Salmonella enterica serotypes from human and nonhuman sources in Sao Paulo State, Brazil, 2004-2020

Unveiling the Genomic Landscape of Understudied Salmonella enterica Serovars from Poultry and Human: Implications for Food Safety

Despite the bacteria of the genus Salmonella are pathogens of zoonotic importance, the factors associated with some serovars genetic diversity remain unclear. We investigated genotypic profiles of antimicrobial resistance, plasmid replicons, and virulence factors in 301 S. enterica genomes from human and animal sources, supplemented by ten sequenced genomes from fecal samples of laying hens in Brazil. Many antimicrobial resistance genes have been detected across various Salmonella serovars; with a limited number of unique resistance genes predicted in poultry isolates compared to human isolates. Specifically, among the 52 antimicrobial resistance genes identified, 48% were shared between poultry and human isolates, while 21.1% were exclusive to poultry isolates and 30.7% were exclusive to human isolates. Chromosomal mutations in the gyrA and parC genes were also predicted. To the best of our knowledge, this is the first work to report S. Braenderup carrying the SPI-10. SGI-1 was detected in a few isolates of S. Schwarzengrund from poultry and the CS54 island was solely noticed in genomes referring to the serovars S. Saintpaul and S. Braenderup. Among the serovars analyzed, S. Saintpaul showed the lowest plasmid diversity. A total of 161 (161/271) virulence genes were common to all serovars, the remaining genes were exclusively identified within specific serovars, revealing a distinct distribution pattern within the S. enterica population. Overall, our study brings to light the genetic potential of Salmonella serovars frequently neglected in poultry production, which threatens public health, particularly due to multidrug-resistant profiles against active principles used to treat human infections.

Prevalence of Salmonella serotypes isolated from clinical samples in chicken farms and meat in slaughterhouses in South Korea

Salmonella contamination in poultry is a major public health concern worldwide. This study examined the prevalence and serotype distribution of Salmonella in clinical samples from poultry farms and in fecal and carcass samples from slaughterhouses in South Korea. A total of 525 samples were collected, including 33 clinical samples from broiler chicks and 492 samples from slaughterhouses. Salmonella was detected in 79 % of clinical samples, with S. Westhampton identified as the most prevalent serovar. In slaughterhouse samples, 9 % tested positive, with higher contamination in carcasses (15 %) than in fecal samples (4 %) (P < 0.05). S. Enteritidis was the only serovar present in all three sample types, reinforcing its significance in poultry and human infections. Seasonal variations showed increased Salmonella prevalence in slaughterhouses during warmer months, underscoring the need for enhanced control measures. These findings highlight the importance of biosecurity in farms and strict hygiene protocols in processing facilities to reduce Salmonella contamination in poultry production.

Landscape of Bacterial Enteric Disease and Traveler´s Diarrhea in South America

Diarrheal disease is a global public health threat. Cases of enteric disease caused by bacterial enteropathogens result in a significant health burden and can lead to antimicrobial resistance patterns that increase and evolve over time and geography, posing serious health challenges for local populations as well as civilian travelers and military personnel deployed to endemic regions. This review describes the prevalence of the most common bacterial agents of diarrheal disease in South America, as well as the distribution patterns of antibiotic resistance and predominant strains that are present in the region. Furthermore, the development of relevant prevention and treatment strategies are described, and United States Naval Medical Research Unit SOUTH disease surveillance and enteric disease research efforts in this regional context are highlighted.

The Effect of Lipopolysaccharides from Salmonella enterica on the Size, Density, and Compressibility of Phospholipid Vesicles

The properties of the large unilamellar vesicles (LUVs) from 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC), modified by lipopolysaccharides (LPS) from Salmonella enterica sv. Enteritidis, which mimics Gram-negative bacteria, were studied by various physical methods. LPS, in the range of 0/20/50 % w/w relative to the lipid, had a regulatory role in the structure of the LUVs toward the lower size, low polydispersity, and over-a-month size stability due to the lower negative zeta potential. The addition of LPS resulted in increased density, which determined the ultrasound velocity and the specific adiabatic compressibility. In a 0.5/1/2 mg/mL concentration range, the total lipid content did not significantly affect the size of LUVs and influenced the density-related attributes similarly to the LPS content. A positive correlation was found between temperature and vesicle size, and a negative correlation was found between temperature and density and compressibility-except for the anomaly behavior at 25 °C, around the melting point of DMPC.

Trends in antimicrobial susceptibility patterns in Salmonella from human and nonhuman sources in Sao Paulo State, Brazil, 2016-2023

Antimicrobial resistance constitutes a significant global challenge to public health and development, in which non-typhoidal Salmonella emerges as a critical concern. This study investigates the prevalence and antimicrobial resistance profiles of Salmonella isolates from both human and nonhuman sources. A total of 2,511 Salmonella isolates that had been collected from 2016 to 2023 were analyzed, of which 1,724 underwent antimicrobial susceptibility testing. The main focus lied on the 10 most prevalent serotypes, totaling 957 isolates. Serotyping showed the diverse distribution of serotypes, with Heidelberg, Typhimurium, Enteritidis, and the monophasic Salmonella Typhimurium occurring most often. Antimicrobial resistance was common since 512 strains resisted at least one drug and 319 several drugs. Notably, the Heidelberg and Mbandaka serotypes, predominantly occurring in nonhuman samples, showed multidrug resistance. Salmonella Typhi remained susceptible to antimicrobials. Resistance to nalidixic acid, tetracycline, sulfonamides, and ampicillin was prevalent, whereas all isolates remained susceptible to imipenem. A reduction in susceptibility rates for aminoglycosides was observed over the study period. Extended-spectrum β-lactamase production occurred in 4.4% of the isolates, of which Heidelberg configured the most prevalent extended-spectrum β-lactamase-positive serotype. These findings underscore the importance of surveillance and effective monitoring to control this pathogen, highlighting the necessity of prioritizing public health efforts.

High prevalence and genomic features of multidrug-resistant Salmonella enterica isolated from chilled broiler chicken on retail sale in the United Arab Emirates

Non-typhoidal Salmonella represents a significant global concern for food safety and One Health. Despite the United Arab Emirates (UAE) being a leading consumer of chicken meat globally, there is a lack of comprehensive understanding regarding the prevalence and genomic characteristics of Salmonella within the country. This study aims to address this gap by conducting a thorough analysis of Salmonella prevalence, antimicrobial resistance, and genomic profiles of isolates obtained from whole broiler carcasses retailed under chilled conditions in the UAE. Our findings reveal that Salmonella was detected in 41.2 % (130/315) of the sampled chilled broiler carcasses, with notable variability observed among samples sourced from six different companies. Phenotypic antimicrobial resistance (AMR) testing, among 105 isolates, highlighted high resistance rates to tetracycline (97.1 %), nalidixic acid (93.3 %), ampicillin (92.4 %), azithromycin (75.2 %), ciprofloxacin (63.8 %), and ceftriaxone (54.3 %). Furthermore, a concerning 99 % (104/105) of the isolates exhibited multidrug resistance. Whole-genome sequencing (WGS) of 60 isolates identified five serovars, with S. infantis/Sequence Type (ST) 32 (55 %) and S. Minnesota/ST-458 (28.3 %) being the most prevalent. WGS analysis unveiled 34 genes associated with antimicrobial resistance, including mcr-1.1 (only in two isolates), conferring resistance to colistin. The two major serovars, Infantis and Minnesota, exhibited significant variation (P-values <0.001) in the distribution of major AMR genes (aadA1, blaCMY-2, blaSHV-12, qnrB19, qnrS1, sul1, and sul2). Notably, the gene qacEdelta, conferring resistance to quaternary ammonium compounds commonly found in disinfectants, was universally present in all S. Infantis isolates (n = 33), compared to only one S. Minnesota isolate. Additionally, all S. Infantis isolates harbored the IncFIB (pN55391) plasmid replicon type. Major serovars exhibited distinct distributions of antimicrobial resistance genes, underscoring the importance of serovar-specific surveillance. These findings emphasize the critical need for continuous surveillance and intervention measures to address Salmonella contamination risks in poultry products, providing valuable insights for public health and regulatory strategies not only in the UAE but also globally.

Detection of pathogenic bacteria in retailed shrimp from Bangladesh

The presence of pathogenic bacteria is a problem that might be present in farmed shrimp due to exposure in the environment or post-harvest handling. Retail farmed shrimp in Bangladesh (Penaeus monodon and Macrobrachium rosenbergii) were tested for common pathogenic bacteria namely Salmonella, L. monocytogenes, Vibrio spp., and E. coli. None of these bacteria were found and instead Enterobacter cloacae, Escherichia fergusonii, Proteus penneri, Klebsiella aerogenes, Enterococcus faecalis, Serratia marcescens, Citrobacter freundii, and Aeromonas dhakensis were detected. Pathogenic bacteria found in Bangladeshi shrimp may be due to the farm environment, poor handling during harvest or post-harvest, or unhygienic market conditions. The results indicate that retail shrimp from Bangladesh have food safety concerns. Proper laws and policies need to be enforced and implemented to ensure food safety related to fish and shrimp.

A multicenter genomic epidemiological investigation in Brazil, Chile, and Mexico reveals the diversity and persistence of Salmonella populations in surface waters

This study examined the diversity and persistence of Salmonella in the surface waters of agricultural regions of Brazil, Chile, and Mexico. Research groups (three in 2019-2020 and five in 2021-2022) conducted a long-term survey of surface water across 5-8 months annually (n = 30 monthly). On-site, each team filtered 10-L water samples with modified Moore Swabs to capture Salmonella, which were then isolated and identified using conventional microbiological techniques. Salmonella isolates were sequenced on Illumina platforms. Salmonella was present in 1,493/3,291 water samples (45.8%), with varying isolation rates across countries and years. Newport, Infantis, and Typhimurium were the most frequent among the 128 different serovars. Notably, 22 serovars were found in all three countries, representing almost half of the 1,911 different isolates collected. The resistome comprised 72 antimicrobial resistance (AMR) genes and six point mutations in three genes. At least one AMR determinant was observed in 33.8% (646/1,911) of the isolates, of which 47.4% (306/646) were potentially multidrug resistant. Phylogeny based on core genome multilocus sequence typing (cgMLST) showed that most isolates clustered according to sequence type and country of origin. Only 14 cgMLST multi-country clusters were detected among the 275 clusters. However, further analysis confirmed that close genetic relatedness occurred mostly among isolates from the same country, with three exceptions. Interestingly, isolates closely related phylogenetically were recovered over multiple years within the same country, indicating the persistence of certain Salmonella in those areas. In conclusion, surface waters in these regions are consistently contaminated with diverse Salmonella, including strains that persist over time.IMPORTANCESalmonella is a leading foodborne pathogen responsible for millions of illnesses, hospitalizations, and deaths annually. Although Salmonella-contaminated water has now been recognized as an important contamination source in the agrifood chain, there is a lack of knowledge on the global occurrence and diversity of Salmonella in surface water. Moreover, there has been insufficient research on Salmonella in surface waters from Latin American countries that are major producers and exporters of agricultural products. Incorporating genetic profiling of Salmonella isolates from underrepresented regions, such as Latin America, enhances our understanding of the pathogen's ecology, evolution, antimicrobial resistance, and pathogenicity. Moreover, leveraging genomic data derived from pathogens isolated from diverse geographical areas is critical for assessing the potential public health risk posed by the pathogen and expediting investigations of foodborne outbreaks. Ultimately, global efforts contribute significantly to reducing the incidence of foodborne infections.

Large-scale salmonella outbreak associated with banh mi, Viet Nam, 2024

Objective

To investigate the cause of a foodborne outbreak that occurred in Dong Nai province, Viet Nam, in 2024, and implement control measures.

Methods

An initial investigation was conducted to confirm the outbreak, which was followed by epidemiological and environmental investigations to find the plausible causative food item. Clinical specimens and food samples were tested to identify the pathogen.

Results

A total of 547 symptomatic cases were recorded, of whom two were in severe condition requiring extracorporeal membrane oxygenation and ventilation, one of whom died. Among 99 interviewed cases, the mean incubation time was 9 hours (range 2-24 hours), with the main symptoms being fever, abdominal pain, diarrhoea and vomiting. All patients had eaten banh mi from a local bakery. Salmonella spp. were identified in food samples and clinical specimens. The bakery halted production, and the outbreak ended after 1 week.

Discussion

All the patients were exposed to only one food in common, which facilitated the investigation process. This outbreak is a reminder to small retailers and take-away shops of the importance of food safety management in preventing similar future outbreaks. All food handlers must comply with food hygiene principles, especially in hot temperatures, which boosts bacterial growth.

Characteristics of Nontyphoid Salmonella Isolated from Human, Environmental, Animal, and Food Samples in Burkina Faso: A Systematic Review and Meta-Analysis

Salmonella is one of the world's leading causes of zoonotic and foodborne illnesses. Recently, antimicrobial resistance (AMR) has become one of the most critical challenges to public health and food safety. Herein, we employed a meta-analysis to determine the pooled prevalence and spatiotemporal distribution of serovars and antimicrobial resistance in NTS in Burkina Faso. To find eligible articles, a comprehensive literature search of PubMed, African Journals Online, ScienceDirect, Google Scholar, and the gray literature (university libraries) in Burkina was conducted for the period from 2008 to 2020. Studies meeting the inclusion criteria were selected and assessed for risk of bias. To assess the temporal and spatial relationships between serotypes and resistant strains from humans, animals, food, and the environment, a random-effects statistical model meta-analysis was carried out using the Comprehensive Meta-Analysis Version 3.0 program. The NTS prevalence rates were 4.6% (95% CI: 3-7) and 20.1% (95% CI: 6.6-47.4) in humans and animals, respectively, and 16.8% (95% CI: 10.5-25.8) and 15.6% (95% CI: 8.2-27.5) in food and the environment, respectively. Most NTS serovars were S. Derby, reported both in food and animals, and S. Typhimurium, reported in humans, while S. Croft II, S. Jodpur II, and S. Kentucky were the most prevalent in the environment. NTS isolates were highly resistant to erythromycin, amoxicillin, cefixime, and cephalothin, with a pooled prevalence of multidrug resistance of 29% (95% CI: 14.5-49.5). The results of this review show a high diversity of Salmonella serotypes, as well as high antibiotic resistance in Salmonella isolates from animal, human, food, and environmental samples in Burkina, calling for a consolidated "One Health" approach to better understand the drivers of pathogen emergence, spread, and antimicrobial resistance, as well as the formulation of intervention measures needed to limit the risk associated with the disease.

High levels of multidrug-resistant isolates of genetically similar Salmonella 1,4, [5],12:I:- from Brazil between 1983 and 2020

Introduction. Salmonella 1,4, [5],12:i:- strains with different antimicrobial resistance profiles have been associated with foodborne disease outbreaks in several countries. In Brazil, S. 1,4, [5],12:i:- was identified as one of the most prevalent serovars in São Paulo State during 2004-2020.Gap Statement. However, few studies have characterized this serovar in Brazil.Aim. This study aimed to determine the antimicrobial resistance profiles of S. 1,4, [5],12:i:- strains isolated from different sources in Southeast Brazil and compare their genetic diversity.Methodology. We analysed 113 S. 1,4, [5],12:i:- strains isolated from humans (n=99), animals (n=7), food (n=5) and the environment (n=2) between 1983 and 2020. Susceptibility testing against 13 antimicrobials was performed using the disc diffusion method for all the strains. Plasmid resistance genes and mutations in the quinolone resistance-determining regions were identified in phenotypically fluoroquinolone-resistant strains. Molecular typing was performed using enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) for all strains and multilocus sequence typing (MLST) for 40 selected strains.Results. Of the 113 strains, 54.87 % were resistant to at least one antimicrobial. The highest resistance rates were observed against ampicillin (51.33 %), nalidixic acid (39.82 %) and tetracycline (38.05 %). Additionally, 39 (34.51 %) strains were classified as multidrug-resistant (MDR). Nine fluoroquinolone-resistant strains exhibited the gyrA mutation (Ser96→Tyr96) and contained the qnrB gene. The 113 strains were grouped into two clusters using ERIC-PCR, and most of strains were present in one cluster, with a genetic similarity of ≥80 %. Finally, 40 strains were typed as ST19 using MLST.Conclusion. The prevalence of MDR strains is alarming because antimicrobial treatment against these strains may lead to therapeutic failure. Furthermore, the ERIC-PCR and MLST results suggested that most strains belonged to one main cluster. Thus, a prevalent subtype of Salmonella 1,4, [5],12:i:- strains has probably been circulating among different sources in São Paulo, Brazil, over decades.

Polymyxin Resistance in Salmonella: Exploring Mutations and Genetic Determinants of Non-Human Isolates

Until 2015, polymyxin resistance was primarily attributed to chromosomal mutations. However, with the first report of mobile colistin resistance (mcr-1) in commensal Escherichia coli from food animals in China, the landscape has changed. To evaluate the presence of polymyxin resistance in Salmonella spp., a drop screening test for colistin and polymyxin B was carried out on 1156 isolates of non-human origin (animals, food, and the environment), received in Brazil, between 2016 and 2021. Subsequently, 210 isolates with resistant results in the drop test were subjected to the gold-standard test (broth microdilution) for both colistin and polymyxin B. Whole-genome sequencing (WGS) of 102 resistant isolates was performed for a comprehensive analysis of associated genes. Surprisingly, none of the isolates resistant to colistin in the drop test harbored any of the mcr variants (mcr-1 to mcr-10). WGS identified that the most common mutations were found in pmrA (n= 22; T89S) and pmrB (n = 24; M15T, G73S, V74I, I83A, A111V). Other resistance determinants were also detected, such as the aac(6')-Iaa gene in 72 isolates, while others carried beta-lactamase genes (blaTEM-1blaCTX-M-2, blaCMY-2). Additionally, genes associated with fluoroquinolone resistance (qnrB19, qnrS1, oqxA/B) were detected in 11 isolates. Colistin and polymyxin B resistance were identified among Salmonella from non-human sources, but not associated with the mcr genes. Furthermore, the already-described mutations associated with polymyxin resistance were detected in only a small number of isolates, underscoring the need to explore and characterize unknown genes that contribute to resistance.

Genomic and proteomic analysis of Salmonella Enteritidis isolated from a patient with foodborne diarrhea

Salmonella is a major cause of foodborne diseases and clinical infections worldwide. This study aimed to investigate the drug resistance, genomic characteristics, and protein expression of foodborne Salmonella in Shanxi Province. We isolated a strain of Salmonella Enteritidis from patient feces and designated it 31A. The drug resistance of 31A against 14 antibiotics was determined using an antimicrobial susceptibility test. Whole-genome sequencing and quantitative proteomic analysis were performed on the 31A strain. Functional annotation of drug resistance genes/proteins and virulence genes/proteins was conducted using various databases, such as VFDB, ARDB, CAZY, COG, KOG, CARD, GO, and KEGG. The focus of this study was understanding the mechanisms related to food poisoning, and the genetic evolution of 31A was analyzed through comparative genomics. The 31A strain belonged to ST11 Salmonella Enteritidis and showed resistance to β-lactam and quinolone antibiotics. The genome of 31A had 70 drug resistance genes, 321 virulence genes, 12 SPIs, and 3 plasmid replicons. Functional annotation of these drug resistance and virulence genes revealed that drug resistance genes were mainly involved in defense mechanisms to confer resistance to antibiotics, while virulence genes were mainly associated with cellular motility. There were extensive interactions among the virulence genes, which included SPI-1, SPI-2, flagella, fimbriae, capsules and so on. The 31A strain had a close relationship with ASM2413794v1 and ASM130523v1, which were also ST11 Salmonella Enteritidis strains from Asia and originated from clinical patients, animals, and food. These results suggested minimal genomic differences among strains from different sources and the potential for interhost transmission. Differential analysis of the virulence and drug resistance-related proteins revealed their involvement in pathways related to human diseases, indicating that these proteins mediated bacterial invasion and infection. The integration of genomic and proteomic information led to the discovery that Salmonella can survive in a strong acid environment through various acid resistance mechanisms after entering the intestine with food and then invade intestinal epithelial cells to exert its effects. In this study, we comprehensively analyzed the drug resistance and virulence characteristics of Salmonella Enteritidis 31A using a combination of genomic and proteomic approaches, focusing on the pathogenic mechanism of Salmonella Enteritidis in food poisoning. We found significant fluctuations in various virulence factors during the survival, invasion, and infection of Salmonella Enteritidis, which collectively contributed to its pathogenicity. These results provide important information for the source tracing, prevention, and treatment of clinical infections caused by Salmonella Enteritidis.

Virulence potential of Salmonella 1,4, [5],12:i:- strains isolated during decades from different sources in the Southeast region of Brazil

Salmonella 1,4, [5],12:i:- is one of the most prevalent serovars associated with gastroenteritis in several countries, including Brazil. However, few studies have analyzed the virulence potential of this variant in this country. Therefore, this study aimed to characterize S. 1,4, [5],12:i:- strains isolated in Southeast Brazil. To this end, 113 S. 1,4, [5],12:i:- strains isolated from different sources between 1983 and 2020 were analyzed. For all strains, the frequencies of 11 virulence genes were investigated using PCR and the molecular typing was performed using pulsed-field gel electrophoresis (PFGE). Furthermore, 40 strains isolated from human and non-human sources were characterized by survival under acid and oxidative stress, and virulence analysis in Galleria mellonella was performed for 20 selected strains. All virulence genes were detected in more than 91% of the strains. The studied strains were grouped into four clusters using PFGE. Most strains were present in one cluster, named PFGE-A, with a genetic similarity of ≥ 79.5%. All 40 strains survived acid stress after 10 min and 1 h of exposure. Under oxidative stress, all 40 strains survived after 10 min, and 36 survived after 1 h of exposure. In the G. mellonella assay, nine isolates from non-human sources and six isolates from human showed high-to-intermediate virulence profiles. In conclusion, the pathogenic potential of the strains studied was corroborated by the high frequency of all the virulence genes identified. The PFGE results suggested that most strains belonged to one main cluster that has been prevailing in the São Paulo State, Brazil. The S. 1,4, [5],12:i:- strains isolated from human and non-human sources successfully survived the unfavorable conditions in the human gastrointestinal tract. Finally, strains isolated from non-human sources showed a higher proportion of isolates with high to intermediate virulence profiles in G. mellonella than in human isolates, suggesting a possible difference between isolates from different origins.

Training in modern statistical methodologies and software tools for the definition and analysis of (stochastic) quantitative microbial risk assessment models with a comparison between the Hungarian and Spanish food supply chains

Human pathogenic Salmonella enterica strains have been infecting people since historical times. The original human pathogens, typhoid Salmonella strains (e.g. S. Typhi) played a huge role in the previous centuries but nowadays in the developed world the number of cases or outbreaks caused by these serotypes deceased due to the development of personal and public hygiene. Nowadays in these regions the animal-borne zoonotic serotypes (e.g. S. Enteritidis) became more important because of their high prevalence in intensive animal husbandry. But these bacteria can also appear in fruits and vegetables. The fellow joined the scientific work of the Polytechnic University of Cartagena, Spain about the safety of plant-based products, where he could gain experience in microbiological laboratory exercises and theoretical calculations of statistics and modelling. The activities in the laboratory were part of the research lines already established at the host institution, being based on the protocols they have already implemented. Nonetheless, the fellow had the opportunity to design his own experiment, do the experimental work required and analysed the data within the context of a qualitative microbiological risk assessment. The main focus was on the heat resistance of two strains of zoonotic Salmonella spp. at different temperatures. Experiments were done using a reference strain and an extremely resistant variant to evaluate this rare phenotype. The experiments were executed using a Mastia thermoresistometer, a device patented by the host institution that provides more control when studying thermal treatments than traditional methods. The data was analysed using the principles of predictive microbiology, using the D-value as an estimate of heat resistance that provides insight into the bacterial behaviour. For this, the fellow used the bioinactivation software, developed within the host group. Through the work and results the fellow learned the principles of quantitative microbiological risk assessment (QMRA) and predictive microbiology, which was the aim for the EU-FORA programme.

Development and evaluation of an indirect enzyme-linked immunosorbent assay based on a recombinant SifA protein to detect Salmonella infection in poultry

Salmonella is an important zoonotic pathogen that not only endangers food safety and human health, but also causes considerable economic losses to the poultry industry. Therefore, it is essential to establish a rapid, sensitive, and specific diagnostic method for the early detection of Salmonella infection in poultry. In this study, we developed a novel enzyme-linked immunosorbent assay (ELISA) for the detection of anti-Salmonella antibodies using a recombinant SifA protein. Amino acid sequence comparison revealed that SifA is a relatively conserved secretory protein across Salmonella serotypes. Therefore, we hypothesized that SifA can serve as a detection antigen for diagnostic testing. The SifA protein was expressed in Escherichia coli and used as a coating antigen to establish an SifA-ELISA. Control sera from specific-pathogen-free (SPF) chickens infected with Salmonella or several other non-Salmonella pathogens were then tested using the SifA-ELISA. Specificity testing demonstrated that the SifA-ELISA could detect antibodies against 3 different serotypes of Salmonella, whereas antibodies against other non-Salmonella pathogens could not be detected. Compared to the SifA-ELISA, the Salmonella plate agglutination test (PAT) failed to detect antibodies in serum samples from chickens infected with Salmonella Typhimurium. This result suggests that our SifA-ELISA may be better than PAT at detecting Salmonella infection. Comparing clinical sera, we observed a similar rate of Salmonella positivity between SifA-ELISA and PAT (92.6%). In addition, anti-SifA antibodies were continuously detected during Salmonella infection of SPF chickens, demonstrating that SifA-ELISA could consistently detect high levels of antibodies for at least 8 wk. Furthermore, the intra-assay and interassay coefficients of variation (CV) of the SifA-ELISA were below 10%, which is considered acceptable. In summary, the SifA-ELISA established here is a promising and reliable method for detection of anti-Salmonella antibodies in poultry and may contribute to the early diagnosis of Salmonella infection.