OCCURRENCE OF ARS IN FOODS OF ANIMAL ORIGIN

The occurrence of ARs in foods of animal origin has emerged as a major concern for both public health and food safety. These residues primarily result from the administration of antibiotics in livestock production for therapeutic, prophylactic, and, in some cases, growth-promoting purposes. When these drugs are misused or when mandatory withdrawal periods are not observed before slaughter or milk collection, residual compounds may persist in food products such as meat, milk, eggs, and fish [4, 31]. This issue is particularly pronounced in intensive production systems and in regions where regulatory frameworks are weak or inadequately enforced [2].

Beyond their mere presence, ARs exhibit considerable variability across geographical regions, food categories, and antibiotic classes, reflecting differences in veterinary practices, regulatory enforcement, production systems, and surveillance capacities. These variations indicate that AR contamination is influenced not only by antibiotic usage patterns but also by disparities in monitoring infrastructure and regulatory compliance. Consequently, contamination levels vary substantially across countries and production sectors, underscoring the need for context-specific control measures and harmonized surveillance programs.

A comparative synthesis of global prevalence patterns of ARs in foods of animal origin is presented in Table 1[3, 5, 9, 22, 40–47].

Numerous studies worldwide have confirmed the presence of ARs in food products, often exceeding established MRLs. For example, in Nigeria, more than 80% of meat samples tested positive for oxytetracycline residues, frequently exceeding safe thresholds [40]. In Pakistan, approximately 40% of milk samples contained tetracyclines and sulfonamides [3], whereas 32% of beef samples in Ethiopia exceeded MRLs for tetracycline residues [5]. Similarly, in Bangladesh, 28% of poultry meat samples were contaminated with ciprofloxacin residues [22].

These findings indicate that contamination is not only widespread but also heterogeneous, with markedly higher prevalence rates observed in low- and middle-income countries, where enforcement of withdrawal periods and veterinary oversight remains limited [2, 11]. In contrast, high-income regions tend to exhibit lower but persistent contamination levels, reflecting stronger surveillance systems but incomplete elimination of residues. These regional disparities underscore the importance of strengthening residue-monitoring programs and harmonizing regulatory practices at the international level.

Dairy products

The dairy sector has been extensively studied due to the high global consumption of milk and dairy products. In the European Union, approximately 12% of raw milk samples have been reported to contain ARs, with β-lactams and tetracyclines being the most frequently detected compounds [41]. In Cameroon, penicillin residues have been identified in raw milk obtained from local farms [42]. The persistence of residues in milk is largely influenced by pharmacokinetic factors, including drug lipophilicity, protein binding, and excretion pathways, which facilitate accumulation within mammary tissues. Moreover, incomplete compliance with withdrawal periods remains a major driver of contamination.

Meat and poultry products

Meat products are equally affected by AR contamination. In Brazil, macrolides and quinolones have been detected in poultry meat, with approximately 15% of samples exceeding permissible limits [43]. In Egypt, oxytetracycline residues have been reported in beef and lamb [44], whereas sulfonamide residues were detected in 20% of beef and chicken samples in Ghana [9]. Compared with dairy products, contamination in meat is often associated with prolonged antibiotic retention in tissues, particularly in muscle and liver, and reflects cumulative exposure throughout the animal's lifespan. Intensive production systems further exacerbate this problem through repeated antibiotic administration.

Fish and aquaculture products

Seafood, particularly aquaculture-derived products, represents an increasingly important source of AR exposure. In Thailand, farmed shrimp were found to contain high concentrations of fluoroquinolones, including enrofloxacin and ciprofloxacin [45]. In Vietnam, chloramphenicol residues detected in fish have resulted in export restrictions [46], whereas oxytetracycline residues were identified in 18% of aquaculture fish samples in Egypt [9]. Aquaculture systems are especially vulnerable because antibiotics are often introduced directly into water, leading to environmental persistence and bioaccumulation in aquatic organisms. This route of contamination differs considerably from that observed in terrestrial livestock systems, highlighting the need for sector-specific monitoring and management strategies.

Food category | Region/ Country | Antibiotic class detected | Prevalence (%) | MRL exceedance | Detection method | Key observations | References
Meat (beef) | Nigeria | Tetracyclines (oxytetracycline) | >80% | High | LC-MS/microbiological assay | Widespread misuse and poor compliance with withdrawal periods | [40]
Milk | Pakistan | Tetracyclines, sulfonamides | ~40% | Moderate–High | ELISA/LC-MS | Dairy contamination associated with prophylactic use | [3]
Beef | Ethiopia | Tetracyclines | ~32% | High | LC-MS | Weak regulatory monitoring | [5]
Poultry meat | Bangladesh | Fluoroquinolones (ciprofloxacin) | ~28% | High | high-performance liquid chromatography (HPLC)/ELISA | Intensive poultry production pressure | [22]
Raw milk | European Union | β-lactams, tetracyclines | ~12% | Low–Moderate | LC-MS | Strong surveillance but persistent low-level contamination | [41]
Milk | Cameroon | β-lactams (penicillin) | Detected | Variable | Microbiological assay | High risk for artisanal dairy fermentation | [42]
Poultry meat | Brazil | Macrolides, quinolones | ~15% | Moderate | LC-MS | Influence of intensive industrial production | [43]
Beef and lamb | Egypt | Tetracyclines | Significant levels | Moderate–High | ELISA/LC-MS | Inadequate veterinary oversight | [44]
Meat (beef/chicken) | Ghana | Sulfonamides | ~20% | Moderate | Microbiological assay | Limited monitoring infrastructure | [9]
Shrimp (aquaculture) | Thailand | Fluoroquinolones | High | High | LC-MS | Excessive antibiotic use in aquaculture systems | [45]
Fish | Vietnam | Chloramphenicol | Detected | High | LC-MS | Trade-related contamination concerns | [46]
Fish (aquaculture) | Egypt | Tetracyclines | ~18% | Moderate–High | ELISA | Aquaculture-associated contamination | [9]
Eggs | India | Tetracyclines | ~23% | Moderate | ELISA | Poor compliance with withdrawal periods | [47]
Eggs | Ethiopia | Tetracyclines | ~15% | Moderate | LC-MS | Emerging contamination concern | [5]

Eggs and other animal-derived products

Eggs are also susceptible to AR contamination. In India, 23% of egg samples contained tetracycline residues [47], whereas 15% of egg samples from Ethiopia showed oxytetracycline contamination [5]. Residues in eggs are primarily associated with systemic distribution of antibiotics in laying hens, followed by deposition within the yolk and albumen. This issue is of particular concern because eggs are widely consumed by vulnerable population groups, including children and older adults.