Molecular Screening Of Virulence Genes In Avian Pathogenic Esherichia Coli

Abstract

Avian pathogenic Escherichia coli (APEC) causes colibacillosis, which is one of the main causes of economic losses in the poultry industry worldwide. This disease occurs only when the E. coli infecting strain presents virulence factors (encoded by specific genes) that enable the adhesion and proliferation in the host organism. Herin, 15 E. coli strains of different serogroups isolated from birds with colibacillosis were assigned to their phylogenetic groups and analyzed for the occurrence of 11 virulence associated genes. phylogenetic typing showed that group B2 was the largest (33.3%, 5/15) followed by group B1 (26.7%, 4/15), groups A and D were similar in size (22.1%, 19/86). The virulence profiles showed that ompA was found in most isolates 14/15 (93.3%). The iss gene was found in13/15 (86.6%). Followed by traT and iutA genes which were found in12/15 (80%). cvaC, stx2 and tsh genes were present in 9/15(60%), 7/15(46%) and of the isolates, respectively. Only one isolate gave positive amplification for stx1 and ibeA genes each. The hly gene was not encountered in any of the tested isolates.

Molecular Analysis of Escherichia coli Strains Causing Respiratory Troubles in Chickens in Egypt

“…The present study aimed to characterize APEC strains from broilers with respiratory signs, air sac lesions and variable mortalities in different broiler breeds (17-35 days old) based on serogrouping, virulence and antimicrobial resistance. Similar signs were recorded by many authors with variable mortalities and complications [7,[31][32][33].…”

“…The ColV operon consists of genes for ColV synthesis (cvaC) and ColV immunity (cvi) and two genes for ColV export (cvaA and cvaB) [72]. In the present study the prevalence of cvaC was 9% which is much lower than that recorded by Rodriguez-Siek et al [73]; McPeake et al [74]; and Abd El Tawab et al, [7] who recorded cvaC percentage 66.8% ,99.1% and 60% respectively. Our findings are similar to results recorded by Kwon et al [75] and Arabi et al [76] who detected cvaC percentage 16% and 14.2% respectively.…”

“…Similarly, in flocks at Dakahlia Governorate the serotypes O2 and O78 percentages were 35.6% and 30.5%, respectively [32]. Also O78 was the most predominant serotypes in Sharkia Governorate with percentages of 20% and 33.33% [7,10]. In this study, the percentage of O26 was (5%), O145 (5%), O44 (10%) while Eid and Erfan, [8] isolated O26:K60 (10.7%) and O145, O44 (3.6% each).…”

“…Six virulence plasmid mediated genes (tsh, iss, iucD, cvaC, fim H and ompT) are among the most genes associated with APEC strains, distinguishing them from avian fecal E. coli [4]. In Egypt, different serogroups of APEC were isolated from chicken flocks for example O1, O2, O26, O44, O78, O124, O145 and O158 [7][8][9][10][11] as well as non typeable strains [9]. ß-lactamase production confers resistance to most β-lactams [12], especially in isolates from intensive broiler productions [13].…”