Background:The mecA gene is a key factor that allows bacterial cells to resist several antibiotics. Aim: This study was conducted to detect the mecA gene polymorphism in ovine wounds and its possible association with the structure and function of penicillin binding protein A2 (PBP2A). Methods: One genetic locus of 1,967 bp that covered the majority of the coding regions of the mecA gene within methicillin-resistant Staphylococcus aureus (MRSA) DNA sequences was designed. Results: In addition to standard microbiological tests, PCR-sequencing reactions and phylogenetic analyses confirmed the identity of the targeted MRSA bacteria. Seven novel missense SNPs, including N57T, N115Y, D120N, D139N, G152V, E189K, and F211V, were observed in the mecA amplicons. Multiple state-of-the-art in silico tools were utilized to assess the consequences of each observed SNP in terms of its effect on the corresponding PBP2A protein structure and function. It was shown that some MRSA isolates exhibited a highly PBP2A-damaging SNP, G152V, which showed an entirely deleterious effect on the PBP2A. Furthermore, G152V induced an alteration in the PBP2A interaction with its receptor, which presumably reduced its affinity to bind with the beta-lactams. Conclusion: The present report indicated a possible role for the observed deleterious G152V SNP in the reduction of PBP2A binding with beta-lactams, which has led to a remarkable increase in MRSA's resistance to antibiotics.

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Brucellosis is consider one of the utmost common bacterial infectious illness that infect man and animals. unfortunately, A worldwide community in the developing country didn't provide active assistance for reducing it spread out globally. Therefore, the aim of this study is the synthesis of chitosan nanoparticles loaded with rifampin to overcome bacterial resistance and provide high intracellular penetration and the potential for potent intracellular antibacterial activity. The study was conducted from October 2019 to September 2021, Of 57 positive clinical specimens identified in the present study, 25 (65.78%), 20 (74.07%), and 12 (66.66%) were isolated from vaginal swabs, fetal membranes, and fetal abomasum contents, respectively. From the results of SEM images of NPs, it was clear that RIF-loaded CHNPs presented irregular surfaces or rough with spherical shape and presence of some particle aggregates. The RIF-CHNPs particle size observed using SEM images was 260.54 nm, while the diameter was 150.23 nm. In addition, the antibacterial activity were also measured and the results shows that the MIC values for RIF, CHNPs and RIF-CHNPs and they were 4, 2.5 and 0.625 ug/ml, respectively. While the EE % and DL % of RIF were measured spectrophotometrically. Loaded antibiotic formulation gave good percentage of entrapment efficiency and drug loading at concentration 50 mg/ml. Then the EE % at concentration 50 mg/ml was re-estimated in different pH values and the best EE% was at pH 5. In conclusion, the antibacterial activity of drug nanocarrier against B. melitensis found that it had a relatively low MIC 0.625 ug/ml. whereas the inhibitory concentrations were about 4 μg/ml and 2.5 μg/ml for the RIF and CHTNPs, respectively. Indicating there were 6.4 times reduction in MIC for RIF-CHTNPs and 1.6 time reduction for CHTNPs comparing to MIC of antibiotic alone.