Multi-drug-resistant enterotoxigenic and enterohemorrhagic Escherichia coli isolated from children with diarrhea

Prevalence of common diarrheagenic enterobacteriaceae in Iran (2000-2023): a systematic review and meta-analysis

OBJECTIVE

Bacterial gastroenteritis is a significant public health concern, capable of causing severe infections. Among the various pathogens involved, those belonging to the Enterobacteriaceae family are the most frequently isolated and associated with gastrointestinal disorders. This study aimed to investigate the prevalence of common diarrheagenic Enterobacteriaceae in Iran over the past two decades, from 2000 to 2023.

METHODS

A comprehensive systematic search was conducted across multiple databases, including EMBASE, HINARI, MEDLINE, PubMed, Google Scholar, and the Cochrane Library. The focus was on observational published studies reporting the prevalence of diarrheagenic Enterobacteriaceae in Iran during 2000 and 2023. The criteria did not restrict patient demographics such as age, gender, health conditions, or occupation. This meta-analysis employed a 95% confidence interval (CI) for analysis. Evidence of heterogeneity was determined using an I² value greater than 50%. To explore potential sources of heterogeneity, subgroup analysis and meta-regression analysis were performed. Statistical analyses were executed using R version 4.3.2 along with the meta package. A p-value less than 0.05 was considered statistically significant.

RESULTS

Out of 3,701 papers reviewed, 56 studies met the inclusion criteria and were analyzed. The overall pooled prevalence of diarrheagenic Enterobacteriaceae species from 2000 to 2023 was 14.0% (95% CI: 0.11-0.17). Subgroup analysis revealed Shigella spp. had the highest prevalence at 18.0% (95% CI: 0.13-0.24; I²=99%), followed by diarrheagenic Escherichia coli at 11.0% (95% CI: 0.09-0.15; I²=97%), Salmonella spp. at 9.0% (95% CI: 0.05-0.17; I²=99%), and Yersinia spp. at 2.0% (95% CI: 0.00-0.10; I²=94%). Prevalence trends showed Shigella spp. increasing from 4% (95% CI: 0.03-0.08) in 2000-2004 to 36% (95% CI: 0.20-0.55) in 2021-2023. Diarrheagenic E. coli (DEC) showed no clear pattern, ranging from 5% (95% CI: 0.01-0.24) to 17% (95% CI: 0.07-0.36). Salmonella spp. exhibited more significant fluctuations, rising from 6% (95% CI) in both 2000-2004 and 2005-2008 periods to 20% (95% CI: 0.03-0.66) in 2009-2012 and 30% (95% CI: 0.11-0.60) in 2017-2020. Yersinia spp. was only determined in 2000-2004 with a pool prevalence of 12% (95% CI: 0.00-0.91). Sub-species analysis revealed Shigella sonnei was the most prevalent species among Shigella spp. in Iran, accounting for 42% of cases (95% CI: 0.33-0.52). Regarding DEC species, Enteroaggregative E. coli (EAEC) and Enterotpathogenic E. coli (EPEC) had the highest rate at 15% (95% CI). Furthermore, a pool prevalence of 2% (95% CI: 0.00-0.89) was reported for Yersinia enterocolitica among diarrheagenic Enterobacteriaceae in Iran.

CONCLUSION

This meta-analysis provides valuable insights into the prevalence of diarrheagenic Enterobacteriaceae in Iran over the past two decades. The findings highlight the significant impact of these pathogens on public health, with Shigella spp. showing the highest prevalence and increasing trends. Further research should investigate the factors contributing to the prevalence of diarrheagenic Enterobacteriaceae, including genetic diversity of diarrheagenic Enterobacteriaceae isolates, molecular mechanisms underlying the virulence of these pathogens, or antibiotic resistance patterns.

Circulation of enterotoxigenic Escherichia coli (ETEC) isolates expressing CS23 from the environment to clinical settings

IMPORTANCE

The importance of clean water cannot be overstated. It is a vital resource for maintaining health and well-being. Unfortunately, water sources contaminated with fecal discharges from animal and human origin due to a lack of wastewater management pose a significant risk to communities, as they can become a means of transmission of pathogenic bacteria like enterotoxigenic E. coli (ETEC). ETEC is frequently found in polluted water in countries with a high prevalence of diarrheal diseases, such as Bolivia. This study provides novel insights into the circulation of ETEC between diarrheal cases and polluted water sources in areas with high rates of diarrheal disease. These findings highlight the Choqueyapu River as a potential reservoir for emerging pathogens carrying antibiotic-resistance genes, making it a crucial area for monitoring and intervention. Furthermore, the results demonstrate the feasibility of a low-cost, high-throughput method for tracking bacterial pathogens in low- and middle-income countries, making it a valuable tool for One Health monitoring efforts.

Prevalence of Multidrug-Resistant Diarrheagenic Escherichia coli in Asia: A Systematic Review and Meta-Analysis

Diarrhea is one of the leading causes of morbidity and mortality in developing countries. Diarrheagenic Escherichia coli (DEC) is an important bacterial agent for diarrhea in infants, children, and international travelers, and accounts for more than 30% of diarrheal cases in children less than 5 years old. However, the choices of antimicrobial agents are now being limited by the ineffectiveness of many first-line drugs, in relation to the emergence of antimicrobial-resistant E. coli strains. The aim of this systematic review and meta-analysis was to provide an updated prevalence of antimicrobial-resistant DEC in Asia. A comprehensive systematic search was conducted on three electronic databases (PubMed, ScienceDirect, and Scopus), where 40 eligible studies published between 2010 and 2022 were identified. Using meta-analysis of proportions and a random-effects model, the pooled prevalence of DEC in Asian diarrheal patients was 22.8% (95% CI: 16.5–29.2). The overall prevalence of multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL)-producing DEC strains was estimated to be 66.3% (95% CI: 58.9–73.7) and 48.6% (95% CI: 35.1–62.1), respectively. Considering antimicrobial drugs for DEC, the resistance prevalence was highest for the penicillin class of antibiotics, where 80.9% of the DEC isolates were resistant to amoxicillin and 73.5% were resistant to ampicillin. In contrast, resistance to carbapenems such as imipenem (0.1%), ertapenem (2.6%), and meropenem (7.9%) was the lowest. The relatively high prevalence estimation signifies that the multidrug-resistant DEC is a public health threat. Effective antibiotic treatment strategies, which may lead to better outcomes for the control of E. coli infections in Asia, are necessary.

Frequency of five Escherichia Coli pathotypes in Iranian adults and children with acute diarrhea

Background

Knowledge about the distribution of Escherichia Coli (E. coli) pathotypes in Iran is limited. This nation-wide survey aims to provide a comprehensive description of the distribution of five pathogenic E. coli in Iran.

Methods

Stool samples were collected from 1,306 acute diarrhea cases from 15 provinces (2013–2014). E. coli-positive cultures underwent PCR testing for the detection of STEC, ETEC, EPEC, EAEC, and EIEC pathotypes. Pathotype frequency by province, age-group, and season was estimated.

Results

979 diarrhea samples (75.0%) were culture-positive for E. coli (95% CI: 72.6, 77.3%), and 659 (50.5%) were pathogenic E. coli (95% CI: 47.8, 53.2%). STEC was the most frequent pathotype (35.4%). ETEC (14.0%) and EPEC (13.1%) were the second and the third most frequent pathotypes, respectively. EAEC (4.3%) and EIEC (0.3%) were not highly prevalent. Fars (88.7%) and Khorasan-e-Razavi (34.8%) provinces had the highest and lowest frequencies, respectively. E. coli pathotypes were more frequent in warmer than cooler seasons, showed the highest frequency among children under five years of age (73%), and had no significant association with participants’ gender.

Conclusions

Diarrheagenic E. coli may be an important cause of acute diarrhea in adults and children in Iran. STEC and ETEC seem to be widespread in the country with a peak in warmer seasons, impacting the recommended use of seasonal STEC and ETEC vaccines, especially in high-risk groups. Monitoring the incidence of E. coli pathotypes, serotypes, and antibiotic resistance over time is highly recommended for evaluation of interventions.

Protective Immunity Against Enterotoxigenic Escherichia coli by Oral Vaccination of Engineered Lactococcus lactis

Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of diarrhea in children globally, and thus suitable vaccines are desired. Antigen display on lactic acid bacteria is a reliable approach for efficient oral vaccination and preventing bowel diseases. To develop an oral vaccine against ETEC, the gene of the binding domain from heat-labile toxin (LTB), a key ETEC virulence factor, was codon-optimized and cloned into a construct containing a signal peptide and an anchor for display on L. lactis. Bioinformatics analysis showed a codon adaptation index of 0.95 for the codon-optimized gene. Cell surface expression of LTB was confirmed by transmission electron microscopy and blotting. White New Zealand rabbits were immunized per os (PO) with the recombinant L. lactis, and the antibody titers were assayed with ELISA. In vitro neutralization assay was performed using mouse adrenal tumor cells and rabbit ileal loop test was performed as the in vivo assay. ELISA results indicated that oral administration of the engineered L. lactis elicited a significant production of IgA in the intestine. In vitro neutralization assay showed that the effect of the toxin could be neutralized with 500 µg/ml of IgG isolated from the oral vaccine group. Furthermore, the dose of ETEC causing fluid accumulation in the ileal loop test showed a tenfold increase in rabbits immunized with either recombinant L. lactis or LTB protein compared to other groups. Our results imply that recombinant L. lactis could potentially be an effective live oral vaccine against ETEC toxicity.

Multi-Drug-Resistant Diarrheagenic Escherichia coli Pathotypes in Pediatric Patients with Gastroenteritis from Central Iran

Background

Diarrheagenic Escherichia coli (DEC) is a significant cause of gastroenteritis and a major public health problem. This study investigates the prevalence and the antibiotic resistance patterns of DEC that were isolated from infectious diarrhea samples of pediatric patients from central Iran.

Patients and Methods

Pediatric diarrhea samples were collected from 230 pediatric patients visiting the hospital. E. coli pathotypes were diagnosed by using conventional culture methods and PCR. Antibiotic resistance profiles, the frequency of multi-drug resistance (MDR), and the phenotypic and genotypic characteristics of extended spectrum-β-lactamase (ESBL), AmpC and integron-associated genes were analyzed.

Results

Of the 230 samples of infectious diarrhea, 91 (39.5%) produced E. coli isolates. Of these, 32 cases (35.1%) were identified as DEC by culture and PCR. The frequency of the E. coli pathotypes obtained was as follows: EAEC 11/32 (34.3%), EPEC 9/32 (28.1%), ETEC 6/32 (18.7%), EIEC 3/32 (9.3%), and EHEC 3/32 (9.3%). The antibiotic resistance rates were greater for nalidixic acid (30/32; 93.7%), ampicillin (29/32; 90.6%), and tetracycline (25/32; 78.1%) than for any of the other tested antibiotics. High levels of MDR (25/32; 78.1%) and the presence of ESBL (18/32; 56.2%) and AmpC (9/32; 28.1%) were observed in the DEC isolates. The isolates showed a higher frequency of the ESBL genes [bla_TEM (18/18; 100%), bla_CTX-M15 (17/18; 94.4%)], and AmpC [bla _CIT (4/9; 44.4%) and bla_DHA (4/9; 44.4%)] than of the other ESBL and AmpC genes.

Conclusion

Compared to the previous study, DEC appeared to be the second-most abundant agent of diarrhea in pediatric patients after Campylobacter jejuni, with frequent MDR and ESBL presence.

An overview of diarrheagenic Escherichia coli in Iran: A systematic review and meta-analysis

BACKGROUND

Diarrheagenic Escherichia coli (DEC) is a common enteric pathogen that causes a wide spectrum of gastrointestinal infections, particularly in developing countries. This is a systematic review and meta-analysis to determine the prevalence of DEC in various geographical regions in Iran.

MATERIALS AND METHODS

English (PubMed, Web of Science, Scopus, Embase, Cochrane Library, and Google Scholar) and Persian (IranMedex, SID, Magiran, and Iran Doc) databases were comprehensively searched from January 1990 to April 2017. Study selection and data extraction were performed by two independent reviewers. After assessing heterogeneity among studies, a random effects model was applied to estimate pooled prevalence. Data analyses were done with the Stata software (version 12.0). This meta-analysis was registered with PROSPERO, number CRD42017070411.

RESULTS

A total of 73 studies with 18068 isolates were eligible for inclusion within the meta-analysis. The results of random effects model showed that the most prevalent DEC pathotypes were enterotoxigenic E. coli (ETEC) (16%; 95% confidence interval [CI]: 11%-23%), enteroaggregative E. coli (11%; 95% CI: 8%-15%), atypical enteropathogenic E. coli (EPEC) (11%; 95% CI: 8%-14%), Shiga toxin-producing E. coli (9%; 95% CI: 6%-13%), diffuse adherent E. coli (6%; 95% CI: 6%-12%), enteroinvasive E. coli (4%; 95% CI: 2%-6%), and typical EPEC (3%; 95% CI: 1%-5%).

CONCLUSION

This study showed that DEC infections in the Iranian population have low frequency. Our data suggest that the ETEC pathotype can be regarded as one of the most important etiological agents of diarrhea in this country. However, the prevalence of DEC pathotypes is diverse in different regions of Iran.

Preparation of porcine enterotoxigenic Escherichia coli (ETEC) ghosts and immunogenic analysis in a mouse model

Enterotoxignenic Escherichia coli (ETEC)-associated colibacillosis causes high levels of morbidity and mortality in neonatal piglets. Vaccination is among effective strategy to fight against ETEC-related diseases. Bacterial ghosts (BGs) are empty bacterial envelopes, which substain subtle antigenic comformation in bacterial outer membrane. In this study, a BG vaccine was generated using porcine ETEC isolated strain DQ061 and evaluated its safety and immunogenicity in a mouse model. The recombinant bacteria were constructed by transformation of lysis plasmid pHH43 and generation of BGs was conducted in a lysis rate of 99.93% by incubation of the recombinant bacteria at 42 °C for 2 h. Mice were immunized subcutaneously twice in 2-week intervals with BGs, BGs emulsified with ISA 206 adjuvant, or formalin-inactivated ETEC vaccine after safety test. Mice with either of two BG vaccines developed higher titer of antibodies, secreted higher titer of interleukin 4, gamma interferon and alpha tumor necrosis factor after 2 doses than those with formalin-inactivated ETEC vaccine or those with adjuvant placebo (P < 0.01). The quantity of CD4⁺ and CD8⁺ T lymphocyte in spleen was higher in both BG groups than that in the inactivated vaccine group or adjuvant group 2 weeks post boost immunization (P < 0.05). The vaccinated mice were challenged intraperitoneally with 10 × LD₅₀ dose of DQ061. Mice with the BGs plus adjuvant were completely protected against challenge, compared to 60% protection of mice with the inactivated vaccine. Mice exhibited decreased tissue lesion and reduced bacterial loads in the BGs groups by comparison with those with the inactivated vaccine or adjuvant only. Our results validated that the ETEC BGs bear high safety and immunogenicity in a mouse model, suggesting a potential of further evaluation in a pig model.

Antibiotic resistance and molecular characterization of diarrheagenic Escherichia coli and non-typhoidal Salmonella strains isolated from infections in Southwest China

BACKGROUND

Bacterial diarrhea is one of the most common causes for medical consultations, mortality and morbidity in the world. Diarrheagenic Escherichia coli (DEC) and non-typhoidal Salmonella (NTS) are major intestinal pathogens in developing countries, and the indiscriminate use of antibiotics has greatly contributed to resistant strains. Hence, the aim of the present study is to identify the antimicrobial resistance patterns and the molecular characteristics of DEC and NTS in southwest, China.

METHODS

1121 diarrheal patients and 319 non-diarrheal subjects across all age groups were recruited from four sentinel hospitals from June 2014 to July 2015 in Kunming City, Yunnan Province. Each stool specimen was collected to detect DEC and NTS with standard microbiological and molecular methods. Antimicrobial resistance testing was performed with the Kirby-Bauer disk diffusion method, and the standards for antimicrobial susceptibility testing complied with the Clinical and Laboratory Standards Institute (CLSI). Molecular characterization of strains was carried out using pulsed-field gel electrophoresis (PFGE). A structured questionnaire was used to record basic epidemiological data (e.g. sex, age, residence, season, etc.). Data were analyzed using Chi-square or Fisher's exact test.

RESULTS

DEC was detected in 127 (11.33%) diarrhea cases and 9 (2.82%) non-diarrheal cases (χ2 = 20.69, P < 0.001, OR = 4.36, 95% CI: 2.19-8.65), and the prevalence of NTS isolated from diarrhea cases was higher than that of non-diarrheal cases across all age groups (n = 42, 3.75%, n = 1, 0.31%, χ2 = 10.10, P = 0.002, OR = 12.38, 95% CI: 1.70-90.29). The rates of resistance to ten antibiotics of DEC and NTS showed significant differences (χ 2  = 386.77, P < 0.001; χ2 = 191.16, P < 0.001). The rates of resistance to Amoxicillin and Clavulafiate (AMC), Cephalothin (CEP), Gentamicin (GEN) and Sulfamethoxazole-Trimethoprim (SXT) of DEC isolated from diarrhea cases were higher than those of NTS isolated from diarrhea patients (37.01% vs 14.29%, χ2 = 7.57, P = 0.006; 29.92% vs 11.90%, χ2 = 5.40, P = 0.02; 37.01% vs 11.90%, χ2 = 5.80, P = 0.016; 62.20% vs 26.19%, χ2 = 16.44, P < 0.001; respectively). Ciprofloxacin (CIP) was the most sensitive antibiotic for DEC and NTS strains isolated from diarrhea cases. Resistance rates of DEC isolates from cases and controls to more than three kinds antimicrobials (multidrug resistance, MDR) showed no significant differences (81.10% vs 88.89%, P = 0.33). Pulsotype patterns of DEC strains were highly diverse; however, the pulsotype pattern of NTS strains was closely related to the serotype. The pattern of S. enteritidis was highly similar, but the S. enterica Typhimurium strain was discrete.

CONCLUSIONS

Antibiotic resistance of Enterobacteriaceae is of great concern. The societal effects of antibiotic use justify strict monitoring to combat increases in antimicrobial resistance. Molecular epidemiology and systematic epidemiological investigation can provide accurate evidence for tracking the infection source.

The antimicrobial activity of probiotic bacteria Escherichia coli isolated from different natural sources against hemorrhagic E. coli O157:H7

Background

Diarrheal diseases have been seen in all geographical areas throughout the world. Therefore, considering treatment, could be deemed a necessary action.

Objective

The aim of this study was to determine the antimicrobial effect of probiotic bacterial strains isolated from different natural sources against 2 pathotypes of pathogenic E. coli.

Methods

This cross-sectional study of Martyr Chamran University of Ahvaz was carried out from December 2013 to July 2014. A total of 13 probiotic colonies isolated from 20 samples of traditional dairy products including (yogurt, cheese, milk) and 20 samples of vegetables including carrots and cabbages (red and white) of which 5 isolates were selected to evaluate the antimicrobial effect against 2 Escherichia coli pathotypes, randomly. Antimicrobial effect was evaluated using two methods: disk diffusion and well diffusion tests and measuring growth inhibition zones of probiotics against 2 pathotypes of pathogenic E. coli.

Results

Obtained results showed growth inhibition effects of all 5 probiotic strains against Escherichia coli pathotypes in both used methods. All selected strains showed considerable antimicrobial effect on Escherichia coli O157:H7 strain, but had no inhibitory effect against Enterohemorrhagic Escherichia coli.

Conclusion

This study demonstrated considerable antimicrobial effect against E. coli O157:H7 strain. Due to this, characteristic and similar antimicrobial effects of probiotics bacteria, increasing use of the probiotics as a natural and modern method for prevention of different diseases is recommended.

CS21 positive multidrug-resistant ETEC clinical isolates from children with diarrhea are associated with self-aggregation, and adherence

BACKGROUND

Enterotoxigenic Escherichia coli (ETEC) colonize the human intestinal mucosa using pili and non-pili colonization factors (CFs). CS21 (also designated Longus) is one of the most prevalent CFs encoded by a 14 kb lng DNA cluster located in a virulence plasmid of ETEC; yet limited information is available on the prevalence of CS21 positive ETEC isolates in different countries. The aim of this study was to evaluate the prevalence of CS21 among ETEC clinical isolates from Mexican and Bangladeshi children under 5 years old with diarrhea and to determine the phenotypic and genotypic features of these isolates.

METHODS

ETEC clinical isolates positive to lngA gene were characterized by genotype, multidrug-resistance, self-aggregation, biofilm formation, and adherence to HT-29 cell line.

RESULTS

A collection of 303 E. coli clinical isolates were analyzed, the 81.51% (247/303) were identified as ETEC, 30.76% (76/247) were st (+)/lt (+), and 25.10% (62/247) were positive for the lngA gene. Among the lngA (+) ETECs identified, 50% of isolates (31/62) were positive for LngA protein. The most frequent serotype was O128ac:H12 found in 19.35% (12/62) of lngA (+) ETEC studied. Multidrug-resistance (MDR) lngA (+) ETEC isolates was identified in 65% (39/60), self-aggregation in 48.38% (30/62), and biofilm formation in 83.87% (52/62). ETEC lngA (+) isolates were able to adhere to HT-29 cells at different levels. Two lngA isogenic mutants were constructed in the ETEC E9034A and ETEC73332 clinical isolate, showing a 77% and 98% reduction in adherence, respectively with respect to the wild type.

CONCLUSION

ETEC isolates that have the lngA gene showed features associated with self-aggregation, and adherence to HT-29 cells, important characteristics in the human gut colonization process and pathogenesis.