Risk factors and outcome of Shigella encephalopathy in Bangladeshi children

Risk Factors of Seizure in Childhood Shigellosis

Objectives

Shigellosis is one of the common causes of bacterial diarrhea in children. Seizures are common in shigellosis. It is essential to identify the risk factors of seizure in this disease.

Materials & Methods

This study was conducted on 224 children with shigellosis. The patients were divided into: With (case groups = 63 cases) and without seizures (control group = 161 cases). Groups were compared regarding different variables such as age, gender, clinical symptoms, and laboratory findings. Data analysis was done using statistical tests and SPSS software. Logistic regression analysis was used to determine the risk factors of seizures.

Results

Out of 224 cases of children with shigellosis, 107 (47.8%) were male and 117 (52.2%) female. Significant differences were observed between the two groups in terms of age, history of febrile convulsions, frequency of bloody diarrhea, frequency of fever, duration of diarrhea before hospitalization, abdominal pain, increase in BUN, hyponatremia, hypocalcemia, and red blood cell count in stool (P<0.05). Logistic regression analysis showed that a history of febrile seizure, fever, and hyponatremia are the risk factors for seizures in shigellosis.

Conclusion

This study concluded that a history of febrile seizure, fever, and hyponatremia are risk factors for seizure in childhood shigellosis, thus rapid diagnosis and treatment of childhood shigellosis with risk factors is very important.

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.

Bacterial Profiles of Brain in Downer Cattle with Unknown Etiology

Downer cow can be caused by muscular paralysis, neurological damage, metabolic disorder, and/or the complication of microbial infection. However, downer cow with unknown etiology is issued because of the non-detection of its bacterial etiological agent. In this study, differences in the bacterial community in brain tissues between downer cattle with unknown etiology and healthy slaughtered cattle are investigated. Bacterial diversity and representative genera between downer and normal cattle were significantly different (p < 0.05). There are significant differences in representative genera of downer and normal cattle, especially the significance, fold change, and area under the receiver operating characteristic curve score (p < 0.05). Furthermore, the prediction of functional genes in brain microbiota between the downer and normal cattle revealed differences in the cluster of orthologous gene categories, such as lipid transport and metabolism, secondary metabolite biosynthesis, and signal transduction (p < 0.05). This study revealed a significant difference in microbiota between the downer and normal cattle. Thus, we demonstrate that representative genera from downer cattle through 16S rRNA gene amplicon sequencing and microbiota analysis have the potential as candidates for bacterial etiological agents for downer cow.

An in silico hierarchal approach for drug candidate mining and validation of natural product inhibitors against pyrimidine biosynthesis enzyme in the antibiotic-resistant Shigella flexneri

Shigella flexneri is the main causative agent of the communicable diarrheal disease, shigellosis. It is estimated that about 80-165 million cases and > 1 million deaths occur every year due to this disease. S. flexneri causes dysentery mostly in young children, elderly and immunocompromised patients, all over the globe. Recently, due to the emergence of S. flexneri antibiotic resistance strains, it is a dire need to predict novel therapeutic drug targets in the bacterium and screen natural products against it, which could eliminate the curse of antibiotic resistance. Therefore, in current study, available antibiotic-resistant genomes (n = 179) of S. flexneri were downloaded from PATRIC database and a pan-genome and resistome analysis was conducted. Around 5059 genes made up the accessory, 2469 genes made up the core, and 1558 genes made up the unique genome fraction, with 44, 34, and 13 antibiotic-resistant genes in each fraction, respectively. Core genome fraction (27% of the pan-genome), which was common to all strains, was used for subtractive genomics and resulted in 384 non-homologous, and 85 druggable targets. Dihydroorotase was chosen for further analysis and docked with natural product libraries (Ayurvedic and Streptomycin compounds), while the control was orotic acid or vitamin B13 (which is a natural binder of this protein). Dynamics simulation of 50 ns was carried out to validate findings for top-scored inhibitors. The current study proposed dihydroorotase as a significant drug target in S. flexneri and 4-tritriacontanone & patupilone compounds as potent drugs against shigellosis. Further experiments are required to ascertain validity of our findings.

The Utility of Bedside Assessment Tools and Associated Factors to Avoid Antibiotic Overuse in an Urban PICU of a Diarrheal Disease Hospital in Bangladesh

BACKGROUND

Antibiotic exposure in the pediatric intensive care unit (PICU) is very high, although 50% of all antibiotics may be unnecessary. We aimed to determine the utility of simple bedside screening tools and predicting factors to avoid antibiotic overuse in the ICU among children with diarrhea and critical illness.

METHODS

We conducted a retrospective, single-center, case-control study that included children aged 2-59 months who were admitted to PICU with diarrhea and critical illness between 2017 and 2020.

RESULTS

We compared young children who did not receive antibiotics (cases, n = 164) during ICU stay to those treated with antibiotics (controls, n = 346). For predicting the 'no antibiotic approach', the sensitivity of a negative quick Sequential Organ Failure Assessment (qSOFA) was similar to quick Pediatric Logistic Organ Dysfunction-2 (qPELOD-2) and higher than Systemic Inflammatory Response Syndrome (SIRS). A negative qSOFA or qPELOD-2 score calculated during PICU admission is superior to SIRS to avoid antibiotic overuse in under-five children. The logistic regression analysis revealed that cases were more often older and independently associated with hypernatremia. Cases less often had severe underweight, altered mentation, age-specific fast breathing, lower chest wall in-drawing, adventitious sound on lung auscultation, abdominal distension, developmental delay, hyponatremia, hypocalcemia, and microscopic evidence of invasive diarrhea (for all, p < 0.05).

CONCLUSION

Antibiotic overuse could be evaded in PICU using simple bedside screening tools and clinical characteristics, particularly in poor resource settings among children with diarrhea.

Target Product Profile and Development Path for Shigellosis Treatment with Antibacterials

Enteric infection with Shigella spp. can lead to symptoms ranging from acute watery diarrhea to sudden, severe dysentery. Approximately 212 000 diarrheal deaths annually are attributed to Shigella with a disproportionate impact in low-resource countries. The impact in under-resourced countries was illustrated by a reanalysis of the Global Enteric Multicenter Study which found that Shigella was the leading pathogen associated with moderate-to severe diarrhea in children under 5 years old. While recent studies have highlighted the burden of the disease, there has been a concurrent reduction in therapeutic options for the treatment of shigellosis as drug resistant strains increase in prevalence. In addition, increasing reports of drug resistant shigellosis cases in the men who have sex with men community confirm that the impact is not limited to low-resource countries. Despite the urgent need for new treatments, a target product profile (TPP) has not been established, and there is no clear development path for antibacterial treatments. To address this troubling concern, this manuscript describes a TPP for antishigellosis small molecule therapeutics and a development path that integrates currently available preclinical and clinical models of Shigella infection.

Pathogen-specific risk of seizure in children with moderate-to-severe diarrhoea: Case control study with follow-up

OBJECTIVE

To determine the pathogen-specific risk of seizure in under-five children hospitalised with moderate-to-severe diarrhoea (MSD) in rural settings.

METHOD

This was a prospective case-control study with follow-up, conducted in a sentinel facility of Global Enteric Multicenter Study in Mirzapur, a rural community of Bangladesh between 2007 and 2010. Children aged 0-59 months who presented with MSD and seizure constituted the cases whereas those who did not have seizure comprised the controls. MSD was defined if the episodes were associated with dehydration or dysentery or required hospitalisation with diarrhoea or dysentery. All enrolled children were followed up at home within 50-90 days of enrolment. A total of 64 cases and 128 randomly selected controls formed the analysable dataset.

RESULTS

The result of logistic regression analysis after adjusting for potential confounders revealed that shigellosis (Shigella species, OR = 5.34, 95% CI = 2.37-12.04) particularly S. flexneri (OR = 3.34, 95% CI = 1.48-7.57), S. flexneri 6 (OR = 23.24, 95% CI = 2.79-193.85), S. sonnei (OR = 6.90, 95% CI = 2.34-19.85); norovirus (OR = 6.77, 95% CI = 1.69-27.11), fever (OR = 16.75, 95% CI = 1.81-154.70) and loss of consciousness (OR = 35.25, 95% CI = 1.71-726.20) were the independent risk factors for seizure in MSD children. At enrolment, cases had lower WHZ (P = 0.006) compared to their peers, follow-up anthropometrics showed significant improvement in WHZ (P < 0.001) and WAZ (P < 0.05), whereas deterioration in HAZ (P < 0.001) in both cases and controls.

CONCLUSION

Childhood MSD episodes particularly due to Shigella and norovirus are often associated with seizure. Prompt identification and appropriate management of children with shigellosis may reduce occurrence and adverse consequences of seizure linked with MSD.

Recent insights into Shigella

PURPOSE OF REVIEW

Diarrhoea is a major global health problem, and recent studies have confirmed Shigella as a major contributor to this burden. Here, we review recent advances in Shigella research; focusing on their epidemiology, pathogenesis, antimicrobial resistance, and the role of the gut microbiome during infection.

RECENT FINDINGS

Enhanced epidemiological data, combined with new generation diagnostics, has highlighted a greater burden of Shigella disease than was previously estimated, which is not restricted to vulnerable populations in low-middle income countries. As we gain an ever more detailed insight into the orchestrated mechanisms that Shigella exploit to trigger infection, we can also begin to appreciate the complex role of the gut microbiome in preventing and inducing such infections. The use of genomics, in combination with epidemiological data and laboratory investigations, has unravelled the evolution and spread of various species. Such measures have identified resistance to antimicrobials as a key contributor to the success of specific clones.

SUMMARY

We need to apply novel findings towards sustainable approaches for treating and preventing Shigella infections. Vaccines and alternative treatments are under development and may offer an opportunity to reduce the burden of Shigella disease and restrict the mobility of antimicrobial resistant clones.

Plasmids of Shigella flexneri serotype 1c strain Y394 provide advantages to bacteria in the host

Background

Shigella flexneri has an extremely complex genome with a significant number of virulence traits acquired by mobile genetic elements including bacteriophages and plasmids. S. flexneri serotype 1c is an emerging etiological agent of bacillary dysentery in developing countries. In this study, the complete nucleotide sequence of two plasmids of S. flexneri serotype 1c strain Y394 was determined and analysed.

Results

The plasmid pINV-Y394 is an invasive or virulence plasmid of size 221,293 bp composed of a large number of insertion sequences (IS), virulence genes, regulatory and maintenance genes. Three hundred and twenty-eight open reading frames (ORFs) were identified in pINV-Y394, of which about a half (159 ORFs) were identified as IS elements. Ninety-seven ORFs were related to characterized genes (majority of which are associated with virulence and their regulons), and 72 ORFs were uncharacterized or hypothetical genes. The second plasmid pNV-Y394 is of size 10,866 bp and encodes genes conferring resistance against multiple antibiotics of clinical importance. The multidrug resistance gene cassette consists of tetracycline resistance gene tetA, streptomycin resistance gene strA-strB and sulfonamide-resistant dihydropteroate synthase gene sul2.

Conclusions

These two plasmids together play a key role in the fitness of Y394 in the host environment. The findings from this study indicate that the pathogenic S. flexneri is a highly niche adaptive pathogen which is able to co-evolve with its host and respond to the selection pressure in its environment.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1455-1) contains supplementary material, which is available to authorized users.

Identification and management of Shigella infection in children with diarrhoea: a systematic review and meta-analysis

BACKGROUND

Shigella infections are a leading cause of diarrhoeal death among children in low-income and middle-income countries. WHO guidelines reserve antibiotics for treating children with dysentery. Reliance on dysentery for identification and management of Shigella infection might miss an opportunity to reduce Shigella-associated morbidity and mortality. We aimed to systematically review and evaluate Shigella-associated and dysentery-associated mortality, the diagnostic value of dysentery for the identification of Shigella infection, and the efficacy of antibiotics for children with Shigella or dysentery, or both.

METHODS

We did three systematic reviews (for mortality, diagnostic value, and antibiotic treatment of Shigella and dysentery), and meta-analyses where appropriate, of studies in resource-limited settings. We searched MEDLINE, Embase, and LILACS database for studies published before Jan 1, 2017, in English, French, and Spanish. We included studies of human beings with diarrhoea and accepted all study-specific definitions of dysentery. For the mortality and diagnostic value searches, we excluded studies that did not include an effect estimate or data necessary to calculate this estimate. The search for treatment included only randomised controlled trials that were done after Jan 1, 1980, and assessed antibiotics in children (aged <18 years) with dysentery or laboratory-confirmed Shigella. We extracted or calculated odds ratios (ORs) and 95% CIs for relative mortality and did random-effects meta-analysis to arrive at pooled ORs. We calculated 95% CIs assuming a binomial distribution and did random-effects meta-regression of log-transformed sensitivity and specificity estimates for diagnostic value. We assessed the heterogeneity of papers included in these meta-analyses using the I2 statistic and evaluated publication bias using funnel plots. This review is registered with PROSPERO (CRD42017063896).

FINDINGS

3649 papers were identified and 60 studies were included for analyses: 13 for mortality, 27 for diagnostic value, and 20 for treatment. Shigella infection was associated with mortality (pooled OR 2·8, 95% CI 1·6-4·8; p=0·000) whereas dysentery was not associated with mortality (1·3, 0·7-2·3; p=0·37). Between 1977 and 2016, dysentery identified 1·9-85·9% of confirmed Shigella infections, with sensitivity decreasing over time (p=0·04). Ten (50%) of 20 included antibiotic trials were among children with dysentery, none were placebo-controlled, and two (10%) evaluated antibiotics no longer recommended for acute infectious diarrhoea. Ciprofloxacin showed superior microbiological, but not clinical, effectiveness compared with pivmecillinam, and no superior microbiological and clinical effectiveness compared with gatifloxacin. Substantial heterogeneity was reported for meta-analyses of the Shigella-associated mortality studies (I2=78·3%) and dysentery-associated mortality studies (I2=73·2%). Too few mortality studies were identified to meaningfully test for publication bias. No evidence of publication bias was found in this analysis of studies of diagnostic value.

INTERPRETATION

Current WHO guidelines appear to manage dysentery effectively, but might miss opportunities to reduce mortality among children infected with Shigella who present without bloody stool. Further studies should quantify potential decreases in mortality and morbidity associated with antibiotic therapy for children with non-dysenteric Shigella infection.

FUNDING

Bill & Melinda Gates Foundation and the Center for AIDS Research International Core.