en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <p dir="ltr"><strong>Introduction:</strong> <em>Aloe Vera</em> compounds have inhibitory activity on fungi, bacteria, and viruses. This study examines the antibacterial activity of <em>A. Vera</em> purified extracts including gel, boiled skin, boiled gel, and distilled extract against pathogenic bacteria, <em>Staphylococcus aureus</em>, methicillin-resistant <em>S. aureus</em> (MRSA), <em>Klebsiella pneumonia</em> and <em>Pseudomonas aeruginosa</em> were elucidated. <strong>Method:</strong> The bacterial strains were collected from veterinary hospital. Freshly collected <em>A. vera</em> leaves were used for the juice extraction of gel, skin and distilled extracts. Antibacterial effects of various <em>A. Vera</em> extracts were evaluated using broth microdilution method. The crude polysaccharides of boiled skin extract were purified by phenol method; and fractionated by anion exchange chromatography. For each bacterium, minimum inhibitory concentration of various <em>A. Vera</em> extracts was determined. The protein expression changes of treated bacteria were detected by SDS-PAGE electrophoresis. <strong>Results:</strong> The distillate extract exhibited more antibacterial effects than other extracts. Out of seven-carbohydrate fractions of the skin extract, the fractions 6 and 7 had antibacterial effects on <em>S. aureus</em> and MRSA at 0.089 and 0.134 mg/ml, respectively; also fraction 5 showed antibacterial effects on MRSA at 0.113 mg/ml concentration. The protein profiles of these strains before and after treatment with <em>A. Vera</em> showed significant differences at 175, 60, 200 and 70 kDa protein bands of <em>S. aureus</em>, MRSA, <em>P. aeruginosa</em> and <em>K. pneumonia</em>, respectively. <strong>Conclusion:</strong> This finding showed that the distillate extract despite the minimal amount of carbohydrate and protein was more efficient against both Gram-positive and Gram negative bacteria.</p> Aloe Vera, Extracts, Antibacterial 6 10 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-89-2&slc_lang=en&sid=1 Darioush Gharibi d.gharibi@scu.ac.ir No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran Mohammad Khosravi dr.khosravim@gmail.com Yes Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran Zohreh Hosseini hossini895818@gmail.com No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran Fatemeh Boroun dr_mnemati58@yahoo.com No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran Seyedeh Kolsum Barzgar dvm_barzegar@yahoo.com No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran Ali Forughi Far mamad_kh17@yahoo.com No Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran