Summer_Lab_Exam_#3_Review.pptx

MacCONKEY AGAR Is it a selective media? Why? Bile salts and crystal violet dye prevent the growth of Gram positive organisms Is it a differential media? Why? Lactose and neutral red dye allows differentiation between lactose fermentors and non-fermentors On this plate which colony type is a lactose fermentor and which is a non-fermentor? TRIPLE SUGAR IRON AGAR How did the media get it's name? It contains 3 sugars (which 3 and are they all in the same amounts?) and ferrous sulfate (what is this for?) How do you inoculate the media and why? Stab the butt (anaerobic conditions) and streak the slant (aerobic conditions) What compounds in the media make it differential? TRIPLE SUGAR IRON AGAR Interpret the results from each tube A B C D E HEKTOEN ENTERIC AGAR What makes this media selective? Bile salts will not allow Gram positive organisms to grow What makes this media differential? The 3 sugars in the media (what are they?), the two dyes in the media (what are they) and ferric ammonium citrate (what's that for?) A D C B BLOOD AGAR Is this a selective or differential media? Differential (why?) Which plate shows which type of hemolysis pattern and what has happened to the red blood cells in the media? Alpha hemolysis = incomplete lysis Beta hemolysis = complete lysis Gamma hemolysis = no lysis EMB AGAR What does EMB stand for? Eosin and Methylene Blue What is the purpose of these dyes in the media? The dyes inhibit the growth of Gram positive organisms What makes this media differential? Presence of sucrose and lactose plus the 2 dyes A D C B COAGULASE TEST A B Which tube contains a coagulase positive organism? Tube B Does this organism have a bound or free coagulase? The organism could have both. A tube test shows both bound and free coagulase. You would need to do a slide test to determine if the organism has a bound coagulase. A B 1. 2. Which coagulase tube corresponds with which bacteria growing on the Mannitol Salt agar plate? Tube A corresponds with bacteria 1 Tube B corresponds with bacteria 2 What is the bacteria in tube B? Staphylococcus aureus