Shigella Strains Research Articles

Antibiotic resistance and serotype distribution of Shigella strains in Bangladesh over the period of 2014-2022: evidence from a nationwide hospital-based surveillance for cholera and other diarrheal diseases.

This nationwide study in Bangladesh assessed Shigella infections from 2014 to 2022 from clinical samples. S. flexneri was predominant, with concerning antibiotic resistance, notably to ciprofloxacin and nalidixic acid in over 96% of isolates. This emphasizes the urgency of prudent antibiotic use and improved hygiene. The findings provide crucial antimicrobial resistance patterns of Shigella species, highlighting the need for ongoing resistance monitoring and potentially informing future vaccine trials.

SPATEs promote the survival of Shigella to the plasma complement system upon local hemorrhage and bacteremia

Shigella spp. are the causative agents of shigellosis, which remains a leading cause of death in children under the age of 5. Symptoms of shigellosis include bloody diarrhea, associated to colon hemorrhage; in more severe cases, Shigella bacteremia is induced. These clinical features indicate that Shigella are exposed and survive exposure to plasma, locally and systemically, although this has not yet been studied at a molecular level. In this report, we confirmed in a guinea pig model of shigellosis that both S. flexneri 5a and S. sonnei induced local hemorrhages and we demonstrated that Shigella reached CD31+/CD34+ blood vessels located in the mucosa during the late stages of infection, and further disseminated in the bloodstream. These results confirmed the exposure of Shigella to plasma components during its virulence cycle. We demonstrated that all the tested Shigella strains survived plasma exposure in vitro, and we showed that Serine Protease Autotransporters of Enterobacteriaceae (SPATEs) contribute to Shigella dissemination within the colonic mucosa and in the bloodstream. We have confirmed that SPATEs are expressed and secreted in poorly oxygenated environments encountered by Shigella during late infection stages. We further demonstrated that SPATEs promoted Shigella survival in plasma, by cleaving complement component 3 (C3), thereby impairing the complement system activation. We have shown here that the ability of Shigella to survive plasma exposure is a key factor in its virulence, both within primary foci and systemically.

Structural and functional characterization of the IpaD π-helix reveals critical roles in DOC interaction, T3SS apparatus maturation, and Shigella virulence

Shigella spp. are highly pathogenic members of the Enterobacteriaceae family, causing ∼269 million cases of bacillary dysentery and >200,000 deaths each year. Like many Gram-negative pathogens, Shigella rely on their type three secretion system (T3SS) to inject effector proteins into eukaryotic host cells, driving both cellular invasion and evasion of host immune responses. Exposure to the bile salt deoxycholate (DOC) significantly enhances Shigella virulence and is proposed to serve as a critical environmental signal present in the small intestine that prepares Shigella’s T3SS for efficient infection of the colonic epithelium. Here, we uncover critical mechanistic details of the Shigella-specific DOC signaling process by describing the role of a π-helix secondary structure element within the T3SS tip protein IpaD. Biophysical characterization and high-resolution structures of IpaD mutants lacking the π-helix show that it is not required for global protein structure, but that it defines the native DOC binding site and prevents off target interactions. Additionally, Shigella strains expressing the π-helix deletion mutants illustrate the pathogenic importance of its role in guiding DOC interaction as flow cytometry and gentamycin protection assays show that the IpaD π-helix is essential for DOC-mediated apparatus maturation and enhanced invasion of eukaryotic cells. Together, these findings add to our understanding of the complex Shigella pathogenesis pathway and its evolution to respond to environmental bile salts by identifying the π-helix in IpaD as a critical structural element required for translating DOC exposure to virulence enhancement.

Antimicrobial susceptibility and virulence gene analysis of Shigella species causing dysentery in Iranian children: Implications for fluroquinolone resistance

Shigella species significantly impact global health due to their role in diarrheal diseases. A 2019–2022 cross-sectional study on 432 stool samples from pediatric patients in Mashhad, Iran, identified Shigella spp. and tested their susceptibility to 12 antimicrobials by the disk diffusion method. The presence of virulence factors, namely ipaH, virA, stx1, and stx2, as well as plasmid-mediated quinolone resistance (PMQR) genes, including qnrA, qnrB, qnrC, qnrD, and qnrS, were ascertained through the utilization of polymerase chain reaction techniques. Sequencing of 15 isolates detected mutations within quinolone resistance-determining regions (QRDRs) at the gyrA and parC genes, indicating fluoroquinolone (FQ) resistance. 19.2 % (83/432) of stool samples contained Shigella, primarily S. sonnei (77.1 %), followed by S. flexneri (21.6 %) and S. boydii (1.2 %). Most isolates were from children under five (55.4 %). All strains had the ipaH gene, lacked stx1 and stx2, and 86.7 % had virA. High resistance was noted for ampicillin and tetracycline (84.3 % each), trimethoprim-sulfamethoxazole (81.9 %), and azithromycin (60.2 %). 87.1 % of isolates were multidrug-resistant (MDR). The most common PMQR genes were qnrA and qnrS (41 % each). The qnrD gene, prevalent in 36.1 % of cases, is reported in Iran for the first time. The most common PMQR profile was qnrADS (15.7 %). Resistance to nalidixic acid and ciprofloxacin was 45.8 % and 12 %, respectively. The Shigella isolates exhibited mutations in the gyrA (at codons 83, 87, and 211) and parC (at codons 80, 84, 93, 126, 128, 129, and 132) genes. The D87Y mutation in the gyrA gene was the most common in Shigella isolates, occurring in 73 % of cases. The F93S and L132T mutations in the parC gene were unique to this study. Empirical FQ therapy in patients infected with MDR Shigella, possessing PMQR determinants and/or mutations in the QRDRs of gyrA and parC, may escalate the risks of secondary diseases, extended treatment duration, therapeutic failure, and resistance spread. Consequently, the necessity for continuous surveillance and genetic testing to detect FQ-resistant Shigella strains is of paramount importance.

Occurrence of Antibiotic Resistant Salmonella and Shigella in Diarrheal cases Resulting from a Common Source Consumption of Contaminated Water

Study’s Novelty/ Excerpt This study evaluated the prevalence and antibiotic resistance of Salmonella and Shigella in diarrheal cases related to contaminated water consumption in Jimeta-Yola metropolis, Adamawa State, Nigeria. Among 78 stool samples, 47.4% showed growth of Salmonella Typhi, Salmonella Typhimurium, and Shigella species, with Shigella being the most prevalent. Antibiotic susceptibility testing revealed high resistance to Ampicillin, Cephalexin, and Co-trimoxazole across all isolates, while Gentamicin and Ciprofloxacin emerged as the most effective antibiotics, underscoring the necessity for safe water practices, improved hygiene, and regular monitoring to mitigate these infections. Full Abstract Antimicrobial resistance of Salmonella and Shigella remains a significant public health concern globally, particularly in developing nations like Nigeria. This study aimed to assess the prevalence and antibiotic susceptibility of Salmonella and Shigella strains in diarrheal cases linked to the consumption of contaminated water from a shared source in Jimeta-Yola metropolis, Adamawa State. A total of 78 stool samples were obtained for culture using standard methods, with 37 (47.4%) displaying growth of Salmonella and Shigella strains. Through appropriate biochemical tests, the isolates were identified as Salmonella Typhi (35.1%), Salmonella Typhimurium (8.1%), and Shigella species (56.8%), with Shigella exhibiting the highest occurrence. Antibiotic susceptibility testing was conducted using ten selected antibiotics: Ampicillin, Ceftriaxone, Cephalexin, Chloramphenicol, Ciprofloxacin, Co-trimoxazole, Gentamicin, Nitrofurantoin, Ofloxacin, and Tetracycline. Salmonella Typhi isolates showed 76.9% susceptibility to Gentamicin and Ceftriaxone, 61.5% susceptibility to Ofloxacin, 53.8% susceptibility to Chloramphenicol, Ciprofloxacin, Nitrofurantoin, 38.5% susceptibility to Tetracycline, 30.8% susceptibility to Co-trimoxazole, and 23.1% susceptibility to Cephalexin. Shigella species exhibited 95.2% susceptibility to Ofloxacin, 90.5% susceptibility to Gentamicin, 85.7% susceptibility to Ciprofloxacin, 66.7% susceptibility to Ceftriaxone, 57.1% susceptibility to Chloramphenicol, 52.4% susceptibility to Nitrofurantoin, 33.3% susceptibility to Tetracycline, 28.6% susceptibility to Co-trimoxazole, 19% susceptibility to Cephalexin, and 4.8% susceptibility to Ampicillin. Meanwhile, Salmonella Typhimurium displayed 66.7% susceptibility to Ofloxacin, 100% susceptibility to Gentamicin, Chloramphenicol, Nitrofurantoin, Ciprofloxacin, and 33.3% susceptibility to Ampicillin, Cephalexin, Tetracycline, Co-trimoxazole, and Ceftriaxone. The study highlights the persistent high prevalence of Salmonella and Shigella infections and the emergence of complete resistance to Ampicillin, Cephalexin, and Co-trimoxazole. However, Gentamicin and Ciprofloxacin are identified as effective treatment options for infections caused by these pathogens. Therefore, ensuring the availability of safe water sources, promoting hygienic practices, treating drinking water at the point of use (POU) such as boiling, and continuous monitoring are crucial in controlling the dissemination of these organisms

Phytochemical screening, investigation of the antisalmonella, antishigella, and antioxidant properties of the leaves of Rauvolfia vomitoria Afzel.

Rauvolfia vomitoria is a plant acclimatized in Benin - Africa that people use to treat several illnesses such as malaria, cough, typhoid fever, madness, toothache, diabetes, and nausea. The most used organs are leaves, stems, and roots. Thus, the purpose of this work is to contribute to the valorization of R. vomitoria by chemical and biological studies of this plant. Phytochemical analyses of the powder extracts were performed and revealed the presence of alkaloids, tannins, flavonoids, anthocyanins, saponins, terpenes, coumarins, mucilages, reducing compounds, free anthracene derivatives, bound anthracene derivatives (O-glycosides and C-glycosides) with absence of leuco-anthocyanins, quinone derivatives, steroids and cardiotonic glycosids. Evaluation of antisalmonella and antishigella properties of ethanol-water (70:30; V/V) and ethanolic extracts of R. vomitoria leaves showed minimum inhibitory concentrations (MIC) greater than 2000 µg.mL-1 against Salmonella and Shigella strains. The ethanolic extract was the most active by ABTS and FRAP methods and had very good antioxidant activity at scavenging concentration (SC50) equal to 138,62 µg.mL-1 and 185,99 µg.mL-1 respectively

The Tomato Variety Affects the Survival of Shigella flexneri 2a in Fruit Pericarp.

The presence of enteric pathogens in produce can serve as a significant means of transmitting infections to consumers. Notably, tomatoes, as a type of produce, have been implicated in outbreaks caused by various human pathogens, such as Salmonella enterica and pathogenic Escherichia coli. However, the survival characteristics of Shigella spp. in tomatoes have not been thoroughly investigated. In this study, we assess the survival of S. flexneri 2a in two distinct varieties of post-harvested tomatoes. S. flexneri 2a was used to inoculate both regular-sized Vine tomatoes and cherry-type Mini Plum tomatoes. Our findings reveal no significant difference in Shigella survival in the pericarp of both varieties on day 2 post-inoculation. However, a significant disparity emerges on day 6, where all recovered Shigella colonies exclusively belong to the Mini Plum variety, with none associated with the Vine type. When Shigella was inoculated into the locular cavity (deep inoculation), no significant difference between varieties was observed. Additionally, we investigate the potential role of the SRL pathogenicity island (SRL PAI) in the survival and fitness of S. flexneri 2a in post-harvested tomatoes. Our results indicate that while the SRL PAI is not linked to the survival of the strains in tomato, it does impact their fitness. These findings underscore the variability in Shigella strains' survival capabilities depending on the tomato variety, highlighting the importance of understanding Shigella ecology beyond the human host and identifying molecular determinants influencing bacterial survival to mitigate the risk of future outbreaks. The significance of this data on Shigella persistence in fresh vegetables should not be underestimated, as even a small number of Shigella cells can pose a threat to the health of individuals.

Isolation and Identification of Shigella SonneiProducing Shiga Toxin from Children with Bloody Diarrhea and Evaluation of the Inhibition Effectiveness of Zinc oxide Nanoparticles

Shigella infection strains producing shiga toxin results in bloody diarrheais a dangerous symptom in children under five years of age that can even lead to death. Therefore, this study was conducted to isolate Shigella strains producing shiga toxin from 150 samples which were taken from bloody stool of children under the five years of age. They were suffering from the diarrhea during the period from March 2021 to March 2022 in Tikrit city, Iraq. The results showed the possibility to isolate six isolates of Shigella sonnei at ratio 4% of the total samples. The isolates producing shiga toxin were identified by using stx1 gene. The results showed two isolates of Shigella possessing stx1 gene, at ratio 33.33 of total S. sonnei strains. The two isolates producing shiga toxin have been submitted to NCBI, then accepted as Iraqi strains in NCBI under the registration numbers OK127759.1 and OK127760.1. The Iraqi strains registered in NCBI showed agreement with a global strain of 99-100% that were recorded by registration numbers in Malaysia (CP060117.1), China (CP000038.1), United Kingdom (CP066810.1), Hungary (CP019689.1), Somalia (CP023645.1), Spain (CP022672.1), Italy (CP035008.1), India (CP041322.1), Australia (CP045932.1), Nigeria (CP046286.1), Switzerland (CP049183.1), USA (CP053751.1) and South Korea (CP055292.1). As for the sensitivity test, the results showed that the strain OK127759.1 was resistant to antibiotics azithromycin, ceftazidime, cefotaxime, ceftriaxone, augmentin and tetracycline. And it was sensitive to gentamicin and intermediately sensitive to ampicillin, chloramphenicol and nalidixic acid. As for the strain OK127760.1, the results showed his strain was intermediately sensitive to gentamicin and resistant to the other antibiotics which were used in the test. ZnO-NPs with a concentration of 200 μg/ml showed the highest inhibitory effectiveness against S. sonnei strains OK127759.1 and OK127760.1 with inhibition diameter of 22 mm and 21 mm respectively.

Genome-Wide Investigation Reveals Potential Therapeutic Targets in Shigella spp.

Shigella stands as a major contributor to bacterial dysentery worldwide scale, particularly in developing countries with inadequate sanitation and hygiene. The emergence of multidrug-resistant strains exacerbates the challenge of treating Shigella infections, particularly in regions where access to healthcare and alternative antibiotics is limited. Therefore, investigations on how bacteria evade antibiotics and eventually develop resistance could open new avenues for research to develop novel therapeutics. The aim of this study was to analyze whole genome sequence (WGS) of human pathogenic Shigella spp. to elucidate the antibiotic resistance genes (ARGs) and their mechanism of resistance, gene-drug interactions, protein-protein interactions, and functional pathways to screen potential therapeutic candidate(s). We comprehensively analyzed 45 WGS of Shigella, including S. flexneri (n = 17), S. dysenteriae (n = 14), S. boydii (n = 11), and S. sonnei (n = 13), through different bioinformatics tools. Evolutionary phylogenetic analysis showed three distinct clades among the circulating strains of Shigella worldwide, with less genomic diversity. In this study, 2,146 ARGs were predicted in 45 genomes (average 47.69 ARGs/genome), of which only 91 ARGs were found to be shared across the genomes. Majority of these ARGs conferred their resistance through antibiotic efflux pump (51.0%) followed by antibiotic target alteration (23%) and antibiotic target replacement (18%). We identified 13 hub proteins, of which four proteins (e.g., tolC, acrR, mdtA, and gyrA) were detected as potential hub proteins to be associated with antibiotic efflux pump and target alteration mechanisms. These hub proteins were significantly (p < 0.05) enriched in biological process, molecular function, and cellular components. Therefore, the finding of this study suggests that human pathogenic Shigella strains harbored a wide range of ARGs that confer resistance through antibiotic efflux pumps and antibiotic target modification mechanisms, which must be taken into account to devise and formulate treatment strategy against this pathogen. Moreover, the identified hub proteins could be exploited to design and develop novel therapeutics against MDR pathogens like Shigella.

Prevalence and changing antimicrobial resistance profiles of Shigella spp. isolated from diarrheal patients in Kolkata during 2011-2019.

The primary aim of this study was to investigate the occurrence, characteristics, and antimicrobial resistance patterns of various Shigella serogroups isolated from patients with acute diarrhea of the Infectious Diseases Hospital in Kolkata from 2011-2019. During the study period, Shigella isolates were tested for their serogroups, antibiotic resistance pattern and virulence gene profiles. A total of 5.8% of Shigella spp. were isolated, among which S. flexneri (76.1%) was the highest, followed by S. sonnei (18.7%), S. boydii (3.4%), and S. dysenteriae (1.8%). Antimicrobial resistance against nalidixic acid was higher in almost all the Shigella isolates, while the resistance to β-lactamases, fluoroquinolones, tetracycline, and chloramphenicol diverged. The occurrence of multidrug resistance was found to be linked with various genes encoding drug-resistance, multiple mutations in the topoisomerase genes, and mobile genetic elements. All the isolates were positive for the invasion plasmid antigen H gene (ipaH). Dendrogram analysis of the plasmid and pulsed-field electrophoresis (PFGE) profiles revealed 70-80% clonal similarity among each Shigella serotype. This comprehensive long-term surveillance report highlights the clonal diversity of clinical Shigella strains circulating in Kolkata, India, and shows alarming resistance trends towards recommended antibiotics. The elucidation of this study's outcome is helpful not only in identifying emerging antimicrobial resistance patterns of Shigella spp. but also in developing treatment guidelines appropriate for this region.

Molecular Characterization of Multidrug-Resistant Shigella flexneri.

Due to their propensity for causing diarrheal illnesses and their rising susceptibility to antimicrobials, Shigella infections constitute a serious threat to global public health. This extensive study explores the frequency, antibiotic resistance, genetic evolution, and effects of Shigella infections on vulnerable groups. The research covers a wide range of geographical areas and sheds information on how the prevalence of Shigella species is evolving.Shigella strain antimicrobial resistance patterns are thoroughly examined. Multidrug resistance (MDR) has been found to often occur in investigations, especially when older antimicrobials are used. The improper use of antibiotics in China is blamed for the quick emergence of resistance, and variations in resistance rates have been seen across different geographical areas. Shigella strains' genetic makeup can be used to identify emerging trends and horizontal gene transfer's acquisition of resistance genes. Notably, S. sonnei exhibits the capacity to obtain resistance genes from nearby bacteria, increasing its capacity for infection. The study also emphasizes the difficulties in accurately serotyping Shigella strains due to inconsistencies between molecular and conventional serology. These results highlight the necessity of reliable diagnostic methods for monitoring Shigella infections. In conclusion, this study emphasizes how dynamic Shigella infections are, with varying patterns of occurrence, changing resistance landscapes, and genetic adaptability. In addition to tackling the rising problem of antibiotic resistance in Shigella infections, these findings are essential for guiding efforts for disease surveillance, prevention, and treatment.

Anti-Shigella and antioxidant-based screening of some Cameroonian medicinal plants, UHPLC-LIT-MS/MS fingerprints, and prediction of pharmacokinetic and drug-likeness properties of identified chemicals.

Ethnopharmacological relevanceShigella infection is a public health problem responsible for approximately 700,000 deaths annually. The management of this disease is impaired by the emergence of multidrug-resistant Shigella species, highlighting the urgent need to search for alternative treatment options. In this regard, investigating medicinal plants traditionally used for the treatment of dysentery, diarrheal infections, and/or associated symptoms in endemic regions might provide an opportunity to identify phytochemicals that could be further used as a basis for the development of future anti-shigella drug candidates. Aim of the studyThis study was designed to investigate the anti-shigella and antioxidant-based ethnopharmacological potency of some Cameroonian medicinal plants with an emphasis on pharmacokinetic properties of the identified chemical pharmacophore. Materials and methodsBriefly, plant species were selected and collected based on their ethnopharmacological uses and information reported in the literature. Crude aqueous, ethanolic, methanolic, and hydroethanolic (30:70, v/v) extracts from these plants were prepared and then screened for their anti-Shigella activity against four Shigella strains and cytotoxicity against Vero and Raw cell lines using microdilution and resazurin-based methods, respectively. The antioxidant activities of potent extracts were evaluated using DPPH, ABTS, NO, and FRAP scavenging assays. The chemical profile of potent extracts was performed using the UHPLC-LIT-MS/MS and the pharmacokinetic properties, druglikeness, and likely molecular targets of the chemical scaffolds identified were predicted using SwissADME and SwissTargetPredictor. ResultsThirty-nine (39) plants belonging to 26 plant families were harvested. Out of the 228 extracts tested, 18 extracts originating from 6 plants (15.38 %) were active (MICs 250–1000 μg/mL) and nontoxic toward Vero (CC50 129.25–684.55 μg/mL) and Raw cell lines (CC50 336.20 to >1000 μg/mL). Six potent extracts from the two plants exhibited moderate to potent DPPH (SC50 8.870–54.410 μg/mL), ABTS (SC50 12.020–27.36 μg/mL), and NO (SC50 0.02–195.85 μg/mL) scavenging activities. Later, these extracts showed interesting ferric iron-reducing power (1.28–12.14 μg equivalent NH2OH/g of extract). The shortest onset of action time (4 and 6 h) observed following inhibition kinetics studies was observed with extracts BFSHE, PMSE, and PMSM. The UHPLC-LIT-MS/MS and some databases (Mass Spectral Library (NIST 14), Human Metabolome Database (HMD), MassBank, SuperNatural 3.0, The Food Database (FooDB), and Chemical Entities of Biological Interest (ChEBI)) allowed the annotation of 18 and 17 metabolites in the extracts from stem bark of P. macrophylla and B. ferruginea respectively. Pharmacokinetic prediction of these chemicals showed that compound 6 (4,6a-bis(Hydroxymethyl)-9a-methyl-3-oxo-1a,1b,3,5,6,6a,7a,9a-octahydrobis (oxireno)[2′,3':5,6; 2″,3'':9,10]cyclodeca[1,2-b]furan-5-yl methacrylate), compound 8 (Corynoxeine), and compounds 35 (Stachybotrydial acetate) demonstrated acceptable druglike and pharmacokinetic properties and might act through inhibition of kinase, transferase, protease, oxidoreductase, and family AG protein-linked receptors. ConclusionThe findings from this investigation demonstrated that Cameroonian medicinal plants are suitable reservoirs of anti-Shigella and antioxidant agents with good drug candidate properties.

Shigella virulence protein VirG is a broadly protective antigen and vaccine candidate

Diarrhea caused by Shigella has been associated with high morbidity and mortality in young children worldwide. There are no licensed vaccines, and those clinically advanced have restricted coverage as they elicit serotype-specific immunity while disease is caused by multiple circulating serotypes. Our group had previously reported a close association between serum antibodies to the Shigella virulence factor VirG (or IcsA) and clinical protection in infected individuals. VirG is highly conserved among Shigella strains and appealing as a broad-spectrum vaccine candidate. In this study, we investigated the immunogenicity and protective capacity of VirG as a subunit vaccine in mice. The surface-exposed alpha (α) domain of VirG (VirGα) was produced as a recombinant protein. This region has almost identical immune reactivity to full-length VirG. Administered intramuscularly with alum, VirGα elicited robust immune responses and high protective efficacy against S. flexneri 2a and S. sonnei. Almost complete protection was afforded by VirGα given intranasally with the E. coli double mutant heat-labile toxin (dmLT). VirGα-specific antibodies recognized VirG expressed on live Shigella, and blocked Shigella adhesion and invasion to human colonic cells. These results show for the first time that VirGα is a promising cross-protective vaccine candidate to prevent Shigella infection.

Characterization of genotypes and antimicrobial resistance profiles of clinical isolates of Shigella from patients in the southern region of Iran

BackgroundShigella spp., which are facultative anaerobic bacilli within the Enterobacteriaceae family, present a significant public health burden due to their role as prominent contributors to diarrheal diseases worldwide. A molecular analysis can facilitate the identification and assessment of outbreaks involving this bacterium. So, we aimed to investigate the antibiotic susceptibility pattern and clonal relatedness of clinical Shigella spp. isolates obtained from patients with diarrhea in Hormozgan province, South of Iran.MethodsFrom 2019 to 2021, a cross-sectional investigation was conducted on 448 stool samples obtained from patients who were experiencing diarrhea, in the southern region of Iran. Shigella spp. isolates were identified based on biochemical and serological tests. All Shigella species were verified using species-specific polymerase chain reaction (PCR), followed by susceptibility testing to antimicrobial agents. Subsequently, genotyping of all Shigella species was conducted using ERIC-PCR.ResultsOut of a total of 448 stool samples, the presence of Shigella was detected in 62 cases, accounting for a prevalence rate of 13.84%. Among the identified isolates, the majority were attributed to S. flexneri, representing 53.23% of the cases. This was followed by S. sonnei at 24.19% and S. boydii at 22.58%. Notably, no instances of S. dysenteriae were found. The highest prevalence of Shigella isolates was observed in infants and children under the age of five. A significant proportion of the identified isolates demonstrated resistance to various antibiotics. Specifically, high resistance rates were noted for ampicillin (90.78%), piperacillin–tazobactam (87.1%), cefixime (83.87%), trimethoprim–sulfamethoxazole (83.87%), cefotaxime (82.26%), and ceftriaxone (80.65%). In addition, a substantial number (87.1%) of the isolates exhibited a multidrug-resistant (MDR) phenotype. Using the ERIC-PCR method, a total of 11 clusters and 6 distinct single types were identified among all the Shigella isolates.ConclusionA notable occurrence of antibiotic-resistant Shigella species has been noted, with multi-drug resistant (MDR) strains presenting an increasing challenge for treating shigellosis worldwide, and this includes Iran. Techniques such as ERIC-PCR are useful for assessing the genetic variation and connections between Shigella strains, which indirectly contributes to understanding antimicrobial resistance patterns. Further research is needed to explore the specific correlation between resistance genes and ERIC genotyping patterns in Shigella strains.

Refining Immunogenicity through Intradermal Delivery of Outer Membrane Vesicles against Shigella flexneri in Mice

Shigellosis remains a global health concern, especially in low- and middle-income countries. Despite improvements in sanitation, the absence of a licensed vaccine for human use has prompted global health organizations to support the development of a safe and effective multivalent vaccine that is cost-effective and accessible for limited-resource regions. Outer Membrane Vesicles (OMVs) have emerged in recent years as an alternative to live attenuated or whole-inactivated vaccines due to their immunogenicity and self-adjuvating properties. Previous works have demonstrated the safety and protective capacity of OMVs against Shigella flexneri infection in mouse models when administered through mucosal or intradermal routes. However, some immunological properties, such as the cellular response or cross-protection among different Shigella strains, remained unexplored. In this study, we demonstrate that intradermal immunization of OMVs with needle-free devices recruits a high number of immune cells in the dermis, leading to a robust cellular response marked by antigen-specific cytokine release and activation of effector CD4 T cells. Additionally, functional antibodies are generated, neutralizing various Shigella serotypes, suggesting cross-protective capacity. These findings highlight the potential of OMVs as a promising vaccine platform against shigellosis and support intradermal administration as a simple and painless vaccination strategy to address this health challenge.

Contribution of the Rapid LAMP-Based Diagnostic Test (RLDT) to the Evaluation of Enterotoxigenic Escherichia coli (ETEC) and Shigella in Childhood Diarrhea in the Peri-Urban Area of Ouagadougou, Burkina Faso.

The estimates of enterotoxigenic Escherichia coli (ETEC) and Shigella burden in developing countries are limited by the lack of rapid, accessible, and sensitive diagnostics and surveillance tools. We used a "Rapid LAMP based Diagnostic Test (RLDT)" to detect ETEC and Shigella in diarrheal and non-diarrheal stool samples from a 12-month longitudinal cohort of children under five years of age in a peri-urban area of Ouagadougou in Burkina Faso (West Africa). To allow comparison with the RLDT-Shigella results, conventional culture methods were used to identify Shigella strains in the stool samples. As conventional culture alone cannot detect ETEC cases, a subset of E. coli-like colonies was tested using conventional PCR to detect ETEC toxins genes. Of the 165 stool samples analyzed for ETEC, 24.9% were positive when using RLDT against 4.2% when using culture followed by PCR. ETEC toxin distribution when using RLDT was STp 17.6% (29/165), LT 11.5% (19/165), and STh 8.5% (14/165). Of the 263 specimens tested for Shigella, 44.8% were positive when using RLDT against 23.2% when using culture. The sensitivity and specificity of the RLDT compared to culture (followed by PCR for ETEC) were 93.44% and 69.8% for Shigella and 83.7% and 77.9% for ETEC, respectively. This study indicates that both Shigella and ETEC are substantially underdiagnosed when using conventional culture and highlights the potential contribution of the new RLDT method to improve enteric disease burden estimation and to guide future efforts to prevent and control bacterial enteric infection and disease.

Molecular detection of genes encoding resistance to tetracycline and quinolones among Shigella strains isolated from children with acute diarrhea in southwest Iran.

An increase in the antibiotic resistance of Shigella isolates has caused major global challenges in antimicrobial therapy. Knowledge of local antibiotic resistance trends is essential for selecting appropriate antibiotic treatment regimens. This study aimed to evaluate the frequency of efflux-mediated tetracycline resistance (tet) and plasmid-mediated quinolone resistance (qnr) genes among Shigella isolates. This survey investigated 91 Shigella isolates, obtained from children with acute diarrhea. The isolates were identified using standard biochemical tests and confirmed by polymerase chain reaction (PCR) assay. Besides, the susceptibility of isolates to six selected antibiotics was assessed by the disk diffusion method. All tetracycline-resistant and nalidixic acid and ciprofloxacin resistant strains were screened for tet and qnr genes by a multiplex PCR assay. According to the results of antibiotic susceptibility tests, the highest level of antibiotic resistance was related to tetracycline (80.2%) and doxycycline (78.1%), respectively. All isolates were sensitive to tigecycline. The PCR results showed that 40.6%, 3.1%, 21.8%, 61.6% and 28.7% of the isolates carried qnrA, qnrB, qnrS, tetA, and tetB genes, respectively. None of the isolates contained tetC and tetD genes. The current findings revealed that tetA and qnrA genes might play a key role in conferring tetracycline and quinolone resistance.

Environmental DNA transformation resulted in an active phage in Escherichia coli.

The achievement of an active biological entity from environmental DNA is important in the field of phage. In this study, the environmental DNA extracted from hospital wastewater was transferred into Escherichia coli DH10B and Escherichia coli BL21 with chemical transformation and electroporation. After transformation, overnight cultures were filtered and used as phage source. The efficacies of the techniques were evaluated with spot test and double-layer agar assay. The emerged phage, named as ADUt, was purified and host-range analysis was performed. Phage DNA was isolated, sequenced and restriction profile was determined. The genome was assembled. The phylogenetic tree was constructed via VipTree. The extracted DNA resulted in active phage by the transformation of E. coli DH10B, but not E. coli BL21. The chemical transformation was found more successful than electroporation. ADUt phage was found to be polyvalent and effective against limited strains of Shigella and Escherichia genera. The phage genome size and GC ratio are 166904 bp and 35.67%, respectively. ADUt is a member of Straboviridae family and Tequatrovirus genus. This is the first study that uses environmental DNA for acquiring active phage, which may be an important source of new phage discovery. The result showed that DNA transformation yields active bacteriophage with both chemical transformation and electroporation.

A next-generation GMMA-based vaccine candidate to fight shigellosis

Shigellosis is a leading cause of diarrheal disease in low-middle-income countries (LMICs). Effective vaccines will help to reduce the disease burden, exacerbated by increasing antibiotic resistance, in the most susceptible population represented by young children. A challenge for a broadly protective vaccine against shigellosis is to cover the most epidemiologically relevant serotypes among >50 Shigella serotypes circulating worldwide. The GMMA platform has been proposed as an innovative delivery system for Shigella O-antigens, and we have developed a 4-component vaccine against S. sonnei, S. flexneri 1b, 2a and 3a identified among the most prevalent Shigella serotypes in LMICs. Driven by the immunogenicity results obtained in clinic with a first-generation mono-component vaccine, a new S. sonnei GMMA construct was generated and combined with three S. flexneri GMMA in a 4-component Alhydrogel formulation (altSonflex1-2-3). This formulation was highly immunogenic, with no evidence of negative antigenic interference in mice and rabbits. The vaccine induced bactericidal antibodies also against heterologous Shigella strains carrying O-antigens different from those included in the vaccine. The Monocyte Activation Test used to evaluate the potential reactogenicity of the vaccine formulation revealed no differences compared to the S. sonnei mono-component vaccine, shown to be safe in several clinical trials in adults. A GLP toxicology study in rabbits confirmed that the vaccine was well tolerated. The preclinical study results support the clinical evaluation of altSonflex1-2-3 in healthy populations, and a phase 1–2 clinical trial is currently ongoing.

Trends in antimicrobial resistance of Shigella species in Peru, 2011-2020.

To describe the frequency of antimicrobial resistance rates and spatial-temporal distribution of Shigella species from the last 10 years in Peru. A cross-sectional descriptive study was carried out. A total of 1668 Shigella strains, remitted as part of the national enteric pathogen surveillance from 2011 to 2020, were analysed. The strains were confirmed by conventional tests and serotyped with polyvalent and monovalent antibodies. Also, antimicrobial susceptibility was performed according to the Kirby-Bauer method. The most frequent Shigella species was S. sonnei (49.2%), followed by S. flexneri (42.2%), S. boydii (7.9%) and S. dysenteriae (0.7%). Phase II (46.29%) was the most frequent serotype in S. sonnei, serotype 2a (43.61%) in S. flexneri, serotype 2 in S. boydii and serotype 4 in S. dysenteriae. High rates of resistance were detected for trimethoprim/sulfamethoxazole (91.0%), tetracycline (88.4%), ampicillin (73.9%) and chloramphenicol (64.9%), moderate rates for amoxicillin/clavulanic acid (25.1%), ciprofloxacin (16.7%) and nalidixic acid (14.8%), and low rates for cefotaxime (1.74%), nitrofurantoin (0.7%) and ceftazidime (0.6%). Moreover, antimicrobial resistance to fluoroquinolones increased considerably from 2017 to 2020. S. sonnei was the most frequent species, which have a large proportion of strains resistant to trimethoprim/sulfamethoxazole, and a growing trend of resistance to ciprofloxacin and nalidixic acid. This increase in resistance to commonly used antibiotics in treatments is alarming, threatening the control and management of these currently treatable infections.