Bacillus stearothermophilus Disk Assay for Determining Ampicillin Residues in Fish Muscle

Abstract

The Bacillus stearothermophilus disk assay for penicillin in milk (AOAC official method) was adapted for the determination of ampicillin in fish muscle. The method was evaluated in 2 species of cultured fish: channel catfish and striped bass. Recoveries of ampicillin ranged from 99 to 104% when muscle specimens from both species were spiked at concentrations of 0.025-1.00 μg/g. The lower limit of determination (LOD) was 0.025 μg/g. The assay was applied to monitor the elimination of ampicillin from the muscle of striped bass after intravascular administration (dosage of 10 mg/kg body weight). The mean concentrations in the muscle declined from 1.160 μg/g at 2 h to 0.063 μg/g at 18 h. The half-life of ampicillin in the muscle was 3.6 h. Ampicillin concentrations were below LOD at 24 h. No inhibitory activity was observed in the muscle of control fish.

Application and evaluation of a high-resolution mass spectrometry screening method for veterinary drug residues in incurred fish and imported aquaculture samples

“…), but these compounds were not observed. The levels of AMP found in fish at these time points are consistent with a previous study where AMP was detected after 18 h at 63 μg/kg after IV dosing striped bass (10 mg/kg) [33].…”

“…Analogs of penicillin are difficult to analyze at residue levels due to their high polarity and instability. Although these drugs are not approved for use in aquaculture in the USA, there is some concern they may be used for control of infection in farmed fish [15, 30–33]. AMOX is approved for use in fish in other countries.…”