitalized was recorded. In the Campania region, the total number of confirmed human cases for the diseases investigated was 1924, with Hepatitis A and the Salmonellosis as the first most reported (1009 and 825 cases, respectively). The incidence rates of gastroenteritis under study were lower than those in Italy and European Union in the same period, with the exception of Hepatitis A whose incidence was higher than that recorded in Italy. Data on hospitalizations pointed out the onset of severe forms of infection also for listeriosis and campylobacteriosis, whose incidence was very low (27 and 63 cases, respectively). Unfortunately, no information on the foods implicated is available. Although probably underestimated, gastroenteritis due to foodborne agents still represents a burden in Campania, and continuous monitoring and implementation of the currently available regional surveillance system is required. Full article

Background: A regional antibiotic susceptibility database of certain pathogens is crucial for first-line physicians in terms of providing clinical judgement and appropriate selection of antimicrobial agents. The aim of this study is to update the epidemiological data of Salmonella serogroups and drug resistance in pediatric patients. Methods: This is a single-center retrospective study enrolling patients aged from 0 to 18 years who were hospitalized with cultured proven non-typhoidal Salmonella (NTS) infection from 2004 to 2019. The isolates were collected and the demographic data, serogroups of Salmonella and antimicrobial susceptibilities were further analyzed. Results: A total of 1583 isolates of NTS were collected. Serogroup C2 was prone to cause invasive non-typhoidal salmonellosis (iNTS), especially bacteremia. Patients aged < 2 years were associated with serogroups B and C2 infection, while those aged ≥ 2 years were associated with serogroups D and E infection. The prevalence of serogroup B declined with simultaneous increase in prevalence of serogroups D and E. Serogroups B and E were associated with ceftriaxone resistance, while Serogroup D was less drug-resistant than the others. The prevalence of ceftriaxone-resistant Salmonella had not increased, although more ciprofloxacin-resistant isolates were found in iNTS infection. Conclusions: Age < 2 years is a risk factor of iNTS for children, and the distribution of serogroup changes should be closely monitored. Ceftriaxone is still the drug of choice for treating pediatric iNTS infection, and although no increase was observed in the prevalence of ceftriaxone-resistant strains in this study, continuing surveillance of such cases is warranted. Full article