Antibiotics In Food Production Research Articles

The Fate of Bacteriophages in Recirculating Aquaculture Systems (RAS)—Towards Developing Phage Therapy for RAS

Aquaculture production has increased tremendously during the last decades, and new techniques have been developed, e.g., recirculating aquaculture systems (RAS). In RAS, the majority of water volume is circulated via mechanical and biological filters and reused in the tanks. However, the prevention and treatment of diseases in these systems are challenging, as the pathogens spread throughout the system, and the addition of chemicals and antibiotics disrupts the microbiome of the biofilters. The increasing antibiotic resistance has made phage therapy a relevant alternative for antibiotics in food production. Indeed, as host-specific and self-replicating agent they might be optimal for targeted pathogen eradication in RAS. We tested the survival and spread of Flavobacterium columnare -infecting phage FCL-2 in recirculating aquaculture fish farm with rainbow trout (Oncorhynchus mykiss) in a fully controlled study. After a single addition, phage persisted in water samples collected from tank, fixed bed, moving bed, and aeration unit up to 14 days, and in the water of rearing tanks, rainbow trout mucus, and bioreactor carrier media from the fixed and moving bed biofilters for 21 days. Furthermore, phage adsorbed preferentially to moving bed carrier media, which contained biofilm attached and from which higher phage numbers were recovered. This study shows phages as a potent strategy for maintaining biosecurity in RAS systems.

The impact of antibiotic exposure in water and zebrafish gut microbiomes: A 16S rRNA gene-based metagenomic analysis

In order to supply human demand for food, the aquaculture industry has been growing fast in the last years, being fish usually cultivated in overcrowded conditions. Hence, to prevent the rapidly disease spreading, antibiotics may be applied to both sick and healthy animals. Due to its broad spectrum, oxytetracycline (OTC) is one of the most used antibiotics in food-production. Yet, although useful to prevent infections, antibiotics may reshape aquatic animals' microbiome, disturbing hosts’ welfare. However, the impact of this exposure to the organism microbiome and its surrounding environment is poorly understood. Then, the objective of this study was to analyze in detail the long-term effect of OTC in both zebrafish gut and water microbiomes. Zebrafish adults were exposed, via water, for two months to three concentrations of OTC (0, 10 and 10000 μg/L). Total DNA was extracted from gut and water samples and the V3–V4 region of the bacterial 16 S rRNA gene was sequenced using Illumina technology. Results of alpha and beta-diversity analyses revealed that long-term exposure to OTC impacted both zebrafish gut and water microbiomes. In water samples, effects were observed even at the lowest (10 μg/L) OTC concentration tested resulting in an increase in Deltaproteobacteria, namely the Myxococcales and Bdellovibrionales orders. On the other hand, effects on zebrafish gut were only observed at the highest concentration with the selection of Alphaproteobacteria and Actinobacteria classes. Although these classes are common in fish gut, the increase of Actinobacteria may represent a health problem since some genera like Gordonia are linked to some human infection disease. Nevertheless, in both gut and water, it was observed a decrease in Gamaproteobacteria, probably due to OTC mode of action. In silico functional metagenomic analysis revealed that OTC exposure selected general detoxification mechanisms. In addition, the abundance of functional genes involved in Quorum Sensing (QS) increased under OTC exposure suggesting that QS may help bacteria to survive OTC stress. Thus, future studies should consider post-exposure scenarios for a deeper analysis of the water and zebrafish gut resistome, since bacteria may react differently after exposure ceased.

Erythromycin-resistant lactic acid bacteria in the healthy gut of vegans, ovo-lacto vegetarians and omnivores.

Diet can affect the diversity and composition of gut microbiota. Usage of antibiotics in food production and in human or veterinary medicine has resulted in the emergence of commensal antibiotic resistant bacteria in the human gut. The incidence of erythromycin-resistant lactic acid bacteria (LAB) in the feces of healthy vegans, ovo-lacto vegetarians and omnivores was analyzed. Overall, 155 LAB were isolated and characterized for their phenotypic and genotypic resistance to erythromycin. The isolates belonged to 11 different species within the Enterococcus and Streptococcus genera. Enterococcus faecium was the dominant species in isolates from all the dietary categories. Only 97 out of 155 isolates were resistant to erythromycin after Minimum Inhibitory Concentration (MIC) determination; among them, 19 isolates (7 from vegans, 4 from ovo-lacto vegetarians and 8 from omnivores) carried the erm(B) gene. The copresence of erm(B) and erm(A) genes was only observed in Enterococcus avium from omnivores. Moreover, the transferability of erythromycin resistance genes using multidrug-resistant (MDR) cultures selected from the three groups was assessed, and four out of six isolates were able to transfer the erm(B) gene. Overall, isolates obtained from the omnivore samples showed resistance to a greater number of antibiotics and carried more tested antibiotic resistance genes compared to the isolates from ovo-lacto vegetarians and vegans. In conclusion, our results show that diet does not significantly affect the occurrence of erythromycin-resistant bacteria and that commensal strains may act as a reservoir of antibiotic resistance (AR) genes and as a source of antibiotic resistance spreading.

Pharming animals: a global history of antibiotics in food production (1935\u20132017)

Since their advent during the 1930s, antibiotics have not only had a dramatic impact on human medicine, but also on food production. On farms, whaling and fishing fleets as well as in processing plants and aquaculture operations, antibiotics were used to treat and prevent disease, increase feed conversion, and preserve food. Their rapid diffusion into nearly all areas of food production and processing was initially viewed as a story of progress on both sides of the Iron Curtain. However, from the mid-1950s onwards, agricultural antibiotic use also triggered increasing conflicts about drug residues and antimicrobial resistance (AMR). Significantly, antibiotic concerns did not develop evenly but instead gave rise to an international patchwork of different regulatory approaches. During a time of growing concerns about AMR and a post-antibiotic age, this article reconstructs the origins, global proliferation, and international regulation of agricultural antibiotics. It argues that policymakers need to remember the long history of regulatory failures that has resulted in current antibiotic infrastructures. For effective international stewardship to develop, it is necessary to address the economic dependencies, deep-rooted notions of development, and fragmented cultural understandings of risk, which all contribute to drive global antibiotic consumption and AMR.

Potential for Bacteriophage Endolysins to Supplement or Replace Antibiotics in Food Production and Clinical Care.

There is growing concern about the emergence of bacterial strains showing resistance to all classes of antibiotics commonly used in human medicine. Despite the broad range of available antibiotics, bacterial resistance has been identified for every antimicrobial drug developed to date. Alarmingly, there is also an increasing prevalence of multidrug-resistant bacterial strains, rendering some patients effectively untreatable. Therefore, there is an urgent need to develop alternatives to conventional antibiotics for use in the treatment of both humans and food-producing animals. Bacteriophage-encoded lytic enzymes (endolysins), which degrade the cell wall of the bacterial host to release progeny virions, are potential alternatives to antibiotics. Preliminary studies show that endolysins can disrupt the cell wall when applied exogenously, though this has so far proven more effective in Gram-positive bacteria compared with Gram-negative bacteria. Their potential for development is furthered by the prospect of bioengineering, and aided by the modular domain structure of many endolysins, which separates the binding and catalytic activities into distinct subunits. These subunits can be rearranged to create novel, chimeric enzymes with optimized functionality. Furthermore, there is evidence that the development of resistance to these enzymes may be more difficult compared with conventional antibiotics due to their targeting of highly conserved bonds.

Opportunities and prospects biosensor technologies for food analysis

Existing developments in the field of biosensor technologies with the possibility of practical application for establishing food safety indicators were considered. The classification of biosensors is described depending on the physical phenomena underlying its work, the essence and examples of specific developments for the determination of microorganisms, heavy metals and antibiotics in food products are presented. Prospects of biosensor technologies in the food industry are estimated.

Antibiotic susceptibility, plasmid isolation and curing of some foodborne pathogens

The indiscriminate use of antibiotics by individuals as well as in food production has been tagged one of the major reasons for the spread of antibiotic resistance in pathogens. Thus, there is a concern that foodborne bacteria may act as reservoirs of antibiotic resistance genes when distributed in large doses with food. This study aimed at determining the antibiotic susceptibility, plasmid isolation and curing of foodborne bacteria isolated from ready to eat (RTE) foods and salads in eating centers at the Benson Idahosa University, Benin City. Isolates were Enterobacter aerogenes, Escherichia coli, Staphylococcus aureus, Bacillus spp., Micrococcus sp. and Salmonella sp with S. aureus occurring most frequently. Total resistance to cefuroxime and augmentin as well as considerable resistance to ceftazidime and cefixime were observed in all isolates in antimicrobial susceptibility tests were done on Mueller-Hinton agar. Relative sensitivity to gentamicin, ofloxacin, nitrofurantoin and ciprofloxacin were observed. Plasmid profiling indicated that all isolates possess plasmids ranging from 100 bp to 1 kbp. Plasmid curing using sodium dodecyl sulfate (SDS) improved the sensitivity of isolates to antibiotics they were previously sensitive to but most isolates remained resistance to ceftazidime, cefuroxime, cefixime, and augmentin. This study shows that foodborne bacteria can possess and possibly transfer persistent antibiotic resistance plasmids thus calling for more caution in the use of antibiotics in food production and reduced antibiotics abuse. Further research is currently ongoing to cure the isolates of all plasmids and to elucidate how these plasmids are being transferred.

Methods for the separation, preconcentration, and determination of tetracycline antibiotics

The data published in the last five years concerning the determination of tetracycline antibiotics in different samples are generalized. Sample preparation procedures for real samples, including liquid extraction from solid matrices, pressurized liquid extraction, matrix solid-phase dispersion, QuEChERS method, and solid-phase extraction, are compared. The following important determination techniques are discussed: chromatographic, electrophoretic, spectroscopic, and electrochemical. The determination of the above antibiotics in food products, feed, environmental samples, pharmaceuticals, and biological fluids is exemplified.

THE EFFECT OF PHYTOSANITARY MEASURES AGAINST FIRE BLIGHT IN INFECTED APPLE ORCHARDS

Fire blight causes enormous losses in pome fruit production worldwide. Due to the lack of resistance against its causative agent Erwinia amylovora, fruit growers appear defenseless against this bacteriosis. Since the usage of antibiotics in food production is undesirable and there is no approved substance with the same efficiency as streptomycin available, phytosanitary measures were tested for effectiveness against fire blight in apple orchards in Switzerland. Pathogen abundance was monitored by taking samples from different tissue followed by real-time PCR-based quantification throughout the years 2008 to 2011. Examinations were conducted in orchards which applied or did not apply phytosanitary control measures. Conclusions from these examinations could be used to modify recommendations for good cultural practices and, as consequence, to help reducing the pathogen load in the orchards without using antibiotics or other control agents.

Simple colorimetric detection of doxycycline and oxytetracycline using unmodified gold nanoparticles

The interaction between tetracycline antibiotics and gold nanoparticles was studied. With citrate-coated gold nanoparticles as colorimetric probe, a simple and rapid detection method for doxycycline and oxytetracycline has been developed. This method relies on the distance-dependent optical properties of gold nanoparticles. In weakly acidic buffer medium, doxycycline and oxytetracycline could rapidly induce the aggregation of gold nanoparticles, resulting in red-to-blue (or purple) colour change. The experimental parameters were optimized with regard to pH, the concentration of the gold nanoparticles and the reaction time. Under optimal experimental conditions, the linear range of the colorimetric sensor for doxycycline/oxytetracycline was 0.06–0.66 and 0.59–8.85 μg mL−1, respectively. The corresponding limit of detection for doxycycline and oxytetracycline was 0.0086 and 0.0838 μg mL−1, respectively. This assay was sensitive, selective, simple and readily used to detect tetracycline antibiotics in food products.

Aptasensor for ampicillin using gold nanoparticle based dual fluorescence–colorimetric methods

A gold nanoparticle based dual fluorescence-colorimetric method was developed as an aptasensor to detect ampicillin using its single-stranded DNA (ssDNA) aptamer, which was discovered by a magnetic bead-based SELEX technique. The selected aptamers, AMP4 (5'-CACGGCATGGTGGGCGTCGTG-3'), AMP17 (5'-GCGGGCGGTTGTATAGCGG-3'), and AMP18 (5'-TTAGTTGGGGTTCAGTTGG-3'), were confirmed to have high sensitivity and specificity to ampicillin (K(d), AMP7 = 9.4 nM, AMP17 = 13.4 nM, and AMP18 = 9.8 nM, respectively). The 5'-fluorescein amidite (FAM)-modified aptamer was used as a dual probe for observing fluorescence differences and color changes simultaneously. The lower limits of detection for this dual method were a 2 ng/mL by fluorescence and a 10 ng/mL by colorimetry for ampicillin in the milk as well as in distilled water. Because these detection limits were below the maximum residue limit of ampicillin, this aptasensor was sensitive enough to detect antibiotics in food products, such as milk and animal tissues. In addition, this dual aptasensor will be a more accurate method for antibiotics in food products as it concurrently uses two detection methods: fluorescence and colorimetry.

Genome-based analysis of virulence genes in a non-biofilm-forming Staphylococcus epidermidis strain (ATCC 12228).

Staphylococcus epidermidis strains are diverse in their pathogenicity; some are invasive and cause serious nosocomial infections, whereas others are non-pathogenic commensal organisms. To analyse the implications of different virulence factors in Staphylococcus epidermidis infections, the complete genome of Staphylococcus epidermidis strain ATCC 12228, a non-biofilm forming, non-infection associated strain used for detection of residual antibiotics in food products, was sequenced. This strain showed low virulence by mouse and rat experimental infections. The genome consists of a single 2499 279 bp chromosome and six plasmids. The chromosomal G + C content is 32.1% and 2419 protein coding sequences (CDS) are predicted, among which 230 are putative novel genes. Compared to the virulence factors in Staphylococcus aureus, aside from delta-haemolysin and beta-haemolysin, other toxin genes were not found. In contrast, the majority of adhesin genes are intact in ATCC 12228. Most strikingly, the ica operon coding for the enzymes synthesizing interbacterial cellular polysaccharide is missing in ATCC 12228 and rearrangements of adjacent genes are shown. No mec genes, IS256, IS257, were found in ATCC 12228. It is suggested that the absence of the ica operon is a genetic marker in commensal Staphylococcus epidermidis strains which are less likely to become invasive.

Occurrence of glycopeptide resistance among Enterococcus faecium isolates from conventional and ecological poultry farms.

Occurrence of glycopeptide resistance among Enterococcus faecium isolates from conventional and ecological poultry farms.

Analysis of veterinary residues in foods

Increasing world population, and particularly the urbanisation of that population, has meant that efforts are constantly being made to increase food production. This enhanced productivity, especially using intensive rearing practices as in poultry, eggs and veal production, has been accompanied by, and in many cases made possible by, the use of chemicals (Fig. 1). These may take the form of drugs to prevent or cure disease, feed additives or chemical implantation for growth promotion, tranquillisers to reduce stress before slaughter and oestrous-synchronising agents to control breeding or milk production. Consequently, worries have arisen about chemical residues in food and their possible toxic effects. The problem was addressed as early as 1969 in the U.K. with the publication of the Swann report’ in which the use of antibiotics in food production was investigated following fears of bacterial resistance building up in the animal’s gut flora possibly passing antibiotic resistance onto bacteria either indigenous to man or, perhaps more importantly, pathogenic to man. Also, antibiotic residues present in animal products could result in hypersensitivity in some people, and the development of a reservoir of antibiotic resistance in man’s natural bacterial flora. Many countries now have laws governing the use of veterinary drugs and drug residues in foods. Regulations vary from country to country reflecting differences in disease patterns and animal husbandry practices. A recent report2 of a joint FAO/WHO expert consultation on veterinary drug residues stresses the need for the establishment of internationally agreed maximum residue limits (MRLs) so that food products are not excluded from world markets. Commodities for which MRLs are needed must be identified and agreements on the residue data for establishing MRLs made. Further problems include the difficulty of identification of drug residues and their metabolites in animal tissues, their quantitation at levels well below the MRLs, and the need to establish and control withdrawal periods before slaughter. Drug residues can occur in all edible products of treated animals and analytical methods must be able to cope with different levels of fat and other interfering compounds which may be present. Recent pharmacokinetic studies2 have shown that a rapid initial fall in applied drug concentration is followed by a much slower phase of depletion, emphasizing the importance of withdrawal periods and the need for extremely sensitive and selective techniques for the identification and quantitation of residues. Two types of analytical approach are required. The first, the most cost effective, consists of rapid screening techniques for presumptive evidence of the nature and levels of substances present. Screening methods should be amenable to both multiresidue analysis and use outside the laboratory. Unequivocal identification and quantitation of suspected positive samples using more expensive instrumental techniques forms the second approach.