Reconnaissance of 47 antibiotics and associated microbial risks in seafood sold in the United States

Abstract

Aquaculture production has nearly tripled in the last two decades, bringing with it a significant increase in the use of antibiotics. Using liquid chromatography/tandem mass spectrometry (LC-MS/MS), the presence of 47 antibiotics was investigated in U.S. purchased shrimp, salmon, catfish, trout, tilapia, and swai originating from 11 different countries. All samples (n= 27) complied with U.S. FDA regulations and five antibiotics were detected above the limits of detection: oxytetracycline (in wild shrimp, 7.7 ng/g of fresh weight; farmed tilapia, 2.7; farmed salmon, 8.6; farmed trout with spinal deformities, 3.9), 4-epioxytetracycline (farmed salmon, 4.1), sulfadimethoxine (farmed shrimp, 0.3), ormetoprim (farmed salmon, 0.5), and virginiamycin (farmed salmon marketed as antibiotic-free, 5.2). A literature review showed that sub-regulatory levels of antibiotics, as found here, can promote resistance development and publications linking aquaculture to this have increased more than 8-fold from 1991–2013. Although this study was limited in size and employed sample pooling, it represents the largest reconnaissance of antibiotics in U.S. seafood to date, providing data on previously unmonitored antibiotics and on farmed trout with spinal deformities. Results indicate low levels of antibiotic residues and general compliance with U.S. regulations. The potential for development of microbial drug resistance was identified as a key concern and research priority.

Antibiotics in early life and obesity

“…40 Meat from farmed fish also frequently have antibiotic residues detected, raising the concern that practices in aquaculture also could introduce antibiotics into the human food chain. 41 …”

Trends in Microextraction Techniques for Sample Preparation

“…Polyethylene disks, conventionally used as frits in solid phase extraction cartridges, can be also used as stirred units by simply piercing them with a metallic wire. This material is hydrophobic and it is indicated for the extraction of hydrophobic compounds [66]. The material exhibits sufficient thermal stability to allow for its mild thermal desorption in a conventional headspace vial.…”

“…The analysis was carried out using a triple quadrupole LC-MS/MS with positive electrospray ionization and MRM mode. A reverse-phased C 18 column was used for the separation of the drugs, and the mobile phase consisted of HPLC-grade water with formic acid and ammonium formate (A) and a mixture 1:1 (v:v) of methanol-acetonitrile [66].…”

Agricultural Applications for Antimicrobials. A Danger to Human Health: An Official Position Statement of the Society of Infectious Diseases Pharmacists

“…Although strict regulations in the United States and European Union theoretically limit the presence of antibiotic residuals in imported fish products, this is not always the case. A recent study of seafood purchased in the southwestern United States but originating from 11 different countries found that five antibiotics were routinely detectable in various sources including so‐called antibiotic‐free salmon . Of note, none of the antibiotics exceeded the federally determined MRL.…”