The role of nanostructured surface layer and production of β- lactamase in penicillin resistant Bacillus cereus strains

S-layer proteins form the outermost cell envelope component of a broad spectrum of bacteria and archaea which inhibits antibiotic entry into the bacterial cells. The aim of this research was to study the role of nanostructured surface layer and production of β– lactamase in penicillin resistant Bacillus cereus strains isolated from staff hands and hospital surfaces. This research was carried out on 274 samples during the years 2005-2007 in Azzahra hospital and Isfahan University. Bacterial strains were cultured in TSA for 16 h then surface proteins were separated using electrophoresis with 10X SDS-PAGE. Antibiogram was performed according to Kirby Bauer method. β–lactamase production was investigated using acidimetric method. Isolation frequency of B. cereus strains was %9.49. Eleven (84/6%) and one (7/7%) strains of B. cereus isolated from staff hands and hospital surfaces were producer of nanostructured surface layer respectively. Unlike to S-layer producer strains, non S-layer producer strains were more sensitive to antibiotics. All S-layer producer strains produced β–lactamase. A high prevalence of β–lactamase and S-layer producer B. cereus strains was observed in our setting that can contribute to an increase of the antibiotic resistance in nosocomial infection.