Molecular Investigation of colibacillosis in Newborn Calves with Diarrhea in Kerman City

Background and Objectives: Escherichia coli is among the common bacterial enteric pathogens with potency of causing intestinal diseases. Several classes of diarrhea-causing E. coli are now identified on the basis of production of virulence factors. Enterotoxigenic E. coli strains (ETEC) infection are the most common type of colibacillosis of newborn calves. Bovine enteric colibacillosis is an economically important disease in neonatal calves caused by enterotoxigenic Escherichia coli (ETEC). The key virulence factors of ETEC in diarrhea are enterotoxins and fimbrial adhesins. Fimbrial adhesins interpose attachment of bacteria to the surface of host epithelium cells and beginning of bacterial colonization ETEC strains that produce K99 (F5) and F41 fimbria are the most commonly associated with diarrhea in calve diarrhea. Heat-labile (LT) and heat-stable (STa, STb), rupture intestinal fluid homeostasis and cause fluid hyper secretion that results in diarrhea. This disease makes death ranging from first several hours until three weeks after birth. The aim of current study was to investigate the prevalence of calf colibacillosis in new born calves in Kerman city by PCR. Materials and Methods:A total of 155 diarrheic neonatal calves at 1–30 days of age were studied during one year (Feacal sample from 107 diarrhoeic newborn calve and 48 samples of non-diarrheal calves). They were isolated from less than one-month old calves from farms located near to Kerman city. Briefly, fecal samples were collected from each calve, transported to the microbiology laboratory on ice and processed on the same day. Then, sub cultured on Mac Conky, and EMB (Eosin methylene blue) agar plates and incubated at 37 oC for 24 hr. STa ‚F5 and F41 fimbriae genes of isolated E. coli were detected by multiplex PCR. Results : E. coli was isolated from 78 diarrheic samples, 24 of which being positive for the above virulence factors (15 of them had STa and K99 genes, and 3 of them had STa, K99 and F41 genes and 3 of them K99 gene, 2 of which consisted of STa gene and 1 sample had only F41 gene). From 48 non-diarrheic samples, E. coli was isolated from all samples and 10 samples were positive for virulence factor genes.(8 sample had STa,K99 gene and 2 sample only had STa gene). Conclusion: Enterotoxigenic, E. coli strains has an important role in the pathogenesis of diarrhea in newborn calves in Kerman.