名校医学微生物学28.ppt

Isolation and identification of pyogenic cocci Objective of Experiment To master basic principle and method,which use to isolate and identify pyogenic cocci from clinical specimens. To diagnose clinical disease and guide doctors to select proper medicines . Identified method for Staphylococci Gram-stain Isolation and culture Pure culture Direct identification Direct identification The mannitol fermentation test. The Coagulase Test The Dnase Test The phage typing test Animal Experiment The mannitol fermentation test.  Inoculate the bacteria into a mannitol micro-tube,incubate at 370C for 18h.S.aureus will ferment mannitol to produce acid,which causes the medium to turn yellow. Test of Microbiological experiment While a patient is infected by pathogenic enterobacteria (Salmonella),how to diagnose with microbiological methods in lab? (simple procedure) While a patient is infected by pyogenic cocci,how to diagnose with microbiological methods in lab?(simple procedure) While a patient is infected by influenza virus,how to diagnose with microbiological methods in lab?(simple procedure) The Coagulase Test Coagulase is an enzyme converting fibrinogen into fibrin promoting blood clotting. It might be a virulence factor with the coagulated blood around the bacteria protecting them from the immune system. Coagulase-negative strains are often as pathogenic as coagulase-positive strains. The Slide Coagulase Test The Tube coagulase Test The Dnase Test Inoculate Dnase agar plates with a loop so that the growth is in plaques about 1 cm in diameter.Incubate at 370C overnight.Flood the plate with 1 N hydrochloric acid.Clearing around the colonies indicates Dnase activity.The hydrochloric acid reacts with unchanged deoxyribonucleic acid to give a cloudy precipitate.A few other bacteria,e.g. Serratia,may give a positive reaction. The phage typing test This test is used to trace the infective agent in epidemiology if necessary. It is usually not done