As a notorious pathogen, V. cholerae elaborates several toxins and factors that play important roles in the organ ism’s virulence. Cholera toxin (CT) is primarily responsible for the key features of cholera (Table 1). Release of this toxin causes mucosal cells to hypersecrete water and electrolytes into the lumen of the gastrointestinal tract. The result is profuse, watery diarrhea, leading to dramatic fluid loss. The fluid loss results in severe dehydration and hypotension that, without medical intervention, frequently lead to death. This toxin-mediated disease does not require the organism to penetrate the mucosal barrier. Therefore, blood and the inflammatory cells typical of dysenteric stools are notably absent in cholera. Instead, “rice water stools,” composed of fluids and mucous flecks, are the hallmark of cholera toxin activity.

Table1. Pathogenesis and Spectrum of Diseases

V. cholerae is divided into three major subgroups; V. cholerae O1, V. cholerae O129, and V. cholerae non-O1. The somatic antigens O1 and O139 associated with the V. cholerae cell envelope are positive markers for strains capable of epidemic and pandemic spread of the disease. Strains carrying these markers almost always produce cholera toxin, whereas non-O1/non-O139 strains do not produce the toxin and hence do not produce cholera. Therefore, although these somatic antigens are not virulence factors per se, they are important virulence and epidemiologic markers that provide important information about V. cholerae isolates. The non-O1/non-O139 strains are associated with nonepidemic diarrhea and extraintestinal infections.

V. cholerae produces several other toxins and factors, but the exact role of these in disease is still uncertain (see Table 1). To effectively release toxin, the organism first must infiltrate and distribute itself along the cells lining the mucosal surface of the gastrointestinal tract. Motility and chemotaxis mediate the distribution of organisms, and mucinase production allows penetration of the mucous layer. Toxin coregulated pili (TCP) provide the means by which bacilli attach to mucosal cells for release of cholera toxin.

Depending on the species, other vibrios are variably involved in three types of infection: gastroenteritis, wound infections, and bacteremia. Although some of these organisms have not been definitively associated with human infections, others, such as Vibrio vulnificus, are known to cause fatal septicemia, especially in patients suffering from an underlying liver disease.

Aeromonas spp. are similar to Vibrio spp. in terms of the types of infections they cause. Although these organisms can cause gastroenteritis, most frequently in children, their role in intestinal infections is not always clear. Therefore, the significance of their isolation in stool specimens should be interpreted with caution. Severe watery diarrhea has been associated with Aeromonas strains that produce a heat-labile enterotoxin and a heat-stable enterotoxin. In addition to diarrhea, complications of infection with Aeromonas spp. include hemolytic-uremic syndrome and kidney disease.

C. violaceum is not associated with gastrointestinal infections, but acquisition of this organism by contamination of wounds can lead to fulminant, life-threatening systemic infections.

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الشؤون الدينية يضاعف نشاطه الإرشادي والعقائدي في شهر صفر

شعبة فاطمة بنت أسد تسلّم نتائج امتحانات الفصل الدراسي الثاني لطالبات المدرسة القرآنية

العتبة العباسية المقدسة تواصل أعمال تهيئة مجموعة مواكب أم البنين (عليها السلام) لخدمة زائري الأربعين

إذاعة الكفيل النسوية تطلق دورة تدريبية بعنوان (سلامة اللغة العربية)

المزيد

الآخبار الصحية

"شعور لا مفر منه" في الحياة يهدد حياة الملايين بالموت المبكر!

أعراض للخرف قد تظهر في المشي.. كيف نكتشفها؟

ماذا يحدث لسكر الدم عند شرب القهوة؟

سرطان القلب.. لماذا يعد من أندر أنواع السرطانات؟

المزيد

الآخبار التكنلوجية

صهر أردوغان يطلق منصة تواصل جديدة.. تنافس فيسبوك ؟!

غوغل تطلق "مرشد الويب" لتنظيم نتائج البحث بالذكاء الاصطناعي

بعد 20 عاما.. رصد أصغر أفعى في العالم مجددا في بربادوس !

ذكر أم أنثى؟.. دراسة تنسف الاعتقاد الشائع حول جنس المولود

المزيد

مواضيع ذات صلة

Bacterial Virulence Factors : Toxins

Laboratory Diagnosis of Vibrio, Aeromonas, Chromobacterium, and Related Organisms

Laboratory Diagnosis of Alcaligenes, Bordetella (Non-pertussis), Comamonas, and Similar Organisms

Antimicrobial Susceptibility Testing and Therapy of Rhizobium, Ochrobactrum, and Similar Organisms

Laboratory Diagnosis of Rhizobium, Ochrobactrum, and Similar Organisms

Antimicrobial Susceptibility Testing and Therapy of Pseudomonas, Burkholderia, and Similar Organisms

Chlamydia trachomatis

Mycoplasma Pneumonia

Leptospira interrogans

Laboratory Diagnosis of Pseudomonas, Burkholderia, and Similar Organisms

Pathogenesis and Spectrum of Disease of Pseudomonas, Burkholderia, and Similar Organisms

Antimicrobial Susceptibility Testing and Therapy of Acinetobacter, Stenotrophomonas, and Similar Organisms