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2.
Gut Microbes ; 16(1): 2331985, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38549437

RESUMO

Shigella flexneri causes severe diarrheal disease worldwide. While many aspects of pathogenesis have been elucidated, significant knowledge gaps remain regarding the role of putative chromosomally-encoded virulence genes. The uncharacterized sap gene encoded on the chromosome has significant nucleotide sequence identity to the fluffy (flu) antigen 43 autotransporter gene in pathogenic Escherichia coli. Here, we constructed a Δsap mutant in S. flexneri strain 2457T and examined the effects of this mutation on bacterial cell aggregation, biofilm formation, and adherence to colonic epithelial cells. Analyses included the use of growth media supplemented with glucose and bile salts to replicate small intestinal signals encountered by S. flexneri. Deletion of the sap gene in 2457T affected epithelial cell adherence, resulted in quicker bacterial cell aggregation, but did not affect biofilm formation. This work highlights a functional role for the sap gene in S. flexneri pathogenesis and further demonstrates the importance of using relevant and appropriate gastrointestinal signals to characterize virulence genes of enteropathogenic bacteria.


Assuntos
Microbioma Gastrointestinal , Sistemas de Secreção Tipo V , Sistemas de Secreção Tipo V/genética , Shigella flexneri/genética , Células Epiteliais/microbiologia , Mutação , Escherichia coli , Proteínas de Bactérias/genética
3.
ACS Infect Dis ; 10(2): 377-383, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38252850

RESUMO

Shigellosis poses an ongoing global public health threat. The presence and length of the O-antigen in lipopolysaccharide play critical roles in Shigella pathogenesis. The plasmid-mediated opt gene encodes a phosphoethanolamine (PEtN) transferase that catalyzes the addition of PEtN to the O-antigen of Shigella flexneri serotype X and Y strains, converting them into serotype Xv and Yv strains, respectively. Since 2002, these modified strains have become prevalent in China. Here we demonstrate that PEtN-mediated O-antigen modification in S. flexneri increase the severity of corneal infection in guinea pigs without any adaptive cost. This heightened virulence is associated with epithelial cell adhesion and invasion, as well as an enhanced inflammatory response of macrophage. Notably, PEtN addition allow S. flexneri to attenuate the binding of complement C3 and better resist phagocytosis, potentially contributing to the retention of S. flexneri in the host environment.


Assuntos
Etanolaminas , Antígenos O , Shigella flexneri , Animais , Cobaias , Antígenos O/genética , Antígenos O/metabolismo , Sorotipagem , Plasmídeos , Shigella flexneri/genética , Shigella flexneri/metabolismo
4.
Eur J Cell Biol ; 103(1): 151381, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38183814

RESUMO

The facultative intracellular pathogen Shigella flexneri invades non-phagocytic epithelial gut cells. Through a syringe-like apparatus called type 3 secretion system, it injects effector proteins into the host cell triggering actin rearrangements leading to its uptake within a tight vacuole, termed the bacterial-containing vacuole (BCV). Simultaneously, Shigella induces the formation of large vesicles around the entry site, which we refer to as infection-associated macropinosomes (IAMs). After entry, Shigella ruptures the BCV and escapes into the host cytosol by disassembling the BCV remnants. Previously, IAM formation has been shown to be required for efficient BCV escape, but the molecular events associated with BCV disassembly have remained unclear. To identify host components required for BCV disassembly, we performed a microscopy-based screen to monitor the recruitment of BAR domain-containing proteins, which are a family of host proteins involved in membrane shaping and sensing (e.g. endocytosis and recycling) during Shigella epithelial cell invasion. We identified endosomal recycling BAR protein Sorting Nexin-8 (SNX8) localized to IAMs in a PI(3)P-dependent manner before BCV disassembly. At least two distinct IAM subpopulations around the BCV were found, either being recycled back to cellular compartments such as the plasma membrane or transitioning to become RAB11A positive "contact-IAMs" involved in promoting BCV rupture. The IAM subpopulation duality was marked by the exclusive recruitment of either SNX8 or RAB11A. Hindering PI(3)P production at the IAMs led to an inhibition of SNX8 recruitment at these compartments and delayed both, the step of BCV rupture time and successful BCV disassembly. Finally, siRNA depletion of SNX8 accelerated BCV rupture and unpeeling of BCV remnants, indicating that SNX8 is involved in controlling the timing of the cytosolic release. Overall, our work sheds light on how Shigella establishes its intracellular niche through the subversion of a specific set of IAMs.


Assuntos
Fosfatos de Fosfatidilinositol , Shigella , Humanos , Shigella/fisiologia , Vacúolos/metabolismo , Células Epiteliais/fisiologia , Shigella flexneri/genética , Células HeLa , Nexinas de Classificação/metabolismo
5.
Microb Pathog ; 188: 106539, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38211835

RESUMO

BACKGROUND: Shigella is one of the major causes of dysenteric diarrhea, which is known shigelosis. Shigelosis causes 160,000 deaths annually of diarrheal disease in the global scale especially children less than 5 years old. No licensed vaccine is available against shigelosis, therefore, efforts for develop an effective and safe vaccine against Shigella as before needed. The reverse vaccinology (RV) is a novel strategy that evaluate genome or proteome of the organism to find a new promising vaccine candidate. In this study, immunogenicity of a designed-recombinant antigen is evaluated through the in silico studies and animal experiments to predict a new immunogenic candidate against Shigella. METHODS: In the first step, proteome of Shigella flexneri was obtained from UniProtKB and then the outer membrane and extracellular proteins were predicted. In this study TolC as an outer membrane protein was selected and confirmed among candidates. In next steps, pre-selected protein was evaluated for transmembrane domains, homology, conservation, antigenicity, solubility, and B- and T-cell prediction by different online servers. RESULT: TolC as a conserved outer membrane protein, using different immune-informatics tools had acceptable scores and was selected as the immunogenic antigen for animal experiment studies. Recombinant TolC protein after expression and purification, was administered to BALB/c mice over three intraperitoneal routes. The sera of mice was used to evaluate the IgG1 production assay by indirect-ELISA. The immunized mice depicted effective protection against 2LD50 of Shigella. Flexneri ATCC12022 (challenge study). CONCLUSION: Therefore, the reverse vaccinology approach and experimental test results demonstrated that TolC as a novel effective and immunogenic antigen is capable for protection against shigellosis.


Assuntos
Disenteria Bacilar , Vacinas contra Shigella , Shigella , Humanos , Criança , Animais , Camundongos , Pré-Escolar , Shigella flexneri/genética , Vacinas de Subunidades Proteicas , Vacinas contra Shigella/genética , Proteoma , Disenteria Bacilar/prevenção & controle , Proteínas Recombinantes/genética , Vacinas Sintéticas/genética , Proteínas de Membrana , Anticorpos Antibacterianos
6.
Nat Commun ; 15(1): 318, 2024 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-38182620

RESUMO

The transcriptional antisilencer VirB acts as a master regulator of virulence gene expression in the human pathogen Shigella flexneri. It binds DNA sequences (virS) upstream of VirB-dependent promoters and counteracts their silencing by the nucleoid-organizing protein H-NS. However, its precise mode of action remains unclear. Notably, VirB is not a classical transcription factor but related to ParB-type DNA-partitioning proteins, which have recently been recognized as DNA-sliding clamps using CTP binding and hydrolysis to control their DNA entry gate. Here, we show that VirB binds CTP, embraces DNA in a clamp-like fashion upon its CTP-dependent loading at virS sites and slides laterally on DNA after clamp closure. Mutations that prevent CTP-binding block VirB loading in vitro and abolish the formation of VirB nucleoprotein complexes as well as virulence gene expression in vivo. Thus, VirB represents a CTP-dependent molecular switch that uses a loading-and-sliding mechanism to control transcription during bacterial pathogenesis.


Assuntos
DNA , Shigella flexneri , Humanos , Shigella flexneri/genética , Virulência/genética , Hidrólise , Expressão Gênica
7.
Int J Antimicrob Agents ; 63(2): 107070, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38141834

RESUMO

Bacillary dysentery caused by Shigella spp. is a significant concern for human health. Small non-coding RNA (sRNA) plays a crucial role in regulating antibiotic resistance and virulence in Shigella spp. However, the specific mechanisms behind this phenomenon are still not fully understood. This study discovered two sRNAs (sRNA1039 and sRNA1600) that may be involved in bacterial resistance and virulence. By constructing deletion mutants (WT/ΔSR1039 and WT/ΔSR1600), this study found that the WT/ΔSR1039 mutants caused a two-fold increase in sensitivity to ampicillin, gentamicin and cefuroxime, and the WT/ΔSR1600 mutants caused a two-fold increase in sensitivity to cefuroxime. Furthermore, the WT/ΔSR1600 mutants caused a decrease in the adhesion and invasion of bacteria to HeLa cells (P<0.01), and changed the oxidative stress level of bacteria to reduce their survival rate (P<0.001). Subsequently, this study explored the molecular mechanisms by which sRNA1039 and sRNA1600 regulate antibiotic resistance and virulence. The deletion of sRNA1039 accelerated the degradation of target gene cfa mRNA and reduced its expression, thereby regulating the expression of pore protein gene ompD indirectly and negatively to increase bacterial sensitivity to ampicillin, gentamicin and cefuroxime. The inactivation of sRNA1600 reduced the formation of persister cells to reduce resistance to cefuroxime, and reduced the expression of type-III-secretion-system-related genes to reduce bacterial virulence by reducing the expression of target gene tomB. These results provide new insights into Hfq-sRNA-mRNA regulation of the resistance and virulence network of Shigella sonnei, which could potentially promote the development of more effective treatment strategies.


Assuntos
Disenteria Bacilar , Pequeno RNA não Traduzido , Shigella , Humanos , Shigella sonnei/genética , Virulência/genética , Células HeLa , Cefuroxima/metabolismo , Shigella flexneri/genética , Disenteria Bacilar/microbiologia , Ampicilina/farmacologia , Ampicilina/metabolismo , Resistência Microbiana a Medicamentos , Gentamicinas , RNA Mensageiro , Pequeno RNA não Traduzido/genética , Pequeno RNA não Traduzido/metabolismo , Antibacterianos/farmacologia , Antibacterianos/metabolismo
8.
Dis Model Mech ; 17(1)2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38131137

RESUMO

Shigella flexneri is a human-adapted pathovar of Escherichia coli that can invade the intestinal epithelium, causing inflammation and bacillary dysentery. Although an important human pathogen, the host response to S. flexneri has not been fully described. Zebrafish larvae represent a valuable model for studying human infections in vivo. Here, we use a Shigella-zebrafish infection model to generate mRNA expression profiles of host response to Shigella infection at the whole-animal level. Immune response-related processes dominate the signature of early Shigella infection (6 h post-infection). Consistent with its clearance from the host, the signature of late Shigella infection (24 h post-infection) is significantly changed, and only a small set of immune-related genes remain differentially expressed, including acod1 and gpr84. Using mutant lines generated by ENU, CRISPR mutagenesis and F0 crispants, we show that acod1- and gpr84-deficient larvae are more susceptible to Shigella infection. Together, these results highlight the power of zebrafish to model infection by bacterial pathogens and reveal the mRNA expression of the early (acutely infected) and late (clearing) host response to Shigella infection.


Assuntos
Disenteria Bacilar , Animais , Humanos , Disenteria Bacilar/genética , Shigella flexneri/genética , Shigella flexneri/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/microbiologia , Inflamação/microbiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
9.
Nat Commun ; 14(1): 7715, 2023 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-38001075

RESUMO

Shigellosis, a leading cause of diarrhoeal mortality and morbidity globally, predominantly affects children under five years of age living in low- and middle-income countries. While whole genome sequence analysis (WGSA) has been effectively used to further our understanding of shigellosis epidemiology, antimicrobial resistance, and transmission, it has been under-utilised in sub-Saharan Africa. In this study, we applied WGSA to large sub-sample of surveillance isolates from South Africa, collected from 2011 to 2015, focussing on Shigella flexneri 2a and Shigella sonnei. We find each serotype is epidemiologically distinct. The four identified S. flexneri 2a clusters having distinct geographical distributions, and antimicrobial resistance (AMR) and virulence profiles, while the four sub-Clades of S. sonnei varied in virulence plasmid retention. Our results support serotype specific lifestyles as a driver for epidemiological differences, show AMR is not required for epidemiological success in S. flexneri, and that the HIV epidemic may have promoted Shigella population expansion.


Assuntos
Anti-Infecciosos , Disenteria Bacilar , Shigella , Criança , Humanos , Pré-Escolar , Disenteria Bacilar/epidemiologia , África do Sul/epidemiologia , Shigella/genética , Shigella flexneri/genética , Genômica
10.
Commun Biol ; 6(1): 1204, 2023 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-38007587

RESUMO

VirB is a transcriptional activator of virulence in the gram-negative bacterium Shigella flexneri encoded by the large invasion plasmid, pINV. It counteracts the transcriptional silencing by the nucleoid structuring protein, H-NS. Mutations in virB lead to loss of virulence. Studies suggested that VirB binds to specific DNA sequences, remodels the H-NS nucleoprotein complexes, and changes DNA supercoiling. VirB belongs to the superfamily of ParB proteins which are involved in plasmid and chromosome partitioning often as part of a ParABS system. Like ParB, VirB forms discrete foci in Shigella flexneri cells harbouring pINV. Our results reveal that purified preparations of VirB specifically bind the ribonucleotide CTP and slowly but detectably hydrolyse it with mild stimulation by the virS targeting sequences found on pINV. We show that formation of VirB foci in cells requires a virS site and CTP binding residues in VirB. Curiously, DNA stimulation of clamp closure appears efficient even without a virS sequence in vitro. Specificity for entrapment of virS DNA is however evident at elevated salt concentrations. These findings suggest that VirB acts as a CTP-dependent DNA clamp and indicate that the cellular microenvironment contributes to the accumulation of VirB specifically at virS sites.


Assuntos
Proteínas de Ligação a DNA , Shigella flexneri , Virulência/genética , Shigella flexneri/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fatores de Virulência/genética , Regiões Promotoras Genéticas , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , DNA/metabolismo
11.
Indian J Med Res ; 158(3): 303-310, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37815071

RESUMO

Background & objectives: The study of Shigella pathogenesis at present is severely hampered by the lack of a relevant animal model that replicates human bacillary dysentery. Different Shigella serogroups cause varying severity of clinical illness. Ex vivo colonization of Shigella flexneri, S. dysenteriae and S. sonnei were characterized in human paediatric colonic pinch biopsies in the in vitro organ culture (IVOC) model to study the invasiveness of Shigella by gentamicin protection assay (GPA). Furthermore, the expression of antimicrobial peptides (AMPs) in response to different serotypes of Shigella was also studied in IVOC model. Methods: IVOC explants were inoculated with 109 colony forming units of different serotypes of Shigella and recovery of bacteria studied. Histopathological analysis was carried out to study inflammatory immune responses. GPA was done to elucidate the invasiveness of different serotypes of Shigella. Secretions of AMPs were measured by enzyme-linked immunosorbent assay (ELISA). Western blotting was performed to check the expression of AMPs and nuclear factor kappa B in IVOC explants. Results: After 24 h post-infection, the colon biopsies showed intense inflammatory reaction. In both IVOC and GPA, S. dysenteriae 1 was the most invasive as compared to S. flexneri and S. sonnei. S. sonnei was the least invasive. ELISA demonstrated that S. sonnei dampened the HBD (human ß-defensin)-2 responses whereas there was augmentation by S. dysenteriae and there was a modest but non-significant increase by S. flexneri. A modest increase in HBD-3 by S. sonnei and S. flexneri was observed but was not found to be significant. However, western blotting data showed upregulation of all AMPs by all serotypes. Western blotting is more sensitive than ELISA. Interpretation & conclusions: In the present study, differences in invasiveness and AMP production induced by different serotypes of Shigella were found. Human intestinal IVOC represents a model system to investigate early interaction between pathogenic bacteria and the human gut.


Assuntos
Disenteria Bacilar , Shigella , Animais , Criança , Humanos , Sorogrupo , Peptídeos Antimicrobianos , Shigella/genética , Disenteria Bacilar/genética , Disenteria Bacilar/microbiologia , Shigella flexneri/genética
12.
Front Cell Infect Microbiol ; 13: 1257361, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37780843

RESUMO

Introduction: Laboratory teaching of medical microbiology involves highly pathogenic microorganisms, thus posing potential biosafety risks to the students and the teacher. To address these risks, non/low-pathogenic microorganisms were modified to mimic highly pathogenic ones or highly pathogenic microorganisms were attenuated directly using the CRISPR/Cas9 technology. This study describes the modification of Escherichia coli DH5α to mimic Shigella and its evaluation as a safe alternative for medical laboratory teaching. Methods: To generate E. coli DH5α△FliC△tnaA2a, the tnaA and FliC genes in E. coli DH5α were knocked out using CRISPR/Cas9 technology; a plasmid bearing the O-antigen determinant of S. flexneri 2a was then constructed and transformed. Acid tolerance assays and guinea pig eye tests were used to assess the viability and pathogenicity, respectively. Questionnaires were used to analyze teaching effectiveness and the opinions of teachers and students. Results: The survey revealed that most teachers and students were inclined towards real-time laboratory classes than virtual classes or observation of plastic specimens. However, many students did not abide by the safety regulations, and most encountered potential biosafety hazards in the laboratory. E. coli DH5α△FliC△tnaA2a was biochemically and antigenically analogous to S. flexneri 2a and had lower resistance to acid than E. coli. There was no toxicity observed in guinea pigs. Most of teachers and students were unable to distinguish E. coli DH5α△FliC△tnaA2a from pure S. flexneri 2a in class. Students who used E. coli DH5α△FliC△tnaA2a in their practice had similar performance in simulated examinations compared to students who used real S. flexneri 2a, but significantly higher than the virtual experimental group. Discussion: This approach can be applied to other high-risk pathogenic microorganisms to reduce the potential biosafety risks in medical laboratory-based teaching and provide a new strategy for the development of experimental materials.


Assuntos
Escherichia coli , Shigella , Humanos , Animais , Cobaias , Escherichia coli/genética , Shigella flexneri/genética , Contenção de Riscos Biológicos , Shigella/genética , Virulência
13.
Sci Rep ; 13(1): 16582, 2023 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-37789081

RESUMO

Azithromycin (AZM) resistance among Shigella is a major public health concern. Here, we investigated the epidemiology of Shigella flexneri serotype 1b recovered during 2016-2018 in Ontario, to describe the prevalence and spread of AZM resistance. We found that 72.3% (47/65) of cases were AZM-resistant (AZMR), of which 95.7% (45/47) were among males (P < 0.001). Whole-genome based phylogenetic analysis showed three major clusters, and 56.9% of isolates grouped within a single closely-related cluster (0-10 ∆SNP). A single AZMR clonal population was persistent over 3 years and involved 67.9% (36/53) of all male cases, and none reported international travel. In 2018, a different AZMR cluster appeared among adult males not reporting travel. A proportion of isolates (10.7%) with reduced susceptibility to ciprofloxacin (CIP) due to S83L mutation in gyrA were AZM susceptible, and 71.4% reported international travel. Resistance to AZM was due to the acquisition of mph gene-bearing incFII plasmids having > 95% nucleotide similarity to pKSR100. Plasmid-borne resistance limiting treatment options to AZM, ceftriaxone (CRO) and CIP was noted in a single isolate. We characterized AZMR isolates circulating locally among males and found that genomic analysis can support targeted prevention and mitigation strategies against antimicrobial-resistance.


Assuntos
Azitromicina , Disenteria Bacilar , Masculino , Humanos , Azitromicina/farmacologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Shigella flexneri/genética , Ontário/epidemiologia , Filogenia , Neisseria gonorrhoeae/genética , Ciprofloxacina/farmacologia , Sequenciamento Completo do Genoma , Testes de Sensibilidade Microbiana , Farmacorresistência Bacteriana/genética , Disenteria Bacilar/tratamento farmacológico , Disenteria Bacilar/epidemiologia
14.
mSphere ; 8(6): e0040823, 2023 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-37830809

RESUMO

IMPORTANCE: Given the genomic diversity between S. flexneri serotypes and the paucity of data to support serotype-specific phenotypic differences, we applied in silico and in vitro functional analyses of archetype strains of 2457T (Sf2a), J17B (Sf3a), and CH060 (Sf6). These archetype strains represent the three leading S. flexneri serotypes recommended for inclusion in multivalent vaccines. Characterizing the genomic and phenotypic variation among these clinically prevalent serotypes is an important step toward understanding serotype-specific host-pathogen interactions to optimize the efficacy of multivalent vaccines and therapeutics. This study underpins the importance for further large-scale serotype-targeted analyses.


Assuntos
Genômica , Shigella flexneri , Shigella flexneri/genética , Sorogrupo , Perfilação da Expressão Gênica , Vacinas Combinadas
15.
Gut Microbes ; 15(2): 2256767, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37741806

RESUMO

The enteric pathogens have evolved to utilize elements from their surroundings to optimize their infection strategies. A common mechanism to achieve this is to employ intestinal compounds as signals to control the activity of a master regulator of virulence. Shigella flexneri (S. flexneri) is a highly infectious entero-invasive pathogen which requires very few organisms to cause invasion of the colonic mucosa. The invasion program is controlled by the virulence master regulator VirF. Here, we show that the fatty acids commonly found in the colon can be exploited by S. flexneri to repress its virulence, allowing it to energetically finance its proliferation, thus increasing its pathogenicity. Colonic fatty acids such as oleic, palmitoleic and cis-2-hexadecenoic acid were shown to directly bind to VirF and mediate its prompt degradation. These fatty acids also disrupted the ability of VirF to bind to its target DNA, suppressing the transcription of the downstream virulence genes and significantly reducing the invasion of S. flexneri to colonic epithelial cells. Treatment with colonic fatty acids significantly increased the growth rate of the pathogen only under invasion-inducing conditions, showing that the reduction in the burden of virulence promotes a growth advantage. These results demonstrate the process by which S. flexneri can employ intestinal compounds as signals to increase its numbers at its preferred site of invasion, highlighting the mechanism by which the full spectrum of shigellosis is achieved despite a miniscule infectious dose. This highlights an elegant model of environmental adaption by S. flexneri to maximize the pathogenic benefit.


Assuntos
Microbioma Gastrointestinal , Shigella flexneri , Shigella flexneri/genética , Virulência , Intestinos , Ácidos Graxos
16.
PLoS One ; 18(6): e0275353, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37319254

RESUMO

Shigellaa Gram-negative, non-motile bacillus, is the primary causative agent of the infectious disease shigellosis, which kills 1.1 million people worldwideevery year. The children under the age of five are primarily the victims of this disease. This study has been conducted to assess the prevalence of shigellosis through selective plating, biochemical test and conventional PCR assays, where the samples were collected from suspected diarrheoal patients. Invasive plasmid antigen H (ipaH) and O-antigenic rfc gene were used to identify Shigella spp. and S. flexneri respectively. For validation of these identification, PCR product of ipaH gene of a sample (Shigella flexneri MZS 191) has been sequenced and submitted to NCBI database (GenBank accession no- MW774908.1). Further this strain has been used as positive control. Out of 204, around 14.2% (n = 29)(P> 0.01) pediatric diarrheoal cases were screened as shigellosis. Another interesting finding was that most of shigellosis affected children were 7 months to 1 year (P> 0.01).The significance of this study lies in the analyses of the occurrenceand the molecular identification of Shigellaspp. and S. flexneri that can be utilized in improving the accurate identification and the treatment of the most severe and alarming shigellosis.


Assuntos
Disenteria Bacilar , Shigella , Criança , Humanos , Disenteria Bacilar/diagnóstico , Disenteria Bacilar/epidemiologia , Bangladesh/epidemiologia , Shigella/genética , Diarreia/epidemiologia , Diarreia/complicações , Shigella flexneri/genética
17.
Microbiol Spectr ; 11(4): e0477722, 2023 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-37255425

RESUMO

During an investigation into a cluster of Shigella flexneri serotype 2a cases in an underserved community, we assessed the relatedness of human and rat S. flexneri isolates utilizing a novel PCR targeting insertion sites (IS-PCR) of mobile elements in the Shigella genome characteristic of the cluster strain. Whole-genome sequences of S. flexneri (n = 50) associated with the cluster were analyzed. De novo genome assemblies were analyzed by a Geneious V10.2.6 motif search, and two unique IS were identified in all human Shigella sequences of the local cluster. Hydrolysis probe PCR assays were designed to detect these sequences consisting of forward and reverse primers to amplify across each insertion site and a hydrolysis probe spanning the insertion site. IS-PCR was performed for three Shigella PCR-positive culture-negative rat intestine specimens from this community. Both insertion sites were detected in the de novo genome assemblies of all clinical S. flexneri isolates (n = 50). Two of the three PCR-positive culture-negative rat samples were positive for both unique ISs identified in the human S. flexneri isolates, suggesting that the rat Shigella species strains were closely related to the human strains in the cluster. The cycle threshold (Ct) values were >35, indicating that the bacterial load was very low in the rat samples. Two unique IS were identified in clinical isolates from a community S. flexneri cluster. Both IS targets were identified in PCR-positive (Shigella spp.), culture-negative rat tissue and clinical isolates from humans, indicating relatedness. IMPORTANCE This article describes a novel molecular method to show relatedness between bacterial infections, which may not be able to grow in the laboratory due to treatment with antibiotics or for bacteria requiring unique conditions to grow well. Uniquely, we applied this technique to Shigella isolates from human cases associated with a local cluster in an underserved community, as well as rat samples from the same community. We believe that this novel approach can serve as a complementary method to support outbreak/cluster investigation for Shigella spp.


Assuntos
Disenteria Bacilar , Shigella , Humanos , Animais , Ratos , Disenteria Bacilar/epidemiologia , Disenteria Bacilar/microbiologia , Elementos de DNA Transponíveis , Shigella/genética , Shigella flexneri/genética , Reação em Cadeia da Polimerase
18.
Biomolecules ; 13(5)2023 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-37238693

RESUMO

The tripartite complex AcrAB-TolC is the major RND pump in Escherichia coli and other Enterobacteriaceae, including Shigella, the etiological agent of bacillary dysentery. In addition to conferring resistance to many classes of antibiotics, AcrAB plays a role in the pathogenesis and virulence of several bacterial pathogens. Here, we report data demonstrating that AcrAB specifically contributes to Shigella flexneri invasion of epithelial cells. We found that deletion of both acrA and acrB genes causes reduced survival of S. flexneri M90T strain within Caco-2 epithelial cells and prevents cell-to-cell spread of the bacteria. Infections with single deletion mutant strains indicate that both AcrA and AcrB favor the viability of the intracellular bacteria. Finally, we were able to further confirm the requirement of the AcrB transporter activity for intraepithelial survival by using a specific EP inhibitor. Overall, the data from the present study expand the role of the AcrAB pump to an important human pathogen, such as Shigella, and add insights into the mechanism governing the Shigella infection process.


Assuntos
Proteínas de Bactérias , Proteínas de Escherichia coli , Humanos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Shigella flexneri/genética , Shigella flexneri/metabolismo , Células CACO-2 , Antibacterianos/farmacologia , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética
19.
Microbiol Spectr ; 11(3): e0077823, 2023 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-37140433

RESUMO

The pathogenicity of Shigella, the intracellular pathogen responsible for human bacillary dysentery, depends on a coordinated and tightly regulated expression of its virulence determinants. This is the result of a cascade organization of its positive regulators, with VirF, a transcriptional activator belonging to the AraC-XylS family, in a pivotal position. VirF itself is submitted to several well-known regulations at the transcriptional level. In this work, we present evidence for a novel posttranslational regulatory mechanism of VirF mediated by the inhibitory interaction with specific fatty acids. By homology modeling and molecular docking analyses, we identify a jelly roll motif in the structure of ViF capable of interacting with medium-chain saturated and long-chain unsaturated fatty acids. In vitro and in vivo assays show that capric, lauric, myristoleic, palmitoleic, and sapienic acids interact effectively with the VirF protein, abolishing its transcription-promoting activity. This silences the virulence system of Shigella, leading to a drastic reduction in its ability to invade epithelial cells and proliferate in their cytoplasm. IMPORTANCE In the absence of a valid vaccine, the main therapeutic approach currently used to treat shigellosis is based on the use of antibiotics. The emergence of antibiotic resistance jeopardizes the future effectiveness of this approach. The importance of the present work resides both in the identification of a new level of posttranslational regulation of the Shigella virulence system and in the characterization of a mechanism offering new opportunities for the design of antivirulence compounds, which may change the treatment paradigm of Shigella infections by limiting the emergence of antibiotic-resistant bacteria.


Assuntos
Disenteria Bacilar , Shigella , Humanos , Virulência , Ácidos Graxos/metabolismo , Simulação de Acoplamento Molecular , Shigella flexneri/genética , Fatores Reguladores de Interferon/metabolismo , Fatores Reguladores de Interferon/farmacologia , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica
20.
Emerg Infect Dis ; 29(7): 1473-1475, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37204919

RESUMO

In Los Angeles, California, USA, persistent, refractory shigellosis was diagnosed in an immunocompetent man who has sex with men. Whole-genome sequencing augmented phenotypic antimicrobial susceptibility testing to comprehensively profile bacterial drug resistance and appropriately guide therapy and clear the infection.


Assuntos
Disenteria Bacilar , Shigella , Masculino , Humanos , Shigella flexneri/genética , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Disenteria Bacilar/diagnóstico , Disenteria Bacilar/tratamento farmacológico , Disenteria Bacilar/epidemiologia , Farmacorresistência Bacteriana , Los Angeles , Testes de Sensibilidade Microbiana
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