Search Results (387)

This study investigated water quality, metal ion concentrations, and antibiotic residues specifically enrofloxacin (ENR) and its metabolite ciprofloxacin (CIP), across six American shad (Alosa sapidissima) aquaculture sites over a one-year period. Water and sediment samples were analyzed to determine contamination levels, and ENR-degrading bacteria were isolated from the culture environment to explore their potential use in bioremediation. Findings showed that NH₃-N and total suspended solids (TSS) exceeded recommended standards at all sampling sites. Elevated levels of Li, Na (except S1), Fe, Ni (except S2 and S4), Sr, and Cu were found at site S3. Site S5 recorded the highest concentrations of Al, As, and Pb, while Cd was most abundant at S6. In sediments, S5 showed higher levels of Mg, K (except S3), Ca, Cr, Mn, Fe, Ni, As, Pb, Cu, and Zn (except S3). ENR and CIP were detected in all water and sediment samples, with a 100% detection rate. The highest ENR (16.68–3215.95 mg·kg⁻¹) and CIP (3.90–459.60 mg·kg⁻¹) concentrations in water occurred at site S6, following a seasonal pattern of autumn > winter > summer > spring. In sediments, the maximum ENR (41.43–133.67 mg·kg⁻¹) and CIP (12.36–23.71 mg·kg⁻¹) levels were observed in spring. Two ENR-degrading bacterial strains were successfully isolated and identified as Enterococcus and Bacillus. Optimal degradation was achieved at 30 °C, pH 8.0, 6% inoculum, and 3000 Lux, resulting in a 64.2% reduction in ENR after 72 h. Under slightly different conditions (25 °C, pH 10), degradation reached 58.5%. This study provides an efficient strain resource for the bioremediation of ENR pollution in the aquaculture water of American shad. Full article

Antibiotic use in aquaculture has become widespread to sustain production and control bacterial diseases, but it poses significant ecological and human health risks due to residue accumulation and resistance development. This study investigated the occurrence, dominance, and combined use of sulfonamide and fluoroquinolone antibiotics in freshwater fish aquaculture ponds around Wuxi, China. Here, the term aquaculture refers specifically to the controlled farming of freshwater fish species such as carp and crucian carp in managed pond systems. A total of 80 water samples (collected exclusively from pond waters) were obtained from 40 ponds during the high intensity rearing and harvest stage of fish. Residues of enrofloxacin and sulfonamide antibiotics were analyzed using a validated LC–MS/MS method with detection limits in the low nanogram-per-liter range. Results revealed that antibiotics were ubiquitous in pond waters, with enrofloxacin emerging as the dominant compound in August, reaching concentrations of up to 2.36 µg/L. By October, sulfonamides, particularly sulfamethoxazole and sulfadiazine, became more prevalent, with a maximum sulfadiazine concentration exceeding 4 µg/L. Multivariate analyses demonstrated a clear seasonal shift in antibiotic profiles, while correlation analyses indicated limited combined use in summer but notable co-occurrence of sulfonamides in autumn. These findings underscore that antibiotic application patterns in aquaculture are strongly linked to production stages, with potential consequences for environmental safety, resistance development, and food security. Effective monitoring, stricter regulation, and alternative disease management strategies are urgently required to mitigate risks and promote sustainable aquaculture practices. Full article

In order to find the biochemical effects of Aeromonas hydrophila and its therapeutic chemical, enrofloxacin (ENR), on American shad (Alosa sapidissima A. Wilson), four groups were set up: a control group (C), an A. hydrophila group (A), an A. hydrophila + 70 mg·L⁻¹ enrofloxacin (ENR) group (E1), and an A. hydrophila + 140 mg·L⁻¹ ENR group (E2). Histological, enzymatic activities, transcriptome, and proteomics have been performed. MDA, PPO, AKP, TNF-α, and AMPK were significantly increased, while AhR and EROD were decreased in the liver of American shad after treatment with A. hydrophila. AhR and EROD showed a significant decrease in E1 group; MDA, PPO, AKP, and AMPK were significantly increased, while AhR and EROD decreased in E2 group. A. hydrophila significantly increased ferroptosis, TGF-β signaling pathway, etc. Ferroptosis, pyrimidine metabolism, and glycerolipid metabolism significantly increased in E1 group, while protein processing in endoplasmic reticulum significantly increased in E2 group. A total of 126 shared metabolites were found in the comparisons of A vs. C and E2 vs. C, and the main enriched pathway were organic oxygen compounds, lipids, and lipid-like molecules. Except for fluorobenzoate degradation, the pathways of ascorbate and aldarate metabolism, pyrimidine metabolism significantly increased in A and E2 groups, which further resulted in vacuolization, cell shedding, and necrosis in the liver. A. hydrophila led to a significant decrease in lipid metabolism, leading to oxidative stress and energy expenditure. The addition of ENR in aquaculture significantly enhanced liver metabolic abnormalities caused by A. hydrophila. Excessive use of ENR leads to oxidative stress in American shad, affecting its immune system as well as lipid, carbohydrate, and energy metabolism. Full article

Restrictions on adding antibiotics to animal diets have posed challenges in managing gut pathogens, emphasizing the significance of effective non-antibiotic growth promoters to maintain animal health and productivity. This study assessed the efficacy of hydroxamic acid (HA), derived from local maize varieties, as a non-antibiotic growth promoter in broilers. Among 10 different maize varieties, the Azam variety yielded the highest HA concentration (35 ± 7 μg/g of roots), as quantified by high-performance liquid chromatography (HPLC). In vitro antimicrobial assays demonstrated the lowest minimum inhibitory concentration (MIC) of 0.022 mg for Azam-derived HA against pathogenic E. coli. To further assess in vivo efficacy, 108 birds were allocated at random to six treatment groups. The treatments include birds fed a basal diet without an E. coli challenge (negative control); an antibiotic-treated group challenged with E. coli and treated with enrofloxacin at a dosage of 5 milligrams (mg) per kilogram (kg), administered orally once daily from day 5 post-infection (dpi) for 7 consecutive days (standard); broilers challenged with E. coli and supplemented with a basal diet with HA at concentrations of 1, 10, or 100 mg/kg of feed from 5 dpi for one week (HA 1 mg, HA 10 mg, and HA 100 mg, respectively); and broilers challenged with E. coli without enrofloxacin/HA (positive control). The results demonstrated that birds fed a diet supplemented with the HA-100 mg improved the body weight (BW) and feed conversion ratio (FCR) compared to the positive control group. There were no significant differences (p > 0.05) observed for BW and FCR observed for the broilers fed on the standard and HA 100 mg groups. The addition of HA at 100 mg improved (p < 0.05) the hemoglobin (Hb) and packed cell volume (PCV) and reduced (p < 0.05) levels of malondialdehyde (MDA) compared to positive control group. A significantly low carcass weight (p < 0.05) was shown for positive control birds compared to other groups. Our findings indicate that maize-derived HA presents a phytogenic alternative to antibiotics by controlling enteric pathogens and improving health and performance affected by E. coli infection in broilers. Full article

The widespread use of antimicrobial drugs (AMDs) in livestock production contributes to antimicrobial resistance (AMR), a global One Health concern affecting humans, animals, and the environment. This study analyzed AMD residues and the AMR profiles in Escherichia coli and Enterococcus spp./Streptococcus spp. (ES) isolated from lagoon water samples collected from nine California dairies. Antimicrobial susceptibility testing was performed using the microbroth dilution method, and enzyme-linked immunosorbent assay (ELISA) kits were used to detect AMD residues in lagoon water. Overall, residues of florfenicol and tilmicosin were detected in more than 90% of the samples, while tetracycline was detected in 74.2 ± 4.6% of the samples. In contrast, penicillin and sulfamethazone residues were low, observed in only 3.4 ± 1.9% and 32.3 ± 5.0% of samples, respectively. The very low prevalence of penicillin was likely due to limited use in dairy cattle, given its prolonged withdrawal period. Prevalence estimates for AMR in the lagoon samples showed 100% resistance of E. coli to tiamulin, tilmicosin or tylosin and high prevalence against florfenicol (96.0% ± 2.0) or gamithromycin (92.0% ± 1.9). However, low AMR estimates (less than 10%) were observed against other AMDs tested. Similarly, the prevalence estimates for AMR of ES isolates in the studied lagoon were high against florfenicol (95.1% ± 2.0), tildipirosin (97.6% ± 1.7), or tilmicosin (98.8% ± 1.2), but low against ampicillin (4.9% ± 1.9) and penicillin (8.5% ± 2.4). Despite numerical differences in AMR prevalence by season, region, and sampling point, these variations were not statistically significant. Logistic regression models were applied to explore associations between AMD residues and AMR phenotypes where appropriate. Tilmicosin residues were significantly associated with reduced resistance to danofloxacin, enrofloxacin, and tildipirosin in E. coli isolates, while sulfamethoxazole residues were linked to increased tetracycline resistance in Enterococcus spp. The presence of florfenicol residues, potentially originating from treated calves and heifers, helps explain the high prevalence of resistance to this drug in both bacterial species. However, not all AMD residues were associated with AMR, underscoring the complex ecological and genetic factors involved in the development and maintenance of resistance in dairy environments. These findings underscore the importance of integrating AMR surveillance and prudent AMD use practices across all segments of dairy production systems. Full article

This study evaluated the antibacterial efficacy and growth-promoting potential of Moringa oleifera and Thymus vulgaris methanolic extracts in broiler chickens challenged with Escherichia coli O78. In vitro antibacterial screening using agar well diffusion and disc diffusion assays revealed that ciprofloxacin exhibited the strongest inhibitory effect, followed by tetracycline and enrofloxacin, whereas among plant extracts, T. vulgaris was more effective than M. oleifera. The optimal combination (M100T150; 100 mg M. oleifera + 150 mg T. vulgaris) produced the largest inhibition zones against E. coli strains. For the in vivo trial, 540 Ross-308 broiler chicks were distributed into six treatment groups in a completely randomized design and reared for 42 days. Parameters assessed included growth performance, carcass traits, gut pH, ileal microbial counts, and intestinal histomorphology. Results showed that E. coli challenge significantly reduced feed intake, weight gain, carcass yield, and villus integrity while increasing FCR and E. coli counts (p < 0.05). Addition of plant extracts, particularly M100T150, significantly improved weight gain, FCR, Broiler Performance Efficiency Factor (BPEF), and Broiler Farm Economy Index (BFEI) compared to the positive control (p < 0.05). Extracts reduced duodenal and jejunal pH (p < 0.001), suppressed E. coli counts (p = 0.003), and enhanced Lactobacillus populations (p = 0.0004). Histological analysis revealed that extract-supplemented groups had greater villus height and surface area with shallower crypts than the positive control, indicating restoration of gut integrity. These findings suggest that methanolic extracts of M. oleifera and T. vulgaris, particularly in combination, can serve as natural alternatives to antibiotics in broiler production under pathogenic challenge. Full article

Background/Objectives: Bacterial resistance to antimicrobials is a major global health challenge, limiting the effectiveness of conventional therapies and complicating infection control. The aim of this study was to investigate the antibacterial potential of biologically synthesized silver nanoparticles (Bio-AgNP), alone and in combination with ampicillin (AMP) and enrofloxacin (ENRO), against multidrug-resistant (MDR) bacterial isolates of clinical and veterinary relevance. Methods: The antibacterial activity of Bio-AgNP, AMP, and ENRO, alone or in combination, was assessed against reference strains and MDR isolates of Escherichia coli, Salmonella enterica serovar Typhimurium and Enteritidis, and Staphylococcus aureus. Minimum inhibitory concentration (MIC) values were determined, and bacterial tolerance to prolonged antimicrobial exposure was evaluated. Additionally, assays were conducted to explore potential mechanisms of action, including cell membrane permeability and oxidative stress induction. Results: All bacterial strains developed increased MIC values after prolonged exposure to conventional antibiotics, confirming resistance. Only E. coli developed resistance to Bio-AgNP. Notably, the Bio-AgNP + AMP combination effectively restored susceptibility in E. coli, while only S. Enteritidis developed resistance to this combination upon prolonged exposure. The synergistic effect of Bio-AgNP with conventional antibiotics significantly reduced bacterial growth within two hours, compared with longer times observed in monotherapy. Mechanistic analysis suggested that the combinations increased membrane permeability, facilitating antibiotic entry. Conclusions: Bio-AgNPs combined with AMP or ENRO enhanced antibacterial activity and overcame resistance in MDR isolates, representing a promising therapeutic alternative. The biological synthesis of Bio-AgNPs, capped with organic biomolecules, supports their potential as safe adjuvants to conventional antibiotics in combating MDR bacterial infections. Full article

Objectives: The Taihe Black-Boned Silky Fowl (TBSF) is a unique indigenous chicken breed in China, characterized by widespread melanin deposition throughout its body. Fluoroquinolones (FQs) such as enrofloxacin can persist in TBSF for an extended period exceeding 100 days. The aim of this study was to examine the current status and development trends of FQ resistance within the TBSF breeding environment. Methods: Whole-genome sequencing was utilized to identify the molecular presence of quinolone resistance-determining region (QRDR) mutations and plasmid-mediated quinolone resistance (PMQR) genes in Escherichia coli isolates obtained from TBSF farms. Network inference based on strong Spearman correlations (ρ > 0.5) and statistically significant associations (p-value < 0.05) was applied to investigate the co-occurrence patterns among FQ residues, resistance phenotypes, and antibiotic resistance genes. Results: The results showed that FQ residues were identified as the primary contributor to FQ resistance in E. coli isolates. Mutations at QRDR sites were the predominant factor driving FQ resistance, rather than PMQR determinants. This study also reported the first identification of GyrA-S83Q mutation being associated with FQ resistance. Conclusions: It was concluded that E. coli strains in TBSF environments, where chickens have a long-term residual metabolic cycle of antimicrobials, may develop and evolve new mechanisms to adapt to this environment. Further research is warranted to investigate the evolution of FQ resistance in E. coli strains within TBSF environments. Full article

Excessive use of antibiotic growth promoters (AGPs) in broiler rearing has led to severe issues due to antimicrobial resistance and drug residues in meat. This study was conducted to evaluate aqueous Moringa oleifera leaf extract (MOLE) as a natural alternative to antibiotics in broiler chickens. 150 broiler chicks were randomly distributed into five groups: one control, three MOLE-treated groups (60, 90, and 120 mL/L), and one Enrofloxacin-treated group (an antibiotic). The birds were monitored for a 35-day trial period, split further into a starter phase (0–21 days) and a finisher phase (22–35 days). The results were that at the starter phase of their lives, birds treated with MOLE120 experienced better body weight gain and optimal feed conversion ratio (FCR), which showed improved early growth performance. In the finisher phase, the MOLE90 group demonstrated the best FCR and a favorable weight gain, showing better efficiency at later stages. Crude protein digestibility was highest in the MOLE90 group (69.97%), and apparent metabolizable energy also increased in all MOLE-treated groups, especially MOLE120 (2938.9 kcal/kg). Regarding the blood lipid profile, the MOLE90 group had the lowest low-density lipoprotein (LDL) (82.3 mg/dL) and cholesterol (181.7 mg/dL), while MOLE120 achieved the highest high-density lipoprotein (HDL) level (92.6 mg/dL) with significant (p < 0.05) effects across all parameters. Triglycerides were slightly higher in MOLE groups but remained within physiological limits. In conclusion, MOLE supplementation, particularly at 90–120 mL/L, improved performance and blood lipid metabolism in a phase-specific manner. MOLE120 was more effective in early growth, while MOLE90 proved optimal in the finishing stage. This study supports the potential of MOLE as a phytogenic substitute for antibiotics in poultry production. Full article

Fluoroquinolone antibiotics (FQs) are widely applied in veterinary practice and animal husbandry and frequently persist in organic waste liquids (OWLs), creating substantial environmental and health risks when untreated. A high-capacity mesoporous silica aerogel (SA-60) was produced via a cost-effective sol–gel route from water glass, followed by ambient pressure drying at 60 °C for 6 h. SA-60 exhibited pronounced selectivity, providing a maximum adsorption capacity of 630.18 mg·g⁻¹ for enrofloxacin (ENR) in acetonitrile. Adsorption efficiency was weakly dependent on pH. Mechanistic analysis indicated combined physical and chemical interactions, with intra-particle diffusion governing the overall rate. Thermodynamic evaluation showed a spontaneous and endothermic process for ENR adsorption. Organic solvent type and water content were major determinants of adsorption efficiency. Durable performance was observed, with capacity retention above 80% after five adsorption-desorption cycles. The mesoporous architecture (surface area 249.21 m²·g⁻¹; average pore diameter 10.81 nm) supported the high uptake. These results identify SA-60 as a sustainable adsorbent for removing hazardous FQs from OWLs, offering a simple, energy-efficient approach for the source-level control of antibiotic pollution and improved environmental management. Full article

The increasing demand for poultry meat calls for sustainable production methods that address animal welfare and combat antimicrobial resistance (AMR). Commensal Escherichia coli serve as reservoirs of resistance genes that may transfer to pathogens, facilitating AMR spread in agriculture. This study evaluated the efficacy of a bacteriophage cocktail, UPWr_E, applied as a litter spray to reduce total and antibiotic-resistant E. coli in broiler chicken rearing. The cocktail, containing four lytically active phages, was administered for four weeks. Microbiological analyses of litter, feces, and cecal contents showed a significant reduction in total E. coli by 3.2 log₁₀ CFU/g in litter and a decrease in resistant strains to gentamicin, enrofloxacin, tetracycline, and sulfamethoxazole–trimethoprim, compared to controls. No significant changes occurred in E. coli loads in feces or cecal contents, indicating limited impact on the number of commensal E. coli in cecal contents. Phages remained detectable and stable in litter and feces throughout the study. These findings demonstrate the potential of phage therapy as a targeted, environmentally friendly approach to control AMR reservoirs in poultry farming. Incorporating phage-based treatments into AMR management strategies could improve food safety and promote sustainable animal production. Full article

Background: Salmonella infections pose a serious threat to both animal and human health worldwide. Notably, there is an increasing trend in the resistance of Salmonella to fluoroquinolones, the first-line drugs for clinical treatment. Methods: Utilizing Salmonella Typhimurium CICC 10420 as the test strain, ciprofloxacin was used for in vitro induction to develop the drug-resistant strain H1. Changes in the minimum inhibitory concentrations (MICs) of various antimicrobial agents were determined using the broth microdilution method. Transcriptomic and metabolomic analyses were conducted to investigate alterations in gene and metabolite expression. A combined drug susceptibility test was performed to evaluate the potential of exogenous metabolites to restore antibiotic susceptibility. Results: The MICs of strain H1 for ofloxacin and enrofloxacin increased by 128- and 256-fold, respectively, and the strain also exhibited resistance to ceftriaxone, ampicillin, and tetracycline. A single-point mutation of Glu469Asp in the GyrB was detected in strain H1. Integrated multi-omics analysis showed significant differences in gene and metabolite expression across multiple pathways, including two-component systems, ABC transporters, pentose phosphate pathway, purine metabolism, glyoxylate and dicarboxylate metabolism, amino sugar and nucleotide sugar metabolism, pantothenate and coenzyme A biosynthesis, pyrimidine metabolism, arginine and proline biosynthesis, and glutathione metabolism. Notably, the addition of exogenous glutamine, in combination with tetracycline, significantly reduced the resistance of strain H1 to tetracycline. Conclusion: Ciprofloxacin-induced Salmonella resistance involves both target site mutations and extensive reprogramming of the metabolic network. Exogenous metabolite supplementation presents a promising strategy for reversing resistance and enhancing antibiotic efficacy. Full article

Among synanthropic species, European hedgehogs are widely distributed throughout Europe. In recent decades, these animals have increasingly adapted to anthropogenic environments, where they find abundant shelter and food resources, along with fewer natural predators. As with other wildlife, it is likely that their coexistence in cities is also affecting their microbiota, promoting the development of antimicrobial resistance (AMR). This study aimed to assess the occurrence and patterns of AMR in commensal enteric Escherichia coli isolated from hedgehogs (n = 53) living in anthropogenic environments upon admission to a wildlife rescue center in Turin (Italy). The effects of hospitalization on the prevalence and trends of AMR were also assessed. Our results confirm that hedgehogs can harbor resistant E. coli upon admission, in particular against cefazolin (41.5%), ampicillin (37.7%), and enrofloxacin (22.6%). In addition, hospitalization promoted an increase in minimum inhibitory concentration (MIC) values of all antibiotics except imipenem, which led to a significant increase in E. coli that was resistant towards doxycycline, enrofloxacin, and trimethoprim-sulfamethoxazole. Admitted hedgehogs were also carriers of extended-spectrum beta-lactamase-producing E. coli (5.7%), whose presence increased during hospitalization (to 20.8%). These results highlight the role of hospitalizations longer than five days in the acquisition of AMR and suggest that European hedgehogs can become potential carriers of resistant E. coli following hospitalization. Full article

Four entire male sugar gliders (Petaurus breviceps) belonging to the same colony were presented for elective orchiectomy. After clinical examination, dexmedetomidine (120 μg/kg) in combination with ketamine (5 mg/kg) were administered subcutaneously (SC). Once righting and pedal withdrawal reflexes were lost, ringer lactate solution, enrofloxacin and meloxicam were administered SC and a bilateral intratesticular block with lidocaine 0.25% was performed. Heart, respiratory rates and pulse oximetry values were recorded every minute. Onset of sedation, additional use of isoflurane, duration of anaesthesia, duration of surgery, time of recovery after atipamezole administration, quality of recovery and time of food intake were recorded. Postoperative assessment (posture, level of activity, vocalisation, response to manipulation, attention to the surgical wound) was performed hourly until discharge, five hours after surgery. Dexmedetomidine in combination with ketamine provided adequate short-lasting anaesthesia for castration in 3 out of 4 sugar gliders. One sugar glider needed additional isoflurane administration to perform orchiectomy. No perioperative additional analgesia was needed in any sugar glider. Full article

Background: Antimicrobial resistance (AMR) is increasingly acknowledged as a critical global challenge, posing serious risks to human and animal health and potentially disrupting poultry production systems. Commensal bacteria such as Staphylococcus spp., Enterococcus spp., and Escherichia coli may serve as important reservoirs and vectors of resistance genes. Objectives: This study aimed to assess the AMR profiles of bacterial strains isolated from industrial chicken farms in the Dél-Alföld region of Hungary, providing region-specific insights into resistance dynamics. Methods: A total of 145 isolates, including Staphylococcus spp., Enterococcus spp., and E. coli isolates, were subjected to minimum inhibitory concentration (MIC) testing against 15 antimicrobial agents, following Clinical and Laboratory Standards Institute (CLSI) guidelines. Advanced multivariate statistics, machine learning algorithms, and network-based approaches were employed to analyze resistance patterns and co-resistance associations. Results Multidrug resistance (MDR) was identified in 43.9% of Staphylococcus spp. isolates, 28.8% of Enterococcus spp. isolates, and 75.6% of E. coli isolates. High levels of resistance to florfenicol, enrofloxacin, and potentiated sulfonamides were observed, whereas susceptibility to critical antimicrobials such as imipenem and vancomycin remained largely preserved. Discussion: Our findings underscore the necessity of implementing region-specific AMR monitoring programs and strengthening multidisciplinary collaboration within the “One Health” framework with proper animal hygiene and biosecurity measures to limit the spread of antimicrobial resistance and protect both animal and human health. Full article