Occurrence, Phenotypic and Molecular Characteristics of Vancomycin-Resistant Enterococci Isolated from Retail Raw Milk in Egypt

Future impact of thymoquinone-loaded nanoemulsion in rabbits: prospects for enhancing growth, immunity, antioxidant potential and resistance against Pasteurella multocida

Phytochemical nanoemulsions, such as thymoquinone nanoemulsions (TQN), are regarded as innovative alternatives to antimicrobials that significantly improve the performance, digestion, antioxidant potential and immunity of rabbits. Thus, the potential effects of TQN on growth, digestibility, antioxidant potential, immunity and resistance against Pasteurella multocida (P. multocida) in rabbits were assessed. Herein, 240 rabbits were offered either a basal diet or diets fortified with three TQN-graded concentrations. At 60 days of age, rabbits were challenged with multidrug-resistant (MDR) virulent P. multocida strain. Our outcomes described that dietary inclusion of TQN, especially at higher concentrations, significantly enhanced the growth performance of rabbits, which was supported by increasing the levels of jejunal lipase, amylase and trypsin enzymes. Of note, the levels of muscle and jejunal antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and total antioxidant capacity (T-AOC)], serum immunological markers (IgG, IgG, IgM and total Igs) and blood phagocytic percentage were significantly provoked after TQN fortification; meanwhile, the levels of muscle and jejunal MDA, serum biochemical parameters (total cholesterol, TG and LDL), abdominal fat percentage, breast and thigh cholesterol were significantly decreased following TQN supplementations. Our findings showed that TQN protected rabbits against P. multocida experimental challenge as evidenced by reducing P. multocida counts in rabbits' lungs, downregulating the transcription levels of P. multocida virulence-related genes (ptfA, toxA and nanB) at 48 and 96 h post-infection and ameliorating the expression levels of cytokines-related genes (IL-1β, IL-10, IL-8, IL-6, DEFB1, TNF-α, TLR-4 and TLR-2) at 96 h post-infection. Our findings suggest the utilization of TQN in rabbits' diets due to their stimulating effects on digestibility as well as their growth-promoting, anti-inflammatory, antioxidant, antibacterial, anti-virulence and immunostimulant properties, which enhance the rabbits' P. multocida resistance.

Antibiotic Resistance Characterization and Molecular Characteristics of Enterococcus Species Isolated from Combination Probiotic Preparations in China

Enterococci can act as reservoirs for antibiotic-resistant genes that are potentially at risk of being transferred to other bacteria that inhabit in the gastrointestinal tract. The aim of this study was to determine the phenotypic and molecular characteristics of antibiotic-resistant enterococci isolated from probiotic preparations. In total, we isolated 15 suspected Enterococcus species from 5 compound probiotics, which were identified by 16S rDNA as 12 Enterococcus faecium and 3 Enterococcus faecalis. Determination of antimicrobial susceptibility by the microdilution broth method showed widespread resistance to sulfamethoxazole (100%), norfloxacin (99.3%), azithromycin (99.3%), gentamicin (86.7%), and chloramphenicol (20%). Whole genome sequencing of five resistant strains revealed that all had circular DNA chromosomes and that E. faecium J-1-A to J-4-A contained a plasmid, while E. faecalis J-5-A did not. The results of the resistance gene analysis revealed that each strain contained approximately 30 resistance genes, with the antibiotic resistance genes and the multidrug resistance efflux pump genes mdtG, lmrC, and lmrD detected in all strains. The chloramphenicol resistance genes ykkC and ykkD were first identified in E. faecalis. And there were 21, 19, 21, 21, and 29 virulence factors involved in strains, respectively. Further analysis of the gene islands (GIs) revealed that each strain contained more than 10 GIs. The above results confirm the existence of hidden dangers in the safety of probiotics and remind us to carefully select probiotic preparations containing enterococcal strains to avoid the potential spread of resistance and pathogenicity.

Enterococci in the dairy and sausage industry: Is sanitation sufficient to remove biofilm?

Enterococcus spp. were isolated from sausage and yogurt line production. The genomic assay was performed by PCR, and distinct enterococci (n = 28) were identified. Testing revealed that 10.7% of the isolates had a resistant phenotype, 7.1% were resistant to erythromycin (Enterococcus faecium) and 3.5% were resistant to tetracycline (Enterococcus gallinarum). Enterococci cells and biofilm formation in 24 well polystyrene plates and the effect of sanitisation procedures in these biofilms were determined. The sanitisers were chlorinated alkaline H (CAH), chlorinated alkaline A (CAA), quaternary ammonium D (QAD), quaternary ammonium M (QAM), chlorine dioxide (CD), sodium hypochlorite (SH), and peracetic acid (PA). A total of 7 isolates (25%) moderately and the others poorly formed biofilms. The best reduction results were 61 and 55% of the cells with the CAH sanitiser in BHI and water, respectively. The PAA, SH, and CD sanitisers showed low efficiency on Enterococcus planctonics, and the other had an effect on cell growth. The sanitisers CAH, QAD, QAM, PAA, and SH showed efficiency in reducing the cell viability of Enterococcus in biofilms, and values obtained from CAA and CD suggested low biofilm removal capacity. Enterococcus spp. form biofilms and have become a problem in the food industry.