Prevalence of tetA and other antibiotic resistance genes in multidrug-resistant gram-negative bacteria from chicken manure

Poultry manure is used as fertilizer in most parts of the world. It can harbor diverse nature of pathogenic bacteria and may be one of the active sources of resistant pathogens transmissions. Current study was planned to identify the pathogens as well as their antibiotic resistance profile being isolated from chicken’s manure. In present study total (n=60, 100%) fresh fecal samples were collected from commercial chicken’s farms of District Kohat. Samples were initially cultured on different agar media and were incubated at 37°C overnight. Further antibiotics susceptibility and characterization of resistance genes were performed for all the selected pathogens. Only (n=50, 83.3%) of the total isolates showed proper growth. Most frequent pathogens were Escherichia coli (19, 38%) followed by Salmonella (13, 26%), Klebsiella (8, 16%), Shigella (7, 14%) and Pseudomonas (3, 6%). E. coli revealed highest resistance to doxycycline (16, 84.2%), followed by ampicillin (15, 78.9%), amoxicillin (14, 73.7%) and ciprofloxacin (13, 68.5%). Salmonella showed complete resistance to doxycycline (13, 100%) and tetracycline (11, 84.6%), ciprofloxacin (5, 38.5%) and amoxicillin (4, 31.8%). Pseudomonas were completely resistance to ampicillin followed by levofloxacin (2, 66.7%) and ciprofloxacin (1, 33.3%). Klebsiella showed highly resistance to tetracycline (8, 100%), levofloxacin (6, 75%), ciprofloxacin (4, 50%) and amoxicillin (4, 50%). Shigella strains were completely resistant to doxycycline (7, 100%) and ampicillin (6, 85.7%) while showed less resistance to ciprofloxacin (3, 42.8%) and amoxicillin (2, 28.6%). In the present study, four classes of antibiotics resistance genes ( tetA, sul1, str and aadA ) were identified with different frequency. The highest frequency (100%) was found for tetA gene followed by the sul1 and str genes (66.6%) each. The lowest frequency (16.6%) was noted for ( aadA ) gene. It has been concluded that all the isolated pathogens were highly resistant to doxycycline, amoxicillin and erythromycin. To restrict the transmission of resistant pathogens in the environment, it is needed to dispose of poultry manure in proper way, to educate staff of personal hygiene and justified use of antibiotics. • It has been concluded from the current research that five distinct multidrug resistant gram-negative bacteria isolates ( E. coli, Salmonella, Klebsiella, Shigella and Pseudomonas ) were found in chicken manure. • E. coli was the most dominant isolated pathogen. • All the pathogens were highly resistant to doxycycline, amoxicillin and erythromycin while lower resistance rate were observed for ciprofloxacin and levofloxacin against the selected isolates. tetA, str, sul1 , and aadA were characterized as resistance genes. tetA was a prominent gene, detected in all isolates. • Future studies should investigate the genetic mechanisms driving resistance in these pathogens, focusing on horizontal gene transfer and mutation rates. • Additionally, integrating metagenomic approaches can help identify emerging resistance patterns, enabling more targeted and effective interventions in poultry farming.