Muhammad Shahjalal Khan, Naznin Akhtar, Muhammad Ehteshamul Haque, Abanti Barua, Tasneem Chowdhury, Romel Mullick and Abu Sayeed Mohammad Mahmud
In two branches of poultry culture; small local ones and big industrial ones, tetracycline is a common antibiotic, which has been taken as a standard antibiotic in this study. 20 isolates were taken from big poultry farms like Agha Ltd and Denm Poultry. 10 isolates were taken from small local poultry farms like Rahat Poultry and Star Poultry. After collection of samples, total numbers of bacteria with and without tetracycline were counted. In both cases numerous bacterial growths were observed. The normal dose of tetracycline is 30 μg/ml which failed extremely to regulate high bacterial growth. Two dilutions (10-3 and 10-4) of sample 1, 2, 3 and 4 were taken and allowed to grow at different concentrations of tetracycline like 30,60 and 100 μg/ml, where bacterial growth was observed. High concentration of antibiotics for example, above 100 μg/ml may be harmful to humans and animals. After performing sensitivity test against other commonly used antibiotics in poultry, it was found that isolated tetracycline-resistant E. coli were 100% resistant to penicillin and erythromycin,100 sensitive to imipenem, 93.34% resistant to tetracycline, 23.03% resistant to gentamycin and 53.33% resistant to chloramphenicol. These indicated the multidrug resistant property of isolates. Subsequent agarose gel electrophoresis showed no plasmid DNA band in the gel indicating non-existence of any bacterial plasmid and also proved that the observed resistance was chromosomal gene-mediated or at least not plasmid mediated.