RESUMEN

The use of direct nucleic acid amplification of pathogens from food matrices has the potential to reduce time to results over DNA extraction-based approaches as well as traditional culture-based approaches. Here we describe protocols for assay design and experiments for direct amplification of foodborne pathogens in food sample matrices using loop-mediated isothermal amplification (LAMP) and polymerase chain reaction (PCR). The examples provided include the detection of Escherichia coli in milk samples and Salmonella in pork meat samples. This protocol includes relevant reagents and methods including obtaining target sequences, assay design, sample processing, and amplification. These methods, though used for specific example matrices, could be applied to many other foodborne pathogens and sample types.

Asunto(s)

ADN Bacteriano , Microbiología de Alimentos , Leche , Técnicas de Amplificación de Ácido Nucleico , Reacción en Cadena de la Polimerasa , Salmonella , Técnicas de Amplificación de Ácido Nucleico/métodos , Microbiología de Alimentos/métodos , Animales , Leche/microbiología , Salmonella/genética , Salmonella/aislamiento & purificación , ADN Bacteriano/genética , ADN Bacteriano/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Enfermedades Transmitidas por los Alimentos/microbiología , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Técnicas de Diagnóstico Molecular/métodos , Porcinos

RESUMEN

Foodborne pathogens continue to be a major health concern worldwide. Culture-dependent methodologies are still considered the gold standard to perform pathogen detection and quantification. These methods present several drawbacks, such as being time-consuming and labor intensive. The implementation of real-time PCR has allowed to overcome these limitations, and even reduce the cost associated with the analyses, due to the possibility of simultaneously and accurately detecting several pathogens in one single assay, with results comparable to those obtained by classical approaches. In this chapter, a protocol for the simultaneous detection of two of the most important foodborne pathogens, Salmonella spp. and Listeria monocytogenes, is described.

Asunto(s)

Microbiología de Alimentos , Enfermedades Transmitidas por los Alimentos , Listeria monocytogenes , Reacción en Cadena de la Polimerasa Multiplex , Salmonella , Listeria monocytogenes/genética , Listeria monocytogenes/aislamiento & purificación , Microbiología de Alimentos/métodos , Salmonella/genética , Salmonella/aislamiento & purificación , Reacción en Cadena de la Polimerasa Multiplex/métodos , Enfermedades Transmitidas por los Alimentos/microbiología , Enfermedades Transmitidas por los Alimentos/diagnóstico , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Humanos , ADN Bacteriano/genética , ADN Bacteriano/análisis

RESUMEN

BACKGROUND: Foodborne diseases are a growing public health concern worldwide and households are a common setting. This study aimed to explore the epidemiological characteristics of household foodborne disease outbreaks in Zhejiang Province and propose targeted prevention and control measures. METHODS: Descriptive statistical methods were used to analyze household foodborne disease outbreak data collected from the Foodborne Disease Outbreaks Surveillance System in Zhejiang Province from 2010 to 2022. RESULTS: Household foodborne disease outbreaks showed an upward trend during the study period (Cox-Staurt trend test, p = 0.01563 < 0.05). These outbreaks mainly occurred from June to September, with 62.08% (352/567) of all reported outbreaks. The number of reported outbreaks varied in 11 prefectures, with a maximum of 100 and a minimum of only 7. Household foodborne disease outbreaks had a wide spectrum of etiologic factors. Mushroom toxins accounted for the largest proportion of all etiologies (43.39 %) and caused the highest proportion of hospitalization (54.18%) and death (78.26%). Such outbreaks are caused by accidently eating wild poisonous mushrooms. Bacterial infection (16.23%) was the second most common etiology, with Salmonella spp. and Vibrio parahaemolyticus being the primary pathogens. These outbreaks were caused by improper storage, improper processing or a combination of factors, and the foods involved were mainly aquatic animals, eggs and cooked meat. Other identified etiologies included plant toxins (9.52%), chemicals (7.23%), animal toxins (3.70%), and viruses (1.76%). Among the above-mentioned etiologies, mushroom toxins, bacteria, and animal toxins had seasonal characteristics. Analysis of regions and etiologies revealed that the proportion of various etiologies was different in 11 prefectures. Wild mushrooms (43.39%), aquatic animals (9.88%), and toxic plants (8.47%) were the top three foods involved in these outbreaks. The most common factors contributing to household foodborne disease outbreaks were inedibility and misuse (59.08%), followed by multiple factors (7.58%), improper storage (7.41%), and improper processing (7.41%). CONCLUSIONS: Household foodborne disease outbreaks were closely related to the lack of knowledge regarding foodborne disease prevention. Therefore, public health agencies should strengthen residents' surveillance and health education to improve food safety awareness and effectively reduce foodborne diseases in households. In addition, timely publicity and early warning by relevant government departments, the introduction of standards to control the contamination of pathogenic bacteria in raw materials, and strengthened supervision of the sale of substances that may cause health hazards, such as poisonous mushrooms and nitrites, will also help reduce such outbreaks.

Asunto(s)

Brotes de Enfermedades , Enfermedades Transmitidas por los Alimentos , China/epidemiología , Humanos , Enfermedades Transmitidas por los Alimentos/epidemiología , Enfermedades Transmitidas por los Alimentos/microbiología , Composición Familiar , Contaminación de Alimentos/análisis , Contaminación de Alimentos/estadística & datos numéricos , Vibrio parahaemolyticus/aislamiento & purificación , Salmonella/aislamiento & purificación , Animales

RESUMEN

Salmonella is a major bacterial concern for public health globally. Although there are limited documentation on the prevalence of Salmonella species in Cambodia's food chain, some reports indicate that salmonellosis is a severe gastrointestinal infection in its population and especially in children. To investigate the presence of Salmonella spp., 285 food samples (75 meat, 50 seafood, and 160 leafy green vegetable samples) were randomly collected from various local markets in Phnom Penh capital and nearby farms in Cambodia. Concurrently, field observations were conducted to collect data on food hygiene and practices among the relevant actors. All food samples were analyzed using bacterial culture and plate counts, and the findings were confirmed serially with biochemical, serological, and PCR tests. The observational data on food hygiene and practices from farm to market revealed that the spread of Salmonella in the food-value chain from farm to market could pose health risks to consumers. The overall prevalence of Salmonella spp. was 48.4% (138/285), while the prevalence in meat, seafood, and vegetables was 71% (53/75), 64% (32/50), and 33% (53/160), respectively. Mean Salmonella plate count ranged from 1.2 to 7.40 log10 CFU/g, and there was no significant difference in bacterial counts between meat, seafood, and vegetable samples (p > 0.05). The most common serogroups among the isolated Salmonella spp. were B and C. These results suggest that a large proportion of meat, seafood, and vegetable products sold at local markets in Phnom Penh are contaminated with Salmonella spp. This is likely linked to inadequate hygiene and sanitation practices, including handling, storage, and preservation conditions. Observations on farms suggested that the prevalence of Salmonella in vegetables sold at the market could be linked to contamination relating to agricultural practices. Thus, controlling the spread of foodborne salmonellosis through the food-value chain from farms and retailers to consumers is warranted to enhance food safety in Cambodia.

Asunto(s)

Granjas , Contaminación de Alimentos , Carne , Salmonella , Alimentos Marinos , Verduras , Cambodia/epidemiología , Verduras/microbiología , Salmonella/aislamiento & purificación , Salmonella/clasificación , Contaminación de Alimentos/análisis , Contaminación de Alimentos/estadística & datos numéricos , Prevalencia , Alimentos Marinos/microbiología , Carne/microbiología , Animales , Microbiología de Alimentos , Humanos , Higiene

RESUMEN

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.

Asunto(s)

Brotes de Enfermedades , Intoxicación Alimentaria por Salmonella , Humanos , Vietnam/epidemiología , Masculino , Adulto , Femenino , Intoxicación Alimentaria por Salmonella/epidemiología , Intoxicación Alimentaria por Salmonella/microbiología , Persona de Mediana Edad , Preescolar , Niño , Adolescente , Lactante , Salmonella/aislamiento & purificación , Adulto Joven , Enfermedades Transmitidas por los Alimentos/epidemiología , Enfermedades Transmitidas por los Alimentos/microbiología , Microbiología de Alimentos , Anciano

RESUMEN

Chlorine and its derivatives have been used as an antibacterial agent to reduce Salmonella contamination in poultry meat during processing. We evaluated the survival of 4 different Salmonella serotypes (Typhimurium, Enteritidis, Heidelberg, and Gaminara) in the presence of 50 ppm sodium hypochlorite (NaOCl) alone or with the addition of thiourea (radical scavenger) or Dip (iron chelator) to determine the contribution of reactive oxygen species (ROS) in the bactericidal activity of NaOCl. The result showed that for all four serotypes the addition of thiourea or Dip significantly increased the % survival as compared to the respective NaOCl treatment groups, while it was significantly higher with thiourea as compared to Dip (P < 0.05). We also evaluated the survival of 11 deletion mutants of S. Typhimurium, which were demonstrated to increase (∆atpC, ∆cyoA, ∆gnd, ∆nuoG, ∆pta, ∆sdhC, and ∆zwf) or decrease the production of ROS (∆edd, ∆fumB, ∆pykA, and ∆tktB) in Escherichia coli (E. coli), in the presence of 50 ppm. The results showed that only two (∆sdhC and ∆zwf) out of 7 ROS-increasing mutants showed reduced % survival as compared to the wild-type (P < 0.05), while all four deletion ROS-decreasing mutants showed significantly higher % survival as compared to the wild-type (P < 0.05). This work suggests that the production of ROS is a major component of the bactericidal activity of NaOCl against Salmonella serotypes and there might be a significant difference in the metabolic pathways involved in ROS production between Salmonella and E. coli.

Asunto(s)

Antibacterianos , Especies Reactivas de Oxígeno , Salmonella , Especies Reactivas de Oxígeno/metabolismo , Salmonella/efectos de los fármacos , Salmonella/genética , Antibacterianos/farmacología , Hipoclorito de Sodio/farmacología , Cloro/farmacología , Desinfectantes/farmacología , Viabilidad Microbiana/efectos de los fármacos , Tiourea/farmacología , Tiourea/análogos & derivados , Animales , Escherichia coli/efectos de los fármacos , Escherichia coli/genética

RESUMEN

Currently, phage biocontrol is increasingly used as a green and natural technology for treating Salmonella and other infections, but phages exhibit instability and activity loss during storage. Therefore, in this study, the effects of lyophilization on the activity and stability of phage cocktails for the control of multidrug-resistant Salmonella in broiler chickens were determined. Eight serotypes of Salmonella were isolated and identified from broiler chicken farms, and bacteriophages against multidrug-resistant Salmonella enterica subsp. enterica serovar Kentucky, Salmonella enterica subsp. enterica serovar Typhimrium and Salmonella enterica subsp. enterica serovar Enteritidis were isolated. The bacteriophage cocktail was prepared and lyophilized, and it was subjected to in vitro and in vivo examinations. A reconstituted lyophilized bacteriophage cocktail was used for the oral treatment of chicks before and after challenge with multidrug-resistant S. Kentucky. The colonization of cecum by S. Kentucky was detected by using real-time PCR, and the serum levels of IgM, IgA and IL-4 and pathological changes in the different groups were detected. Three Caudovirales phages families were identified including Autographiviridae, Straboviridae and Drexlerviridae against multidrug-resistant S. Kentucky, S. Typhimrium and S. Enteritidis. The groups treated with the bacteriophage cocktail showed no clinical signs, no postmortem lesions, and a mortality rate of 0%, which improved the growth performance parameters. Additionally, the estimated serum levels of IgM, IgA and IL-4 were significantly greater in the bacteriophage cocktail-treated groups. Lyophilization effectively preserves the long-term storage stability of phages. Therefore, lyophilized bacteriophage cocktail therapy is a valuable approach for controlling multidrug-resistant Salmonella infections in broiler chickens.

Asunto(s)

Pollos , Farmacorresistencia Bacteriana Múltiple , Liofilización , Enfermedades de las Aves de Corral , Salmonelosis Animal , Fagos de Salmonella , Salmonella , Animales , Pollos/microbiología , Liofilización/métodos , Enfermedades de las Aves de Corral/microbiología , Enfermedades de las Aves de Corral/terapia , Enfermedades de las Aves de Corral/virología , Enfermedades de las Aves de Corral/prevención & control , Salmonelosis Animal/microbiología , Salmonelosis Animal/terapia , Salmonella/virología , Fagos de Salmonella/fisiología , Ciego/microbiología , Ciego/virología , Terapia de Fagos/métodos , Bacteriófagos/genética , Bacteriófagos/fisiología , Bacteriófagos/aislamiento & purificación

RESUMEN

Controlled human infection model (CHIM) studies, which involve deliberate exposure of healthy human volunteers to an infectious agent, are recognised as important tools to advance vaccine development. These studies not only facilitate estimates of vaccine efficacy, but also offer an experimental approach to study disease pathogenesis and profile vaccine immunogenicity in a controlled environment, allowing correlation with clinical outcomes. Consequently, the data from CHIMs can be used to identify immunological correlates of protection (CoP), which can help accelerate vaccine development. In the case of invasive Salmonella infections, vaccination offers a potential instrument to prevent disease. Invasive Salmonella disease, caused by the enteric fever pathogens Salmonella enterica serovar Typhi (S. Typhi) and S. Paratyphi A, B and C, and nontyphoidal Salmonella (iNTS), remains a significant cause of mortality and morbidity in low- and middle-income countries, resulting in over 200,000 deaths and the loss of 15 million DALYs annually. CHIM studies have contributed to the understanding of S. Typhi infection and provided invaluable insight into the development of vaccines and CoP following vaccination against S. Typhi. However, CoP are less well understood for S. Paratyphi A and iNTS. This brief review focuses on the contribution of vaccine-CHIM trials to our understanding of the immune mechanisms associated with protection following vaccines against invasive Salmonella pathogens, particularly in relation to CoP.

Asunto(s)

Infecciones por Salmonella , Vacunas contra la Salmonella , Humanos , Vacunas contra la Salmonella/inmunología , Infecciones por Salmonella/inmunología , Infecciones por Salmonella/prevención & control , Salmonella typhi/inmunología , Vacunación , Eficacia de las Vacunas , Fiebre Tifoidea/prevención & control , Fiebre Tifoidea/inmunología , Salmonella/inmunología

RESUMEN

Large-scale poultry production in low- and middle-income countries may be a source of adulterated products (e.g., Salmonella contamination, antibiotic residues) that can be disseminated over wide areas. We employed a cross-sectional survey of 199 randomly selected poultry farms in Lagos State, Nigeria, to estimate the prevalence of non-typhoidal Salmonella (NTS), and biosecurity and antibiotic use practices. Pooled fecal samples were collected from laying chickens and from poultry handlers. Selective culture, biochemical assays, and PCR (invA) were used to isolate and confirm NTS isolates. NTS was detected at 14% of farms (28/199) and from 10% of farm workers (6/60). Multivariate logistic regression analysis indicated that antiseptic foot dips reduced the odds ratio (OR) for detecting NTS in chicken feces [OR: 0.55; 95% confidence interval (CI) 0.07-0.58]. Most farms (94.5%, 188/199) used antibiotics for treatment and prophylaxis, but no farms (0/199) exercised withdrawal before sale of products. Most farms (86.4%, 172/199) reported using antibiotic cocktails that included medically important colistin, ciprofloxacin, chloramphenicol, and gentamicin. Egg production in Lagos State relies heavily on antibiotics and antibiotic residues are likely passed to consumers through poultry products, but there is evidence that low-cost biosecurity controls are effective for limiting the presence of NTS on farms.

Asunto(s)

Antibacterianos , Pollos , Enfermedades de las Aves de Corral , Salmonella , Animales , Nigeria/epidemiología , Antibacterianos/farmacología , Salmonella/aislamiento & purificación , Salmonella/efectos de los fármacos , Pollos/microbiología , Enfermedades de las Aves de Corral/microbiología , Enfermedades de las Aves de Corral/prevención & control , Estudios Transversales , Salmonelosis Animal/prevención & control , Salmonelosis Animal/epidemiología , Heces/microbiología , Aves de Corral/microbiología , Crianza de Animales Domésticos/métodos , Humanos , Granjas , Prevalencia

RESUMEN

Rats are particularly important from an epidemiological point of view, because they are regarded as reservoirs for diverse zoonotic pathogens including enteric bacteria. This study is the first to report the emergence of Salmonella serovar Ohio in brown rats (Rattus norvegicus) and food-producing animals in Hungary. We first reveal the genomic diversity of the strains and their phylogenomic relationships in the context of the international collection of S. Ohio genomes. This pathogen was detected in 4.3% (4/92) of rats, captured from multiple sites in Hungary. A whole-genome-based genotype comparison of S. Ohio, Infantis, Enteritidis, and Typhimurium strains showed that 76.4% (117/153) of the virulence and antimicrobial resistance genes were conserved among these serovars, and none of the genes were specific to S. Ohio. All S. Ohio strains lacked virulence and resistance plasmids. The cgMLST phylogenomic comparison highlighted a close genetic relationship between rat and poultry strains of S. Ohio from Hungary. These strains clustered together with the international S. Ohio genomes from aquatic environments. Overall, this study contributes to our understanding of the epidemiology of Salmonella spp. in brown rats and highlights the importance of monitoring to minimize the public health risk of rodent populations. However, further research is needed to understand the route of infection and evolution of this serovar.

Asunto(s)

Genoma Bacteriano , Filogenia , Aves de Corral , Salmonelosis Animal , Salmonella , Animales , Ratas , Hungría , Salmonella/genética , Salmonella/clasificación , Salmonella/patogenicidad , Salmonelosis Animal/microbiología , Salmonelosis Animal/epidemiología , Porcinos , Aves de Corral/microbiología , Virulencia/genética , Secuenciación Completa del Genoma

RESUMEN

BACKGROUND: Foodborne diseases (FBDs) represent a significant risk to public health, with nearly one in ten people falling ill every year globally. The large incidence of foodborne diseases in African low- and middle-income countries (LMIC) shows the immediate need for action, but there is still far to a robust and efficient outbreak detection system. The detection of outbreak heavily relies on clinical diagnosis, which are often delayed or ignored due to resource limitations and inadequate surveillance systems. METHODS: In total, 68 samples of non-typhoidal Salmonella isolates from human, animal and environmental sources collected between November 2021 and January 2023 were analyzed using sequencing methods to infer phylogenetic relationships between the samples. A source attribution model using a machine-learning logit-boost that predicted the likely source of infection for 20 cases of human salmonellosis was also run and compared with the results of the cluster detection. RESULTS: Three clusters of samples with close relation (SNP difference < 30) were identified as non-typhoidal Salmonella in Harar town and Kersa district, Ethiopia. These three clusters were comprised of isolates from different sources, including at least two human isolates. The isolates within each cluster showed identical serovar and sequence type (ST), with few exceptions in cluster 3. The close proximity of the samples suggested the occurrence of three potential outbreaks of non-typhoidal Salmonella in the region. The results of the source attribution model found that human cases of salmonellosis could primarily be attributed to bovine meat, which the results of the phylogenetic analysis corroborated. CONCLUSIONS: The findings of this study suggested the occurrence of three possible outbreaks of non-typhoidal Salmonella in eastern Ethiopia, emphasizing the importance of targeted intervention of food safety protocols in LMICs. It also highlighted the potential of integrated surveillance for detecting outbreak and identifying the most probable source. Source attribution models in combination with other epidemiological methods is recommended as part of a more robust and integrated surveillance system for foodborne diseases.

Asunto(s)

Brotes de Enfermedades , Enfermedades Transmitidas por los Alimentos , Filogenia , Infecciones por Salmonella , Salmonella , Humanos , Etiopía/epidemiología , Salmonella/genética , Salmonella/aislamiento & purificación , Salmonella/clasificación , Enfermedades Transmitidas por los Alimentos/microbiología , Enfermedades Transmitidas por los Alimentos/epidemiología , Animales , Infecciones por Salmonella/epidemiología , Infecciones por Salmonella/microbiología

RESUMEN

Understanding the dynamic evolution of Salmonella is vital for effective bacterial infection management. This study explores the role of the flexible genome, organised in regions of genomic plasticity (RGP), in shaping the pathogenicity of Salmonella lineages. Through comprehensive genomic analysis of 12,244 Salmonella spp. genomes covering 2 species, 6 subspecies, and 46 serovars, we uncover distinct integration patterns of pathogenicity-related gene clusters into RGP, challenging traditional views of gene distribution. These RGP exhibit distinct preferences for specific genomic spots, and the presence or absence of such spots across Salmonella lineages profoundly shapes strain pathogenicity. RGP preferences are guided by conserved flanking genes surrounding integration spots, implicating their involvement in regulatory networks and functional synergies with integrated gene clusters. Additionally, we emphasise the multifaceted contributions of plasmids and prophages to the pathogenicity of diverse Salmonella lineages. Overall, this study provides a comprehensive blueprint of the pathogenicity potential of Salmonella. This unique insight identifies genomic spots in nonpathogenic lineages that hold the potential for harbouring pathogenicity genes, providing a foundation for predicting future adaptations and developing targeted strategies against emerging human pathogenic strains.

Asunto(s)

Genoma Bacteriano , Salmonella , Salmonella/genética , Salmonella/patogenicidad , Genoma Bacteriano/genética , Virulencia/genética , Humanos , Genómica/métodos , Familia de Multigenes , Filogenia , Plásmidos/genética , Infecciones por Salmonella/microbiología , Profagos/genética , Evolución Molecular

RESUMEN

Multiple drug resistance (MDR) has gained pronounced attention among Enterobacterales. The transfer of multiple antimicrobial resistance genes, frequently carried on conjugative incompatibility F (IncF) plasmids and facilitating interspecies resistance transmission, has been linked to Salmonella spp. and E. coli in broilers. In Egypt, the growing resistance is exacerbated by the limited clinical efficacy of many antimicrobials. In this study, IncF groups were screened and characterized in drug-resistant Salmonella spp. and E. coli isolated from broilers. The antimicrobial resistance profile, PCR-based replicon typing of bacterial isolates pre- and post-plasmid curing, and IncF replicon allele sequence typing were investigated. Five isolates of E. coli (5/31; 16.13%) and Salmonella spp. (5/36; 13.89%) were pan-susceptible to the examined antimicrobial agents, and 85.07% of tested isolates were MDR and extensively drug-resistant (XDR). Twelve MDR and XDR E. coli and Salmonella spp. isolates were examined for the existence of IncF replicons (FII, FIA, and FIB). They shared resistance to ampicillin, ampicillin/sulbactam, amoxicillin/clavulanate, doxycycline, cefotaxime, and colistin. All isolates carried from one to two IncF replicons. The FII-FIA-FIB+ and FII-FIA+FIB- were the predominant replicon patterns. FIB was the most frequently detected replicon after plasmid curing. Three XDR E. coli isolates that were resistant to 12-14 antimicrobials carried a newly FIB replicon allele with four nucleotide substitutions: C99→A, G112→T, C113→T, and G114→A. These findings suggest that broilers are a significant reservoir of IncF replicons with highly divergent IncF-FIB plasmid incompatibility groups circulating among XDR Enterobacterales. Supporting these data with additional comprehensive epidemiological studies involving replicons other than the IncF can provide insights for implementing efficient policies to prevent the spreading of new replicons to humans.

Asunto(s)

Alelos , Pollos , Farmacorresistencia Bacteriana Múltiple , Infecciones por Escherichia coli , Escherichia coli , Plásmidos , Enfermedades de las Aves de Corral , Replicón , Animales , Pollos/microbiología , Escherichia coli/genética , Escherichia coli/efectos de los fármacos , Replicón/genética , Farmacorresistencia Bacteriana Múltiple/genética , Plásmidos/genética , Enfermedades de las Aves de Corral/microbiología , Infecciones por Escherichia coli/microbiología , Infecciones por Escherichia coli/veterinaria , Antibacterianos/farmacología , Pruebas de Sensibilidad Microbiana , Salmonella/genética , Salmonella/efectos de los fármacos

RESUMEN

BACKGROUND: The increased resistance rate of Salmonella to third-generation cephalosporins represented by ceftriaxone (CRO) may result in the failure of the empirical use of third-generation cephalosporins for the treatment of Salmonella infection in children. The present study was conducted to evaluate a novel method for the rapid detection of CRO-resistant Salmonella (CRS). METHODS: We introduced the concept of the ratio of optical density (ROD) with and without CRO and combined it with matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) to establish a new protocol for the rapid detection of CRS. RESULTS: The optimal incubation time and CRO concentration determined by the model strain test were 2 h and 8 µg/ml, respectively. We then conducted confirmatory tests on 120 clinical strains. According to the receiver operating characteristic curve analysis, the ROD cutoff value for distinguishing CRS and non-CRS strains was 0.818 [area under the curve: 1.000; 95% confidence interval: 0.970-1.000; sensitivity: 100.00%; specificity: 100%; P < 10- 3]. CONCLUSIONS: In conclusion, the protocol for the combined ROD and MALDI-TOF MS represents a rapid, accurate, and economical method for the detection of CRS.

Asunto(s)

Antibacterianos , Ceftriaxona , Pruebas de Sensibilidad Microbiana , Infecciones por Salmonella , Salmonella , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Ceftriaxona/farmacología , Humanos , Antibacterianos/farmacología , Salmonella/efectos de los fármacos , Infecciones por Salmonella/microbiología , Pruebas de Sensibilidad Microbiana/métodos , Farmacorresistencia Bacteriana , Sensibilidad y Especificidad , Curva ROC

RESUMEN

Salmonella-related foodborne illness is a significant public health concern, with the primary source of human infection being animal-based food products, particularly chicken meat. Lebanon is currently experiencing a dual crisis: the COVID-19 pandemic and an unprecedented economic crisis, which has resulted in substantial challenges to the public health system and food safety. This study aims to assess the prevalence and antibiotic resistance profile of Salmonella in raw poultry meat sold in North Lebanon during this dual crisis. A cross-sectional study was carried out between May 2021 and April 2022 across six different districts in North Lebanon. A total of 288 whole, unprocessed chickens were examined. The isolation and identification of Salmonella isolates were done based on cultural and biochemical properties. All isolates were subjected to antimicrobial susceptibility testing and phenotypic assays for Extended-Spectrum Beta-lactamase (ESBL) detection. The prevalence of Salmonella in raw poultry meat purchased in North Lebanon reached 18.05 % (52/288). The dry season and chilled chicken were significantly associated with an increased risk of Salmonella contamination (P < 0.05). Additionally, 34.61 % of the isolates were potential ESBL producers, and 57.69 % exhibited multidrug resistance (MDR). This study highlights the existence of MDR in chicken meat in North Lebanon, posing a potential health risk if undercooked chicken meat is consumed. This emphasizes the importance of the implementation of preventive strategies and hygienic procedures throughout the food chain to reduce the risk of Salmonella spp. contamination in chicken meats and its potential transmission to humans.

Asunto(s)

COVID-19 , Pollos , Salmonella , Animales , Líbano/epidemiología , Salmonella/efectos de los fármacos , Salmonella/aislamiento & purificación , Estudios Transversales , Prevalencia , COVID-19/epidemiología , COVID-19/prevención & control , Carne/microbiología , Recesión Económica , Farmacorresistencia Bacteriana , Antibacterianos/farmacología , SARS-CoV-2 , Microbiología de Alimentos , Enfermedades de las Aves de Corral/epidemiología , Enfermedades de las Aves de Corral/microbiología , Salmonelosis Animal/epidemiología , Salmonelosis Animal/microbiología

RESUMEN

Concerns are rising about the contamination of recreational waters from human and animal waste, along with associated risks to public health. However, existing guidelines for managing pathogens in these environments have not yet fully integrated risk-based pathogen-specific criteria, which, along with recent advancements in indicators and markers, are essential to improve the protection of public health. This study aimed to establish risk-based critical concentration benchmarks for significant enteric pathogens, i.e., norovirus, rotavirus, adenovirus, Cryptosporidium spp., Giardia lamblia, Campylobacter jejuni, Salmonella spp., and Escherichia coli O157:H7. Applying a 0.036 risk benchmark to both marine and freshwater environments, the study identified the lowest critical concentrations for children, who are the most susceptible group. Norovirus, C. jejuni, and Cryptosporidium presented lowest median critical concentrations for virus, bacteria, and protozoa, respectively: 0.74 GC, 1.73 CFU, and 0.39 viable oocysts per 100 mL in freshwater for children. These values were then used to determine minimum sample volumes corresponding to different recovery rates for culture method, digital polymerase chain reaction and quantitative PCR methods. The results indicate that for children, norovirus required the largest sample volumes of freshwater and marine water (52.08 to 178.57 L, based on the 5th percentile with a 10 % recovery rate), reflecting its low critical concentration and high potential for causing illness. In contrast, adenovirus and rotavirus required significantly smaller volumes (approximately 0.24 to 1.33 L). C. jejuni and Cryptosporidium, which required the highest sampling volumes for bacteria and protozoa, needed 1.72 to 11.09 L and 4.17 to 25.51 L, respectively. Additionally, the presented risk-based framework could provide a model for establishing pathogen thresholds, potentially guiding the creation of extensive risk-based criteria for various pathogens in recreational waters, thus aiding public health authorities in decision-making, strengthening pathogen monitoring, and improving water quality testing accuracy for enhanced health protection.

Asunto(s)

Cryptosporidium , Monitoreo del Ambiente , Microbiología del Agua , Monitoreo del Ambiente/métodos , Humanos , Cryptosporidium/aislamiento & purificación , Norovirus/aislamiento & purificación , Agua Dulce/virología , Medición de Riesgo/métodos , Giardia lamblia/aislamiento & purificación , Recreación , Agua de Mar/virología , Campylobacter jejuni/aislamiento & purificación , Rotavirus/aislamiento & purificación , Salmonella/aislamiento & purificación

RESUMEN

Bacteria have evolved a broad range of systems that provide defence against their viral predators, bacteriophages. Bacteriophage Exclusion (BREX) systems recognise and methylate 6 bp non-palindromic motifs within the host genome, and prevent replication of non-methylated phage DNA that encodes these same motifs. How BREX recognises cognate motifs has not been fully understood. In this study we characterise BREX from pathogenic Salmonella and present X-ray crystallographic structures of the conserved BREX protein, PglX. The PglX N-terminal domain encodes the methyltransferase, whereas the C-terminal domain is for motif recognition. We also present the structure of PglX bound to the phage-derived DNA mimic, Ocr, an inhibitor of BREX activity. Our analyses propose modes for DNA-binding by PglX and indicate that both methyltransferase activity and defence require larger BREX complexes. Through rational engineering of PglX we broaden both the range of phages targeted, and the host motif sequences that are methylated by BREX. Our data demonstrate that PglX is used to recognise specific DNA sequences for BREX activity, contributing to motif recognition for both phage defence and host methylation.

Asunto(s)

Bacteriófagos , Metiltransferasas , Metiltransferasas/metabolismo , Metiltransferasas/genética , Bacteriófagos/genética , Bacteriófagos/enzimología , Cristalografía por Rayos X , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Metilación de ADN , Salmonella/virología , Salmonella/genética , ADN Viral/genética , ADN Viral/metabolismo , Modelos Moleculares

RESUMEN

The H9N2 avian influenza virus (AIV) is spreading worldwide. Presence of H9N2 virus tends to increase the chances of infection with other pathogens which can lead to more serious economic losses. In a previous study, a regulated delayed lysis Salmonella vector was used to deliver a DNA vaccine named pYL233 encoding M1 protein, mosaic HA protein and chicken GM-CSF adjuvant. To further increase its efficiency, chitosan as a natural adjuvant was applied in this study. The purified plasmid pYL233 was coated with chitosan to form a DNA containing nanoparticles (named CS233) by ionic gel method and immunized by intranasal boost immunization in birds primed by oral administration with Salmonella strain. The CS233 DNA nanoparticle has a particle size of about 150 nm, with an encapsulation efficiency of 93.2 ± 0.12 % which protected the DNA plasmid from DNase I digestion and could be stable for a period of time at 37°. After intranasal boost immunization, the CS233 immunized chickens elicited higher antibody response, elevated CD4+ T cells and CD8+ T cells activation and increased T-lymphocyte proliferation, as well as increased productions of IL-4 and IFN-γ. After challenge, chickens immunized with CS233 resulted in the lowest levels of pulmonary virus titer and viral shedding as compared to the other challenge groups. The results showed that the combination of intranasal immunization with chitosan-coated DNA vaccine and oral immunization with regulatory delayed lytic Salmonella strain could enhance the immune response and able to provide protection against H9N2 challenge.

Asunto(s)

Administración Intranasal , Anticuerpos Antivirales , Pollos , Quitosano , Inmunidad Celular , Subtipo H9N2 del Virus de la Influenza A , Vacunas contra la Influenza , Gripe Aviar , Plásmidos , Vacunas de ADN , Esparcimiento de Virus , Animales , Subtipo H9N2 del Virus de la Influenza A/inmunología , Subtipo H9N2 del Virus de la Influenza A/genética , Vacunas de ADN/inmunología , Vacunas de ADN/administración & dosificación , Gripe Aviar/prevención & control , Gripe Aviar/inmunología , Pollos/inmunología , Vacunas contra la Influenza/inmunología , Vacunas contra la Influenza/administración & dosificación , Anticuerpos Antivirales/sangre , Plásmidos/genética , Nanopartículas , Inmunización Secundaria , Linfocitos T CD8-positivos/inmunología , Adyuvantes Inmunológicos/administración & dosificación , Interferón gamma , Interleucina-4 , Adyuvantes de Vacunas , Enfermedades de las Aves de Corral/prevención & control , Enfermedades de las Aves de Corral/inmunología , Enfermedades de las Aves de Corral/virología , Linfocitos T CD4-Positivos/inmunología , Salmonella/inmunología , Salmonella/genética

RESUMEN

Oxaliplatin is currently used for chemotherapy in patients with hepatocellular carcinoma, but its increasing tolerance to tumours over time limits its clinical application. Studies have shown that high PD-L1 expression promotes the polarization of M2 macrophages. The increased infiltration of M2 macrophages, including those in HCC, is positively correlated with poor prognosis in various solid tumours. We found that oxaliplatin promoted the expression of PD-L1 in liver cancer cells, which might be attributed partly to the tolerance of tumours to oxaliplatin. Therefore, in this study, we explored the antitumour effect of attenuated Salmonella carrying siRNA-PD-L1 combined with oxaliplatin via Western blotting, immunohistochemistry, immunofluorescence, and flow cytometry. The results revealed that attenuated Salmonella carrying siRNA-PD-L1 combined with oxaliplatin more significantly inhibited tumour growth in tumour-bearing mice, suppressed the expression of PD-L1 in tumour tissue, increased the apoptosis of tumour cells and the expression of the tumour-related protein cleaved-caspase3, and increased the infiltration of M1 macrophages and T lymphocytes in tumour tissues. Moreover, the combination therapy increased the activation of T cells and the number of T lymphocytes and NK cells in the spleens of the mice and improved the overall antitumour immune response in the mice. Our results confirmed that attenuated Salmonella harbouring siRNA-PD-L1 combined with oxaliplatin had a significant antitumour effect and did not increase the incidence of toxic side effects, providing a theoretical reference for addressing oxaliplatin tolerance in the treatment of hepatocellular carcinoma.

Asunto(s)

Antígeno B7-H1 , Carcinoma Hepatocelular , Neoplasias Hepáticas , Oxaliplatino , ARN Interferente Pequeño , Animales , Oxaliplatino/uso terapéutico , Oxaliplatino/farmacología , Antígeno B7-H1/metabolismo , Antígeno B7-H1/genética , Antígeno B7-H1/antagonistas & inhibidores , ARN Interferente Pequeño/genética , Carcinoma Hepatocelular/tratamiento farmacológico , Carcinoma Hepatocelular/inmunología , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/inmunología , Ratones , Humanos , Antineoplásicos/uso terapéutico , Antineoplásicos/farmacología , Macrófagos/inmunología , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Línea Celular Tumoral , Apoptosis/efectos de los fármacos , Salmonella , Ratones Endogámicos BALB C , Masculino , Terapia Combinada , Modelos Animales de Enfermedad , Linfocitos T/inmunología , Linfocitos T/efectos de los fármacos

RESUMEN

Nontyphoidal Salmonella (NTS) is the main etiological agent of human nontyphoidal salmonellosis. The aim of this study was to analyze the epidemiological characteristics and horizontal transfer mechanisms of antimicrobial resistance (AMR) genes from eight strains of NTS detected in Zhenjiang City, Jiangsu Province, China. Fecal samples from outpatients with food-borne diarrhea were collected in 2022. The NTS isolates were identified, and their susceptibility was tested with the Vitek 2 Compact system. The genomes of the NTS isolates were sequenced with the Illumina NovaSeq platform and Oxford Nanopore Technologies platform. The AMR genes and mobile genetic elements (MGEs) were predicted with the relevant open access resources. Eight strains of NTS were isolated from 153 specimens, and Salmonella Typhimurium ST19 was the most prevalent serotype. The AMR gene with the highest detection rate was AAC(6')-Iaa (10.5%) followed by TEM-1 (7.9%), sul2 (6.6%), and tet(A) (5.3%). Eleven MGEs carrying 34 AMR genes were identified on the chromosomes of 3 of the 8 NTS, including 3 resistance islands, 6 composite transposons (Tns), and 2 integrons. Eighteen plasmids carrying 40 AMR genes were detected in the 8 NTS strains, including 6 mobilizable plasmids, 3 conjugative plasmids, and 9 nontransferable plasmids, 7 of which carried 10 composite Tns and 3 integrons. This study provided a theoretical basis, from a genetic perspective, for the prevention and control of NTS resistance in Zhenjiang City. IMPORTANCE: Human nontyphoidal salmonellosis is one of the common causes of bacterial food-borne illnesses, with significant social and economic impacts, especially those caused by invasive multidrug-resistant nontyphoidal Salmonella, which entails high morbidity and mortality. Antimicrobial resistance is mainly mediated by drug resistance genes, and mobile genetic elements play key roles in the capture, accumulation, and dissemination of antimicrobial resistance genes. Therefore, it is necessary to study the epidemiological characteristics and horizontal transfer mechanisms of antimicrobial resistance genes of nontyphoidal Salmonella to prevent the spread of multidrug-resistant nontyphoidal Salmonella.

Asunto(s)

Secuencias Repetitivas Esparcidas , Infecciones por Salmonella , Salmonella , Humanos , Salmonella/genética , Salmonella/efectos de los fármacos , Salmonella/aislamiento & purificación , Secuencias Repetitivas Esparcidas/genética , Infecciones por Salmonella/microbiología , Infecciones por Salmonella/epidemiología , Antibacterianos/farmacología , China/epidemiología , Farmacorresistencia Bacteriana/genética , Pruebas de Sensibilidad Microbiana , Transferencia de Gen Horizontal , Genoma Bacteriano/genética , Plásmidos/genética , Genómica , Heces/microbiología