Isolation and host range analysis of bacteriophages against XDR Extraintestinal Pathogenic Escherichia coli isolates from broiler chickens with Colibacillosis

BACKGROUND AND ABJECTIVEColibacillosis is an infectious disease that has a significant economic impact on poultry breeders worldwide. This contagious illness is brought on by the specific extra-intestinal pathogenic E. coli (ExPEC) known as avian pathogenic E. coli (APEC). Due to its zoonotic potential and high antibiotic resistance pattern, this bacteria is one of the most troublesome bacterial species. This research aimed to identify bacteriophages specific to multidrug-resistant (MDR) and extensively drug-resistant (XDR) APEC isolates and evaluate the lysis capability of isolated phages.MATERIALS AND METHODSIn this study, ۱۹۶ samples were collected from poultry with Colibacillosis and chicken farms in East Azerbaijan province between June and September ۲۰۲۲. One hundred different APEC isolates were obtained from feces samples, internal organs of chicken carcasses, and food samples. Biochemical tests were performed for initial identification, and then final confirmation was performed by ۱۶s rRNA, iucD, papC, and fimC gene amplifications. Antibiotic susceptibility test evaluated by disc diffusion method. ۵ XDR and ۵ MDR isolates were used as hosts for bacteriophage isolation. Ssewage water samples were collected from Maragheh and Tabriz City, East Azerbaijan, Iran. Phage isolation was performed by Pallavali et al. method. Then, the Adams soft agar method was used to detect of desired phages. Also, phage purification was performed by Sambrook et al. method (with ۳-time repetition). Finally, the host range of purified phages was determined by spot test.RESULTS AND DISCUSSIONAntibiotic susceptibility tests indicated that ۵ strains were XDR, ۸۷ were MDR, and ۸ could not classify into any drug resistance relative groups. The Prevalence frequency of papC, iucD, and fimC virulence factors were ۱۷%, ۶۶%, and ۷۷% respectively. Most APEC strains use fimC, and iucD products, as virulence factors. Thus, fimC and iucD products can be suitable ۱۲۸for vaccine and anti-virulence targets. Totally ۲۰ different phages were isolated, and the host range of phages was between ۴% (effective on only ۱ strain) and ۵۶% (effective on ۱۴ strains). The host range of phages is one of the essential characteristics of these viruses to be chosen as a potential therapeutic agent. However, there is no comprehensive definition for broad-spectrum phages until now. Therefore, viruses with a broader spectrum are usually selected for further experiments in similar studies. Our study determined the phage with lytic activity against ۵۶% of strains as a broad spectrum. In contrast, in similar studies, phages with a spectrum of ۶۰%, ۴۰%, and even ۵% have been selected as broad-spectrum bacteriophages.CONCLUSIONIn summary, the high frequency of MDR drug resistance in APEC isolates with the highest resistance to tetracycline, nalidixic acid, and doxycycline was founded in this study. Additionally, lytic bacteriophages were isolated, and the spectrum of each phage was determined. However, further studies are needed to investigate the presence of different microbial resistance genes and other virulence factors in APEC isolates. It is also suggested to continue sampling wastewater to obtain bacteriophages with a broader spectrum. Overall, bacteriophages can be used to combat antibiotic-resistant bacteria. However, further studies are necessary to quantify the spectrum of the isolated phages and evaluate other characteristics of these phages.

کلیدواژه ها:

Antimicrobial resistance ، Extra-intestinal pathogenic E. coli ، Bacteriophage ، Phage therapy