Antimicrobial Residues in Tissues and Eggs of Laying Hens at Chittagong, Bangladesh

Aim: Antimicrobial residue in animal food products is an important index of food safety. Antimicrobial residues could result from chemotherapeutic or chemoprophylactic use of drugs in food animals. This occurrence of residue in animal food products has received enormous worldwide attention from some local, international, and public health agencies. A crosssectional study was conducted from July to December 2009 to detect the antibiotic residues in tissues and eggs of laying hens at Chittagong of Bangladesh.

Materials and Methods: Microbial inhibition test (MIT) and thin layer chromatography (TLC) methods were used to detect antibacterial residues in poultry tissues (liver, kidney, breast, and thigh muscles) and eggs. The bacteria and pH of the MIT method were as follows: Bacillus subtilis on test agar medium with a pH of 7.2, Bacillus cereus with a pH of 6.0, and Escherichia coli at pH with an 8.0.

Results: The overall prevalence of antibiotic residues detected by MIT was 64% in liver, 63% in kidney, 56% in breast muscle, 50% in thigh muscle, and 60% in eggs. There was significant variation in results between MIT and TLC (p<0.05). Tetracycline residues were found in 48% in liver, 24% in kidneys, 20% in thigh muscles, 26% in breast muscles, and 36% in eggs. Ciprofloxacin residues were found 46% in liver, 42% in kidneys, 34% in thigh muscles, 30% in breast muscles, and 30% in eggs. Enrofloxacin residues were found 40% in livers, 36% in kidneys, 24% in thigh muscles, 20% in breast muscles, and 26% in eggs. Amoxicillin residues were found 48% in livers, 30% in kidneys, 26% in thigh muscles, 22% in breast muscles, and 24% in eggs. The most frequently detected antibiotic residues by both MIT and TLC were found in liver tissue, tetracycline (48%), ciprofloxacin (46%), enrofloxacin (40%), and amoxicillin (42%) were found in liver. Breast muscle tissue was least likely to contain antibiotic residues (24%). Tetracycline (p=0.01) and amoxicillin (p=0.03) residues had significant variation among the various poultry tissues and eggs.

Conclusions: A high percentage of tissues and eggs that could be available for human consumption had antibiotic residues. This study suggests that poultry meat and eggs should not be circulated to markets until the end of the drug's withdrawal period. It is also recommended to observe the withdrawal period of drugs before poultry slaughter or table egg distribution to avoid antimicrobial resistance and to inform both owners and consumers about the risks of antibiotic residues.