abdolmajid ghasemian department of bacteriology, faculty of medical sciences, tarbiat modares university, tehran, ir iran; department of bacteriology, faculty of medical sciences, tarbiat modares university, tehran, ir iran. tel: +98-92182883870 shahin najar peerayeh department of bacteriology, faculty of medical sciences, tarbiat modares university, tehran, ir iran bita bakhshi department of bacteriology, faculty of medical sciences, tarbiat modares university, tehran, ir iran mohsen mirzaee department of laboratory sciences, borujerd branch, islamic azad university, borujerd, ir iran