Changing emergence of Shigella sero-groups in Bangladesh: observation from four different diarrheal disease hospitals

Pathogen-driven gene expression patterns lead to a novel approach to the identification of common therapeutic targets

Developing a common medication strategy for disease control and management could be greatly beneficial. Investigating the differences between diseased and healthy states using differentially expressed genes aids in understanding disease pathophysiology and enables the exploration of protein-drug interactions. This study aimed to find the most common genes in diarrhea-causing bacteria such as Salmonella enterica serovar Typhimurium, Campylobacter jejuni, Escherichia coli, Shigella dysenteriae (CESS) to find new drugs. Thus, differential gene expression datasets of CESS were screened through computational algorithms and programming. Subsequently, hub and common genes were prioritized from the analysis of extensive protein-protein interactions. Binding predictions were performed to identify the common potential therapeutic targets of CESS. We identified a total of 827 dysregulated genes that are highly linked to CESS. Notably, no common gene interaction was found among all CESS bacteria, but we identified 3 common genes in both Salmonella-Escherichia and Escherichia-Campylobacter infections. Later, out of 73 protein complexes, molecular simulations confirmed 5 therapeutic candidates from the CESS. We have developed a new pipeline for identifying therapeutic targets for a common medication strategy against CESS. However, further wet-lab validation is needed to confirm their effectiveness.

Factors associated with dehydrating rotavirus diarrhea in children under five in Bangladesh: An urban-rural comparison

Introduction

Rotavirus is the leading cause of dehydrating diarrhea in young children worldwide. This study aimed to identify the factors associated with dehydrating rotavirus diarrhea in children under five years of age in urban and rural Bangladesh.

Methods

The study analyzed data from 7,758 children under five who presented with rotavirus diarrhea to Dhaka (urban) and Matlab (rural) hospital of icddr,b during 2009–2018, and were enrolled in the Diarrheal Disease Surveillance System. Cases were defined as children having rotavirus isolated in stool specimens presented with dehydrating diarrhea. Controls were children infected with rotavirus have no dehydration. Multivariable logistic regression models were built to identify the factors associated with dehydrating diarrhea.

Results

Among the rotavirus-infected children, 1,784 (34%) in Dhaka and 160 (6%) in Matlab had diarrhea with some or severe dehydration. The female children and age group 24–59 months age was found to be at higher risk of dehydration compared to 6–11 months age. In the multivariable logistic regression model, maternal illiteracy, vomiting, the onset of diarrhea less than 24 hours prior to presenting to the hospital, monsoon months, stunting, and wasting were significantly associated with dehydrating rotavirus diarrhea among children aged 0–59 months in Dhaka. In Matlab, monthly income, duration less than 24 hours prior to attending the hospital, and wasting had an independent significant association with dehydrating rotavirus diarrhea episodes.

Conclusions

Considering factors diversity, educating parents and proper counselling by health care personnel during diarrhea, could lessen the severity of dehydration and the number of hospital visits later on by eliminating the modifiable risk factors among the children, which needs further studies.

Lewis Blood-group Antigens Are Associated With Altered Susceptibility to Shigellosis

In a cohort of infants, we found that lack of the Lewis histo-blood group antigen was associated with increased susceptibility to shigellosis. Broadly inhibiting fucosylation in epithelial cells in vitro decreased invasion by Shigella flexneri. These results support a role for fucosylated glycans in susceptibility to shigellosis.

Pathogen flows from on-site sanitation systems in low-income urban neighborhoods, Dhaka: A quantitative environmental assessment

BACKGROUND

Despite wide usage of on-site sanitation, there is limited field-based evidence on the removal or release of pathogens from septic tanks and other primary treatment systems, such as anaerobic baffled reactors (ABR). In two low-income areas in Dhaka, we conducted a cross-sectional study to explore pathogen loads discharged from commonly used on-site sanitation-systems and their transport in nearby drains and waterways.

METHODS

We collected samples of drain water, drain sediment, canal water, and floodwater from April-October 2019. Sludge, supernatant, and effluent samples were also collected from septic tanks and ABRs. We investigated the presence and concentration of selected enteric pathogens (Shigella, Vibrio cholerae (V. cholerae), Salmonella Typhi (S. Typhi), Norovirus Genogroup-II (NoV-GII), and Giardia) and presence of Cryptosporidium in these samples using quantitative polymerase chain reaction (qPCR).The equivalent genome copies (EGC) of individual pathogens were estimated in each sample by interpolation of the mean Ct value to the corresponding standard curve and the dilution factor for each sample type. Absolute quantification was expressed as log₁₀ EGC per 100 mL for the water samples and log₁₀ EGC per gram for the sediment samples.

RESULTS

Among all samples tested (N = 151), 89% were contaminated with Shigella, 68% with V. cholerae and NoV-GII, 32% with Giardia, 17% with S. Typhi and 6% with Cryptosporidium. A wide range of concentration of pathogens [range: mean log₁₀ concentration of Giardia = 0.74 EGC/100 mL in drain ultrafiltration samples to mean log₁₀ concentration of NoV-GII and Giardia = 7.11 EGC/100 mL in ABR sludge] was found in all environmental samples. The highest pathogen concentrations were detected in open drains [range: mean log₁₀ concentration = 2.50-4.94 EGC/100 mL], septic tank effluent [range: mean log₁₀ concentration = 3.32-4.65 EGC/100 mL], and ABR effluent [range: mean log₁₀ concentration = 2.72-5.13 EGC/100 mL].

CONCLUSIONS

High concentrations of pathogens (particularly NoV-GII, V.cholerae and Shigella) were frequently detected in environmental samples from two low-income urban neighbourhoods of Dhaka city. The numerous environmental exposure pathways for children and adults make these findings of public health concern. These results should prompt rethinking of how to achieve safe sanitation solutions that protect public health in dense low-income areas. In particular, improved management and maintenance regimes, further treatment of liquid effluent from primary treatment processes, and appropriate application of onsite, decentralised and offsite sanitation systems given the local context.

Relation of childhood diarrheal morbidity with the type of tube well used and associated factors of Shigella sonnei diarrhea in rural Bangladesh site of the Global Enteric Multicenter Study

Background

Diarrheal disease still remains a major public health threat and is often associated with fatal outcome especially in children with shigellosis mostly in developing countries. This study aimed to determine the presence of any associations between drinking shallow tube well (STW) water and childhood shigellosis. A total of 1394 children aged 0–59 months who presented with moderate-to-severe diarrhea (MSD) in Kumudini Women’s Medical College and Hospital, Bangladesh, from December 2007 to March 2011 were enrolled into the study.

Results

Among the study children, STW users often represented poor families (44% vs. 37%, p = 0.010); less often had household electricity (60% vs. 68%, p = 0.001) and cemented floor material (12% vs. 21%, p < 0.001); washed hand before eating (79% vs. 84%, p = 0.020); and had Shigella sonnei infections (7.8% vs. 13.1, p = 0.002) compared to deep tube well (DTW) water families (in bivariate analysis). After adjusting for covariates, a significant negative association was observed between childhood MSD episodes due to Shigella sonnei infections and the use of STW water (aOR 0.53, 95% CI 0.36, 0.79).

Conclusions

An emergence of less severe Shigella sonnei has replaced relatively more severe Shigella flexneri among the MSD children from DTW-user families. However, more monitoring in terms of disease surveillance for changes in the distribution of Shigella serogroups and serotypes and its upsurges and antimicrobial susceptibility is essential.

A phase I trial of WRSS1, a Shigella sonnei live oral vaccine in Bangladeshi adults and children

Shigella sonnei live vaccine candidate, WRSS1, which was previously evaluated in US, Israeli and Thai volunteers, was administered orally to Bangladeshi adults and children to assess its safety, clinical tolerability and immunogenicity. In a randomized, placebo-controlled, dose-escalation, age-descending study, 39 adults (18-39 years) and 64 children (5-9 years) were enrolled. Each adult cohort (n = 13) received one dose of 3x10⁴, or three doses of 3 × 10⁵ or 3 × 10⁶ colony forming unit (CFU) of WRSS1 (n = 10) or placebo (n = 3). Each child cohort (n = 16) received one dose of 3x10³, or three doses of 3x10⁴, 3x10⁵, or 3 × 10⁶ CFU WRSS1 (n = 12) or placebo (n = 4). WRSS1 elicited mostly mild and transient reactogenicity events in adults and children. In the 3 × 10⁶ dose group, 50% of the adults shed the vaccine; no shedding was seen in children. At the highest dose, 100% of adults and 40% of children responded with a ≥ 4-fold increase of S. sonnei LPS-specific IgA antibody in lymphocyte supernatant (ALS). At the same dose, 63% of adults and 70% of children seroconverted with IgA to LPS, while in placebo, 33% of adults and 18% of children seroconverted. Both the vaccinees and placebos responded with fecal IgA to LPS, indicating persistent exposure to Shigella infections. In conclusion, WRSS1 was found safe up to 10⁶ CFU dose and immunogenic in adults and children in Bangladesh. These data indicate that live, oral Shigella vaccine candidates, including WRSS1 can potentially be evaluated in toddlers and infants (<2 years of age), who comprise the target population in an endemic environment.

Morbidity and mortality due to shigella and enterotoxigenic Escherichia coli diarrhoea: the Global Burden of Disease Study 1990-2016

Background

Shigella and enterotoxigenic Escherichia coli (ETEC) are bacterial pathogens that are frequently associated with diarrhoeal disease, and are a significant cause of mortality and morbidity worldwide. The Global Burden of Diseases, Injuries, and Risk Factors study 2016 (GBD 2016) is a systematic, scientific effort to quantify the morbidity and mortality due to over 300 causes of death and disability. We aimed to analyse the global burden of shigella and ETEC diarrhoea according to age, sex, geography, and year from 1990 to 2016.

Methods

We modelled shigella and ETEC-related mortality using a Bayesian hierarchical modelling platform that evaluates a wide range of covariates and model types on the basis of vital registration and verbal autopsy data. We used a compartmental meta-regression tool to model the incidence of shigella and ETEC, which enforces an association between incidence, prevalence, and remission on the basis of scientific literature, population representative surveys, and health-care data. We calculated 95% uncertainty intervals (UIs) for the point estimates.

Findings

Shigella was the second leading cause of diarrhoeal mortality in 2016 among all ages, accounting for 212 438 deaths (95% UI 136 979–326 913) and about 13·2% (9·2–17·4) of all diarrhoea deaths. Shigella was responsible for 63 713 deaths (41 191–93 611) among children younger than 5 years and was frequently associated with diarrhoea across all adult age groups, increasing in elderly people, with broad geographical distribution. ETEC was the eighth leading cause of diarrhoea mortality in 2016 among all age groups, accounting for 51 186 deaths (26 757–83 064) and about 3·2% (1·8–4·7) of diarrhoea deaths. ETEC was responsible for about 4·2% (2·2–6·8) of diarrhoea deaths in children younger than 5 years.

Interpretation

The health burden of bacterial diarrhoeal pathogens is difficult to estimate. Despite existing prevention and treatment options, they remain a major cause of morbidity and mortality globally. Additional emphasis by public health officials is needed on a reduction in disease due to shigella and ETEC to reduce disease burden.

Funding

Bill & Melinda Gates Foundation.

Spatiotemporal Characteristics of Bacillary Dysentery from 2005 to 2017 in Zhejiang Province, China

Background: This study aimed to analyze the epidemiological and spatiotemporal characteristics of bacillary dysentery in Zhejiang Province and to provide the basis for its monitoring, prevention and control. Methods: This study included cases registered in China Information System for Diseases Control and Prevention from 1 January 2005 to 31 December 2017 in Zhejiang. Descriptive methods were employed to investigate the long trend of this disease: gender distribution, high-risk population, seasonality, and circular distribution was explored to detect the peak period; incidence maps were made to show the incidence trend of disease at county level; spatial autocorrelation was explored and the regions with autocorrelation were detected; and spatiotemporal scan was conducted to map out the high-risk regions of disease and how long they lasted. Statistical significance was assumed at p value of <0.05. Results: A total of 105,577 cases of bacillary dysentery were included, the incidence declining sharply from 45.84/100,000 to 3.44/100,000 with an obvious seasonal peak from July to October. Males were more predisposed to the infection than females. Pre-education children had the highest proportion among all occupation categories. Incidence in all age groups were negatively correlated with the year (p < 0.001), and the incidences were negatively correlated with the age groups in 2005–2008 (p = 0.022, 0.025, 0.044, and 0.047, respectively). Local autocorrelation showed that counties in Hangzhou were high-risk regions of bacillary dysentery. The spatiotemporal scan indicated that all clusters occurred before 2011, and the most likely cluster for disease was found in Hangzhou, Jiaxing and Huzhou. Conclusions: The incidence of bacillary dysentery in Zhejiang from 2005 to 2017 featured spatiotemporal clustering, and remained high in some areas and among the young population. Findings in this study serve as a panorama of bacillary dysentery in Zhejiang and provide useful information for better interventions and public health planning.

Characterization of a serologically atypical Shigella flexneri Z isolated from diarrheal patients in Bangladesh and a proposed serological scheme for Shigella flexneri

Background

Atypical Shigella flexneri Z variant, that agglutinate with E1037 group factor specific monoclonal antisera against Shigella flexneri IV-I but not with other group or type specific antisera, has continuously being isolated in Bangladesh since 1997. Later this serotype has been reported in Indonesia, China and Argentina. Despite being a provisional serotype, continuous isolation of these strains in diverse geographical regions implicated a great necessity to study the overall characteristics of these strains. Therefore, we extensively characterized S. flexneri Z strains using various phenotypic and molecular tools.

Method

Of 3569 S. flexneri isolated between 1997 and 2015, 95 strains were identified as S. flexneri Z using a panel of polyvalent absorbed antisera and monoclonal antisera of S. flexneri (MASF). Of them, randomly selected 65 strains were molecular O-serotyped using multiplex PCR and characterized using different phenotypic and molecular techniques (i.e.biotyping, plasmid profile, virulence marker and PFGE) to determine relationship with other subserotypes of S. flexneri.

Results

All these atypical S. flexneri Z strains were agglutinated with MASF B and IV-I antisera. Concordantly, these strains were positive to opt-gene, responsible for MASF IV-I sero-positive phenotype. However, molecular O-serotyping of all 65 strains could not differentiate between Z and Yb giving similar amplification products (wzx1-5 and opt). Contrarily, MASF based serotypic scheme distinguished among Z and Yb as well as Ya. All these S. flexneri Z showed typical biochemical reaction of S. flexneri, harboured a 140 MDa virulence plasmid and virulence markers namely ipaH, ial, sen, sigA and sepA genes. Along with the virulence plasmid, small plasmids (2.6, 1.8 and 1.6 MDa) were present as core plasmid. Moreover, a middle ranged plasmid and a 4.0 MDa sized plasmid were observed in 65% and 20% strains, respectively. Analysis of PFGE on XbaI-digested chromosomal DNA of Bangladeshi strains showed that S. flexneri Z had a close relatedness with Ya and Yb but completely different than the strains of Xa, Xb, 2a and 2b. This observation was found to be unequivocal while the overall result of biotyping, plasmid profile, and virulence factors was compared. Therefore, we conclude that these atypical serotype Z isolated in Bangladesh had a clonal relationship with Ya and Yb of Bangladesh and the opt gene played an important role in serotypic switching among them. Current serotyping scheme of S. flexneri strains fails to place many such atypical strains (1c, 1c+6, 1d, type 4, and 4c) including S. flexneri Z isolated from different parts of the world. Therefore, an updated serotyping scheme for identification of subserotypes of S. flexneri has been proposed to avoid multiple naming of the same subserotype having similar agglutination pattern.

Antimicrobial resistance profiles of Shigella dysenteriae isolated from travellers returning to the UK, 2004-2017

PURPOSE

Antimicrobial resistance (AMR) profiles of 754 strains of Shigella dysenteriae isolated between 2004 and 2017 from UK travellers reporting symptoms of gastrointestinal (GI) disease were reviewed to look for evidence of emerging AMR associated with travellers' diarrhoea.

METHODOLOGY

A travel history was provided for 72.7 % (548/754) of cases, of which 90.9 % (498/548) reported travel outside the UK within 7 days of onset of symptoms, and 9.1 % (50/498) reported no travel in that time frame. During the course of this study, whole genome sequencing (WGS) was implemented for GI disease surveillance, and we compared phenotypic AMR profiles with those derived from WGS data (n=133).Results/Key findings. The phenotypic and genotypic AMR results correlated well, with 90.1 % (121/133) isolates having concordant results to 10 classes of antimicrobials. Resistance to the first-line drugs commonly used in the treatment of shigellosis was observed throughout the study (ampicillin, 54.1%; chloramphenicol, 33.7 %; sulphonamides, 76.0 %; trimethoprim, 80.0%). Between 2004 and 2017, resistance to all classes of antimicrobials (except the phenicols) increased. The proportion of isolates exhibiting reduced susceptibility to ciprofloxacin increased from 3.8 % in 2004 to 75.7 % in 2017, and this was significantly associated with cases reporting travel to Asia compared to Africa (P<0.001). Of the 201 sequenced isolates, 3.0 % (20/201) had either blaCTX-M-15 or blaCMY-4.

CONCLUSIONS

Increasing MDR, along with resistance to the fluroquinolones and the third generation cephalosporins, in Shigella dysenteriae causing travellers' diarrhoea provides further evidence for the need to regulatethe use of antimicrobial agents and continuous monitoring of emerging AMR.

Determinants of severe dehydration from diarrheal disease at hospital presentation: Evidence from 22 years of admissions in Bangladesh

Background

To take advantage of emerging opportunities to reduce morbidity and mortality from diarrheal disease, we need to better understand the determinants of life-threatening severe dehydration (SD) in resource-poor settings.

Methodology/findings

We analyzed records of patients admitted with acute diarrheal disease over twenty-two years at the International Centre for Diarrhoeal Disease Research, Bangladesh (1993–2014). Patients presenting with and without SD were compared by multivariable logistic regression models, which included socio-demographic factors and pathogens isolated. Generalized additive models evaluated non-linearities between age or household income and SD. Among 55,956 admitted patients, 13,457 (24%) presented with SD. Vibrio cholerae was the most common pathogen isolated (12,405 patients; 22%), and had the strongest association with SD (AOR 4.77; 95% CI: 4.41–5.51); detection of multiple pathogens did not exacerbate SD risk. The highest proportion of severely dehydrated patients presented in a narrow window only 4–12 hours after symptom onset. Risk of presenting with SD increased sharply from zero to ten years of age and remained high throughout adolescence and adulthood. Adult women had a 38% increased odds (AOR 1.38; 95% CI: 1.30–1.46) of SD compared to adult men. The probability of SD increased sharply at low incomes. These findings were consistent across pathogens.

Conclusions/significance

There remain underappreciated populations vulnerable to life-threatening diarrheal disease that include adult women and the very poor. In addition to efforts that address diarrheal disease in young children, there is a need to develop interventions for these other high-risk populations that are accessible within 4 hours of symptom onset.

To best help patients with diarrheal disease, we need to better understand what causes patients to tip from mild disease to severe disease. In this study, we analyzed records of patients presenting to one of the largest hospitals in the world dedicated to the management of diarrheal diseases. Patients with and without severe dehydration (SD) were compared at multiple-levels. We found that: (i) Patients presented with SD after only 4 to 12 hours of symptoms. (ii) The risk of presenting with SD was higher in older children and adult women; suggesting that people might seek help differently based on age and gender. (iii) The extreme poor had a dramatically increased risk of presenting with SD. In summary, these findings highlight the need for rapid interventions that target older children and adult women in addition to ongoing efforts focused on young children.

Gallic acid conjugated with gold nanoparticles: antibacterial activity and mechanism of action on foodborne pathogens

Foodborne pathogens, including Plesiomonas shigelloides and Shigella flexneri B, are the major cause of diarrheal endemics worldwide. Antibiotic drug resistance is increasing. Therefore, bioactive compounds with antibacterial activity, such as gallic acid (GA), are needed. Gold nanoparticles (AuNPs) are used as drug delivery agents. This study aimed to conjugate and characterize AuNP–GA and to evaluate the antibacterial activity. AuNP was conjugated with GA, and the core–shell structures were characterized by small-angle X-ray scattering and transmission electron microscopy. Antibacterial activity of AuNP–GA against P. shigelloides and S. flexneri B was evaluated by well diffusion method. AuNP–GA bactericidal mechanism was elucidated by Fourier transform infrared microspectroscopic analysis. The results of small-angle X-ray scattering showed that AuNP–GA conjugation was successful. Antibacterial activity of GA against both bacteria was improved by conjugation with AuNP because the minimum inhibitory concentration value of AuNP–GA was significantly decreased (P<0.0001) compared to that of GA. Fourier transform infrared analysis revealed that AuNP–GA resulted in alterations of lipids, proteins, and nucleic acids at the bacterial cell membrane. Our findings show that AuNP–GA has potential for further application in biomedical sciences.

Prevalence, resistance patterns, and characterization of integrons of Shigella flexneri isolated from Jiangsu Province in China, 2001-2011

OBJECTIVE

To provide the epidemiology, resistance pattern, and characterization of integrons in Shigella flexneri isolated between 2001 and 2011 in Jiangsu Province.

METHOD

A total of 624 strains of S. flexneri were collected from both outpatients and inpatients in hospitals in Jiangsu Province from January 2001 to December 2011. The Kirby-Bauer disk diffusion method was used to perform the antimicrobial susceptibility test. Polymerase chain reaction (PCR) was used in the detection of integrons. Pulsed-field gel electrophoresis (PFGE) was applied in the homology studies.

RESULT

Serotype 2a accounted for the largest proportion in S. flexneri, namely 26.4 %. Notably, an increasing trend was detected in the resistance to common antimicrobial agents during the period 2001-2011. In recent years, more than 80.0 % isolates of S. flexneri have proved to be resistant to ampicillin, nalidixic acid, and tetracycline. The positive rates of class 1, class 2, and the atypical class 1 integrons in S. flexneri are 69.3 %, 87.8 %, and 89.2 % respectively. Most integrons detected in our research carry genes encoding resistance to trimethoprim and streptomycin.

CONCLUSION

Antimicrobial resistance in S. flexneri has demonstrated a continuous rising trend in Jiangsu Province. A high prevalence of integrons and gene cassettes play an important role in the transmission of drug resistance in S. flexneri. Effective measures are urgently needed to control the spread of multi-drug-resistant S. flexneri, and more continuing active surveillance of antimicrobial resistance should be established worldwide, especially in developing countries.

Shigella Infections in Household Contacts of Pediatric Shigellosis Patients in Rural Bangladesh

To examine rates of Shigella infections in household contacts of pediatric shigellosis patients, we followed contacts and controls prospectively for 1 week after the index patient obtained care. Household contacts of patients were 44 times more likely to develop a Shigella infection than were control contacts (odds ratio 44.7, 95% CI 5.5–361.6); 29 (94%) household contacts of shigellosis patients were infected with the same species and serotype as the index patient’s. Pulsed-field gel electrophoresis showed that 14 (88%) of 16 with infected contacts had strains that were indistinguishable from or closely related to the index patient’s strain. Latrine area fly counts were higher in patient households compared with control households, and 2 patient household water samples were positive for Shigella. We show high susceptibility of household contacts of shigellosis patients to Shigella infections and found environmental risk factors to be targeted in future interventions.

Combination vaccines against diarrheal diseases

Diarrheal diseases remain a leading cause of global childhood mortality and morbidity. Several recent epidemiological studies highlight the rate of diarrheal diseases in different parts of the world and draw attention to the impact on childhood growth and survival. Despite the well-documented global burden of diarrheal diseases, currently there are no combination diarrheal vaccines, only licensed vaccines for rotavirus and cholera, and Salmonella typhi-based vaccines for typhoid fever. The recognition of the impact of diarrheal episodes on infant growth, as seen in resource-poor countries, has spurred action from governmental and non-governmental agencies to accelerate research toward affordable and effective vaccines against diarrheal diseases. Both travelers and children in endemic countries will benefit from a combination diarrheal vaccine, but it can be argued that the greater proportion of any positive impact will be on the public health status of the latter. The history of combination pediatric vaccines indicate that monovalent or single disease vaccines are typically licensed first prior to formulation in a combination vaccine, and that the combinations themselves undergo periodic revision in response to need for improvement in safety or potential for wider coverage of important pediatric pathogens. Nevertheless combination pediatric vaccines have proven to be an effective tool in limiting or eradicating communicable childhood diseases worldwide. The landscape of diarrheal vaccine candidates indicates that there now several in active development that offer options for potential testing of combinations to combat those bacterial and viral pathogens responsible for the heaviest disease burden—rotavirus, ETEC, Shigella, Campylobacter, V. cholera and Salmonella.

Patterns of Bacillary Dysentery in China, 2005-2010

Although the incidence of bacillary dysentery in China has been declining progressively, a considerable disease burden still exists. Few studies have analyzed bacillary dysentery across China and knowledge gaps still exist in the aspects of geographic distribution and ecological drivers, seasonality and its association with meteorological factors, urban-rural disparity, prevalence and distribution of Shigella species. Here, we performed nationwide analyses to fill the above gaps. Geographically, we found that incidence increased along an east-west gradient which was inversely related to the economic conditions of China. Two large endemically high-risk regions in western China and their ecological drivers were identified for the first time. We characterized seasonality of bacillary dysentery incidence and assessed its association with meteorological factors, and saw that it exhibits north-south differences in peak duration, relative amplitude and key meteorological factors. Urban and rural incidences among China’s cities were compared, and disparity associated with urbanization level was invariant in most cities. Balanced decrease of urban and rural incidence was observed for all provinces except Hunan. S. flexneri and S. sonnei were identified as major causative species. Increasing prevalence of S. sonnei and geographic distribution of Shigella species were associated with economic status. Findings and inferences from this study draw broader pictures of bacillary dysentery in mainland China and could provide useful information for better interventions and public health planning.

Extreme hypernatremic dehydration due to potential sodium intoxication: consequences and management for an infant with diarrhea at an urban intensive care unit in Bangladesh: a case report

Introduction

Hypernatremia (serum sodium ≥150mmol/L) is one of the most life-threatening complications of childhood diarrhea, and its management remains challenging, even in a highly advanced critical care setting. This case report describes the acute clinical course and 3-month neurological follow-up after discharge of an infant with extreme hypernatremia in an intensive care unit in Dhaka, Bangladesh.

Case presentation

A 6-month-old Asian Bangladeshi girl of middle-class socioeconomic status was admitted to the intensive care unit of our institution in 2012 with acute watery diarrhea, lethargy and hypernatremia (208mmol/L serum sodium). She had a history of taking excess oral rehydration salt: five packets each, inappropriately prepared, rice-based, properly diluted, glucose-based oral rehydration salt. Her hypernatremia was treated exclusively with oral rehydration salt solution. She experienced seizures on the third day of her hospitalization and was treated with anticonvulsant drugs. Later in the course of her hospitalization, Enterobacter spp bacteremia was detected and successfully treated with ciprofloxacin. Although magnetic resonance imaging of her brain at discharge showed cerebral edema, brain magnetic resonance imaging appeared normal at a follow-up examination 3 months after discharge. Electroencephalograms taken at discharge and at her 3-month follow-up examination also appeared normal.

Conclusions

Successful management of extreme hypernatremia with only oral rehydration salt did not result in observable neurological consequences, which emphasizes the importance of the use of oral rehydration salt for the clinical management of childhood hypernatremia.

Childhood malnutrition in households with contemporary siblings: a scenario from urban Bangladesh

This study aimed to determine the effect of the presence of under-5 siblings (⩾ 1) in a household on childhood malnutrition in urban Bangladesh. During 2000 and 2013, a total of 16,948 under-5 children were enrolled in the Diarrhoeal Disease Surveillance of icddr,b. Under-5 siblings were categorised as ⩾ 1 and none except the child himself. In univariate analysis, the presence of siblings was associated with 1.13 (risk ratios=1.13; 95% CI:1.06-1.20) times higher risk of being stunted, 1.17 (1.09-1.25) times for wasted and 1.19 (1.13-1.26) times underweight compared with their peers who did not have siblings. In multivariate analysis, such associations remained significant for stunting (1.08; 1.01-1.15), wasting (1.12; 1.04-1.21) and underweight (1.13, 1.06-1.19) after controlling for possible confounders such as age of child, sex, parental education, maternal employment, family size, wealth quintile and time (year). The presence of under-5 siblings increases the risk of malnutrition in children in urban Bangladesh.

Distribution and antimicrobial resistance of enteric pathogens in Chinese paediatric diarrhoea: a multicentre retrospective study, 2008-2013

The enteric pathogens causing diarrhoea impair children's health severely. This study retrospectively analysed 1577 pathogens isolated from inpatients and outpatients in six hospitals located in Northern (Inner Mongolia), Northeastern (Hebei), Eastern (Shanghai and Jiangsu), Southern (Hainan) and Central (Hubei) China between 2008 and 2013. Of the 1577 enteric pathogens, Salmonella presented with the highest frequency (36·0%), followed by diarrhoeagenic Escherichia coli (23·7%), Staphylococcus aureus (15·0%), Shigella (13·1%), and Aeromonas (4·6%). The predominant pathogens varied in different regions of China, with Salmonella most prevalent in Shanghai and Hainan, diarrhoeagenic E. coli most prevalent in Inner Mongolia, Jiangsu and Hubei, and Shigella most prevalent in Hebei. Enteric pathogens were more frequently isolated in males (56·9%) than in females (43·1%). The highest proportion of all enteric pathogens was found in infants (67·6%) with a peak in summer and autumn (68·5%). Antimicrobial susceptibility assay demonstrated that Shigella was more resistant to ampicillin, ceftriaxone and sulfamethoxazole than Salmonella. Of the top two serotypes in Salmonella, Typhimurium was more resistant to ciprofloxacin, sulfamethoxazole and chloramphenicol than Enteritidis (P < 0·001). Meanwhile, the resistance rates of Shigella flexneri against ampicillin/sulbactam, ciprofloxacin, and chloramphenicol were significantly higher than those of Shigella sonnei (P < 0·001). Multidrug resistance was apparent in 58·2% of Shigella and 45·9% of Salmonella, and this phenomenon was more pronounced in S. flexneri.

Update on molecular epidemiology of Shigella infection

PURPOSE OF REVIEW

Shigella spp. are important etiologic agents of diarrhea worldwide. This review summarizes the recent findings on the epidemiology, diagnosis, virulence genes, and pathobiology of Shigella infection.

RECENT FINDINGS

Shigella flexneri and Shigella sonnei have been identified as the main serogroups circulating in developing and developed countries, respectively. However, a shift in the dominant species from S. flexneri to S. sonnei has been observed in countries that have experienced recent improvements in socioeconomic conditions. Despite the increasing usage of molecular methods in the diagnosis and virulence characterization of Shigella strains, researchers have been unsuccessful in finding a specific target gene for this bacillus. New research has demonstrated the role of proteins whose expressions are temperature-regulated, as well as genes involved in the processes of adhesion, invasion, dissemination, and inflammation, aiding in the clarification of the complex pathobiology of shigellosis.

SUMMARY

Knowledge about the epidemiologic profile of circulating serogroups of Shigella and an understanding of its pathobiology as well as of the virulence genes is important for the development of preventive measures and interventions to reduce the worldwide spread of shigellosis.

Differences in lineage replacement dynamics of G1 and G2 rotavirus strains versus G9 strain over a period of 22 years in Bangladesh

Group A rotaviruses (RVAs) have been a major cause of severe gastroenteritis in Bangladesh, mainly in children below the age of five. At the icddr,b, RVA strains collection and characterization dates back for more than 20 years. This sample collection was used to study the molecular evolution of the VP7 gene of G1, G2 and G9 RVA strains, which have been circulating in Bangladesh for most of this study period. The evolutionary rates (95% HPD) for G1, G2 and G9 were calculated to be 0.93×10(-3) (0.68-1.18), 1.45×10(-3) (1.12-1.78) and 1.07×10(-3) (0.78-1.39), respectively, which is in line with previous data for the RVA VP7 outer capsid protein, which is under strong negative selective pressure. Bayesian analyses revealed that for the G1 and G2 genotypes, one or multiple lineages co-circulated for one or a few seasons, frequently followed by replacement with genetically different lineages. This can be explained by the existence of a large variety of G1 and G2 RVA lineages and the rapid dissemination of different lineages across the globe. In contrast, circulating G9 lineages were rather closely related to each other across the study period and they were usually derived from variants circulating in the previous season(s). This is consistent with the fact that G9 RVAs have circulated in the human population for less than 20 years, and therefore their genetic diversity is much smaller, not resulting in the replacement of circulating G9 strains by highly divergent G9 lineages from abroad. Such different evolutionary dynamics for different RVA genotypes may alter their response to the selective pressure that might be exerted by the introduction of RVA vaccines and therefore a continued close monitoring is warranted.

Aetiologies of diarrhoea in adults from urban and rural treatment facilities in Bangladesh

The objective of our analysis was to describe the aetiology, clinical features, and socio-demographic background of adults with diarrhoea attending different urban and rural diarrhoeal disease hospitals in Bangladesh. Between January 2010 and December 2011, a total of 5054 adult diarrhoeal patients aged ⩾20 years were enrolled into the Diarrhoeal Disease Surveillance Systems at four different hospitals (two rural and two urban) of Bangladesh. Middle-aged [adjusted odds ratio (aOR) 0·28, 95% confidence interval (CI) 0·23-0·35, P < 0·001] and elderly (aOR 0·15, 95% CI 0·11-0·20, P < 0·001) patients were more likely to present to rural diarrhoeal disease facilities than urban ones. Vibrio cholerae was the most commonly isolated pathogen (16%) of the four pathogens tested followed by rotavirus (5%), enterotoxigenic Escherichia coli (ETEC) (4%), and Shigella (4%). Of these pathogens, V. cholerae (19% vs. 11%, P < 0·001), ETEC (9% vs. 4%, P < 0·001), and rotavirus (5% vs. 3%, P = 0·013) were more commonly detected from patients presenting to urban hospitals than rural hospitals, but Shigella was more frequently isolated from patients presenting to rural hospitals than urban hospitals (7% vs. 2%, P < 0·001). The isolation rate of Shigella was higher in the elderly than in younger adults (8% vs. 3%, P < 0·001). Some or severe dehydration was higher in urban adults than rural adults (P < 0·001). Our findings indicate that despite economic and other progress made, conditions facilitating transmission of V. cholerae and Shigella prevail in adults with diarrhoea in Bangladesh and further efforts are needed to control these infections.

Characteristics of Multidrug Resistant Shigella and Vibrio cholerae O1 Infections in Patients Treated at an Urban and a Rural Hospital in Bangladesh

We determined the frequency of multidrug resistant (MDR) infections with Shigella spp. and Vibrio cholerae O1 at an urban (Dhaka) and rural (Matlab) hospital in Bangladesh. We also compared sociodemographic and clinical features of patients with MDR infections to those with antibiotic-susceptible infections at both sites. Analyses were conducted using surveillance data from the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), for the years 2000–2012. Compared to patients with antibiotic-susceptible for Shigella infections, those in Dhaka with MDR shigellosis were more likely to experience diarrhea for >24 hours, while, in Matlab, they were more likely to stay inhospital >24 hours. For MDR shigellosis, Dhaka patients were more likely than those in Matlab to have dehydration, stool frequency >10/day, and diarrheal duration >24 hours. Patients with MDR Vibrio cholerae O1 infections in Dhaka were more likely than those in Matlab to experience dehydration and stool frequency >10/day. Thus, patients with MDR shigellosis and Vibrio cholerae O1 infection exhibited features suggesting more severe illness than those with antibiotic-susceptible infections. Moreover, Dhaka patients with MDR shigellosis and Vibrio cholerae O1 infections exhibited features indicating more severe illness than patients in Matlab.

Epidemiology and genetic diversity of human astrovirus infection among hospitalized patients with acute diarrhea in Bangladesh from 2010 to 2012

BACKGROUND

Globally, human astroviruses (HAstVs) have emerged as another common cause of non-bacterial acute gastroenteritis. Limited data exist on the epidemiology and genetic diversity of HAstVs in Bangladesh.

OBJECTIVE

We describe the epidemiology of HAstV-associated diarrhea among hospitalized patients, including HAstV genotypes, clinical symptoms and co-infecting pathogens.

STUDY DESIGN

Stool samples were collected from an ongoing diarrhea etiology surveillance during 2010-2012. HAstV was detected using RT-PCR and positive samples were subsequently tested for other common viral and bacterial pathogens. Phylogenetic analysis was performed and genotyped HAstV sequences were compared with previously reported Bangladeshi HAstV strains.

RESULTS

Of 826 fecal specimens, HAstV was detected in 26 cases (3.1%) and the majority of these cases (92%) was observed in children under 3 years of age. For 6 out of the 26 cases (23%) no other co-infecting pathogens were observed, whereas for the 20 remaining cases (77%) a variety of other known enteric viral and bacterial pathogens were observed. Based on the overlap region between ORF1b (RdRp) and ORF2 (capsid), five different genotypes (HAstV-1, -2, -3, -5 and -6) were identified circulating during the study period, with HAstV-1 being the predominant type. Genetic analysis revealed that HAstV-1 strains detected in this study were distantly related (<90% similarity of the capsid protein on the nt level) with HAstV-1 strains previously reported from Bangladesh.

CONCLUSION

Our study provides an epidemiological overview and genetic diversity of HAstVs associated with acute diarrhea in Bangladesh.

Changing trends and serotype distribution of Shigella species in Beijing from 1994 to 2010

Shigella species are a common cause of acute diarrheal disease in China. In this study, we characterized the changing trends and serotype distribution of Shigella species in Beijing from 1994 to 2010. A total of 5999 Shigella strains were isolated and serotyped from the 302nd Hospital in Beijing. The annual number of Shigella isolates reached a peak (n = 1192; 19.84%) in 1996 and then decreased annually, reaching the lowest point (n = 24; 0.41%) in 2010. S. flexneri 2a and S. sonnei were the most frequently isolated Shigella, with their respective isolates making up 53.3% and 27.6% of the total. Isolates of S. flexneri 4c, 4a, and x made up 3% respectively of the total isolates. Significant decreases in percentage of S. flexneri over time were observed. S. sonnei surpassed S. flexneri 2a as the predominant serotype in 2000. Most isolates were recovered from July to September; 13.6% of the isolates were recovered from children aged 0 to 5 years, and 16% were recovered from those aged 21 to 25 years. S. flexneri 2a and 5 were recovered mostly from males (33.41%, p < 0.001; and 0.46%, p < 0.001%; respectively), whereas S. flexneri 2b and 6, and S. sonnei were most often isolated from females. Continuous monitoring of Shigella showed that all 4 species and 27 serotypes were present in Beijing, China, during the study period. The emergence of S. sonnei and the overall decreasing isolation rate of Shigella in Beijing can potentially aid in the development of vaccine and control strategies for shigellosis in the city.

Clinical characteristics, etiology and antimicrobial susceptibility among overweight and obese individuals with diarrhea: observed at a large diarrheal disease hospital, Bangladesh

BACKGROUND

The present study aimed to determine the clinical characteristics and etiology of overweight and obese (OO) individuals with diarrhea attending an urban Dhaka Hospital, International Centre for Diarrheal Disease Research (icddr,b), Bangladesh.

METHODS

Total of 508 under-5 children, 96 individuals of 5-19 years and 1331 of >19 years were identified as OO from the Diarrheal Disease Surveillance System (DDSS) between 1993-2011. Two comparison groups such as well-nourished and malnourished individuals from respective age stratums were selected.

RESULTS

Isolation rate of rotavirus was higher among OO under-5 children compared to malnourished group (46% vs. 28%). Rotavirus infection among OO individuals aged 5-19 years (9% vs. 3%) (9% vs. 3%) and >19 years (6% vs. 4%) (6% vs. 3%) was higher compared to well-nourished and malnourished children. Conversely, Vibrio cholerae was lower among all OO age groups compared to well-nourished and malnourished ones. Shigella (4% vs. 6%) (4% vs. 8%), and Campylobacter (3% vs. 5%) (3% vs. 5%) were lower only among OO in >19 years individuals compared to their counterparts of the same age stratum. Salmonella was similarly isolated in all age strata and nutritional groups. In multinomial logistic regression among under-5 children, significant association was observed only with use of antimicrobials at home [OR-1.97] and duration of hospital stay [OR-0.68]. For individuals aged 5-19 years, use of antimicrobials at home (OR-1.83), some or severe dehydration (OR-3.12), having received intravenous saline (OR-0.46) and rotavirus diarrhea (OR-2.96) were found to be associated with OO respectively. Moreover, significant associations were also found for duration of diarrhea before coming to hospital (>24 hours) (OR-1.24), Shigella (OR-0.46), and Campylobacter (OR-0.58) among >19 years OO individuals along with other associated co-variates in 5-19 years group (all p<0.05).

CONCLUSION AND SIGNIFICANCE

Higher proportion of OO were infected with rotavirus and a greater proportion of them used antimicrobials before coming to the hospital.