Current Status of Multidrug Resistance of Ornithobacterium rhinotracheale from Avian Host

Abstract

Resistance of Ornithobacterium rhinotracheale (ORT) to antibiotics involves a decrease in antibiotic efficacy against the organisms. ORT causes an acute bacterial disease that affects the respiratory system of chickens. This disease results in severe issues of intensive poultry products and public health concern. Therefore, isolation, identification, investigation on antibacterial sensitivity and multidrug resistance patterns of ORT isolates were the main aims of this study. Tracheal samples (n=200) were collected from freshly dead birds with postmortem lesions of respiratory illness. ORT was isolated and identified by classical cultural and molecular methods. Antibacterial sensitivity testing of isolated organisms was carried out by disc diffusion method against seven antibacterial agents. The incidence values of ORT by cultural method were 20.0 and 3.0% from the tracheal samples of dead birds <18 and <18 days old, respectively. Out of 23 cultural positive samples, 15(65.21%) were found positive for the presence of 16S rRNA (625 bp) by PCR. The results of antibiotic sensitivity revealed that 66.6% of isolates were sensitive to amoxicillin, while 60.0 and 46.6% of isolates were sensitive to erythromycin and florfenicol, respectively. For difloxacine and doxycycline, the frequency of sensitive samples was 33.3 and 13.3%, respectively. The highest antimicrobial resistance of QRT isolates was seen against gentamycin and colistin (100%), followed by doxycycline (86.6%) and difloxacine (66.6%). In conclusion, it is very important to update the baseline resistance pattern data for this organism.