ColibacillosisColibacillosis is caused by different strains of Escherichia coli. The disease mainly affects children and travelers. Organisms grow in gut and produce toxin. It may also invade superficial epithelium.
Epidemiology: On the basis of virulence and disease manifestations, 6 distinct groups of E. coli have been described. They are enterotoxigenic (ETEC), enteroinvasive (EIEC), enterohaemorrhagic (EHEC), enteropathogenic (EPEC), enteroaggregative (EaggEC) and diffusely adhering (DAEC) E. coli. Among EHEC, serotype 0157:H7 has emerged as a major pathogen. EPEC is an important cause of infantile diarrhoea and ETEC is the most common cause of traveler’s diarrhoea. EIEC produces an invasive dysentery type of diarrhoeal illness in humans with similar pathogenesis to Shigella.
Clinical features: Incubation period is 24-72 hours. Toxin causes hyper secretion of chloride and water in small intestine. Sudden onset of diarrhoea and/ or vomiting occurs. It is a serious infection in newborn and an important cause of traveler’s diarrhea in adults. The disease is self-limiting and takes 1-3 days for recovery.
Diagnosis: Diagnosis can be done based on isolation and identification of the b a c t e r i a a nd se r o l o gi c a l te s t l ik e in d ir e c t ha e ma g gl u ti n a t i o n . M U G (4 - methyleumbelliferyl-â-D-glucuronide) sorbitol agar is used for selective isolation of E. coli 0157:H7.Detection of virulence genes of pathogenic E. coli by PCR is a rapid and reliable technique. PCR based detection techniques have made it possible to detect genes encoding enterotoxins, cytotoxins and adhesion factors in E. coli strains.
Control and prevention: Prevention can be done by providing public health education for adopting necessary hygiene and environmental sanitary practices. Thorough cooking of food and safe drinking water are essential to check such food- borne infections.