Incidence of diarrhoeagenic Escherichia coli isolated from young children with diarrhoea in the west of Iran

Antibiotic resistance of enteropathogenic bacteria in a teaching hospital in North Khuzestan during a three-year period

Introduction

Gastrointestinal infections affect many people annually. The most common bacterial agents involved in these infections are enteropathogenic bacteria and in the continuation of using broad-spectrum antibiotics, Clostridium difficile-associated diarrhea is involved, especially in hospitalized patients. The aim of the present study was to investigate the pattern of antibiotic resistance among enteropathogenic bacteria.

Materials and Methods

In this cross-sectional study, 163 samples of patients with diarrhea in Dezful Ganjavian Hospital were examined. The samples were cultured in MacConkey, Hektoen enteric agar and GN broth, and cycloserine cefoxitin fructose agar media and incubated under standard conditions. In order to identify enteropathogenic bacteria, biochemical tests and serological confirmatory tests were used. Antibiotic resistance pattern of the isolates was investigated by Kirby-Bauer disk diffusion susceptibility test.

Results

The frequency of pathogenic bacteria includes 41.1% of Shigella flexneri, followed by 41.1% of S. sonnei, 6.7% of Enteropathogenic E. coli, 5.5% of Salmonella enterica Serogroup B, and 5.5% of Shigella dysenteriae. The results revealed a total of 46 patients with orders regarding C. difficile culture, no C. difficile was isolated from the samples. The studied isolates showed the highest resistance to trimethoprim-sulfamethoxazole, and ceftriaxone (88.3%), and the most effective antibiotic in the treatment of patients was ciprofloxacin with 86% sensitivity.

Conclusion

Susceptibility to antibiotics was different among the isolates, which shows that the early identification of the infection agent and the selection of the correct antibiotic treatment are effective in improving the gastrointestinal infection and preventing the spread of the infection.

Quinolone and Macrolide-Resistant Campylobacter jejuni in Pediatric Gastroenteritis Patients from Central Iran

Aims: To determine the prevalence and the antibiotic resistance patterns of Campylobacter jejuni isolated from pediatric diarrhea patients in central Iran. Materials and Methods: Stool specimens (n = 230) were investigated using a modified Gram stain, two specific culture media, and C. jejuni-specific PCR. Antibiotic resistance profiles and relevant resistance genes were determined. Genetic relationships among a selection of the isolates were studied by Fla typing. Results: Out of the 230 diarrhea samples, 48 (20.8%) cases of C. jejuni were identified using modified Gram stain, 45 (19.5%) using the culture media, and 76 (33%) cases were identified using PCR. The highest antibiotic resistance rates were observed in 37 (82.2%) strains against tetracycline, in 32 (71.1%) against ciprofloxacin, and in 31 (68.8%) against erythromycin. Twenty (44.4%) isolates were resistant to ciprofloxacin and erythromycin simultaneously. Genotypic investigations found 36 (97.3%) strains carrying the tet (o) gene, 31 (96.8%) harboring the cmeB gene, 22 (68.7%) strains with the gyrA6 gene, 20 (64.5%) strains containing a 23S rRNA mutation, and 21 (65.6%) strains with the qnrS gene. Fla typing of a random subset of 14 strains revealed 11 different types showing the genomic diversity of the isolates. Strains sharing the same Fla type could be easily distinguished by their resistance gene profile. Conclusions: This is the first study to demonstrate that genetically diverse quinolone-macrolide-resistant C. jejuni is an important cause of gastroenteritis in children from central Iran. Pediatricians should consider these resistance features once the antibiotic prescription is necessary for prevention of possible complications, especially in those under 5 years of age. Of note, most cases of Campylobacter diarrhea are self-limiting and antibiotics should only be prescribed in those cases where severe complications evolve.

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.

Diarrheagenic Escherichia coli and Shigella with High Rate of Extended-Spectrum Beta-Lactamase Production: Two Predominant Etiological Agents of Acute Diarrhea in Shiraz, Iran

This study was conducted to find the etiology of acute diarrhea in Iranian children and determine the antimicrobial resistance patterns. The pathogenic bacteria were recovered from 110/269 (40.9%) diarrheal fecal samples with the following profiles: the most predominant pathogen was diarrheagenic Escherichia coli (DEC) (43.6%), comprising enteroaggregative E. coli (23.6%), enteropathogenic E. coli (10.9%), enteroinvasive E. coli (5.5%), and enterotoxigenic E. coli (3.6%); Shigella spp. (37.3%), Salmonella spp. (12.7%) and Campylobacter jejuni (6.4%) were ranked second and fourth in terms of prevalence, respectively. The rates of extended-spectrum beta-lactamase (ESBL) production were 66.7% and 53.7% in DEC and Shigella, respectively. Resistance to ampicillin (AMP) (95.1%), trimethoprim/sulfamethoxazole (SXT) (73.2%), azithromycin (ATH) (21.9%), and ciprofloxacin (CIP) (14.6%) was observed among Shigella isolates. Multidrug resistance phenotype was observed in 24.4% (10/41) of Shigella isolates, with the most common pattern of resistance to cefotaxime, ceftriaxone, ceftazidime, AMP, SXT, and ATH. This study indicates an alarming increase in the ESBL production of DEC and Shigella spp. and identifies them as the two most prevalent diarrhea-causing enteropathogens in the region. The results show that CIP could be an alternative to third-generation cephalosporins against these two pathogens. Therefore, it is proposed that further investigation be done in the pursuit of alternative antibiotics that are effective against the resistant cases. For instance, one study could look into the comparative clinical effectiveness of third-generation cephalosporins versus CIP, the latter not being presently the drug of choice for the treatment of acute diarrhea in children in Iran.

Evaluation of Prevalence, Homology and Immunogenicity of Dispersin among Enteroaggregative Escherichia coli Isolates from Iran

Background:

Diarrhea, caused by enteroaggregative Escherichia coli (EAEC), is an important infection leading toillness and death. Numerous virulent factors have been described in EAEC. However, their prevalence was highly variable among EAECs of distinct geographic locations. Studies have shown that dispersin (antiaggregation protein, aap) is one of the important and abundant virulent factors in EAEC. In this study, we aimed to determine the presence, conservation, and immunogenicity of aap gene in EAEC isolated from Iranian patients.

Methods:

PCR amplification of aap gene in the EAEC isolates was performed, and the aap gene was cloned in pBAD-gIIIA vector. The sequence of aap gene was analyzed using the ExPASy and BLAST tools. The expression of aap gene was performed in E. coli Top10, and expression confirmation was carried out by SDS-PAGE and Western-blot techniques. Rabbits were immunized with purified dispersin protein emulsified with Freund’s adjuvant. Sera were collected and examined for antibody response. Finally, invitro efficacy of dispersin and anti-dispersin was evaluated.

Results:

The results of PCR showed the presence of aap gene in all of the EAEC isolates with significant homology. Finally, the significant difference between the levels of IgG response in dispersin-injected rabbits and control group was observed.

Conclusion:

Our results were in accordance with other studies that reported the presence of dispersin in the EAEC isolates with high conservation and immunogenicity. Hence, dispersin could be a promising candidate for any probable prevention against EAEC infections.

Expression of enteropathogenic Escherichia coli map is significantly different than that of other type III secreted effectors in vivo

The enteropathogenic Escherichia coli (EPEC) locus of enterocyte effacement (LEE)-encoded effectors EspF and Map are multifunctional and have an impact on the tight junction barrier while the non-LEE-encoded proteins NleH1 and NleH2 possess significant anti-inflammatory activity. In order to address the temporal expression of these important genes in vivo, their promoters were cloned upstream of the luxCDABE operon, and luciferase expression was measured in EPEC-infected mice by bioluminescence using an in vivo imaging system (IVIS). Bioluminescent images of living mice, of excised whole intestines, and of whole intestines longitudinally opened and washed were assessed. The majority of bioluminescent bacteria localized in the cecum by 3 h postinfection, indicating that the cecum is not only a major colonization site of EPEC but also a site of EPEC effector gene expression in mice. espF, nleH1, and nleH2 were abundantly expressed over the course of infection. In contrast, map expression was suppressed at 2 days postinfection, and at 4 days postinfection it was totally abolished. After 2 to 4 days postinfection, when map is suppressed, EPEC colonization is significantly reduced, indicating that map may be one of the factors required to maintain EPEC colonization. This was confirmed in a competitive colonization study and in two models of chronic infection, repeated exposure to ketamine and Citrobacter rodentium infection. Our data suggest that map expression contributes to the maintenance of EPEC colonization.

Animal models of enteroaggregative Escherichia coli infection

Enteroaggregative Escherichia coli (EAEC) has been acknowledged as an emerging cause of gastroenteritis worldwide for over two decades. Epidemiologists are revealing the role of EAEC in diarrheal outbreaks as a more common occurrence than ever suggested before. EAEC induced diarrhea is most commonly associated with travelers, children and immunocompromised individuals however its afflictions are not limited to any particular demographic. Many attributes have been discovered and characterized surrounding the capability of EAEC to provoke a potent pro-inflammatory immune response, however cellular and molecular mechanisms underlying initiation, progression and outcomes are largely unknown. This limited understanding can be attributed to heterogeneity in strains and the lack of adequate animal models. This review aims to summarize current knowledge about EAEC etiology, pathogenesis and clinical manifestation. Additionally, current animal models and their limitations will be discussed along with the value of applying systems-wide approaches such as computational modeling to study host-EAEC interactions.