Veterinary Research Forum

Abstract American foulbrood (AFB) and European foulbrood (EFB) diseases caused by Paenibacillus larvae and Meliscococcus plutonius are prevalent honeybee brood diseases that pose significant economic challenges to the apiculture industry globally. Antibiotic treatment has led to the emergence of antibiotic-resistant strains, encouraging the search for alternative and safe measures to effectively control these diseases. Honeybee gut microbiomes have proven effects on all spectra of honeybee health by enhancing resistance to several diseases via immune modulation and the production of different antimicrobial metabolites. The major part of the gut microbiota is identified as probiotic bacteria, which are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. Probiotics have shown promising health benefits for honeybees. Honeybee gut probiotics provide protection via the production of different metabolites (postbiotics), such as hydrogen peroxide, vitamins, organic acids, free fatty acids, bacteriocins, neurotransmitters, secreted bio-surfactants, and reactive oxygen species. Vast numbers of these gut bacteria and their postbiotics have wide-spectrum antibacterial effects on AFB and EFB. This review highlights the significance of the honeybee gut microbial community, its probiotic potency, and the role of postbiotic metabolites as safe prophylactic measures for preventing AFB and EFB diseases in honeybees.

Abstract This study focuses on understanding how the sensitivity patterns of common probiotic Lactobacillus species differ between healthy and colibacillosis-diseased broiler chickens and explores any correlation between these patterns and avian pathogenic Escherichia coli (APEC). Ileum samples were collected from the healthy (n = 10) and colibacillosis-diseased (n = 10) broiler poultry farms. Lactobacillus and E. coli were identified and incidence rate of six probiotic Lactobacillus species (L. acidophilus, L. brevis, L. casei, L. plantrum, L. delbrueckii, and L. fermenti) was determined, and their susceptibility to different antibiotics (ampicillin, chloramphenicol, erythromycin, kanamycin, tetracycline, and vancomycin) was tested. A total of 120 Lactobacilli were examined. Certain Lactobacillus spp. from healthy birds (L. brevis) and those affected by colibacillosis (L. acidophilus) showed better sensitivity and lower multiple antibiotic resistance to chloramphenicol, erythromycin, and kanamycin. Statistical analysis revealed significant correlations between ampicillin and chloramphenicol, ampicillin and erythromycin, ampicillin and tetracycline, and ampicillin and vancomycin resistance. Also, a significant correlation was observed between erythromycin and tetracycline, and kanamycin and vancomycin. All APEC strains showed multiple antibiotic resistance. A strong positive correlation was found between resistant Lactobacillus spp. and APEC isolates from diseased birds, indicating co-occurrence of antibiotic resistance. The study suggests that antibiotic resistance in APEC and Lactobacillus species may spread through horizontal transfer, highlighting the need for improved anti-microbial management in poultry systems.

Abstract Arsenic (As) contamination in natural water resources has become a great disaster throughout the world posing serious health problems. The current study was performed to evaluate the protective effects of Escherichia coli strain Nissle 1917 (EcN) against As exposure in goldfish (Carassius auratus). Fish were fed three times a day with 4.00% of body weight of diet with different doses (0.00, 1.00 × 10⁶, 1.00 × 10⁷ and 1.00 × 10⁸ CFU g^-1) of EcN for 80 days and then, challenged with 20.00 mg L^-1 As for 96 hr under stagnant flow. Physicochemical characteristics of the inlet water were temperature of 25.10 ± 0.70 ˚C, pH of 7.30 ± 0.20 and dissolved oxygen of 7.30 ± 0.30 mg L^-1 and 50.00% of water was exchanged once a week. Afterwards, fish were euthanized with a clove oil solution (50.00 μL L^-1) and tissues were dissected from each fish and immediately fixed in 10.00% buffered formalin. The histopathological results indicated that the supplemented EcN did not have any side effects on various organs. It was also observed that the damages to kidney, liver, gill and skin were pronounced in fish exposed to As. However, the histopathological damages induced by As in fish tissues were less pronounced in the EcN-treated groups compared to the fish fed with the basal diet. Lamellar blood congestion in gills and epidermal cells detachment from the skin surface as well as hepatocytes, enterocytes and tubular necrosis were reduced in treated groups. These findings indicate that EcN has the potential to ameliorate the As-induced organ toxicity.

Abstract This study was carried out to investigate the stability, antibacterial properties and biofilm removal potential of cell-free supernatant (CFS) of Lactobacillus acidophilus LA5 and Lactobacillus casei 431 against Staphylococcus aureus ATCC 25923. Antibacterial activity of both Lactobacillus strains was measured according to the agar spot method. The CFS was prepared by centrifugation of bacterial suspension at 4000 g for 10 min and the antimicrobial activity was measured using agar-well diffusion. The stability of CFSs during storage at 4.00 ± 2.00 ^°C and 25.00 ± 2.00 ^°C for a period of 4 weeks was measured based on the method of broth micro-dilution assay. Moreover, biofilm removal potential of CFS on 2-days-old biofilm of S. aureus­ developed on polystyrene and glass surfaces was also determined. The efficacy of CFS on bacterial biofilm established on the glass surface was also observed using fluorescence microscope. Results showed that inhibition zones of L. acidophilus (50.26 mm) were greater than L. casei (37.06 mm). The minimum inhibitory concentration of both CFSs remained stable (40 mg mL^-1) during the storage for 28 days at 4.00 and 25.00 ^°C and storage temperature did not affect the antibacterial effectiveness of CFS. The addition of both CFSs significantly removed biofilm developed on both tested surfaces in a concentration-dependent manner. Biofilm removal property of L. acidophilus CFS was generally better than L. casei CFS which was confirmed by fluorescence microscope. The application of CFS of probiotic strains (i.e. Lactobacillus) as antibacterial and biofilm removal compounds could be very suitable to control the growth of food-borne pathogens.