The first report of antimicrobial residues in cultured tilapia fillets in three provinces of Lao PDR
The objective of this study was to investigate antimicrobial residues in the fillets of Nile tilapia fish (n=180) from 3 provinces (Vientiane, Savannakhet Province and Champasak Province) in Lao PDR in the summer, rainy and winter seasons. Clean meat test (CMT) was used for screening the antimicrobial residue samples. Then, the antimicrobial residue groups were examined and identified by the european six-plate test (ESPT), and the concentration of each positive antimicrobial residue from the ESPT was further assessed by high-performance liquid chromatography (HPLC). The evaluation results of the three antimicrobial detection methods were 19.44% (35/180) for the CMT, 22.86% (8/35) for the ESPT and 75% (6/8) for the HPLC. The levels of enrofloxacin and ciprofloxacin residues detected by HPLC did not exceed the maximum residue limits according to the European Union standard. The highest occurrence of positive CMT results among three provinces was in Champasak Province at 26.67%. The occurrence of antimicrobial residues in the summer season was significantly higher than the rainy season (P<0.05), implying that the seasonal climate is an important factor influencing the use of antimicrobials as well as the occurrence of antimicrobial residues in the cultured tilapia fillets in Lao PDR.