In vitro And In vivo Molecular Studies On Some Escherichia coli Serovars Isolated From Chicken.

Abstract

A total number of 16 Escherichia coli serovars were recovered from different colibacillosis diseased chicken organs. Characterization of the isolates was performed by biochemical and serological tests, biofilm formation, antimicrobial susceptibility assays, detection of virulence and antibiotic resistance genes by PCR. The biofilm formation (at OD595) of all E. coli isolates showed a similar trend. eaeA gene was detected in 3 serovars O2:H6, O26:H11 and O44:H18 while, hly gene was detected in 2 serovars O2:H6 and O144:H21. The gene encoding for stx2 was detected in 2 serovars (O55:H7 and O146:H21) while the gene encoding stx1 was not detected in any serovars. Furthermore, all serovars were carrying the encoding blaTEM. blaSHV and blaCTX were detected in 75% and 18.75% of isolates respectively, while blaOXA-1 was not detected in all serovars. Although all isolates were multi-resistant against most of B-lactams antibiotics, they were susceptible to 20 to 80 mg ml-1 of garlic extract. Finally, we demonstrated that a five-oral administration of garlic extract to baby chicks colonized with E. coli reduces the mortalities and significantly increase the body weight. The efficacy of garlic extract as the antibacterial natural product was sufficient as a bactericidal alternative against the multidrug- resistant E. coli isolates.

Keywords

• Allium sativum
• Antibiotic-resistant genes
• Biofilm
• Virulence genes