Authors: MELİKE EKİZOĞLU, SATOSHI KOIKE, IVAN KRAPAC, MAHMUT NEDİM SULTAN, RODERICK MACKIE
Abstract: This study aimed to identify phenotypic and genotypic resistance profiles of bacteria isolated from soil and manure samples obtained from a farm where tetracycline and tylosin were used extensively. Samples were collected from the manure and soil, before and after manure application. All of the 151 bacteria were identified based on BLAST results. Minimum inhibitory concentrations were determined by agar dilution and E-test methods. Class-specific primers were used to amplify 6 erythromycin and 7 tetracycline resistance (Tc^r) genes for 46 tetracycline- and 18 erythromycin-resistant isolates. Tc^r gene sequence identity between different species of isolates was identified to investigate the dissemination of resistance genes. All of the 151 bacteria belonged to 4 different phyla: Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. The majority of the tetracycline-resistant isolates were present in Pseudomonadaceae. Twenty of the isolates, representing 14 different genera, were positive for Tc^r genes. Only 2 isolates possessed the erm(Q) gene. This study probably is the first to describe the presence of tetracycline genes in members of the genera Simplicispira and Agrococcus. Results of the study suggest that the diversity of Tc^r gene-carrying bacteria are increasing. Furthermore, tetracycline-resistant bacteria could be detected 3 months after the manure application.
Keywords: Antibiotic resistance, susceptibility, soil, swine manure, tetracycline, erythromycin
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