Source identification and entry pathways of banned antibiotics nitrofuran and chloramphenicol in shrimp value chain of Bangladesh

Background: Contamination with residues of banned carcinogenic antibiotic drugs like nitrofuran metabolites and chloramphenicol (CAP) in frozen shrimp products has become a major concern of food safety for exporting countries. In the present study an approach was taken to identify the sources of such harmful antibiotics in the shrimp value chain of Bangladesh, one of the major shrimp countries. Material and Methods: Inputs of farms and hatchery systems including feed, feed additives, feed ingredients and therapeutic agents were thought to be the sources of contagion. Fish and shrimp feed, feed ingredients, sediment and water samples of shrimp hatcheries and farms were, therefore, analyzed for 3-Amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), 3-Amino-2-oxazolidinone (AOZ), 1-Amino-hydantoin (AHD), Semicarbazide (SEM) and chloramphenicol (CAP) to identify their source and entry pathways. About 500 g of each 160 feed and feed ingredients were collected in pyrogens free polyethylene sealed bag and transported to Fish Inspection and Quality Control (FIQC) laboratory, Dhaka, Bangladesh. Whereas 500 mL of each 250 soils and water sample were collected from hatcheries. Sample preparation and residual metabolites analysis were conducted using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical assays on an Waters Alliance 2695 series HPLC and Quattro Micro, API mass spectrometer instrumentation (Waters Corporation, USA). Results: Among the analyzed 160 feed samples, 38 were found contaminated with CAP and/or nitrofuran metabolites (AMOZ, AOZ, A H D and SEM), where 11,10, 8, and 9 samples were for shrimp feed, fish feed, poultry feed and feed ingredients. Imported feed ingredients contained with protein concentrates of improper quality were found contaminate with higher level of SEM. Although hatcheries were found free from contamination, whereas sediment and water samples of many shrimp farms were found contaminated with high levels of SEM and CAP. Conclusions: It could be narrated that antibiotic contamination of shrimp products were the use of antibiotic contaminated feed and feed ingredients in the farms; use of poultry litter to fertilize ponds during mixed culture, because poultry were fed with antibiotic medicated feed from zero day of feeding and indiscriminate use of insecticides and pesticides at nearby agricultural farms.