مقالات پذیرفته شده در هشتمین کنگره بین المللی زیست پزشکی
Gastrointestinal Infections Induced by Escherichia coli
Gastrointestinal Infections Induced by Escherichia coli
Mojtaba Asadi,1,*
1. MSc in Bacteriology, Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran.
Introduction: Escherichia coli (E. coli) is a gram-negative bacterium belonging to the Enterobacteriaceae family and is a natural inhabitant of the gut microbiota in humans and animals. Unlike many other bacterial species, E. coli can thrive in oxygen-rich environments that may be detrimental to other microorganisms. While the majority of E. coli strains are benign, certain pathogenic variants can cause severe foodborne illnesses. Gastrointestinal infections attributed to E. coli rank among the foremost causes of infectious diseases globally, often leading to serious gastrointestinal manifestations such as diarrhea, abdominal discomfort, and, in severe cases, life-threatening complications. Notable pathogenic strains include E. coli O157:H7, enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli (STEC), and enterohemorrhagic E. coli (EHEC). This study aims to explore the pathogenic mechanisms, virulence factors, clinical manifestations, diagnostic techniques, and preventive measures associated with gastrointestinal infections caused by this bacterium.
Methods: To conduct this study, reputable scientific databases, including PubMed and Google Scholar, were utilized to collect pertinent information regarding gastrointestinal infections caused by E. coli. Keywords such as "E. coli gastrointestinal infection," "human bacterial gastroenteritis," "diarrheagenic E. coli," and "E. coli pathotypes" were employed in the search. The selected literature focused on the pathogenic mechanisms of E. coli strains that cause gastroenteritis, diagnostic laboratory methods, and clinical symptomatology. The information obtained was systematically analyzed and summarized. In the referenced studies, samples were cultured on various growth media, including MacConkey Agar, and subsequently subjected to biochemical testing (IMVIC). Positive E. coli isolates underwent molecular analysis through PCR and electrophoresis for pathotype identification.
Results: The findings indicate that gastroenteritis caused by E. coli can result from the consumption of contaminated food and water, interpersonal transmission, or contact with infected animals. Inadequate personal and environmental hygiene significantly elevates the risk of these infections, representing a serious public health concern due to the potential for inflammation of the gastrointestinal tract. Accurate diagnosis of E. coli-induced gastrointestinal infections relies on the precise identification of bacterial strains and the virulence genes associated with their respective pathotypes. For instance, the EPEC pathotype is distinguished by the presence of the intimin gene (eae), while STEC is characterized by the stx1 and stx2 virulence genes. EHEC encompasses both intimin and Shiga toxin genes. Based on these characteristics, specific primers targeting these virulence genes have been developed for pathotype identification through PCR testing. The pathogenicity of virulent E. coli strains, such as EPEC and ETEC, begins with their adhesion to the intestinal mucosal surface via pili or fimbriae. Toxins produced by ETEC, including heat-stable and heat-labile toxins, increase the levels of cyclic AMP or GMP in epithelial cells, resulting in fluid and electrolyte loss and subsequently causing watery diarrhea. In contrast, EPEC facilitates the uptake of proteins into host cells, leading to adherence lesions and damaging microvilli, thus disrupting nutrient absorption. Furthermore, Shiga toxin produced by STEC inflicts damage on intestinal cells and stimulates immune responses, which can manifest as diarrhea, vomiting, fever, abdominal pain, and dehydration. Symptoms associated with E. coli-related gastroenteritis include fever, vomiting, bloody diarrhea, and intense abdominal cramps, with severe cases potentially leading to life-threatening complications. Prompt and appropriate medical intervention is essential.
Conclusion: Gastrointestinal infections caused by E. coli pose a significant threat to public health. Given the increasing incidence of these infections and the rising antibiotic resistance observed, there is an urgent need for early diagnosis, appropriate treatment, and the use of targeted antibiotics based on sensitivity testing (disk diffusion), in addition to effective preventive strategies. Implementing these measures is crucial to minimize the complications associated with this disease and to protect public health.