Abstract
BackgroundMisuse of antibiotics in veterinary medicine has the potential to generate residues in animal derived products, which could contributing to the development of an important health risk either through the exposure to antibiotic residues or the transfer of antibiotic resistance among foodborne pathogens as well. Tetracycline (TE) and eptomycin (ST) are commonly used as antibiotics in the Egyptian animal husbandry. The objective of this study, quick detection of TE and ST in fresh local beef tissue samples using radioimmunoassay Charm II technique, isolation and identification of relevant highly resistant bacterial strains. In addition to investigating the effect of gamma radiation on the susceptibility of such resistant strains to TE and ST.ResultsTetracycline (TE) was detected in all collected samples, while ST was detected in 38.46% (5/13) and 87.5% (7/8) of meat and liver samples, respectively.Fifty-one bacterial isolates were isolated from the tested samples, among them, the highest resistant isolates to TE or ST were identified as Streptococcus thoraltensis, Proteus mirabilis (2 isolates) and E. coli (3 isolates). Among them, the highest D10-values in phosphate buffer; 0.807 and 0.480; kGy were recorded with S. thoraltensis and E. coli no.3, respectively. Such values increased to record 0.840 and 0.549 kGy, respectively after artificial inoculation into meat, indicating increased resistance to gamma radiation. Gamma radiation at dose 3 kGy increased the susceptibility of S. thoraltensis up to 50% to TE and ST, while the sensitivity of E. coli no.3 reached up 56% to both antibiotics at the same dose.ConclusionsHigh prevalence of TE in all fresh collected tissue samples suggests an extensively use of TE as antimicrobial in conventional beef production as compared to ST in the Egyptian cows’ husbandry. Moreover, irradiation of food from animal origin by gamma radiation could potentially provide protection against resistant strains. In spite of limited samples used in this study, our data could raise the concerns of public health professionals about a withdrawal period before animals slaughtering, and address the importance of gamma radiation to minimize the hazards of foodborne resistant bacteria.
Highlights
Misuse of antibiotics in veterinary medicine has the potential to generate residues in animal derived products, which could contributing to the development of an important health risk either through the exposure to antibiotic residues or the transfer of antibiotic resistance among foodborne pathogens as well
It involves the use of 3H or 14C labelled radiotracers that compete for the binding sites along with liquid scintillation counter [11, 13], where the amount of radiotracer bound to the receptor sites is counted per 1 min in Charm II scintillation counter and compared to a previously determined control point
This study aims at employing Charm II system for rapid detection of tetracycline and streptomycin in fresh local beef tissue samples, isolating and identifying the relevant highly antibiotic resistant bacteria, with attempt to increase their sensitivity to those antibiotics using gamma radiation
Summary
Misuse of antibiotics in veterinary medicine has the potential to generate residues in animal derived products, which could contributing to the development of an important health risk either through the exposure to antibiotic residues or the transfer of antibiotic resistance among foodborne pathogens as well. Tetracycline (TE) and streptomycin (ST) are widely used in veterinary medicine to treat infections, enhance animal growth and promote social development [4,5,6,7] Both are blocking bacterial protein synthesis through the inhibition of 30S ribosomal subunit, leading to bacterial death [4]. The inappropriate use of such antibiotics in animal production had led to their accumulation, at levels exceeding the relative maximum residue levels (MRLs), within animal tissues such as muscles, heart, liver, kidney [8, 9] Such high levels of antibiotic residues could exert an extreme pressure that might select for resistant pathogenic strains within human tissues upon the consumption of animal-derived food products [4, 9], posing risk to human health and livestock. It involves the use of 3H or 14C labelled radiotracers that compete for the binding sites (receptor sites) along with liquid scintillation counter [11, 13], where the amount of radiotracer bound to the receptor sites is counted per 1 min (cpm) in Charm II scintillation counter and compared to a previously determined control point (cp)
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