Isolation of atypical enteropathogenic Escherichia coli from children with and without diarrhoea in Delhi and the National Capital Region, India

Prevalence and characteristics of 11 potentially diarrhoeagenic microbes in asymptomatic individuals in Norway, 2015-2020

We aimed to estimate the prevalence of potentially diarrhoeagenic microbes (PDMs) in faecal samples from asymptomatic individuals in a high-income country, identify risk factors for carriage and to identify microbial factors that differ between PDMs in asymptomatic versus symptomatic individuals. Samples from 1000 asymptomatic participants were collected, together with a questionnaire, between 2015 and 2020 and examined by PCR for 11 PDMs. Isolates were characterised and potential risk factors were registered. Atypical enteropathogenic Escherichia coli (aEPEC), Yersinia enterocolitica, Shiga toxin-producing E. coli (STEC), enterotoxigenic E. coli (ETEC) and Campylobacter spp. were found in 163 (16%), 20 (2.0%), 17 (1.7%), 12 (1.2%) and 11 (1.1%) asymptomatic individuals, respectively. Other PDMs were rare. Only low virulent STEC, with stx1c, stx2b or stx2f, was detected. Travels outside Europe was a significant risk factor for detecting Campylobacter spp. (odds ratio (OR) 6.99; 95% CI 1.12-43.6) and ETEC (OR 11.4; 95% CI 1.26-102). Individuals ≥65 years of age had lower odds of carrying STEC (OR 0.11; 95% CI 0.02-0.57) or EPEC (OR 0.09; 95% CI 0.05-0.16) than individuals ≤5 years of age. The common finding of PDMs in asymptomatic individuals could have implications for the interpretation of positive findings in clinical samples and infection control measures.

Typical and atypical enteropathogenic Escherichia coli in children with acute diarrhoea: Changing trend in East Delhi

Background

Worldwide around 2 million deaths occur every year due to diarrhoeal illnesses among children less than 5 years of age. Among diarrhoeagenic Escherichia coli, Enteropathogenic E. coli (EPEC) is highly prevalent in both community and hospital settings and is one of the main causes of persistent diarrhea in children in developing countries. EPEC remains underdiagnosed in India due to lack of conventional tools for identification.

Methods

We in this study investigated the prevalence and regional variation of EPEC in paediatric population suffering from diarrhoea in East Delhi, India. Two hundred stool samples were collected from children, aged between 0.5 and 5 years, with acute diarrhoea. E. coli were identified by conventional tests and PCR.

Results

We observed 7% atypical EPEC (aEPEC) and 2.5% typical EPEC (tEPEC), with an overall 9.5% EPEC prevalence amongst total samples. E. coli phylogenetic group A was the predominant. The most common age group affected was 6–23 months with common symptoms being vomiting, watery diarrhoea and severe dehydration. High drug resistance pattern was observed in EPEC isolates.

Conclusion

The study depicts a changing trend of aEPEC over tEPEC in children less than 5 years with diarrhoea, an emerging drug resistant enteropathogen and a public health concern demanding monitoring and surveillance.

Virulence-Related Genes and Coenteropathogens Associated with Clinical Outcomes of Enteropathogenic Escherichia coli Infections in Children from the Brazilian Semiarid Region: a Case-Control Study of Diarrhea

Enteropathogenic Escherichia coli (EPEC) is a major cause of diarrhea in children from developing countries and presents high genetic variability. We aimed to characterize the EPEC virulence-related gene (VRG) distribution and copathogens associated with diarrhea and nutrition-related outcomes in children from the low-income Brazilian semiarid region. A cross-sectional case-control study of diarrhea was conducted in 1,191 children aged 2 to 36 months from the northeast region of Brazil. Stool samples were collected and clinical, epidemiological, and anthropometric data were identified from each child. A broad molecular evaluation of enteropathogens was performed, and EPEC-positive samples were further investigated for 18 VRGs using five multiplex PCRs. EPEC was detected in 28.2% of the study population, with similar proportions among cases and controls. Typical EPEC (tEPEC) infections were more often associated with diarrhea than atypical EPEC (aEPEC) infections, while aEPEC infections presented a higher prevalence. The VRG ler, a negative regulator of the locus of enterocyte effacement, was associated with the absence of diarrhea in aEPEC-positive children; espB, a major component of the type 3 secretion system, was associated with diarrhea in tEPEC-positive children; the presence of procolonization VRGs-the combination of cesT positivity, espP negativity, and the presence of the map gene-was associated with undernutrition; and Campylobacter spp., norovirus, and enteroaggregative E. coli (EAEC) coinfections were associated with increased clinical severity in EPEC-infected children. These data identified tEPEC strains associated with diarrhea and specific VRGs of EPEC (ler, espB, cesT, and map genes) and Campylobacter spp., norovirus, and EAEC to be major contributors to diarrhea and undernutrition in children from a low-income Brazilian region.

Spectrum of diarrhoeagenic Escherichia coli in paediatric population suffering from diarrhoea and as commensals in healthy children

BACKGROUND

Diarrhoeagenic Escherichia coli (DEC) is associated with early death of children in developing countries and are being identified now as an important evolving pathogen. The objective of this study was to perform multiplex polymerase chain reaction (PCR) for simultaneous detection of six categories of DEC in two sets of PCR reactions using 11 virulent genes.

MATERIALS AND METHODS

During 1-year study period, forty isolates each from outpatient, inpatient and healthy groups were collected from children. E. coli was identified using conventional biochemical methods. DNA extraction was done using kit, and the extracted DNA was used as a template for multiplex PCR.

RESULTS

Virulent genes of DEC were detected in 106 (88.33%) samples. Overall, elt and est were detected in 8.33% and 30.83% of specimens; typical, atypical enteropathogenic E. coli and bfp were detected in 13.33%, 29.16% and 19.16% specimens; eagg was detected in 39.16% and east in 13.33% specimens and stx and hyla were isolated in 1.66% specimens each. While diffusely adherent E. coli and enteroinvasive E. coli genes were not isolated.

CONCLUSION

Multiplex PCR is a rapid method for the simultaneous detection of 11 virulent genes of DEC at a time and it will provide a platform in understanding the diarrheal diseases in a more improved manner.

Diarrheagenic Escherichia coli infections among the children of Andaman Islands with special reference to pathotype distribution and clinical profile

Diarrhoeagenic E. coli (DEC) is one of the most common causes of diarrhoeal death in children less than five years globally. It is responsible for 30%-40% of all diarrhoeal episodes in developing countries. It is estimated that 0.12million children died of diarrhoea caused by DEC in 2011 globally. There is no baseline data on the occurrence of DEC diarrhoea in Andaman Islands, the remote islands of India. The study is particularly important as these strains are the emerging enteric pathogen in both developed and developing countries. DEC was screened from E. coli isolates obtained from diarrhoeal stool samples by multiplex PCR with specific primers using stasndard protocols. During the study period, among the 1394 stool samples collected, 95 (6.82%) patients were found infected with DEC. Of the 97 isolates from 95 patients, 68 (70.1%) were EAEC, 19 (19.6%) were EPEC and 10 (10.3%) were ETEC. Of the 19 EPEC isolates, 63.2% were atypical EPEC which is the emerging enteric pathogen among the children in developing as well as developed countries. More than 80% of the patients had watery diarrhoea and 6% of them had invasive diarrhoea. Persistent diarrhoea was also found in three infected children. This study documents the occurrence and type of DEC diarrhoea in Andaman Islands first time and highlights the significant proportions of E. coli diarrhoea being caused by EAEC and atypical EPEC strains.

Prevalence of multi drug resistant enteropathogenic and enteroinvasive Escherichia coli isolated from children with and without diarrhea in Northeast Indian population

Background

Diarrheagenic Escherichia coli are associated with infantile diarrhea in the developing countries. The present study was conducted to determine the occurrence and antimicrobial resistance pattern of enteropathogenic and enteroinvasive E. coli associated with diarrhoea among the paediatric patients.

Methods

A total of 262 stool samples were collected from children with and without diarrhea from Mizoram, Northeast India. E. coli were isolated and subjected to multiplex PCR to detect virulent genes of EPEC (eaeA and bfpA) and EIEC (ial). Isolates were subjected to antimicrobial sensitivity assay using disc diffusion method. Selected eaeA genes were sequenced for identification and genetic relationship.

Results

A total of 334 E. coli was isolated, of which 17.37% were carrying at least one virulent gene. Altogether, 14.97 and 2.40% isolates were categorized as EPEC and EIEC, respectively. Among the DEC isolates, 4.79% were EPEC and 7.78% were EIEC. A total of 8 (2.40%) isolates were EIEC (ial+), of which 6 (1.80%) and 2 (0.60%) were from diarrhoeic and non-diarrhoeic patients, respectively. A total of 24 (41.40%) DEC isolates were MDR (resistance against ≥5 antimicrobials).

Conclusions

A high frequency of EPEC pathotypes associated with paediatric diarrhea was observed in Mizoram, Northeast India and majority of the isolates are resistant to antibiotics with a high frequency of MDR, which is a matter of concern to the public health. This also raises an alarm to the world communities to monitor the resistance pattern and analyse in a global scale to combat the problems of resistance development.

Prevalence of Escherichia coli Virulence Genes in Patients with Diarrhea and a Subpopulation of Healthy Volunteers in Madrid, Spain

Etiological diagnosis of diarrheal diseases may be complicated by their multi-factorial nature. In addition, Escherichia coli strains present in the gut can occasionally harbor virulence genes (VGs) without causing disease, which complicates the assessment of their clinical significance in particular. The aim of this study was to detect and quantify nine VGs (stx1, stx2, eae, aggR, ehxA, invA, est, elt and bfpA) typically present in five E. coli enteric pathotypes [enterohaemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), and enteroinvasive E. coli (EIEC)] in fecal samples collected from 49 patients with acute diarrhea and 32 healthy controls from Madrid, Spain. In addition, the presence of four serotype-related genes (wzx_O104 and fliC_H4, rfb_O157, and fliC_H7) was also determined. Presence of target genes was assessed using a quantitative real-time PCR assay previously developed, and the association of presence and burden of VGs with clinical disease and/or other risk factors was explored. Prevalence of ehxA [typically associated with Shigatoxin producing E. coli (STEC) and (EPEC), invA (EIEC), and the rfb_O157+fliC_H7 (STEC)] combination were significantly (p < 0.02) higher in the diarrheic group, while the wzx_O104+fliC_H4 combination was significantly (p = 0.014) more prevalent in the control group. On the other hand, eae was detected in more than 90% of the individuals in both patient and control populations, and it was not associated with bfpA, suggesting the absence of typical EPEC. No significant differences in the quantitative values were detected for any VG among study groups, but the difference in the load of aggR (EAEC) and invA in the patients with respect to the controls was close to the significance, suggesting a potential role of these VGs in the clinical signs observed when they are present at high levels.

Genetic Diversity of Intimin Gene of Atypical Enteropathogenic Escherichia coli Isolated from Human, Animals and Raw Meats in China

Atypical enteropathogenic Escherichia coli (aEPEC) is considered to be an emerging enteropathogen that is more prevalent than typical EPEC in developing and developed countries. The major adherence factor, intimin, an outer membrane protein encoded by eae, plays a pivotal role in the pathogenesis of aEPEC. This study investigated the distribution and polymorphisms of intimin subtypes of 143 aEPEC strains from diarrheal patients, healthy carriers, animals, and raw meats in China. These aEPEC strains belonged to more than 71 different serotypes, which comprised 52 O serogroups and 24 H types. Sixty-eight different eae genotypes and 19 intimin subtypes were detected. Eighteen, eight, seven, and five intimin subtypes were identified from 86 diarrheal patients, 14 healthy carriers, 19 animals, and 24 raw meats strains, respectively. Intimin β1 was the most prevalent subtype in strains from diarrheal patients (34.88%) and animals (47.37%). There was a statistically significant difference in the distribution of eae-β1 between diarrheal patients and healthy carriers (P = 0.004). Intimin-θ was more predominant among raw meat strains (50%) than among diarrheal patients strains (12.79%, P = 0.0003), healthy carrier strains (7.14%, P = 0.007), or animal strains (15.79%, P = 0.020). The two predominant subtypes (eae-β1 and eae-θ) had considerable polymorphisms with no significant differences among the four sources. PFGE analysis revealed 119 distinct patterns and the strains were clustered into 11 groups with similarity indices ranging from 63% to 100%. These results suggest that in China, aEPEC strains from different sources are highly heterogeneous. Animals and raw meats are important sources of genetically diverse intimin-harboring aEPEC, which might serve as important transmission vehicles of these bacteria.

Oral zinc supplements are ineffective for treating acute dehydrating diarrhoea in 5-12-year-olds

AIM

Many countries have guidelines recommending the use of oral zinc in acute dehydrating diarrhoea in children aged 2 months to 5 years of age, but no guidelines exist for older children. This study tested how effective existing recommendations are in children from 5 to 12 years of age.

METHODS

Children hospitalised with acute dehydrating diarrhoea (n = 134) were randomised to receive 40 mg of oral zinc sulphate tablets or a placebo for 14 days. The primary outcome variable was the time taken for diarrhoea to stop. Secondary outcome variables included time taken for rehydration, duration of hospitalisation and recurrence of diarrhoea in the next 3 months.

RESULTS

The median time for resolution of diarrhoea was 60 h in both groups. The zinc group was marginally better, but not statistically significant, for resolution (hazard ratio = 0.89, 95% CI 0.63-1.24), rehydration (hazard ratio = 0.93, 95% CI 0.66-1.32) and hospitalisation (hazard ratio = 0.94, 95% CI 0.67-1.34). The risk ratio of recurrence for zinc versus placebo (95% CI) was 0.65 [0.37-1.23] [p = 0.11].

CONCLUSION

Daily zinc supplements (40 mg for 14 days) in children aged 5-12 years with acute dehydrating diarrhoea did not shorten the duration of diarrhoea or reduce subsequent episodes. Further adequately sized, community-based trials are needed.

Epidemiology, Antimicrobial Resistance and β-lactamase Genotypic Features of Enteropathogenic Escherichia coli Isolated from Children with Diarrhea in Southern China

The main objective of this study was to investigate the epidemiology, drug resistance and β-lactamase genotype distribution of enteropathogenic Escherichia coli (EPEC) isolated from pediatric patients with diarrhea in southern China. The prevalence of EPEC in children with diarrhea was 3.53%. The commonest serotypes were O55:K59 and O126:K71, and the typical EPEC were more prevalent than atypical EPEC (51 vs 7). Isolates from this region were most commonly found to be resistant to ampicillin and cotrimoxazole, followed by chloramphenicol, ceftriaxone, and ceftazidime. More than 96% of the strains were susceptible to cefoperazone/sulbactam and imipenem. The most common β-lactamase genotypes identified in 58 strains were blaCTX-M-1 (60.3%), blaTEM (56.9%), blaCTX-M-9 (27.6%), and blaSHV (15.5%). Among 58 isolates, 22 strains were found to harbor one β-lactamase gene, and the proportions of resistance to ampicillin, cotrimoxazole, chloramphenicol, ceftriaxone, and ceftazidime, were 81.8%, 63.6%, 40.9%, 18.2%, and 9.1%, respectively. A further 30 strains carrying multiple β-lactamase genes had increased resistance to the above antimicrobial agents (100%, 83.3%, 70.0%, 60.0%, and 30.0%, respectively). In contrast, antibiotic resistance in the last 6 strains without a detectable β-lactamase gene was substantially reduced. Drug resistance may be associated with the β-lactamase gene number, with a greater the number of β-lactamase genes resulting in higher antibiotic resistance.

Potential enterovirulence and antimicrobial resistance in Escherichia coli isolates from aquatic environments in Rio de Janeiro, Brazil

Escherichia coli contamination in aquatic ecosystems has emerged as a relevant concern of public health impact, especially in developing areas. In this study, E. coli isolates were recovered from residential, industrial, agricultural, hospital wastewaters and recreational waters and, further characterized according to diarrheagenic potential, phylotyping and antimicrobial resistance phenotype. Among the total 178 E. coli isolates, antimicrobial resistance was detected in 37% to at least one of the 11 antimicrobials tested. The highest percentage of resistant E. coli was recovered from agricultural wastewaters (57.7%) followed by recreational waters (56.4%), hospital (34.5%), residential (22.7%) and industrial wastewaters (22.2%). Twenty-three resistance profiles (I-XXIII) were detected and 17 isolates exhibited the MDR phenotype. 11.2% of the total E. coli isolates carried diarrheagenic markers: astA (7.3%, 13/178), stx1 (2.8%, 05/178), escV (2.2%, 04/178) and estIa (0.6%, 01/178). All isolates harbored the uidA gene. E. coli isolates were mostly found in phylogenetic groups A (91.6%, 163/178) followed by groups D (5%, 09/178) and B2 (3.4%, 06/178). Specific gene combinations characterized E. coli pathotypes as ETEC (01/20), ATEC (04/20) and STEC (05/20) which belonged to A (75%, 15/20), D (15%, 03/20) and B2 (10%, 02/20) phylogroups. Our results revealed the widespread distribution of E. coli in aquatic systems in Rio de Janeiro. The circulation of pathogenic E. coli and antimicrobial resistance within bacterial population represents high risk to ecosystem and human health and highlights epidemiological surveillance and sanitary improvement.

Prevalence and antibiotic resistance profiles of diarrheagenic Escherichia coli strains isolated from food items in northwestern Mexico

Diarrheogenic Escherichia coli (DEC) strains are an important cause of intestinal syndromes in the developing world mainly affecting children. DEC strains often infect tourists from developed countries traveling to Mexico, causing so-called "traveler diarrhea". DEC strains are typically transmitted by contaminated food and water; however, the prevalence of these strains in food items that are produced, consumed and sometimes exported in northwestern Mexico has not been evaluated. In this study, we conducted a large microbiological survey of DEC strains in 5162 food items and beverages consumed throughout Sinaloa state during 2008 and 2009. We developed a panel of eight sequential PCR reactions that detected the presence of all DEC categories, including typical or atypical variants. Thermotolerant coliforms (also known as fecal coliforms) and E. coli were detected by conventional bacteriology in 13.4% (692/5162) and 7.92% (409/5162) of food items, respectively. Among 409 E. coli isolates, 13.6% (56/409) belonged to DEC strains. Dairy products (2.8%) were the most contaminated with DEC, while DEC strains were not detected in beverages and ice samples. The pathogenic type that was most commonly isolated was EPEC (78.5%), followed by EAEC (10.7%), STEC (8.9%) and ETEC (1.7%). EHEC, DAEC and EIEC strains were not detected. Approximately 80% of EPEC and EAEC strains were classified as atypical variants; they did not adhere to a culture of HEp-2 cell. Of the isolated DEC strains, 66% showed resistance to at least one commonly prescribed antibiotic. In conclusion, the presence of DEC strains in food items and beverages available in northwestern Mexico is low and may not represent a threat for the general population or those traveling to tourist areas.

Specific properties of enteropathogenic Escherichia coli isolates from diarrheal patients and comparison to strains from foods and fecal specimens from cattle, swine, and healthy carriers in Osaka City, Japan

For exhaustive detection of diarrheagenic Escherichia coli, we previously developed a colony-hybridization method using hydrophobic grid-membrane filters in combination with multiplex real-time PCR. To assess the role of domestic animals as the source of atypical enteropathogenic E. coli (aEPEC), a total of 679 samples (333 from foods, fecal samples from 227 domestic animals, and 119 from healthy people) were examined. Combining 48 strains previously isolated from patients and carriers, 159 aEPEC strains were classified by phylogroup, virulence profile, and intimin typing. Phylogroup B1 was significantly more prevalent among aEPEC from patients (50%) and bovine samples (79%) than from healthy carriers (16%) and swine strains (23%), respectively. Intimin type β1 was predominant in phylogroup B1; B1-β1 strains comprised 26% of bovine strains and 25% of patient strains. The virulence profile groups Ia and Ib were also observed more frequently among bovine strains than among porcine strains. Similarly, virulence group Ia was detected more frequently among patient strains than strains of healthy carriers. A total of 85 strains belonged to virulence group I, and 63 of these strains (74%) belonged to phylogroup B1. The present study suggests that the etiologically important aEPEC in diarrheal patients could be distinguished from aEPEC strains indigenous to humans based on type, such as B1, Ia, and β1/γ1, which are shared with bovine strains, while the aEPEC strains in healthy humans are different, and some of these were also present in porcine samples.

Immunization of mice with Lactobacillus casei expressing a beta-intimin fragment reduces intestinal colonization by Citrobacter rodentium

Enteropathogenic Escherichia coli (EPEC) is a common cause of diarrhea in children from developing countries. Intimate adhesion of the bacteria to intestinal cells occurs via binding of the adhesin intimin to the TIR receptor exposed on cell surfaces. Here, Lactobacillus casei expressing a fragment of β-intimin (L. casei-Int(cv)) was tested as mucosal vaccines in mice against intestinal colonization with the murine pathogen Citrobacter rodentium. Oral or sublingual immunization of C57BL/6 mice with L. casei-Int(cv) induced anti-Int(cv) IgA in feces but no IgG in sera. Conversely, anti-Int(cv) IgG was induced in the sera of mice after sublingual immunization with purified Int(cv). All vaccines were able to decrease C. rodentium recovery from feces. However, this reduction was more evident and sustained over time in mice immunized with L. casei-Int(cv) by the sublingual route. These mice also displayed an increase in interleukin 6 (IL-6) and gamma interferon (IFN-γ) secretion by spleen cells 10 days after infection. Additionally, oral or sublingual immunization of C3H/HePas mice, which are highly susceptible to C. rodentium infection, with L. casei-Int(cv) induced anti-Int(cv) antibodies and significantly increased survival after challenge. Immunohistological analysis of colon sections revealed that C. rodentium was located in deep fractions of the tissue from C3H/HePas mice immunized with L. casei whereas superficial staining was observed in colon sections from mice immunized with L. casei-Int(cv.) The results indicate that vaccines composed of L. casei expressing intimin may represent a promising approach and that the C3H/HePas infection model with C. rodentium can be used to evaluate potential vaccines against EPEC.