Screening methods and recent developments in the detection of anticoccidials

Comprehensive Screening of Salinomycin in Feed and Its Residues in Poultry Tissues Using Microbial Inhibition Tests Coupled to Enzyme-Linked Immunosorbent Assay (ELISA)

Salinomycin is a coccidiostat approved as a feed additive for the prevention of coccidiosis in poultry. Official control of its residues is set by the Commission Delegated Regulation (EU) 2022/1644. The aim of our study was to assess the suitability of three microbial inhibition tests (MITs), Premi®Test, Explorer 2.0, and the Screening Test for Antibiotic Residues (STAR) linked to the enzyme-linked immunosorbent assay (ELISA), for the screening of salinomycin residues in the tissues of broiler chickens (breast and thigh muscle, heart, liver, gizzard, kidneys, lungs, spleen, skin, and fat) fed commercially produced feed containing 70 mg.kg-1 of salinomycin in the complete feed. The first residue screening (Sampling A) was performed on the last day of administration of the salinomycin-medicated feed (day 30), and the second screening (Sampling B) was performed on the day of slaughter (day 37) after the expiry of the withdrawal period with the feeding of non-medicated feed. Based on the quantitative confirmation of salinomycin residues in the examined chicken tissues by the ELISA method (Sampling A from 0.025 to 0.241 mg.kg-1; Sampling B from 0.003 to 0.076 mg.kg-1), all the MITs with the preference of the bacterial strain Bacillus stearothermophilus var. calidolactis ATCC 10149 demonstrated the ability to detect the residues of salinomycin in the examined tissues of broiler chickens at the level of the maximum residue limits set from 0.015 to 0.150 mg.kg-1 by Commission Implementing Regulation (EU) 2017/1914 and confirmed the relevance of their sensitivity to the coccidiostat salinomycin.

The Effect of the Supplementation of Humic Substances and Fermented Products in the Feed on the Content of Salinomycin Residues in Poultry Tissues

The presence of antimicrobial residues in products of animal origin is a constant problem for consumer health. The aim of this study was to observe the effect of the addition of humic substances (H), fermented products (F) and a mixture of both (FH) to feed supplemented with the coccidiostat salinomycin, compared with a control group (C), on the content of salinomycin residues in the edible tissues of broiler chickens using two microbial inhibition screening methods, Explorer 2.0 test and the Screening Test for Antibiotic Residues (STAR), and a confirmatory competitive enzyme immunoassay analysis (Salinomycin ELISA Kit). The results of the microbial inhibition tests showed a gradual decline in the positive results in the tissue samples from the last day of salinomycin administration (30th day) tothe last day of fattening (37th day, day of slaughter) in group C and no positive results in the tissue samples from experimental groups H, F and FH slaughtered on the last day of fattening. Using the Salinomycin ELISA Kit, salinomycin was detected in the chicken muscle tissues of all the control and experimental groups. However, no sample from any group contained salinomycin at a concentration exceeding the maximum residue limits set by European law. The high level of significance (p < 0.001) confirmed the positive influence of the administration of humic substances and fermented products on the content of salinomycin residues in chicken tissues.

Critical Evaluation of Two Qualitative Analytical Approaches for Multiclass Determination of Veterinary Drugs in Bovine Muscle Using UHPLC-Q-Orbitrap: The Wind of Change in Brazilian Monitoring

Food safety is recognized as a main requirement for consumers, food industries, and official laboratories. Here, we present the optimization and screening qualitative validation of two multianalyte methods in bovine muscle tissues by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry with an Orbitrap-type analyzer, operated with a heated ionization source in positive and negative mode. This aims for not only the simultaneous detection of veterinary drugs regulated in Brazil but also the prospection of antimicrobials not yet monitored. Two different sample preparation procedures were applied: method A-generic solid-liquid extraction with 0.1% formic acid (v/v) in an aqueous solution of EDTA 0.1% (w/v)-acetonitrile-methanol (1:1:1, v/v/v), followed by an additional ultrasound-assisted extraction and method B-QuEChERS. In both procedures, selectivity showed satisfactory conformity. From a detection capability (CCβ) equivalent to ½ the maximum residue limit, >34% of the analyte resulted in a false positive rate of <5%, preponderant by the QuEChERS method, which exhibited a higher yield of the sample. The results showed the potential application of both procedures in the routine analysis of foods by official laboratories, enabling the expansion of this methodological portfolio as well as its analytical scopes, thus optimizing the control of residues of veterinary drugs in the country.

A Europium Nanosphere-Based Time-Resolved Fluorescent Immunochromatographic Assay for the Rapid Screening of 4,4'-Dinitrocarbanilide: Aiming at Improving Strip Method Performance

Considering that the strip method is simple and convenient for users, a Europium nanosphere-based time-resolved fluorescent immunochromatographic assay (TRFICA) for the rapid screening of 4,4'-dinitrocarbanilide (DNC) was developed to improve the performance of strip assays. After optimization, TRFICA showed IC₅₀, the limit of detection, and cut-off values of 0.4, 0.07, and 5.0 ng mL^-1, respectively. No significant cross-reactivity (CR < 0.1%) with 15 DNC analogs was observed in the developed method. TRFICA was validated for DNC detection in spiked chicken homogenates, and recoveries ranged from 77.3% to 92.7%, with coefficients of variation of <14.9%. Moreover, the time needed for the detection procedure, including the sample pre-treatment, was less than 30 min for TRFICA, which had never been achieved before in other immunoassays. The newly developed strip test is a rapid, sensitive, quantitative, and cost-effective on-site screening technique for DNC analysis in chicken muscle.

Optimization of Adsorbent Layer Type and Developing Solvent in Coccidiostats Sample Preparation with Procedure of Solvent Front Position Extraction

Coccidiostats are drugs used against coccidiosis, a common disease among breeding animals. Their widespread application leads to the appearance of their residues in food, which is potentially harmful for human health and life. The European Union has established limits of concentrations of these drugs in premixtures and food. Nowadays, there are many methods for monitoring coccidiostats’ presence in market products, but their frequent weakness is sample preparation. Solvent Front Position Extraction is a planar chromatography-based sample preparation method that allows for effective assay of samples with coccidiostats when coupled with LC-MS/MS. The purpose of this research was to find common conditions for the effective isolation of eight coccidiostats from biological sample components with both lower and higher retention than the substances of interest. The acquired results were used for effective isolation of monensin and salinomycin from the premixture samples and allowed for their quantitative determination. The application of a semi-automatic device for the development of chromatograms positively impacted the results, confirming the effectiveness of the method for determining coccidiostats in biological samples.

Current research, regulation, risk, analytical methods and monitoring results for nicarbazin in chicken meat: A perspective review

This review presents up-to-date information about current research on nicarbazin, one of the most used anticoccidials in poultry production. The focus is to elucidate regulation concerning nicarbazin, limits for its residues in food, how maximum residue limits in different countries are calculated regarding edible chicken tissues and the possible implications in human health. Analytical methods to extract and quantify this residue, expressed as dinitrocarbanilide (DNC) are presented and discussed, including qualitative screening and quantitative/confirmatory analytical methods. Monitoring results and occurrence of DNC residues in chicken meat are discussed. Additionally, the causes of eventual chicken meat contamination and possible solutions to reduce or eliminate DNC residue in tissues are also presented. The paper concludes with perspectives, the current state of DNC residue analysis and suggestions for future research, especially considering the gap in the study of residue recycling effect due to continuous chicken litter use.

Total Antibiotics — A New Possible Alternative for the Screening of Coccidiostat Residues in Poultry Meat

The Total Antibiotics test is a microbial inhibition test which has been recently introduced for the detection of antibiotics in meat. The aim of this study was to determine whether it would be suitable for the detection of coccidiostats in poultry meat. A comparison with the Premi®Test was assessed also for the suitability of the detection of coccidiostats in poultry meat. A selection of poultry meat samples of different organ parts were assessed with 14 samples from Slovakian farms that had previously been tested for coccidiostats by the Veterinary and Food Institute in Košice. In addition, another 8 samples from varied Slovakian supermarkets such as Lidl, Billa and Tesco with samples of chicken or duck meat, were tested. Each prepared sample was added to the Total Antibiotics kit tubes and incubated. The samples from all sources showed a mixture of positive and negative results for the detection of coccidiostats.

For the Premi®Test, the samples used the same extraction procedure as the Total Antibiotics, placed in Premi®Test kit tubes and incubated. The Premi®Test demonstrated a mixture of positive and negative results, as similar to the Total Antibiotics for coccidiostats in the poultry farm samples. However, the Premi Test revealed many more negative results for the supermarket sources compared to the Total Antibiotics. Therefore, based on the total number of positive results, we concluded that Total Antibiotics is more sensitive for the detection of coccidiostats in poultry meat, but depending on the source of the samples, both Total Antibiotics and Premi®Test had either similar or opposite results for the detection of coccidiostats.

Single-laboratory validation of a multiplex flow cytometric immunoassay for the simultaneous detection of coccidiostats in eggs and feed

Coccidiostats are authorized in the European Union (EU) to be used as poultry feed additives. Maximum (residue) levels (M(R)Ls) have been set within the EU for consumer and animal protection against unintended carry-over, and monitoring is compulsory. This paper describes the single-laboratory validation of a previously developed multiplex flow cytometric immunoassay (FCIA) as screening method for coccidiostats in eggs and feed and provides and compares different approaches for the calculation of the cut-off levels which are not described in detail within Commission Decision 2002/657/EC. Comparable results were obtained between the statistical (reference) approach and the rapid approaches. With the most rapid approach, the cut-off levels for narasin/salinomycin, lasalocid, diclazuril, nicarbazin (DNC) and monensin in egg, calculated as percentages of inhibition (%B/B0), were 60, 32, 76, 80 and 84, respectively. In feed, the cut-off levels for narasin/salinomycin, lasalocid, nicarbazin (DNC) and monensin were 70, 64, 72 and 78, respectively, and could not be determined for diclazuril. For all analytes, except for diclazuril in feed, the rate of false positives (false non-compliant) in blank samples was lower than 1 %, and the rate of false negatives (false compliant) at the M(R)Ls was below 5 %. Additionally, very good correlations (r ranging from 0.994 to 0.9994) were observed between two different analysers, a sophisticated flow cytometer (FlexMAP 3D(®)) and a more cost-efficient and transportable planar imaging detector (MAGPIX(®)), hence demonstrating adequate transferability.