MPharm Year 1_lab_pract_lecture MW.pptx

Introduction to Clinical / Medical Microbiology Dr Murphy Wan [email protected] SM 4.24 x 2114 Laboratory safety Codes of practice – Entering/exiting the lab – Operating within the lab – Working at the bench – Spills – Disposal of tools, etc… – Cleaning area – Leaving the bench Main areas covere...

Introduction to Clinical / Medical Microbiology Dr Murphy Wan [email protected] SM 4.24 x 2114 Laboratory safety Codes of practice – Entering/exiting the lab – Operating within the lab – Working at the bench – Spills – Disposal of tools, etc… – Cleaning area – Leaving the bench Main areas covered in this lab practical Aseptic techniques Cultivation of bacteria on agar Biochemical characteristics – Selective and differential media Gram staining and morphology – Gram staining – Morphological characteristics Aseptic Technique Method used to prevent the transmission of unwanted organisms Microorganisms are everywhere! In the environment and in and on your body Minimize/ eliminate contamination e.g. bench, air How? Using bunsen burner Culture of Bacteria on Solid Medium Single isolated bacteria on the surface of solid media may grow and divide giving rise to bacterial colonies of characteristic appearance. Procedures Preparation of a Nutrient Agar Plate – Take a sterile Petri dish and label the base with your name and the date – Pour the molten agar into the dish and leave to set with the lid on. Spreads a plate with Staphylococcus aureus Aseptic pouring of agar plates Sterilising innoculating loops Quadrant streak pattern for achieving single colonies Label the agar plates (on agar side): Initial, date, organism (Staphylococcus aure Flaming loop Flaming loop Make zig-zag streaks without flaming loop Preparation of bacterial smear For bacteria to be visualised under the microscope they must first be transferred onto the surface of a microscope slide and secured there prior to staining. The transfer of organisms from culture to slide is achieved using the inoculating loop. A bacterial smear may be prepared from either liquid (broth) or solid (agar) culture. Procedures ***Use forceps to hold the slide Gram staining A method to differentiate bacterial species to two large groups (Gram positive and Gram negative) Always the first step for identification of unknown bacteria Gram stain status is important in medicine: the presence or absence of cell wall will change the bacterium’s subseptibility to some antibiotics Overview of G+ and G- 14 Gram staining S. aureus given for gram staining Gram stain results You have been provided with 10 Gram stained (already prepared and stained). Look at as many of the stains as possible and record the Gram stain colour, the shape of the bacteria and their arrangement (for example pairs, chains etc