A multicentre study of Shigella diarrhoea in six Asian countries: disease burden, clinical manifestations, and microbiology

Enhancing insights into diseases through horizontal gene transfer event detection from gut microbiome

Horizontal gene transfer (HGT) phenomena pervade the gut microbiome and significantly impact human health. Yet, no current method can accurately identify complete HGT events, including the transferred sequence and the associated deletion and insertion breakpoints from shotgun metagenomic data. Here, we develop LocalHGT, which facilitates the reliable and swift detection of complete HGT events from shotgun metagenomic data, delivering an accuracy of 99.4%-verified by Nanopore data-across 200 gut microbiome samples, and achieving an average F1 score of 0.99 on 100 simulated data. LocalHGT enables a systematic characterization of HGT events within the human gut microbiome across 2098 samples, revealing that multiple recipient genome sites can become targets of a transferred sequence, microhomology is enriched in HGT breakpoint junctions (P-value = 3.3e-58), and HGTs can function as host-specific fingerprints indicated by the significantly higher HGT similarity of intra-personal temporal samples than inter-personal samples (P-value = 4.3e-303). Crucially, HGTs showed potential contributions to colorectal cancer (CRC) and acute diarrhoea, as evidenced by the enrichment of the butyrate metabolism pathway (P-value = 3.8e-17) and the shigellosis pathway (P-value = 5.9e-13) in the respective associated HGTs. Furthermore, differential HGTs demonstrated promise as biomarkers for predicting various diseases. Integrating HGTs into a CRC prediction model achieved an AUC of 0.87.

Rapid diagnostic tests and loop-mediated isothermal amplification method for the detection of Shigella species: A systematic review and meta-analysis

We meta-analyzed the diagnostic accuracy of rapid diagnostic tests (dipsticks) and loop-mediated isothermal amplification (LAMP) method to detect Shigella species. We searched MEDLINE, Embase, Web of Science and Google Scholar from inception to 2023 for studies reporting on the performance of Shigella dipstick and LAMP tests compared with culture or polymerase chain reaction (PCR). Our search identified 2618 studies, of which fourteen met the inclusion criteria for the systematic review. Ten studies covering 4056 tests (from twelve countries) were included in the meta-analysis. The overall pooled sensitivity and specificity were 98% (95% CI: 94-100) and 97% (95% CI: 92-99), respectively. Pooled sensitivity and specificity of dipsticks were 95% and 98%, respectively. In contrast, LAMP showed higher pooled sensitivity (100%) and diagnostic odds ratio (431752), but similar specificity (97%). LAMP and dipstick tests exhibited promising performance, suggesting that they could be useful for assisting in the diagnosis of shigellosis.

Efficacy of Lactose-Free Milk in Treating Acute Gastroenteritis in Vietnamese Children: A Randomized Controlled Trial

BACKGROUND

Low lactase levels in Asian children appear to be genetically determined or rotavirus-induced gastroenteritis. Consuming lactose-free formula in children with acute gastroenteritis may shorten diarrhea's duration and increase weight gain. This study aims to determine whether lactose-free milk will change the duration of diarrhea and weight gain in Vietnamese children aged 2-24 months with acute gastroenteritis.

MATERIALS AND METHODS

A randomized control trial was performed on 66 children under 24 months of age with acute gastroenteritis at the Gastroenterology Department of Can Tho Children's Hospital. In adjunction to oral rehydration solution, they received either a lactose-free formula (n=33) or a lactose-containing formula (n=33).

OUTCOME MEASURES

Diarrhea duration, weight gain, treatment failure, and days of hospitalization were all studied.

RESULTS

A total of 66 children participated in this trial, with a mean age of 13.4 ± 5.1 months, and 38 participants (57.6%) were male. There were no significant differences between the lactose-free formula group and the lactose-containing formula group in the duration of diarrhea (2.2±0.8 days versus 2.4±0.9 days; P=0.321), percentage of weight gain (1.96 [IQR:1.35-2.36] percent vs. 2.29 [IQR:1.81-2.40] percent; P=0.131), treatment failure rate (33.3% vs. 36.4%; P= 0.796), and days of hospitalization (5.8±1.7 vs. 6.5±2.5 days; P=0.158).

CONCLUSIONS

It may not be necessary to use lactose-free milk routinely in Vietnamese children under 24 months with acute gastroenteritis as the duration of diarrhea, weight change, treatment failure rates, and hospital stay are similar to those of children fed lactose-containing milk.

Field evaluation of a simple and rapid diagnostic test, RLDT to detect Shigella and enterotoxigenic E. coli in Indian children

The diagnostic assays currently used to detect Shigella spp. (Shigella) and enterotoxigenic Escherichia coli (ETEC) are complex or elaborate which make them difficult to apply in resource poor settings where these diseases are endemic. The simple and rapid nucleic acid amplification-based assay "Rapid LAMP-based Diagnostic Test (RLDT)" was evaluated to detect Shigella spp (Shigella) and enterotoxigenic Escherichia coli (ETEC) and determine the epidemiology of these pathogens in Kolkata, India. Stool samples (n = 405) from children under five years old with diarrhea seeking care at the hospitals were tested, and 85(21%) and 68(17%) by RLDT, 91(23%) and 58(14%) by quantitative PCR (qPCR) and 35(9%) and 15(4%) by culture, were positive for Shigella and ETEC, respectively. The RLDT showed almost perfect agreement with qPCR, Kappa 0.96 and 0.89; sensitivity 93% and 98%; specificity 100% and 97% for Shigella and ETEC, respectively. While RLDT detected additional 12% Shigella and 13% ETEC than culture, all culture positives for Shigella and ETEC except one each were also positive by the RLDT, sensitivity 97% and 93% respectively. RLDT is a simple, sensitive, and rapid assay that could be implemented with minimum training in the endemic regions to strengthen the disease surveillance system and rapid outbreak detection.

WHO's essential medicines and AWaRe: recommendations on first- and second-choice antibiotics for empiric treatment of clinical infections

The WHO Model List of Essential Medicines (EML) prioritizes medicines that have significant global public health value. The EML can also deliver important messages on appropriate medicine use. Since 2017, in response to the growing challenge of antimicrobial resistance, antibiotics on the EML have been reviewed and categorized into three groups: Access, Watch, and Reserve, leading to a new categorization called AWaRe. These categories were developed taking into account the impact of different antibiotics and classes on antimicrobial resistance and the implications for their appropriate use. The 2023 AWaRe classification provides empirical guidance on 41 essential antibiotics for over 30 clinical infections targeting both the primary health care and hospital facility setting. A further 257 antibiotics not included on the EML have been allocated an AWaRe group for stewardship and monitoring purposes. This article describes the development of AWaRe, focussing on the clinical evidence base that guided the selection of Access, Watch, or Reserve antibiotics as first and second choices for each infection. The overarching objective was to offer a tool for optimizing the quality of global antibiotic prescribing and reduce inappropriate use by encouraging the use of Access antibiotics (or no antibiotics) where appropriate. This clinical evidence evaluation and subsequent EML recommendations are the basis for the AWaRe antibiotic book and related smartphone applications. By providing guidance on antibiotic prioritization, AWaRe aims to facilitate the revision of national lists of essential medicines, update national prescribing guidelines, and supervise antibiotic use. Adherence to AWaRe would extend the effectiveness of current antibiotics while helping countries expand access to these life-saving medicines for the benefit of current and future patients, health professionals, and the environment.

The Enterics for Global Health (EFGH) Shigella Surveillance Study in Bangladesh

Background

Shigella is an important cause of diarrhea in Bangladeshi children <5 years of age, with an incidence rate of 4.6 per 100 person-years. However, the report was more than a decade old, and data on Shigella consequences are similarly outdated and heterogeneously collected.

Methods

Facility-based disease surveillance is planned to be carried out under the Enterics for Global Health (EFGH) Shigella Surveillance Study consortium for 2 years with aims to optimize and standardize laboratory techniques and healthcare utilization and coverage survey, clinical and anthropometric data collection, safety monitoring and responsiveness, and other related activities. The EFGH is a cohesive network of multidisciplinary experts, capable of operating in concert to conduct the study to generate data that will pave the way for potential Shigella vaccine trials in settings with high disease burden. The study will be conducted within 7 country sites in Asia, Africa, and Latin America.

Conclusions

We outline the features of the Bangladesh site as part of this multisite surveillance network to determine an updated incidence rate and document the consequences of Shigella diarrhea in children aged 6-35 months, which will help inform policymakers and to implement the future vaccine trials.

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.

Exopolysaccharide produced by Lactiplantibacillus plantarum Y12 exhibits inhibitory effect on the Shigella flexneri genes expression related to biofilm formation

Shigella is a specific enteric pathogen in humans, causing symptoms of bacterial dysentery. The biofilm formation of S. flexneri contributes to the emergence of multidrug resistance and facilitates the establishment of persistent chronic infections. This study investigated the regulatory effects of Lactiplantibacillus plantarum Y12 exopolysaccharide (L-EPS) on gene expression and its spatial hindrance effects in inhibiting the biofilm formation of S. flexneri. The transcriptome analysis revealed a significant impact of L-EPS on the gene expression profile of S. flexneri, with a total of 968 genes showing significant changes (507 up-regulated and 461 down-regulated). The significantly down-regulated KEGG metabolic pathway enriched in phosphotransferase system, Embden-Meyerhf-Parnas, Citrate cycle, Lipopolysaccharide biosynthesis, Cationic antimicrobial peptide resistance, Two-component system. Moreover, L-EPS significantly down-regulated the gene expression levels of fimbriae synthesis (fimF), lipopolysaccharide synthesis (lptE, lptB), anchor protein repeat domain (arpA), virulence factor (lpp, yqgB), antibiotic resistance (marR, cusB, mdtL, mdlB), heavy metal resistance (zraP), and polysaccharide synthesis (mtgA, mdoB, mdoC). The expression of biofilm regulator factor (bssS) and two-component system suppressor factor (mgrB) were significantly up-regulated. The RT-qPCR results indicated that a major component of L-EPS (L-EPS 2-1) exhibited the gene regulatory effect on the S. flexneri biofilm formation. Furthermore, electrophoresis and isothermal microtitration calorimetry demonstrated that the interaction between L-EPS 2-1 and eDNA is electrostatic dependent on the change in environmental pH, disrupting the stable spatial structure of S. flexneri biofilm. In conclusion, L-EPS inhibited the biofilm formation of S. flexneri through gene regulation and spatial obstruction effects.

Genomic, transcriptomic, and phenotypic differences among archetype Shigella flexneri strains of serotypes 2a, 3a, and 6

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.

Shigella as a Cause of Diarrhea Hospitalization in Children Under Five: Evaluation by Conventional and Molecular Methods

BACKGROUND AND OBJECTIVES

Shigella is an important cause of diarrhea in children under five, often missed by conventional laboratory methods. Blood in stools has always been a syndromic indicator for Shigella diarrhea, but most cases present with watery diarrhea without blood. This study aimed to determine the frequency of Shigella detected by molecular and conventional methods in children under five. Additionally, we aimed to study the clinical profile and outcome of children with Shigella diarrhea managed as per current diarrhea treatment guidelines.

METHODS

In this hospital-based prospective observational study, stool samples from 150 children (age range: one month to five years) with acute diarrhea (duration < seven days) were subjected to routine microscopic examination, stool culture, and DNA extraction. The extracted DNA from stored stool samples was subjected to polymerase chain reaction (PCR) amplification using a specific primer for the invasion plasmid antigen H gene sequence (ipaH) gene at 424 bp. Results were interpreted in the context of the percentage of isolation of Shigella by molecular (PCR) and conventional methods (stool microscopy and culture) and the follow-up outcome in terms of recurrence of diarrhea or dysentery and growth faltering over three months after discharge.

RESULTS

Shigella infection was diagnosed in stool samples by PCR from 13 (8.7%) children, whereas it was isolated by conventional stool culture in only one (0.7%) child. The sensitivity of culture was only 7.7% against PCR for the diagnosis of Shigella infection, whereas blood in stools had a sensitivity of 15.4%. The majority of Shigella PCR-positive cases (11 out of 13) presented with non-bloody diarrhea. None of the evaluated clinical predictors had a significant association with the Shigella infection. No statistically significant difference was found between PCR-positive and PCR-negative children at the end of follow-up (P>0.05).

CONCLUSION

The majority of children with Shigella infection present with watery diarrhea rather than bloody diarrhea, and a history of blood in stools is a poor marker for the diagnosis of shigellosis. The diagnostic performance of stool culture is also very low compared to stool PCR for the diagnosis of Shigella diarrhea.

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

Objective

To describe the frequency of antimicrobial resistance rates and spatial-temporal distribution of Shigella species from the last 10 years in Peru.

Methods

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.

Results

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.

Conclusion

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.

Mitogen-Activated Protein Kinases (MAPKs) and Enteric Bacterial Pathogens: A Complex Interplay

Diverse extracellular and intracellular cues activate mammalian mitogen-activated protein kinases (MAPKs). Canonically, the activation starts at cell surface receptors and continues via intracellular MAPK components, acting in the host cell nucleus as activators of transcriptional programs to regulate various cellular activities, including proinflammatory responses against bacterial pathogens. For instance, binding host pattern recognition receptors (PRRs) on the surface of intestinal epithelial cells to bacterial pathogen external components trigger the MAPK/NF-κB signaling cascade, eliciting cytokine production. This results in an innate immune response that can eliminate the bacterial pathogen. However, enteric bacterial pathogens evolved sophisticated mechanisms that interfere with such a response by delivering virulent proteins, termed effectors, and toxins into the host cells. These proteins act in numerous ways to inactivate or activate critical components of the MAPK signaling cascades and innate immunity. The consequence of such activities could lead to successful bacterial colonization, dissemination, and pathogenicity. This article will review enteric bacterial pathogens' strategies to modulate MAPKs and host responses. It will also discuss findings attempting to develop anti-microbial treatments by targeting MAPKs.

The preventive effect of Glycyrrhiza polysaccharide on lipopolysaccharide-induced acute colitis in mice by modulating gut microbial communities

Acute colitis is characterised by an unpredictable onset and causes intestinal flora imbalance together with microbial migration, which leads to complex parenteral diseases. Dexamethasone, a classic drug, has side effects, so it is necessary to use natural products without side effects to prevent enteritis. Glycyrrhiza polysaccharide (GPS) is an α-d-pyranoid polysaccharide with anti-inflammatory effects; however, its anti-inflammatory mechanism in the colon remains unknown. This study investigated whether GPS reduces the lipopolysaccharide (LPS)-induced inflammatory response in acute colitis. The results revealed that GPS attenuated the upregulation of tumour necrosis factor-α, interleukin (IL)-1β, and IL-6 in the serum and colon tissues and significantly reduced the malondialdehyde content in colon tissues. In addition, the 400 mg/kg GPS group showed higher relative expressions of occludin, claudin-1, and zona occludens-1 in colon tissues and lower concentrations of diamine oxidase, D-lactate, and endotoxin in the serum than the LPS group did, indicating that GPS improved the physical and chemical barrier functions of colon tissues. GPS increased the abundance of beneficial bacteria, such as Lactobacillus, Bacteroides, and Akkermansia, whereas pathogenic bacteria, such as Oscillospira and Ruminococcus were inhibited. Our findings indicate that GPS can effectively prevent LPS-induced acute colitis and exert beneficial effects on the intestinal health.

The changing epidemiology of shigellosis in Australia, 2001-2019

Shigellosis is an increasing cause of gastroenteritis in Australia, with prolonged outbreaks reported in remote Aboriginal and Torres Strait Islander (hereafter "First Nations") communities and among men who have sex with men (MSM) in major cities. To determine associations between Shigella species and demographic and geographic factors, we used multivariate negative binomial regression to analyse national case notifications of shigellosis from 2001 to 2019. Between 2001 and 2019, Australian states and territories reported 18,363 shigellosis cases to the National Notifiable Diseases Surveillance System (NNDSS), of which age, sex and organism information were available for >99% (18,327/18,363) of cases. Of the cases included in our analysis, 42% (7,649/18,327) were S. sonnei, 29% (5,267/18,327) were S. flexneri, 1% (214/18,327) were S. boydii, less than 1% (87/18,327) were S. dysenteriae, and species information was unknown for 28% (5,110/18,327) of cases. Males accounted for 54% (9,843/18,327) of cases, and the highest proportion of cases were in children aged 0-4 years (19%; 3,562/18,327). Crude annual notification rates ranged from 2.2 cases per 100,000 in 2003 and 2011 to 12.4 cases per 100,000 in 2019. Nationally, notification rates increased from 2001 to 2019 with yearly notification rate ratios of 1.04 (95% CI 1.02-1.07) for S. boydii and 1.05 (95% CI 1.04-1.06) for S. sonnei. Children aged 0-4 years had the highest burden of infection for S. flexneri, S. sonnei and S. boydii; and males had a higher notification rate for S. sonnei (notification rate ratio 1.24, 95% CI 1.15-1.33). First Nations Australians were disproportionately affected by shigellosis, with the notification rate in this population peaking in 2018 at 92.1 cases per 100,000 population. Over the study period, we also observed a shift in the testing method used to diagnose shigellosis, with culture independent diagnostic testing (CIDT) increasing from 2014; this also coincided with an increase in notifications of untyped Shigella. This change in testing methodology may have contributed to the observed increase in shigellosis notifications since 2014, with CIDT being more sensitive than culture dependent testing methods. The findings of this study provide important insights into the epidemiological characteristics of shigellosis in Australia, including identification of high-risk groups. This can be used to inform public health prevention and control strategies, such as targeted communication programs in First Nations communities and places with high levels of interaction between young children, such as childcare centres. Our study findings also highlight the implications of culture independent testing on shigellosis surveillance, particularly a reduction in the availability of species level information. This emphasises the continued importance of culture dependant testing for national surveillance of shigellosis.

Burden of Shigella in South Asia: a systematic review and meta-analysis

BACKGROUND

Shigella remains one of the most common causes of diarrhoea in South Asia. Current estimates of the prevalence of Shigella are critical for guiding control measures. We estimated the prevalence of Shigella species and serogroups in South Asia.

METHODS

We performed a systematic review using PubMed, EMBASE, Google Scholar and Web of Science for peer-reviewed studies published between 2000 and 19 June 2022. We also manually searched the reference lists of the reviewed studies to identify additional studies. We included studies that detected the presence of Shigella in stool by culture or polymerase chain reaction (PCR). Studies associated with outbreaks were excluded. Two investigators independently reviewed the studies, extracted the data and performed quality assessment. A random-effects meta-analysis was performed to determine the pooled prevalence of Shigella.

RESULTS

Our search yielded 5707 studies, of which 91 studies from five South Asian countries were included in the systematic review, 79 in the meta-analysis of Shigella prevalence and 63 in the meta-analysis of Shigella serogroups prevalence. The pooled prevalence of Shigella was 7% [95% confidence interval (CI): 6-7%], with heterogeneity (I2 = 98.7; P < 0.01). The prevalence of Shigella was higher in children aged <5 years (10%; 95% CI: 8-11%), in rural areas (12%; 95% CI: 10-14%) and in studies using PCR (15%; 95% CI: 11-19%). Shigella flexneri (58%) was the most abundant serogroup, followed by Shigella sonnei (19%), Shigella boydii (10%) and Shigella dysenteriae (9%). Shigella flexneri 2a was the most frequently isolated serotype (36%), followed by serotype 3a (12%), serotype 6 (12%) and serotype 1b (6%). The prevalence of non-typeable Shigella was 10.0%.

CONCLUSIONS

Although the prevalence of Shigella in South Asia remains generally high, it varies by age group and geographical area, with data lacking in some countries. Effective Shigella vaccines would be advantageous for both endemic communities and travellers.

Shigellosis in Southeast Asia: A systematic review and meta-analysis

BACKGROUND

Southeast Asia is attractive for tourism. Unfortunately, travelers to this region are at risk of becoming infected with Shigella. We conducted a meta-analysis to provide updates on Shigella prevalence in Southeast Asia, along with their serogroups and serotypes.

METHODS

We conducted a systematic search using PubMed, EMBASE, and Web of Science for peer-reviewed studies from 2000 to November 2022. We selected studies that detected Shigella in stools by culture or polymerase chain reaction (PCR). Two reviewers extracted the data using a standardized form and performed quality assessments using the Joanna Briggs Institute checklist. The random effects model was used to estimate the pooled prevalence of Shigella.

RESULTS

During our search, we identified 4376 studies. 29 studies (from six Southeast Asian countries) were included in the systematic review, 21 each in the meta-analysis of the prevalence of Shigella (Sample size: 109545) and the prevalence of Shigella serogroups. The pooled prevalence of Shigella was 4% (95% CI: 4-5%) among diarrhea cases. Shigella sonnei was the most abundant serogroup in Thailand (74%) and Vietnam (57%), whereas Shigella flexneri was dominant in Indonesia (72%) and Cambodia (71%). Shigella dysenteriae and Shigella boydii were uncommon (pooled prevalence of 1% each). The pooled prevalence of Shigella was 5% (95% CI: 4-6%) in children aged <5 years. The pooled prevalence showed a decreasing trend comparing data collected between 2000-2013 (5%; 95% CI: 4-6%) and between 2014-2022 (3%; 95% CI: 2-4%). Shigella prevalence was 6% in studies that included participants with mixed pathogens versus 3% in those without. Shigella flexneri serotype 2a was the most frequently isolated (33%), followed by 3a (21%), 1b (10%), 2b (3%), and 6 (3%).

CONCLUSIONS

This study provides compelling evidence for the development of effective Shigella vaccines for residents of endemic regions and travellers to these areas.

Phytochemical constituents of Inula britannica as potential inhibitors of dihydrofolate reductase: A strategic approach against shigellosis

Shigella dysenteriae type 1 is considered as an epidemic in different developing countries, which is responsible for the most severe form of bacterial dysentery. It habitually can develop to the most severe form of dysentery with deadly complications. Development of drugs against this disease is still ongoing. Therefore, we used in silico studies to screen the Inula britannica phytocompounds that are used in traditional Chinese and Kampo Medicines and have activities against different diseases. Spinacetin, eupatin, chrysoeriol and diosmetin were successfully passed through the docking-based screening and absorption, distribution, metabolism, excretion and toxicity (ADMET) filtration. The estimated docking affinities of eupatin, diosmetin, chrysoeriol and spinacetin with Dihydrofolate reductase type 1 (DHFR-1), were -6.5, -6.5, -6.3 and -6.1 kcal/mol, respectively. Which were selected for further investigations based on their favorable ADME/Tox characteristics. Then, the 100 ns molecular dynamics (MD) simulations of apo DHFR, spinacetin-DHFR, eupatin-DHFR, chrysoeriol-DHFR and diosmetin-DHFR complexes were carried out. The RMSD fluctuations of the spinacetin, eupatin, chrysoeriol and diosmetin inside the binding site were explored. Subsequently, the effect of binding Spinacetin, eupatin, chrysoeriol and diosmetin upon the dynamic stability of protein was assessed. Additionally, Principal Component Analysis (PCA) and Hydrogen bond analysis was performed for the apo protein and the protein ligand complexes. The results revealed that chrysoeriol and eupatin has good inhibitory effects against DHFR-1 as treatment for Shigella dysenteriae type when compared to other compounds under study. Hence this study implies that eupatin and chrysoeriol are a significantly potential drug like molecule for the treatment of Shigellosis and must undergo validation through in vivo and in vitro experiments.Communicated by Ramaswamy H. Sarma.

Cluster of cases due to Shigella flexneri producing CTX-M-15 in Spain

The aim of our study was to delineate an outbreak of gastroenteritis caused by Shigella flexneri and affecting sixteen persons between May and June 2014 in Bilbao, Spain. All patients exhibited symptoms after consuming kebab in the same kebab shop.The outbreak is described through the clinical cases, the microbiological and molecular genetic diagnosis, and the epidemiologic investigation. Minimum inhibitory concentrations for ampicillin, amoxicillin plus clavulanic acid, third and fourth generation cephalosporins, carbapenems, monobactams, aminoglycosides, fluoroquinolones, co-trimoxazole, colistin and tigecycline were measured. The S. flexneri strains were screened by PCR for TEM, SHV, CTX-M beta-lactamases and plasmidic AmpCs and aac(6')-Ib gene. Serotyping, pulsed field gel-electrophoresis, conjugation assay, plasmid sizing by S1 enzyme digestion and Southern blot hybridization were accomplished.All the S. flexneri isolates proved to be serotype 2 and produced extended-spectrum beta-lactamase (ESBL). Carbapenems, fluoroquinolones, tigecycline, colistin, and co-trimoxazole remained active antibiotics. All the strains harboured blaCTX-M-15 and blaOXA-1 genes. The strains hosted two high-molecular weight plasmids of 100 and 230 kb, respectively. According to the hybridization assay blaCTX-M-15 was located on the plasmid of 230 kb. The identical pulsotype verified the presence of outbreak.Remarkable, that one of the food handlers has travelled recently to Pakistan, where ESBL-producing Shigella strains had been reported previously. To the best of our knowledge, this is the first outbreak caused by CTX-M-15-expressing S. flexneri in Spain and as well as in Europe.

Antimicrobial resistance in shigellosis: A surveillance study among urban and rural children over 20 years in Bangladesh

Antimicrobial resistance against shigellosis is increasingly alarming. However, evidence-based knowledge gaps regarding the changing trends of shigellosis in Bangladesh exist due to the scarcity of longitudinal data on antimicrobial resistance. Our study evaluated the last 20 years antimicrobial resistance patterns against shigellosis among under-5 children in the urban and rural sites of Bangladesh. Data were extracted from the Diarrheal Disease Surveillance System (DDSS) of Dhaka Hospital (urban site) and Matlab Hospital (rural site) of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b) between January 2001 and December 2020. We studied culture-confirmed shigellosis cases from urban Dhaka Hospital (n = 883) and rural Matlab Hospital (n = 1263). Since 2001, a declining percentage of shigellosis in children observed in urban and rural sites. Moreover, higher isolation rates of Shigella were found in the rural site [1263/15684 (8.1%)] compared to the urban site [883/26804 (3.3%)] in the last 20 years. In both areas, S. flexneri was the predominant species. The upward trend of S. sonnei in both the study sites was statistically significant after adjusting for age and sex. WHO-recommended 1st line antibiotic ciprofloxacin resistance gradually reached more than 70% in both the urban and rural site by 2020. In multiple logistic regression after adjusting for age and sex, ciprofloxacin, azithromycin, mecillinam, ceftriaxone, and multidrug resistance (resistance to any two of these four drugs) among under-5 children were found to be increasing significantly (p<0.01) in the last 20 years in both sites. The study results underscore the importance of therapeutic interventions for shigellosis by appropriate drugs based on their current antibiogram for under-5 children. These observations may help policymakers in formulating better case management strategies for shigellosis.

Characterization of Functional B-Cell Epitopes at the Amino Terminus of Shigella Invasion Plasmid Antigen B (IpaB)

Shigella invasion plasmid antigen B (IpaB) plays an important role in causing shigellosis. While IpaB's protein structure, contribution to disease mechanism, and protective immunity against Shigella infection have been well studied, the significance of individual antigenic domains, especially at the N terminus, has not been systematically characterized. In an attempt to identify IpaB protein functional epitopes and to construct an optimized polyvalent multiepitope fusion antigen (MEFA) immunogen for development of a protein-based cross protective Shigella vaccine, in this study, we in silico identified immunodominant B-cell epitopes from the IpaB N terminus, fused each epitope to carrier protein CsaB (the major subunit of enterotoxigenic Escherichia coli CS4 adhesin) for epitope fusion proteins, immunized mice with each epitope fusion protein, examined IpaB-specific antibody responses, and assessed antibody functional activity against Shigella bacterial invasion. A total of 10 B-cell continuous epitopes were identified from IpaB N terminus, and after being fused to carrier protein CsaB, each epitope induced anti-IpaB IgG responses in the intramuscularly immunized mice. While in vitro antibody invasion inhibition assays demonstrated that antibodies derived from each identified epitope were functional, epitopes 1 (LAKILASTELGDNTIQAA), 2 (HSTSNILIPELKAPKSL), and 4 (QARQQKNLEFSDKI) induced antibodies to inhibit Shigella sonnei and Shigella flexneri invasion at levels similar to those of recombinant IpaB protein, suggesting that these three IpaB epitopes can be used potentially as IpaB-representing antigens to induce protective anti-IpaB antibodies and for construction of an epitope-based polyvalent MEFA protein immunogen for Shigella vaccine development. IMPORTANCE Currently, there are no effective measures for control or prevention of Shigella infection, the most common cause of diarrhea in children 3 to 5 years of age in developing countries. Challenges in developing Shigella vaccines include virulence heterogeneity among species and serotypes. To overcome virulence heterogeneity challenge and to develop a protein-based multivalent Shigella vaccine, we targeted a panel of virulence factors, including invasion plasmid antigens, identified functional antigenic domains or epitopes as representative antigens, and applied the novel epitope- and structure-based vaccinology platform multiepitope fusion antigen (MEFA) to integrate functional antigenic domains or epitopes into a backbone immunogen to produce a polyvalent immunogen for cross protective antibodies. Identification of functional IpaB epitopes from this study enhances our understanding of IpaB immunogenicity and allows us to directly utilize IpaB epitopes for construction of a cross protective polyvalent Shigella immunogen and to accelerate development of a protein-based Shigella vaccine.

Clonal serotype 1c multidrug-resistant Shigella flexneri detected in multiple institutions by sentinel-site sequencing

Shigella flexneri is a major diarrhoeal pathogen, and the emergence of multidrug-resistant S. flexneri is of public health concern. We report the detection of a clonal cluster of multidrug-resistant serotype 1c (7a) S. flexneri in Singapore in April 2022. Long-read whole-genome sequence analysis found five S. flexneri isolates to be clonal and harboring the extended-spectrum β-lactamases bla_CTX−M−15 and bla_TEM−1. The isolates were phenotypically resistant to ceftriaxone and had intermediate susceptibility to ciprofloxacin. The S. flexneri clonal cluster was first detected in a tertiary hospital diagnostic laboratory (sentinel-site), to which the S. flexneri isolates were sent from other hospitals for routine serogrouping. Long-read whole-genome sequence analysis was performed in the sentinel-site near real-time in view of the unusually high number of S. flexneri isolates received within a short time frame. This study demonstrates that near real-time sentinel-site sequence-based surveillance of convenience samples can detect possible clonal outbreak clusters and may provide alerts useful for public health mitigations at the earliest possible opportunity.

Flies (Musca domestica, Calliphora vomitoria, Sarcophadigae) and Cokroaches (Periplaneta americana) Control Based on Botanical Insecticides in Outdoor Food Processing Areas

Abstract Background Pathogenic agents can be spread by flies and cockroaches. Food processing areas are favored by insects, Control is carried out to prevent contamination of food. The use of synthetic insecticides causes environmental damage, resistance, and contamination of food that is processed and served. Natural ingredients containing active ingredients can be used as insect repellents that are safer because they can be decomposed by nature. Research Objective This study aims to determine the ability to use the concentration formula and duration of exposure to clove flower extract and bay leaf extract against the repelling capability of flies and cockroaches in outdoor restaurants. Method This research is field experiment research, which studies the effect of concentration formulations and exposure time of clove flower extract and bay leaf extract in repelling flies and cockroaches in food processing facilities. Experiments were carried out with 3 levels of formulation: Clove flower extract and bay leaf extract, namely 20%: 25%, 20%: 30%, 25%: 30% with 3 levels of exposure  time, namely 30 minutes, 45 minutes and 60 minutes. Outdoor restaurant as a place to observe the density of flies and the density of cockroaches, the temperature and humidity of the dining room/food serving room. Data analysis using two-way ANOVA analysis and Tukey's test. Results: The results of this study indicate that the formula of clove flower extract and bay leaf extract has an effect on the density of flies and cockroaches in outdoor restaurants. The mixed formula of 25% -30% extract with 60 minutes of exposure can repel flies by 100% in the outdoor dining area.   Conclusion The mixed formula of Clove flower extract and bay leaf extract can be used to control the density of flies and cockroaches in outdoor food processing areas.  

Rapid generation of Shigella flexneri GMMA displaying natural or new and cross-reactive O-Antigens

Generalized modules for membrane antigens (GMMA) are exosomes released from engineered Gram-negative bacteria and represent an attractive vaccine platform for the delivery of the O-Antigen (OAg), recognized as the key target for protective immunity against several pathogens such as Shigella. Shigella is a major cause of disease in Low- and Middle-Income countries and the development of a vaccine needs to deal with its large serotypic diversity. All S. flexneri serotypes, except serotype 6, share a conserved OAg backbone, corresponding to serotype Y. Here, a GMMA-producing S. flexneri scaffold strain displaying the OAg backbone was engineered with different OAg-modifying enzymes, either individually or in combinations. This strategy rapidly yielded GMMA displaying 12 natural serotypes and 16 novel serotypes expressing multiple epitopes combinations that do not occur in nature. Importantly, a candidate GMMA displaying a hybrid OAg elicited broadly cross-bactericidal antibodies against a large panel of S. flexneri serotypes.

Shigella-Controlled Human Infection Models: Current and Future Perspectives

Shigella-controlled human infection models (CHIMs) are an invaluable tool utilized by the vaccine community to combat one of the leading global causes of infectious diarrhea, which affects infants, children and adults regardless of socioeconomic status. The impact of shigellosis disproportionately affects children in low- and middle-income countries (LMICs) resulting in cognitive and physical stunting, perpetuating a cycle that must be halted. Shigella-CHIMs not only facilitate the early evaluation of enteric countermeasures and up-selection of the most promising products but also provide insight into mechanisms of infection and immunity that are not possible utilizing animal models or in vitro systems. The greater understanding of shigellosis obtained in CHIMs builds and empowers the development of new generation solutions to global health issues which are unattainable in the conventional laboratory and clinical settings. Therefore, refining, mining and expansion of safe and reproducible infection models hold the potential to create effective means to end diarrheal disease and associated co-morbidities associated with Shigella infection.

Shigellosis seasonality and transmission characteristics in different areas of China: A modelling study

Objective

In China, the burden of shigellosis is unevenly distributed, notably across various ages and geographical areas. Shigellosis temporal trends appear to be seasonal. We should clarify seasonal warnings and regional transmission patterns.

Method

This study adopted a Logistic model to assess the seasonality and a dynamics model to compare the transmission in different areas. The next-generation matrix was used to calculate the effective reproduction number (R_eff) to quantify the transmissibility.

Results

In China, the rate of shigellosis fell from 35.12 cases per 100,000 people in 2005 to 7.85 cases per 100,000 people in 2017, peaking in June and August. After simulation by the Logistic model, the ‘peak time’ is mainly concentrated from mid-June to mid-July. China's ‘early warning time’ is primarily focused on from April to May. We predict the ‘peak time’ of shigellosis is the 6.30th month and the ‘early warning time’ is 3.87th month in 2021. According to the dynamics model results, the water/food transfer pathway has been mostly blocked off. The transmissibility of different regions varies greatly, such as the mean R_eff of Longde County (3.76) is higher than Xiamen City (3.15), higher than Chuxiong City (2.52), and higher than Yichang City (1.70).

Conclusion

The ‘early warning time’ for shigellosis in China is from April to May every year, and it may continue to advance in the future, such as the early warning time in 2021 is in mid-March. Furthermore, we should focus on preventing and controlling the person-to-person route of shigellosis and stratified deploy prevention and control measures according to the regional transmission.

YfiB: An Outer Membrane Protein Involved in the Virulence of Shigella flexneri

The intracellular pathogen Shigella flexneri, which is the causative agent of bacillary dysentery, significantly influences the worldwide implication of diarrheal infections, consequentially causing about 1.1 million deaths each year. Due to a nonavailability of an authorized vaccine and the upsurge of multidrug resistance amongst Shigella strains, there has been a huge demand for further genetic analyses which could help in the advancement of new/improved drugs, and finding vaccine candidates against the pathogen. The present study aims to illustrate the role of the yfiB gene in Shigella virulence, part of the periplasmic YfiBNR tripartite signalling system. This system is involved in the regulation of cyclic-di-GMP levels inside the bacterial cells, a vital messenger molecule impacting varied cellular processes such as biofilm formation, cytotoxicity, motility, synthesis of exopolysaccharide, and other virulence mechanisms such as adhesion and invasion of the bacteria. Through a combination of genetic, biochemical, and virulence assays, we show how knocking out the yfiB gene can disrupt the entire YfiBNR system and affect the native c-di-GMP levels. We found that this subsequently causes a negative effect on the biofilm formation, bacterial invasion, host–surface attachment, and the overall virulence of Shigella. This study also carried out a structural and functional assessment of the YfiB protein and determined critical amino acid residues, essential for proper functioning of this signalling system. The present work improves our understanding of the in vivo persistence and survival of Shigella, brings light to the c-di-GMP led regulation of Shigella virulence, and provides a prospective new target to design anti-infection drugs and vaccines against S. flexneri and other bacterial pathogens.

Bacteriophage Sf6 host range mutant that infects Shigella flexneri serotype 2a2 strains

Shigella flexneri serotype 2a₂ (II:9;10) is the most prevalent strain in causing bacillary dysentery in developing countries. Chemical modifications such as glucosylation, O-acetylation, and phosphoethanolamine modifications of lipopolysaccharide (LPS) O antigen (Oag) contribute to the emergence of various serotypes. Sf6 is a Shigella-specific bacteriophage that infects only a limited range of S. flexneri serotypes [X, Y]. LPS Oag is the primary receptor for bacteriophage Sf6 where it uses its tailspike protein (TSP) in binding and hydrolysing LPS Oags. Sf6TSP has recently been shown to be capable of hydrolysing the LPS Oag of Type II strains, albeit modestly. Phage therapy has regained attention in recent years as an alternative therapeutic approach. Therefore, this study aimed to expand the host range of Sf6 to the prevalent S. flexneri serotype 2a₂ strain. We discovered a new lytic Sf6 host range mutant that is capable of infecting S. flexneri serotype 2a₂ and identified residues in Sf6TSP that may potentially be involved in binding and hydrolysing serotype 2a₂ LPS Oag. This work increased the limited Shigella-specific bacteriophage collection and may be useful in the future for phage therapy and/or biocontrolling of S. flexneri in contaminated food and water.

Pathogenomic analyses of Shigella isolates inform factors limiting shigellosis prevention and control across LMICs

Shigella spp. are the leading bacterial cause of severe childhood diarrhoea in low- and middle-income countries (LMICs), are increasingly antimicrobial resistant and have no widely available licenced vaccine. We performed genomic analyses of 1,246 systematically collected shigellae sampled from seven countries in sub-Saharan Africa and South Asia as part of the Global Enteric Multicenter Study (GEMS) between 2007 and 2011, to inform control and identify factors that could limit the effectiveness of current approaches. Through contemporaneous comparison among major subgroups, we found that S. sonnei contributes ≥6-fold more disease than other Shigella species relative to its genomic diversity, and highlight existing diversity and adaptative capacity among S. flexneri that may generate vaccine escape variants in <6 months. Furthermore, we show convergent evolution of resistance against ciprofloxacin, the current WHO-recommended antimicrobial for the treatment of shigellosis, among Shigella isolates. This demonstrates the urgent need to integrate existing genomic diversity into vaccine and treatment plans for Shigella, providing a framework for the focused application of comparative genomics to guide vaccine development, and the optimization of control and prevention strategies for other pathogens relevant to public health policy considerations.

Development and Application of a Multiplex Fluorescent PCR for Shigella Detection and Species Identification

This study was to develop a multiplex fluorescent PCR for Shigella detection and species identification. Five primer pairs for Shigella detection and species identification were designed by Primer Premier 5.0. The multiplex fluorescent PCR was optimized by varying single parameter while other parameters were maintained. The multiplex fluorescent PCR assay could correctly detect Shigella and identify four Shigella species with a detection limits of 10 pg genomic DNA per reaction. Testing different strains and clinical samples confirmed the sensitivity and specificity of the multiplex fluorescent PCR. The newly developed multiplex fluorescent PCR assay is simple, sensitive and specific for Shigella detection and species identification. It has a potential to be used in routine Shigella detection and species identification in clinical laboratories.

Shigella Outer Membrane Vesicles as Promising Targets for Vaccination

The clinical symptoms of shigellosis, a gastrointestinal infection caused by Shigella spp. range from watery diarrhea to fulminant dysentery. Endemic infections, particularly among children in developing countries, represent the majority of clinical cases. The situation is aggravated due to the high mortality rate of shigellosis, the rapid dissemination of multi-resistant Shigella strains and the induction of only serotype-specific immunity. Thus, infection prevention due to vaccination, encompassing as many of the circulating serotypes as possible, has become a topic of interest. However, vaccines have turned out to be ineffective so far. Outer membrane vesicles (OMVs) are promising novel targets for vaccination. OMVs are constitutively secreted by Gram-negative bacteria including Shigella during growth. They are composed of soluble luminal portions and an insoluble membrane and can contain toxins, bioactive periplasmic and cytoplasmic (lipo-) proteins, (phospho-) lipids, nucleic acids and/or lipopolysaccharides. Thus, OMVs play an important role in bacterial cell–cell communication, growth, survival and pathogenesis. Furthermore, they modulate the secretion and transport of biomolecules, the stress response, antibiotic resistance and immune responses of the host. Thus, OMVs serve as novel secretion machinery. Here, we discuss the current literature and highlight the properties of OMVs as potent vaccine candidates because of their immunomodulatory, antigenic and adjuvant properties.

Identification of vaccine and drug targets in Shigella dysenteriae sd197 using reverse vaccinology approach

Shigellosis is characterized as diarrheal disease that causes a high mortality rate especially in children, elderly and immunocompromised patients. More recently, the World Health Organization advised safe vaccine designing against shigellosis due to the emergence of Shigella dysenteriae resistant strains. Therefore, the aim of this study is to identify novel drug targets as well as the design of the potential vaccine candidates and chimeric vaccine models against Shigella dysenteriae. A computational based Reverse Vaccinology along with subtractive genomics analysis is one of the robust approaches used for the prioritization of drug targets and vaccine candidates through direct screening of genome sequence assemblies. Herein, a successfully designed peptide-based novel highly antigenic chimeric vaccine candidate against Shigella dysenteriae sd197 strain is proposed. The study resulted in six epitopes from outer membrane WP_000188255.1 (Fe (3+) dicitrate transport protein FecA) that ultimately leads to the construction of twelve vaccine models. Moreover, V9 construct was found to be highly immunogenic, non-toxic, non-allergenic, highly antigenic, and most stable in terms of molecular docking and simulation studies against six HLAs and TLRS/MD complex. So far, this protein and multiepitope have never been characterized as vaccine targets against Shigella dysenteriae. The current study proposed that V9 could be a significant vaccine candidate against shigellosis and to ascertain that further experiments may be applied by the scientific community focused on shigellosis.

Lambda Red Recombineering in Shigella flexneri

Shigellosis remains a major cause of severe diarrheal disease and death throughout the world. Vaccine development against shigellosis has been hampered by an incomplete understanding of the molecular mechanisms by which Shigella spp. causes disease and difficulties in manipulating Shigella spp. genomes. While homologous recombination protocols for the construction of precise gene deletions exist, construction of mutants in S. flexneri has not become commonplace. We describe the steps for construction of gene deletions using λ-red recombination using tools that we have developed in our laboratory.

Antimicrobial resistant Shigella in North India since the turn of the 21st century

PURPOSE

The ubiquitous presence and rampant spread of antibiotic resistant strains of Shigella spp is a major public health concern. Therefore, monitoring the trends of antimicrobial resistance in them is essential.

METHODS

A total of 15440 stool samples were inoculated on MacConkey agar, lysine deoxycholate agar and Selenite F enrichment broth from 2001 to 2015.Out of 491 shigellae isolated, 250 isolates were recovered from our culture collection. Antimicrobial susceptibility was performed by Kirby Bauer disc diffusion method, E-test and phenotypic resistance screening for ESBL and AmpC production was performed. For the detection of beta-lactamase genes, PCR for blaTEM, blaSHV, blaOXA, blaCTX-M-15, CMY-2 and mphA PCR in isolates with decreased susceptibility to azithromycin(DSA) was performed.

RESULTS

S. flexneri (n ​= ​173) was most common, followed by S.dysenteriae (n ​= ​24), S.sonnei (n ​= ​23), S.boydii (n ​= ​10) and Non agglutinating Shigella (NAG, n ​= ​20). A see-saw pattern in the prevalence of S. flexneri and S. dysenteriae and rising prevalence of S. sonnei and NAG was seen. Majority (77%) of the isolates had MICs >4 ​mg/L for ciprofloxacin and >50% had high MIC₉₀ (12 ​mg/L) for ceftriaxone and cefepime (8 ​mg/L). Nearly 20% of S.flexneri were resistant to third generation cephalosporin by disc diffusion and 33.7% had MIC ≥1 ​μg/mL. Among the ceftriaxone resistant isolates (n ​= ​29) the blaTEM beta-lactamase resistance gene was seen in all, blaCTX-M-15 in 37%, blaCMY-2 in 45.6% and blaOXA in 52%. The first report of DSA at our institute was in 2001 (n ​= ​1, 2.5%) which increased to 35.1% (n ​= ​40) in 2011-15. The isolates with DSA included S. flexneri (n ​= ​40), S. boydii (n ​= ​4) and S. sonnei (n ​= ​1) and plasmid mediated resistance to azithromycin by mphA gene was detected in 19 out of 40 isolates of S. flexneri.

CONCLUSION

Global emergence of resistance Shigella is a matter of concern and calls for systematic monitoring and periodic updates of countrywide and local antibiogram.

The evolutionary history of Shigella flexneri serotype 6 in Asia

Shigella flexneri serotype 6 is an understudied cause of diarrhoeal diseases in developing countries, and has been proposed as one of the major targets for vaccine development against shigellosis. Despite being named as S. flexneri, Shigella flexneri serotype 6 is phylogenetically distinct from other S. flexneri serotypes and more closely related to S. boydii. This unique phylogenetic relationship and its low sampling frequency have hampered genomic research on this pathogen. Herein, by utilizing whole genome sequencing (WGS) and analyses of Shigella flexneri serotype 6 collected from epidemiological studies (1987–2013) in four Asian countries, we revealed its population structure and evolutionary history in the region. Phylogenetic analyses supported the delineation of Asian Shigella flexneri serotype 6 into two phylogenetic groups (PG-1 and −2). Notably, temporal phylogenetic approaches showed that extant Asian S. flexneri serotype 6 could be traced back to an inferred common ancestor arising in the 18^th century. The dominant lineage PG-1 likely emerged in the 1970s, which coincided with the times to most recent common ancestors (tMRCAs) inferred from other major Southeast Asian S. flexneri serotypes. Similar to other S. flexneri serotypes in the same period in Asia, genomic analyses showed that resistance to first-generation antimicrobials was widespread, while resistance to more recent first-line antimicrobials was rare. These data also showed a number of gene inactivation and gene loss events, particularly on genes related to metabolism and synthesis of cellular appendages, emphasizing the continuing role of reductive evolution in the adaptation of the pathogen to an intracellular lifestyle. Together, our findings reveal insights into the genomic evolution of the understudied Shigella flexneri serotype 6, providing a new piece in the puzzle of Shigella epidemiology and evolution.

Spatial heterogeneity of bacillary dysentery and the impact of temperature in the Beijing-Tianjin-Hebei region of China

Previous studies indicate that the incidence of bacillary dysentery is closely related to meteorological factors. However, the impact of temperature and the spatial heterogeneity of the disease in regions of unbalanced socioeconomic development remains unclear. Therefore, this research collected data for 29,639 daily bacillary dysentery cases in children under 5 years of age, as well as the meteorological variables from China's Beijing-Tianjin-Hebei region, to analyze the spatial pattern of bacillary dysentery and reveal its nonlinear association with temperature. The SatScan method was employed first, to detect the spatial heterogeneity of the disease risk, and then the distributed lag nonlinear model (DLNM) was used to analyze the relationships between the daily minimum, mean, and maximum temperatures and bacillary dysentery in the stratified heterogeneous regions. The results indicated that bacillary dysentery incidence presented statistically significant spatial heterogeneity. The area of highest risk was found to be Beijing and its neighboring regions, which have high population densities. There was also a positive association between bacillary dysentery and temperature. Hotter temperatures were accompanied by higher relative risks. In the most likely spatial cluster region, the excess risk (ER) values for a 1°C rise in minimum, mean, and maximum temperatures above the median were 4.65%, 11.30%, and 19.21%, respectively. The effect of temperature on bacillary dysentery peaked at a lag of 3 to 4 days. The findings of this study will aid risk assessments and early warning systems for bacillary dysentery.

Spatio-temporal analysis of bacillary dysentery in Sichuan province, China, 2011-2019

Background

Bacillary dysentery (BD) is a common infectious disease in China and causes enormous economic burdens. The purpose of this study was to describe the epidemiological characteristics of BD and to identify its possible hot spots and potentially high-risk areas in Sichuan province of China.

Methods

In this study, we collected monthly BD incidence reports of 181 counties in Sichuan province, China, from January 2011 to December 2019. Descriptive statistics were used to evaluate the epidemic characteristics of BD. Moran’s I index was applied to investigate the yearly patterns of the spatial distribution. And spatio-temporal scanning statistics with the spatial unit set as county and the temporal unit set as month were used to investigate the possible high-risk region. Meanwhile, the circular moving windows were also employed in the spatio-temporal scanning to scan the study areas.

Results

The annual incidence of BD ranged between 16.13/100,000 and 6.17/100,000 person-years from 2011 to 2019 in Sichuan. The majority of the cases were children aged 5 years or younger. For the descriptive statistics, a peak from May to October was observed in temporal analysis, the epidemics were mainly concentrated in the northwest and southwest of Sichuan in spatial analysis. After 2016, the scope of BD significantly narrowed and severe epidemic areas were relatively stable. For the spatial autocorrelation analysis, a high global autocorrelation was observed at the county level, and the high–high clusters mainly distributed in the northwest and southwest of Sichuan. For the spatio-temporal scanning, the spatiotemporal clusters of BD occurred every year from 2011 to 2019. The most likely cluster areas mainly distributed in the southwest and northwest of Sichuan at the beginning, and then gradually concentrated in the southwest. The secondary cluster mainly concentrated in the northwest and its surrounding areas. Moreover, the 2nd secondary cluster was relatively small and mainly distributed in the central area. No clusters were noted in eastern Sichuan.

Conclusions

Based on our current analysis, BD is still a common challenge in Sichuan, especially for counties in the southwest and northwest in summer and autumn. More disease prevention and control measures should be taken in such higher-risk susceptible areas at a certain time to allocate the public health resources rationally, and finally reduce the spread of BD.

Increasing the High Throughput of a Luminescence-Based Serum Bactericidal Assay (L-SBA)

Serum bactericidal assay (SBA) is the method to investigate in vitro complement-mediated bactericidal activity of sera raised upon vaccination. The assay is based on incubating the target bacteria and exogenous complement with sera at different dilutions and the result of the assay is represented by the sera dilution being able to kill 50% of bacteria present in the inoculum. The traditional readout of the assay is based on measurement of colony-forming units (CFU) obtained after plating different reaction mixes on agar. This readout is at low throughput and time consuming, even when automated counting is used. We previously described a novel assay with a luminescence readout (L-SBA) based on measurement of ATP released by live bacteria, which allowed to substantially increase the throughput as well as to reduce the time necessary to perform the assay when compared to traditional methods. Here we present a further improvement of the assay by moving from a 96-well to a 384-well format, which allowed us to further increase the throughput and substantially reduce costs while maintaining the high performance of the previously described L-SBA method. The method has been successfully applied to a variety of different pathogens.

Acute watery diarrhea surveillance during the Rohingya Crisis 2017-2019 in Cox's Bazar, Bangladesh

INTRODUCTION

Forcibly Displaced Myanmar Nationals fled into Cox's Bazar, Bangladesh due to internal conflict. Considering the public health situation, a surveillance network was established to identify the enteric pathogens and early detection of cholera epidemics. Purpose of this manuscript is to report the clinical, epidemiological determinants of cholera and other enteric pathogens among hospitalized diarrhoeal patients from FDMNs and host community.

METHODOLOGY

A total of 11 sentinel surveillance sites were established around the camps in Ukhia and Teknaf Upazila, Cox's Bazar. Rapid diagnostic testing was conducted for immediate detection of cholera cases. Stool samples were transferred to the icddr,b laboratory for culture.

RESULT

A total of 8134 participants with diarrhea were enrolled from 2017- 2019: 4881 were FDMNs and 3253 from the Bangladeshi host community. Among the FDMNs, the proportion of V. cholerae 0.7%, ETEC 4.9% and Shigella 1.5%. The distributions from host community were 1.2% V. cholerae, 1.8% ETEC and 1.1% Shigella. Similar risk factors have been identified for the diarrhoeal pathogens for both communities.

CONCLUSION

This surveillance helped to monitor the situation of diarrheal diseases including cholera in refugee camps as well as in the neighboring host community. These findings lead policy makers to take immediate preventive measures.

The Ecology and Antibiotic Resistance Patterns of Gastrointestinal Tract Infections in A Tertiary Care Hospital in Oman

A wide range of gastrointestinal (GI) illnesses is caused by foodborne bacteria that can arise from either a direct bacterial infection or bacterial toxin ingestion. The treatment of these infections has been hampered by the appearance of resistant strains. This current study aims to investigate the prevalence of Gastrointestinal tract (GIT) infections in Omani patients and their resistance pattern against commonly used antibiotics. Seven hundred and ninety fresh stool samples were obtained from Omani patients attending Sultan Qaboos University Hospital with GI manifestation from the 1st of June to the 30th of November 2019. Bacterial identification in stool samples was carried out by inoculation in culture media, microscopical examination and biochemical tests confirmed by MALDI. BD PhoenixTM. The antibiotics sensitivity testing was carried out by the Manual disk diffusion method and by MALDI. BD PhoenixTM. Out of 790 stool samples, 49 samples were positive for GIT bacterial infections. Salmonella spp. was the most prevalent isolate and more associated with children less than ten years old. Out of the 49 bacterial isolates, 3 (6.1%) were Clostridium difficili, 4 (8.2%) were Shigella flexneri, 5 (10.2%) were Campylobacter jejuni, and different Salmonella spp. serotypes were detected such as Salmonella Kentucky (8.2%), Salmonella enteritidis (6.1%), Salmonella infantis (4.1%), Salmonella welteverden (4.1%), Salmonella typhimurium (4.1%), Salmonella anatum (2.0%), Salmonella tesvia (2.0%), Salmonella Uganda (2.0%), Salmonella Arizona (2.0%) and (40.8%) of other Salmonella spp. serotypes. Eighty percent of isolated Campylobacter jejuni were resistant to Ciprofloxacin and Tetracycline. Salmonella spp. and Shigella flexneri were highly resistant to Amikacin, Gentamicin, and Cefuroxime. The low level of bacterial infection detected among screened patients in the present study indicates the excellent hand washing hygiene practice in reducing GIT infections among patients in Oman. This good hand washing hygiene practice is of great help in the efforts of controlling the spread of other severe diseases like COVID-19. However, detecting the emerging of antibiotic-resistant of GIT bacterial pathogens among patients in Oman, such as Salmonella and Shigella to a commonly used antibiotic such as Gentamicin, is alarming.

Sex differences in shigellosis incidence rates: analysis of national data from nine countries using meta-analytic method

BACKGROUND

Sex differences in the incidence of infectious diseases can provide insight to the biological mechanism of infection, disease susceptibility, severity and vaccine development. The consistency of age-specific sex differences in the incidence rates (IRs) of shigellosis is unclear.

METHODS

National data on cases of shigellosis by sex, age group and calendar year were obtained from nine countries, for a period of 6-25 years. The male to female incidence rate ratios (RR) were calculated by country, years and age group. For each age group, meta-analytic methods were used for computing pooled incidence RRs by country and years. Meta-regression was performed to estimate the contribution of age, country and time period to the differences in the male : female RRs.

RESULTS

In the age groups <1, 1-4, 5-9 and 10-14, there were excess IRs in males. The pooled incidence RRs (with 95% CI) were 1.21 (1.14-1.28), 1.17 (1.12-1.22), 1.04 (1.00-1.09) and 1.09 (1.01-1.18), respectively. In young adults, there was excess IR in females with RR = 0.80 (0.72-0.9). In middle aged and older adults, there was a slight excess in males with RR = 1.01 (0.89-1.15) and RR = 1.18 (1.09-1.28), respectively. In the meta-regression, age was the only variable that significantly contributed to the variation in the RRs.

CONCLUSIONS

The higher IRs in male infants and young children does not appear to be related to behavioral factors and genetic and hormonal factors could be important. In the older age groups, the higher rates in adult females may be due to behavioral factors.

Antimicrobial resistance in Shigella species: Our five years (2015-2019) experience in a tertiary care center in north India

PURPOSE

Shigella is the second leading cause of diarrhoeal mortality especially in children <5 years of age in African and Asian countries. Rapid changes are occurring in the epidemiology of shigellosis and Shigella are increasingly becoming highly drug resistant. To determine the serogroup distribution and antimicrobial resistance of Shigella isolated at our tertiary care centre in North India.

METHODS

A retrospective study was conducted where demographic details along with antimicrobial susceptibility data of Shigella isolated from stool specimens from 1^st January 2015 till 31^st December 2019 were retrieved from records and analyzed by WHONET 2019 software.

RESULTS

Shigella species was isolated in 1.31% (n = 137) of a total of 10,456 stool samples. Males predominated (n = 82; 59.8%) and majority of cases were admitted (n = 94; 68.6%). Children ≤5 years of age (n = 47; 34.3%) were the most commonly affected. Adults in the 21-40 age group contributed 27% of cases (n = 37). Overall, Shigella flexneri (n = 87; 63.5%) was the most common serogroup followed by non-agglutinable Shigella (n = 28; 20.4%) while Shigella sonnei (n = 12, 8.8%) and Shigella boydii (n = 9, 6.6%) fluctuated over the years. Shigella dysenteriae reappeared in 2019 after a hiatus of ten years. Overall, 45.3% (n = 62) of isolates were multidrug resistant to CLSI recommended drugs and high resistance was noted for ampicillin/amoxicillin (68.1%), cotrimoxazole (75.8%) ciprofloxacin (61.5%) and ceftriaxone/cefotaxime (45.2%).

CONCLUSIONS

Shigella have become highly drug resistant to fluoroquinolones and cephalosporins. Community based studies are required to truly assess the burden of AMR in India.

Prevalence and associated risk factors of Shigella flexneri isolated from drinking water and retail raw foods in Peshawar, Pakistan

This study was designed to investigate the prevalence and associated risk factors of Shigella flexneri isolated from drinking water and retail raw food samples in Peshawar, Pakistan. A total of 1,020 different samples were collected from various areas of Peshawar between January 2016 and May 2017, followed by identification of S. flexneri through biochemical, serological, and 16S rRNA gene sequencing. Potential risk factors associated with the development and spreading of S. flexneri infection were also investigated. Overall, 45 (4.41%) samples were positive for Shigella species. Among these samples, the predominant species was S. flexneri (n = 44) followed by S. boydii (n = 1). Interestingly, S. sonnei and S. dysenteriae isolates were not found in any sample. The isolation rate of S. flexneri in drinking water samples, market raw milk, and fruits/vegetables from Peshawar were 6.47%, 3.5%, and 2.9%, respectively. The phylogenetic reconstruction showed genetic diversity among three clades, as clades I and II have isolates of S. flexneri that were circulating within the drinking water, milk, fruits/vegetables, while clade III isolates were recovered from milk samples. Most of S. flexneri were detected in June to September. Potential risk factors of S. flexneri were water sources contaminated by toilet wastes (p = 0.04), surface water drainage (p = 0.0002), hospital wastes (p = 0.01), unhygienic handling (p < 0.05), and transportation of raw food (p = 0.04). In conclusion, S. flexneri isolates of closely related lineage originating from non-clinical samples might be associated with an increased human risk to shigellosis in Pakistan, as significant numbers of S. flexneri were observed in the drinking water and retail raw food samples. PRACTICAL APPLICATION: This study demonstrated the presence of S. flexneri in drinking water and retail raw food samples which seem to possess a serious threat to public health. Potential sources of food and water contamination should properly be monitored by public health authorities to reduce cases of shigellosis.

Host Genome-Wide Association Study of Infant Susceptibility to Shigella-Associated Diarrhea

Shigella is a leading cause of moderate-to-severe diarrhea globally and the causative agent of shigellosis and bacillary dysentery. Associated with 80 to 165 million cases of diarrhea and >13% of diarrheal deaths, in many regions, Shigella exposure is ubiquitous while infection is heterogenous. To characterize host-genetic susceptibility to Shigella-associated diarrhea, we performed two independent genome-wide association studies (GWAS) including Bangladeshi infants from the PROVIDE and CBC birth cohorts in Dhaka, Bangladesh. Cases were infants with Shigella-associated diarrhea (n = 143) and controls were infants with no Shigella-associated diarrhea in the first 13 months of life (n = 446). Shigella-associated diarrhea was identified via quantitative PCR (qPCR) threshold cycle (C_T ) distributions for the ipaH gene, carried by all four Shigella species and enteroinvasive Escherichia coli Host GWAS were performed under an additive genetic model. A joint analysis identified protective loci on chromosomes 11 (rs582240, within the KRT18P59 pseudogene; P = 6.40 × 10^-8; odds ratio [OR], 0.43) and 8 (rs12550437, within the lincRNA RP11-115J16.1; P = 1.49 × 10^-7; OR, 0.48). Conditional analyses identified two previously suggestive loci, a protective locus on chromosome 7 (rs10266841, within the 3' untranslated region [UTR] of CYTH3; P _conditional = 1.48 × 10^-7; OR, 0.44) and a risk-associated locus on chromosome 10 (rs2801847, an intronic variant within MPP7; P _conditional = 8.37 × 10^-8; OR, 5.51). These loci have all been indirectly linked to bacterial type 3 secretion system (T3SS) activity, its components, and bacterial effectors delivered into host cells. Host genetic factors that may affect bacterial T3SS activity and are associated with the host response to Shigella-associated diarrhea may provide insight into vaccine and drug development efforts for Shigella-associated diarrheal disease.

Burden, Antibiotic Resistance, and Clonality of Shigella spp. Implicated in Community-Acquired Acute Diarrhoea in Lilongwe, Malawi

Although numerous studies have investigated diarrhoea aetiology in many sub-Saharan African countries, recent data on Shigella species’ involvement in community-acquired acute diarrhoea (CA-AD) in Malawi are scarce. This study investigated the incidence, antibiotic susceptibility profile, genotypic characteristics, and clonal relationships of Shigella flexneri among 243 patients presenting with acute diarrhoea at a District Hospital in Lilongwe, Malawi. Shigella spp. were isolated and identified using standard microbiological and serological methods and confirmed by identifying the ipaH gene using real-time polymerase chain reaction. The isolates’ antibiotic susceptibility to 20 antibiotics was determined using the VITEK 2 system according to EUCAST guidelines. Genes conferring resistance to sulfamethoxazole (sul1, sul2 and sul3), trimethoprim (dfrA1, dfrA12 and dfrA17) and ampicillin (oxa-1 and oxa-2), and virulence genes (ipaBCD, sat, ial, virA, sen, set1A and set1B) were detected by real-time PCR. Clonal relatedness was assessed using ERIC-PCR. Thirty-four Shigella flexneri isolates were isolated (an overall incidence of 14.0%). All the isolates were fully resistant to sulfamethoxazole/trimethoprim (100%) and ampicillin (100%) but susceptible to the other antibiotics tested. The sul1 (79%), sul2 (79%), sul3 (47%), dfrA12 (71%) and dfrA17 (56%) sulfonamide and trimethoprim resistance genes were identified; Oxa-1, oxa-2 and dfrA1 were not detected. The virulence genes ipaBCD (85%), sat (85%), ial (82%), virA (76%), sen (71%), stx (71%), set1A (26%) and set1B (18%) were detected. ERIC-PCR profiling revealed that the Shigella isolates were genetically distinct and clonally unrelated, indicating the potential involvement of genetically distinct S. flexneri in CA-AD in Malawi. The high percentage resistance to ampicillin and sulfamethoxazole/trimethoprim and the presence of several virulence determinants in these isolates emphasises a need for continuous molecular surveillance studies to inform preventive measures and management of Shigella-associated diarrhoeal infections in Malawi.

Computational Identification of Essential Enzymes as Potential Drug Targets in Shigella flexneri Pathogenesis Using Metabolic Pathway Analysis and Epitope Mapping

Shigella flexneri is a facultative intracellular pathogen that causes bacillary dysentery in humans. Infection with S. flexneri can result in more than a million deaths yearly and most of the victims are children in developing countries. Therefore, identifying novel and unique drug targets against this pathogen is instrumental to overcome the problem of drug resistance to the antibiotics given to patients as the current therapy. In this study, a comparative analysis of the metabolic pathways of the host and pathogen was performed to identify this pathogen's essential enzymes for the survival and propose potential drug targets. First, we extracted the metabolic pathways of the host, Homo sapiens, and pathogen, S. flexneri, from the KEGG database. Next, we manually compared the pathways to categorize those that were exclusive to the pathogen. Further, all enzymes for the 26 unique pathways were extracted and submitted to the Geptop tool to identify essential enzymes for further screening in determining the feasibility of the therapeutic targets that were predicted and analyzed using PPI network analysis, subcellular localization, druggability testing, gene ontology and epitope mapping. Using these various criteria, we narrowed it down to prioritize 5 novel drug targets against S. flexneri and one vaccine drug targets against all strains of Shigella. Hence, we suggest the identified enzymes as the best putative drug targets for the effective treatment of S. flexneri.

Distribution characteristics of bioaerosols inside pig houses and the respiratory tract of pigs

Particulate matter (PM) is a carrier of many substances. Microorganisms are vital constituents contained in PM, and their varieties and concentrations are closely connected to human health and animal production. This study aimed to investigate the distribution characteristics of bioaerosols inside a pig house and in the respiratory tract of pigs. Environmental indices inside a nursery pig house were monitored in winter, including temperature, relative humidity, total suspended particulate (TSP), PM₁₀, PM_2.5, NH₃, CO₂, CO and NO. The concentrations of airborne culturable bacteria, fungi and Escherichia coli were detected. Then, 16S rRNA sequencing technology was applied to identify different-sized bioaerosols and bacteria in the respiratory tract of piglets. The results showed that the concentration of airborne culturable bacteria inside the pig house was significantly higher than that outside, and no significant difference was found among culturable fungi and Escherichia coli. The 16S rRNA results showed that the bacterial aerosols presented high similarity to the bacteria in the respiratory tract of piglets. The airborne bacterial aerosols within the size range of 1.1-3.3 µm showed high similarity to the bacteria in the lower respiratory tract (bronchus and lung) of piglets. In addition, four potential pathogenic bacterial genera (Escherichia-Shigella, Streptococcus, Acinetobacter, Pseudomonas) were identified both in the bacterial aerosols and the respiratory tract of piglets. These results will provide a significant scientific basis for exploring the potential risk of aerosols from animal houses to human and animal health.

Laboratory-based surveillance of Shigella spp. from human clinical cases in Colombia, 1997-2018

INTRODUCTION

Shigellosis is endemic in low-and middle-income countries, causing approximately 125 million episodes of diarrhea and leading to approximately 160 .000 deaths annually one-third of which is associated with children.

OBJECTIVE

To describe the characteristics and antimicrobial resistance profiles of Shigella species recovered in Colombia from 1997 to 2018.

MATERIALS AND METHODS

We received isolates from laboratories in 29 Colombian departments. We serotyped with specific antiserum and determined antimicrobial resistance and minimal inhibitory concentrations for ten antibiotics with Kirby-Bauer tests following the Clinical and Laboratory Standards Institute recommendations.

RESULTS

We analyzed 5,251 isolates of Shigella spp., most of them obtained from stools (96.4%); 2,511 (47.8%) were from children under five years of age. The two most common species were S. sonnei (55.1%) and S. flexneri (41.7%). The highest resistance rate was that of tetracycline (88.1%) followed by trimethoprim-sulfamethoxazole (79.3%) and ampicillin (65.5%); 50.8% of isolates were resistant to chloramphenicol, 43.6% to amoxicillin/clavulanic acid, and less than 1% to cefotaxime, ceftazidime, gentamicin, and ciprofloxacin. In S. sonnei, the most common resistance profile corresponded to trimethoprim-sulfamethoxazole (92%) whereas in S. flexneri the most common antibiotic profiles were multidrug resistance.

CONCLUSIONS

In Colombia, children under five years are affected by all Shigella species. These findings should guide funders and public health officials to make evidence based decisions for protection and prevention measures. The antimicrobial resistance characteristics found in this study underline the importance of combating the dissemination of the most frequently isolated species, S. sonnei and S. flexneri.

Evolutionary histories and antimicrobial resistance in Shigella flexneri and Shigella sonnei in Southeast Asia

Conventional disease surveillance for shigellosis in developing country settings relies on serotyping and low-resolution molecular typing, which fails to contextualise the evolutionary history of the genus. Here, we interrogated a collection of 1,804 Shigella whole genome sequences from organisms isolated in four continental Southeast Asian countries (Thailand, Vietnam, Laos, and Cambodia) over three decades to characterise the evolution of both S. flexneri and S. sonnei. We show that S. sonnei and each major S. flexneri serotype are comprised of genetically diverse populations, the majority of which were likely introduced into Southeast Asia in the 1970s-1990s. Intranational and regional dissemination allowed widespread propagation of both species across the region. Our data indicate that the epidemiology of S. sonnei and the major S. flexneri serotypes were characterised by frequent clonal replacement events, coinciding with changing susceptibility patterns against contemporaneous antimicrobials. We conclude that adaptation to antimicrobial pressure was pivotal to the recent evolutionary trajectory of Shigella in Southeast Asia.

In vitro growth-inhibitory effects of Portulaca oleracea L. formulation on intestinal pathogens

Introduction

Empirical evidence suggests that Portulaca oleracea L. treats enteric infections, including dysentery, cholera, and acute infectious gastroenteritis.

Aim

The aim of this study is to clarify the growth-inhibitory effects of Portulaca oleracea L. extract against 56 strains of intestinal pathogens.

Methodology

‘Gogyo-so-cha (GSC)’ was used as the P. oleracea L. formulation. A growth curve analysis was used to measure the growth-inhibitory effects of GSC, and Shiga toxin induction was measured using the latex agglutination test.

Results

GSC demonstrated strong bactericidal effects against Shigella dysenteriae and Vibrio cholerae strains from various isolates. GSC demonstrated weak or no bactericidal effects against intestinal commensal bacteria, including Enterococcus spp. and Escherichia coli. GSC did not induce Shigella toxins.

Conclusion

GSC significantly inhibited the growth of intestinal pathogens, including S. dysenteriae and V. cholerae, without adversely affecting the intestinal flora, supporting the usage of GSC in traditional Chinese medicine. Taken together, GSC would be of immense value in the developing world, where diarrhoeal infectious diseases continue to pose a major health risk.