The Relative Change in Expression Level of Avian Pathogenic Escherichia coli -Associated Virulence Genes after Antibiotic Treatment

Abstract

This study aimed to determine which antibiotic is the most vulnerable and resistant to pathogen and to study the change of expression fold after antibiotic-treatment in compare to isolate without treatment by Reverse Transcription Quantitative Polymerase Chain Reaction RT-qPCR technique. A total of 55 samples with omphalitis symptoms in chicks in Baghdad province. These samples were cultivation, molecular analysis and antimicrobial susceptibility. Fifty isolates showed blue-black colonies on culture Eosin Methylene Blue and pink colonies on MacConkey agar and five isolates showed negative results. of Identification by PCR analysis for detection the 16S rRNA gene. The results of nucleotide sequencing were submitted in GenBank/NCBI database through accession number (OR142657.1). Antimicrobial susceptibility tested showed that the isolates were resistant to ampicillin, amikacin. Four E. coli out 50 isolate chosen for the minimum inhibitory concentration (MIC) exhibited by the ampicilin against tested E. coli bacteria, neomycin and combination of ampicillin and neomycin In particular, the result of gene expression the change in expression fold was analyzed using the Livak formula. The results showed that treatment with neomycin had a higher suppression effectiveness on the studied genes compared to ampicillin. Additionally, the combination treatment (Amp/Neo) did not exhibit a clear suppression effect on the genes, which could be attributed to the antagonistic action of ampicillin when used with neomycin.