Identification and antibiotic susceptibility profiling of Escherichia Coli isolated from chicken cloacal sample in Dhaka Wet Market, Bangladesh

Abstract

"The rise of antibiotic-resistant Escherichia coli (E. coli) in poultry is a major public health concern, as these bacteria can transfer to humans, posing risks of difficult-to-treat infections. Understanding E. coli prevalence and antibiotic resistance in poultry, especially in high-density commercial farming systems, is essential for developing strategies to manage this issue. Method: A total of 60 cloacal swab samples were collected from live chickens across twelve locations in Dhaka. Samples were spread on Macconkey agar and presumptive E. coli colony was taken based on Colony morphology which was round in shape and light pink in color. These colonies were picked and further sub-cultured on UTI media for screening purposes. On HI chrome UTI media purple color colonies were suspected as E.coli. From there four isolates were collected and streaked on Nutrient agar media for DNA extraction and other molecular identification processes. After that performing Polymerase Chain Reaction (PCR) and gel electrophoresis presumptive E.coli was identified from the chicken cloacal sample. Furthermore, antibiotic susceptibility testing was also done for these positive isolates by using Kirby-Bauer disk disc diffusion method followed by CLSI guideline Results: Our study found a high prevalence of E. coli in commercial broiler chicken and backyard poultry chicken (Shonali and Desi) with an overall prevalence rate of 78.33% across sampled locations. Broiler chicken showed higher E.coli contamination which is 66%. Comparatively, native breeds (Shonali and Desi chickens) showed lower E. coli prevalence, 21% and 15% respectively. A high resistance to tetracycline (89%), ciprofloxacin (59%), Amoxicillin (44%) was observed in antibiotic susceptibility tests and lower resistance was noted for meropenem and imipenem.

Conclusion: The findings demonstrate that high-density commercial poultry farming is associated with increased E. coli prevalence and higher levels of antibiotic resistance, particularly for commonly used antibiotics like tetracycline. In contrast, indigenous breeds raised in less intensive conditions exhibit lower rates of E. coli contamination and resistance. This study highlights the need for stricter antibiotic regulations and improved farming practices to curb the spread of antibiotic-resistant E. coli in poultry "