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Objective@#To investigate risk factors and the nature of the outbreak of bacillary dysentery in Lhasa City, so as to customize targeted prevention and control measures.@*Methods@#Using on site epidemiological investigation, the suspected, probable and confirmed cases of bacillary dysentery in one school and one kindergarten in Lhasa City from June 26 to July 1, 2022 were collected, and additional cases were identified through interview from school staffs and family members, reviewing morning examination records and tracking records of school illness related absence. A case control study was conducted to investigate suspicious meals and drinking raw water, and polymerase chain reaction (PCR) was performed to detect Shigella line nucleic acid fragment in the patients feces, anal swabs, retained food, and terminal water.@*Results@#A total of 55 cases were found in two schools, with the prevalence rate of 15.41% in total and 16.71% in students ( n =53), 7.5% in staff ( n =2). The epidemic curve was suggestive of a point source exposure. The prevalence rate among students who walk to school and students who live in the school showed no difference (16.10%，17.09%)( χ 2=0.05, P >0.05), and the prevalence rate was higher among elementary school students than kindergarten students (19.83%，6.67%)( χ 2=7.13, P <0.05). Case control comparisons showed a direct association between drinking raw water and morbidity in the case and control groups during June 24-26 ( OR=4.01, 95%CI =1.75-9.19, P < 0.05). A total of 23 fecal Shigella nucleic acid positives were detected from the two schools, two from the end water in front of the cafeteria door, and two from sludge in the sewage pipe around the wellhead.@*Conclusions@#The outbreak of bacillary dysentery is caused by the contamination of the pipe network water. Health administrative departments should improve the supervision and management of drinking water health safety, and schools should strengthen the management of water supply facilities for effectively prevent of waterborne infectious disease outbreaks.
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Background & objectives: Shiga toxin (Stx) is produced by Shigella dysenteriae, a Gram-negative, facultative anaerobic bacillus that causes shigellosis, haemolytic uraemic syndrome (HUS) and Reiter's syndrome. The detection methods for shiga toxin needs to be rapid, accurate, reliable and must be extensively evaluated under field conditions. The aim of this study was to develop rapid, sensitive and specific detection method for Stx. Methods: Mice and rabbits were immunized with purified recombinant Shiga toxin B (rStxB). Using these antibodies dot ELISA, sandwich ELISA and flow through assay were developed. Results: The high-titre antibodies specifically reacted with purified rStxB. Dot-ELISA, sandwich ELISA and flow-through assay were developed and standardized that could detect StxB with limit of detection (LOD) of 9.75, 9.7 ng/ml and 0.46 ?g/cassette, respectively. Interpretation & conclusions: The rStxB was used to produce antibodies to avoid handling of pathogen. The Flow through assay 'developed was specific, rapid and field amenable.
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Shiga toxin (Stx), which can be divided into Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2), is an important virulence factor of Shigella spp. and certain strains of Escherichia coli. Stx, enco-ded by λ-like phage, blocks protein synthesis through removal of an adenine residue from the 28S rRNA. Stx can also induce apoptosis through multiple pathways. Humans may suffer from diarrhea, hemorrhagic colitis ( HC) and hemolytic uremic syndrome ( HUS) and even death when infected with Shiga toxin-producing bac-teria. At present, there is no specific treatment for diseases caused by Stx. In recent years, the application of Stx in cancer therapy and imaging has aroused great interest. This review provided a brief overview of Stx in its nomenclature, typing, structure, genetics, pathogenesis and application perspectives.
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Objective To understand the epidemiological characteristics of bacillary dysentery and etiological characteristics of Shigella in Tianjin, and to provide evidence for the prevention and control measures. Methods The data of disease surveillance information reporting system from 2008 to 2014 were analyzed retrospectively. A total of 3955 stool samples came from the clinically diagnosed cases of bacillary dysentery were collected, according to the extraction method of stratified sampling in Tianjin city, suburban area, Binhai New Area and suburban area sentinel hospitals, and according to the sampling interval for the May to October from 2008 to 2014. Samples were detected and cultured for Shigella flora. Results (1) Epidemiological characteristics:from 2008 to 2014, a total of 65179 cases of bacillary dysentery were reported in Tianjin city, with an average annual incidence of 72.00/100 thousand. The annual incidence rate showed a downward trend year by year. The incidence was a downward trend, including urban (120.28/100 thousand), suburban areas (70.36/100 thousand), Binhai New Area (64.22/100 thousand) and the outer suburbs (19.39/100 thousand). The onset time was mainly concentrated in June-September, and the peak incidence occurred in August. The incidence rate was higher in people below 5 years old and above the age of 85. The annual incidence rate was higher in male patients of 0 to 24 years old and above 75 years old than that of female. The annual incidence rate was higher in female patients of 50 to 74 years old age group than that of male (P<0.05). The distribution of occupation was scattered among children and retirees. (2) Distribution of bacteria:the 229 Shigella strains were positive (5.79%), including 136 strains of Shigella sonnei (59.39%), 93 strains of Shigella flexneri (40.61%). The 89 strains of Shigella flexneri (4 strains were not detected) were detected in 8 subtypes, F2a (49.44%), F2b (22.47%) and FX (13.48%). The subtypes of Shigella flexneri were detected decreased year by year from 2008 to 2014, showing a single subtype. The highest detection rate of Shigella was found in 10-19 years old (9.55%). The S.sonnei positive rate was the highest in urban (5.09%), and the Shigella flexneri positive rate was the highest in suburban areas (3.09%). Conclusion The key population for the prevention and control of bacillary dysentery in Tianjin is scattered children and old people. It is necessary to strengthen the propaganda and health education to improve the health consciousness of the key population and their daily nursing staff. With the continuous changes of Shigella flora, it is necessary to carry out long-term monitoring to find out the regularity of shigella.
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Shiga toxin producing bacteria are potential causes of serious human disease such as hemorrhagic colitis, severe inflammations of ileocolonic regions of gastrointestinal tract, thrombocytopenia, septicemia, malignant disorders in urinary ducts, hemolytic uremic syndrome (HUS) Shiga toxin 1 (stx1), shiga toxin 2 (stx2), or a combination of both are responsible for most clinical symptoms of these diseases. A lot of methods have been developed so far to detect shiga toxins such as cell culture, ELISA, and RFPLA, but due to high costs and labor time in addition to low sensitivity, they have not received much attention. In this study, PCR-ELISA method was used to detect genes encoding shiga toxins 1 and 2 (stx1 and stx2). To detect stx1 and stx2 genes, two primer pairs were designed for Multiplex-PCR then PCR-ELISA. PCR products (490 and 275, respectively) were subsequently verified by sequencing. Sensitivity and specificity of PCR-ELISA method were determined by using genome serial dilution and Enterobacteria strains. PCR-ELISA method used in this study proved to be a rapid and precise approach to detect different types of shiga toxins and can be used to detect bacterial genes encoding shiga toxins.
Subject(s)
Adult , Aged , Child , Female , Humans , Male , Middle Aged , /chemistry , Shiga Toxin 1/isolation & purification , /isolation & purification , Shigella dysenteriae/chemistry , DNA, Bacterial/genetics , Enzyme-Linked Immunosorbent Assay , /genetics , Feces/microbiology , Genes, Bacterial/genetics , Polymerase Chain Reaction , Sensitivity and Specificity , Shiga Toxin 1/genetics , /genetics , Shigella dysenteriae/geneticsABSTRACT
Aims: This study was carried out to assess the antimicrobial effect of the volatile oil of Thaumatococcus danielli (Benn.) Benth. leaves against selected enteric pathogens and its possible inhibition against a partially purified and characterized extracellular protease of Shigella dysenteriae. Study Design: The volatile oil was used as antibacterial agent against eight enteric pathogens and as potential inhibitor to a partially purified extracellular protease of Shigella dysenteriae. Place and Duration of Study: Department of Biochemistry, Faculty of Science, Lagos State University, Ojo Lagos State, Nigeria; between May – September 2013. Methodology: The volatile oil was extracted by hydrodistillation. The sensitivity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the volatile oil against the pathogens were determined by disc-diffusion and micro-dilution techniques. The extracellular protease of Shigella dysenteriae was partially purified by (NH4)2SO4 salting-out followed by gel filtration chromatography. Enzyme assay was carried out with casein (as substrate) and volatile oil (as inhibitor). Results: The average inhibition zones ranged from 16 – 30 mm. Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecalis remained insensitive to the oil. Shigella dysenteriae and Proteus vulgaris showed highest and lowest sensitivities respectively. Highest purification fold of 2.63 with specific activity of 18.4μmol/min/mg protein were obtained after Sephadex G-75 gel filtration of the enzyme extract. The oil competitively inhibited the partially purified extracellular protease of Shigella dysenteriae with Vmax = 8.33 ΔA/min, Km = 0.85mg/ml (no inhibitor) and apparent Km´ = 1.54mg/ml (inhibitor). Optimal activities of this protease were obtained at pH 7.5 and 30ºC. Conclusion: Though, it may not be clarified whether the oil interacted with the substrate/enzyme. Nevertheless, there was an inhibition of the extracellular protease of Shigella dysenteriae by the volatile oil of Thaumatococcus danielli (Benn.) Benth. It was therefore envisaged that elaborate work on the inhibition of this type of enzyme in pathogens by essential oil would be a platform of arresting infection caused by bacteria.
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In the field of studies of acute toxicity induced by bacterial agents, Shiga toxins have been relevant due to the severity of the extra-intestinal diseases they cause. Numerous studies have shown that Shiga toxin induced apoptosis in different cell types; however, this important process has been little studied in vivo experimental models. In this study, the effects of excretion products of Shigella dysenteriae, in which Shiga toxin is present, were investigated on early larval stages of Zebrafish, an animal model with many advantages over other in vivo experimental models traditionally used. Both the collection of eggs and larvae of Zebrafish, and the product from excretion from Shigella dysenteriae (SdyEP) were performed according to laboratory standards. Also, toxicity bioassay, larvae treatment with pure and diluted solution, 10-1, 10-2, 10-3 , 10-4 and 10-5, v/v SdyEP and cell death in vivo using Acridine Orange (AO) and Ethidium Bromide (EB) were applied. The excretion product of Shigella dysenteriae (SdyEP) effect was expressed in terms of larval mortality and dependent dilution rather than incubation time. The larval population surviving treatment with Shigella excretion product presents severe morphological effects. The larval population generally presents notable severe morphological damage, the necrosis state is represented by the opacity of the larvae after being treated for 24 h (b) compared to control. Other changes associated with larval anatomy were also observed; particularly the caudal end curvature was significant into 10%. The use of AO/EB revealed a distribution pattern from fluorescence into green and orange in surviving larvae SdyEP poisoning, there was a large population of dead cells around the anal and caudal region as evidenced by the presence of orange nuclei in greater numbers as controls in the larvae. The results support the application of coloring AO/EB in Zebrafish experimental models for the evaluation of the toxic action of new molecules and new products with therapeutic potential.
En el campo de los estudios de toxicidad aguda inducida por agentes bacterianos, las toxinas Shiga resultan relevantes debido a la severidad de las enfermedades extra-intestinales que causan. Numerosos estudios han demostrado que la toxina Shiga induce la apoptosis en diferentes tipos de células, sin embargo, este importante proceso ha sido poco estudiado en modelos experimentales in vivo. En este estudio, fueron evaluados los efectos del productos de excreción de Shigella dysenteriae (PESdy), sobre estadios larvarios de pez cebra (Danio rerio), un modelo animal con muchas ventajas sobre otros modelos experimentales in vivo utilizados tradicionalmente. Tanto la recolección de los huevos y larvas de pez cebra, así como la obtención del producto de la excreción, se realizaron de acuerdo a los estándares de laboratorio. Poblaciones larvarias, fueron tratadas con distintas soluciones; pura y diluidas, 101, 10-2, 10-3, 10-4 y 10-5, v/v de PESdy. La muerte celular in vivo, usando naranja de acridina (NA) y bromuro de etidio (BE) fue evaluada. El efecto del SdyEP, se expresó como dependiente de la concentracion y del tiempo de exposición. La población de larvas sobrevivientes, presentaron curvatura troncal en un 10%, en relación a los controles. La necrosis se puso en evidencia a través de la opacidad de las larvas después de 24 h. El uso de NA/BE reveló un patrón de distribución de la fluorescencia en verde y naranja en larvas sobrevivientes al tratamiento. Una granpoblación de células muertas, alrededor de la región anal y caudal, se ponen en evidencia por la presencia de núcleos de naranja en mayor número que en los controles. Los resultados apoyan la aplicación de la coloración NA/BE en modelo experimental de pez cebra, para la evaluación de la acción tóxica de nuevas moléculas y nuevos productos de excreción bacterial con potencial terapéutico.
Subject(s)
Shigella dysenteriae/physiology , Zebrafish , Apoptosis , Shiga Toxin/toxicity , Acridine Orange , Ethidium , LarvaABSTRACT
In the field of studies of acute toxicity induced by bacterial agents, Shiga toxins have been relevant due to the severity of the extra-intestinal diseases they cause. Numerous studies have shown that Shiga toxin induced apoptosis in different cell types; however, this important process has been little studied in vivo experimental models. In this study, the effects of excretion products of Shigella dysenteriae, in which Shiga toxin is present, we investigated on early larval stages of Zebrafish, an animal model with many advantages over other in vivo experimental models traditionally used. Both the collection of eggs and larvae of Zebrafish, and the product from excretion from Shigella dysenteriae (SdyEP) were performed according to laboratory standards. Also, toxicity bioassay, larvae treatment with pure and diluted solution, 10-1, 10-2, 10-3 , 10-4 and 10-5 v/v SdyEP and cell death in vivo using Acridine Orange (AO) and Ethidium Bromide (EB) were applied. The excretion product of Shigella dysenteriae (SdyEP) effect was expressed in terms of larval mortality and dependent dilution rather than incubation time. The larval population surviving treatment with Shigella excretion product presents severe morphological effects. The larval population generally presents notable severe morphological damage, the necrosis state is represented by the opacity of the larvae after being treated for 24 h (b) compared to control. Other changes associated with larval anatomy were also observed; particularly the caudal end curvature was significant into 10%. The use of AO/EB revealed a distribution pattern from fluorescence into green and orange in surviving larvae SdyEP poisoning, there was a large population of dead cells around the anal and caudal region as evidenced by the presence of orange nuclei in greater numbers as controls in the larvae. The results support the application of coloring AO/EB in Zebrafish experimental...
En el campo de los estudios de toxicidad aguda inducida por agentes bacterianos, las toxinas Shiga resultan relevantes debido a la severidad de las enfermedades extra-intestinales que causan. Numerosos estudios han demostrado que la toxina Shiga induce la apoptosis en diferentes tipos de células, sin embargo, este importante proceso ha sido poco estudiado en modelos experimentales in vivo. En este estudio, fueron evaluados los efectos del productos de excreción de Shigella dysenteriae (PESdy), sobre estadios larvarios de pez cebra (Danio rerio), un modelo animal con muchas ventajas sobre otros modelos experimentales in vivo utilizados tradicionalmente. Tanto la recolección de los huevos y larvas de pez cebra, así como la obtención del producto de la excreción, se realizaron de acuerdo a los estándares de laboratorio. Poblaciones larvarias, fueron tratadas con distintas soluciones; pura y diluidas, 10-1, 10-2, 10-3 , 10-4 and 10-5 v/v de PESdy. La muerte celular in vivo, usando naranja de acridina (NA) y bromuro de etidio (BE) fue evaluada. El efecto del PESdy, se expresó como dependiente de la concentración y del tiempo de exposición. La población de larvas sobrevivientes, presentaron curvatura troncal en un 10 por ciento, en relación a los controles. La necrosis se puso en evidencia a través de la opacidad de las larvas después de 24 h. El uso de NA/BE reveló un patrón de distribución de la fluorescencia en verde y naranja en larvas sobrevivientes al tratamiento. Una gran población de células muertas, alrededor de la región anal y caudal, se ponen en evidencia por la presencia de núcleos de naranja en mayor número que en los controles. Los resultados apoyan la aplicación de la coloración NA/BE en modelo experimental...
Subject(s)
Animals , Apoptosis , Larva , Shigella dysenteriae/pathogenicity , Shiga Toxin/toxicity , Zebrafish , Acridine Orange , Cell Death , EthidiumABSTRACT
Background & objectives: The four species of the genus Shigella, namely, S. dysenteriae, S. flexneri, S. boydii and S. sonnei cause a wide spectrum of illness from watery diarrhoea to severe dysentery. Genomes of these four species show great diversity. In this study, NotI, XbaI or I-CeuI restriction enzyme digested genomes of two Shigella dysenteriae isolates belonging to the serotypes 2 and 7 were extensively analyzed to find their relatedness, if any, with the whole genome sequenced strains of S. dysenteriae type 1 and S. flexneri type 2a. Methods: Pulsed-field gel electrophoresis (PFGE) technique was used to determine the diversity of Shigella genomes by rapid construction of physical maps. DNA end labelling, Southern hybridization and PCR techniques were also applied for mapping purposes. Results: The intron-coded enzyme I-CeuI cuts the bacterial genome specifically at its rrn operon. PFGE of I-CeuI digested S. dysenteriae genomes were found to carry seven rrn operons. However, I-CeuI profiles showed distinct restriction fragment polymorphism (RFLP) between the isolates as well as with the whole genome sequenced isolates. Further studies revealed that the genome sizes and I-CeuI linkage maps of the S. dysenteriae type 7 and type 2 isolates were similar to that of S. dysenteriae type 1 and S. flexneri type 2a genomes, respectively. Interpretation & conclusions: Our findings indicate that the type 7 and type 1 isolates of S. dysenteriae were probably evolved from a same precursor, while the type 2 and S. flexneri type 2a were probably evolved and diversified from a common progenitor.
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Haemolytic-uraemic syndrome (HUS) is a serious sequela of diarrhoea and results in a high mortality rate. This systematic review aimed at estimating the proportion of HUS cases that are linked to prior infection due to Shiga toxin-producing Escherichia coli (STEC) or Shigella dysenteriae type 1. A systematic review of the existing literature was done to identify cohort and case-control studies that examined the relationship between STEC and S. dysenteriae type 1 and HUS. After screening 2,516 articles, 11 studies were found that met the inclusion/exclusion criteria. Findings of case-control studies suggest that 60.8% of the HUS cases may be attributable to a previous infection with STEC. In cohort studies, 7.8% of participants with STEC and 8% of participants with S. dysenteriae type 1 developed HUS during follow-up. HUS is linked to diarrhoea due to both STEC and S. dysenteriae type 1. Thus, preventing infections caused by both pathogens is critical for the prevention and control of HUS, especially in areas where timely and effective treatment is not available.
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Objective Clinical strains of Shigella dysenteriae isolated from eastern parts of India in 1988, 1995 and 2002 were examined for the presence of class 1, 2 and 3 integrons which closely related with drug resistance and the distribution of resistance gene cassette in order to clarify the influence of integron system on drug resistance of Shigella dysenteriae. Methods Susceptibility to antimicrobial agents was tested by the disk agar diffusion method. Class 1, 2 and 3 integron genes (intI) were screened by polymerase chain reaction (PCR) in 16 clinical strains with drug resistance.The variable regions of gene cassette of positive strains were sequenced. Results All 16 isolates were resistant to at least 4 agents including β-lactams, aminoglycosides, tetracyclines, sulfonamides,chloramphenicols and quinolones. Class 1 integron gene was detected in 13 strains and all isolates carried class 2 integron which indicated that strains with two integron structures were detected simultaneously and class 3 integron was not detected. Class 1 integron inserted gene cassette was mainly blaara30 -aadA 1 family, conferring resistance to β-lactamase, spectinomycin and streptomycins isolates carried class 2 integron were mainly dfrAl-satl genes cassettes conferring resistance to methoxybenzyl aminopyrimidine and streptothricin, while dfrA\-sat\-aadA\ genes were present only in 4 isolates. Conclusions These data indicate that class 2 integrons are widespread in Shigella dysenteriae strains, and closely associated with multidrug resistance of Shigella.
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The aim of this study was to evaluate the acute cell injury of excretion products present in culture filtrate from Shigella dysenteriae in both whole lower limb of chick embryo ex vivo and myoblasts cells developed in hanging-drop cultures in vitro. Three controls were defined: a) Tyrode's solution b) brain-heart broth infusion (CCC) and c) supernatant not toxigenic of E.coli 0157:H7. Shigella dysenteriae were culture for 24 hours and the excretion products were obtained after centrifugation of the culture. After lh of treatment, the morphologic changes in limbs treated with raw filtrate were evaluated through histopathological examination of sections stained with hematoxylin-eosin (H&E-stain) and Gomori's trichrome by image analysis techniques. Quantification of apoptotic cells was measured by an enzyme-linked immunoassay TUNEL. The morphological feature of apoptosis were evaluated in culture myoblasts. In contrast with controls, the longitudinal section on treated thigh of chick embryo limb-buds show atrophy muscle tissue, detachment of few fibers, 57,14% decrease in the number of cells, and loss of collagen substrate. Apoptotic index percent increase and mitotic index decrease in response to excretion products were observed, but were not significant. Membrane blebbing, vacuolation, small aggregates of chromatin around the nucleus and loss of cell adhesion were observed. Culture filtrate from Shigella dysenteriae produced cytotoxic effect on cell of muscle fibers with acute cell injuries suspected to be related to the apoptotic cell death.
El objetivo del presente trabajo ha sido evaluar el daño celular agudo generado por el producto de excreción de Shigella dysentenae sobre el tejido muscular del miembro inferior de embrión de pollo, así como sobre los mioblastos obtenidos a partir del cultivo de explantes de tejido muscular desarrollado en gota pendiente. Tres controles fueron definidos: a) solución de tiroide b) caldo de infusión cerebro-corazón (CCC), c) producto de excreción bacteriano no toxigénico de E. coli 0157:H7. El producto de excreción fue obtenido a partir de la centrifugación y filtrado del medio de cultivo de Shigella dysentenae con 24 horas de crecimiento. Luego de una hora de tratamiento, los cambios morfológicos del tejido muscular fueron evaluados a través del examen histopatológico, con técnicas de análisis de imágenes sobre cortes teñidos con hematoxilina-eosina (H&E) y Tricrómico de Gomori. El ensayo enzimático TÚNEL fue utilizado para evaluar el índice de apoptosis. Señales morfológicas de muerte celular fueron evaluadas en mioblastos en cultivo En contraste con los controles, el tejido muscular presentó signos de atrofia, con fibras desconectadas y pérdida del 57,14% del número total de células así como pérdida de la matriz de colágeno. Un incremento en el índice apoptótico y una reducción de índice mitótico fueron registrados. Esto último fue no significativo. Los mioblastos en cultivo presentaron signos morfológicos de apoptosis tales como protuberancias en la membrana, vacuolización, agregación de cromatina alrededor del núcleo y pérdida de la adhesión celular. Se concluye que el producto de excreción afecta al tejido muscular esquelético del miembro inferior de embrión de pollo e induce lesiones de toxicidad relacionadas con la muerte celular por apoptosis.
Subject(s)
Animals , Chick Embryo , Shigella dysenteriae , Apoptosis , Muscle, Skeletal/pathology , Shiga Toxin , In Vitro Techniques , Cell Death , Myoblasts , Dysentery, BacillaryABSTRACT
The 47–55 domain of the maturehumanInterleukin- was predicted to be exposed by our computational analysis and confirmed to be so by comparing with X-ray crystallographic as well as nuclear magnetic resonance (NMR) spectroscopic data. Four peptides representing fully or part of this domain with sequences 47–55, 41–61, 45–61and 50–66 were synthesized and tested for their ability to modulate in vivo, the humoral immune response of Balb/c mice to Shigella dysenteriae 116 kDa antigen(s). The smallest immunomodulatory peptide amongst them was found to be the nonapeptide 47–55. To ascertain the structurefunction relationships of this 47-55 peptide, various mutant peptides were synthesized and tested for IL-1ß like activity in vivo. Change of Val47 to Asp47 or to Lys47 enhanced its immunomodulatory activity significantly while the change of Gly49 to Asp49 or Glu50 to Ile50 or Asp54 to Ile54 had no such effect. The peptides 47–55 and its mutants were first tested for their ability to elicit inflammatory response like PGE2 synthesis by a sensitive radioimmunoassay. The peptides which did not have any inflammatory activity were then tested for their ability to stimulate antigen primed T-cells in vitro in the presence of sub-optimal concentration of the antigen.