ABSTRACT
S-layer is the outer protein layer in the most archaea and bacteria. S-layer protects bacteria against phagocytosis and prohibits entry of some biomolecules and some antibiotics and adhesion to matrix proteins. S-layer is a virulence agent in bacteria, beta-lactamase can inactive [beta-lactame antibiotics. According to role of beta-lactame antibiotics in the treatment of infectious diseases with Bacillus spp., increasing frequency of S-layer and beta-lactamase producer Bacillus cereus strains in hospitals lead to increase antibiotic resistant nosocomial infections. In this basic study, 274 samples were evaluated with laboratory methods in Alzahra hospital and Isfahan University between 2004 and 2006. Bacterial identification was performed with microbiological methods, such as staining, chemical test, use of differential and selective Bacillus cereus selective agar media. Bacteria cultured in TSA for 16h, and then separated surface proteins, and finally electrophoresis was performed. S-layer in Bacillus cereus has 97KD molecular weight. Production of beta-lactamase was evaluated by acidometric method. Of 247 isolated bacteria, frequency of Bacillus cereus strains, S-layer and beta-lactamase in S-layer producer Bacillus cereus strains were 9.49%, 46.20% and 100%, respectively. Results showed high prevalence of nano structure S-layer and beta-lactamase producer Bacillus cereus strains in hospital. We recommend controlling bacterial population in crowded places and health and therapeutic centers to decrease producing antibiotic resistance bacteria