Residues of Oxytetracycline, Sulfamethoxazole, Sulfamethoxazole+Trimethoprim and Enrofloxacin after withdrawal time in white shrimp (Penaeus vannamei) detected by Microbial Inhibition Disc Assay versus Screening Test Kit “SAM-Test”

Abstract

Medicated feed had been given to white shrimp (Penaeus vannamei) for 7 days. Shrimp samples, collected at day-1 to day-7 after withdrawal time, were tested for antimicrobial residues by microbial inhibition disk assay (MIDA) and “SAM-Test”. The results from “SAM-Test” indicated much higher numbers of positive (antimicrobial detectable) samples than MIDA. Percentages of positive samples from oxytetracycline, sulfamethoxazole+trimethoprim and enrofloxacin treatment groups were decreased on day-3 or day-4after drug withdrawal but increased on day-5 or day-6. In one of shrimp samples from sulfamethoxazole treatment groups, residues could not be detected on day-4 to day-6 after drug withdrawal but they were detectable again on day-7. These phenomena might indicate that eating behavior of shrimp had retaken antimicrobial residues that were bound on their faeces. Therefore, it is impractical to determine the antibiotic withdrawal period in white shrimp by using withdrawal time of other aquatic animals. Further data of pharmacokinetics is critically important for determining the withdrawal time of antibiotic use in white shrimp farming.

Keywords

• Paneus vanamei
• antimicrobial residue
• microbial assay
• SAM-Test