Thursday, November 21, 2019

Staphylococcus and Streptococcus Lab Report Example | Topics and Well Written Essays - 1000 words

Staphylococcus and Streptococcus - Lab Report Example A petri dish containing 1 TSA 5% sheep blood agar was divided in half. A sterile swab was used to swab the throat and skin. A streak inoculation was performed for each sample on each section of the plate, which was incubated for 24 hours at 37 oC.   The resultant colonies were then tested for Gram staining and the presence of alpha, beta, and gamma hemolytic bacteria. This test was performed by observing the presence or absence of red blood cell hemolysis on sheep blood agar. The next test that was performed was the catalase test to determine the production of enzyme catalase. A small amount of the colony was placed on a glass slide after which a few drops of catalase reagent was dropped on the bacteria. The production of bubble indicated a positive test for catalase. The catalase-positive samples were then tested for bacitracin sensitivity by incubating the colonies in four sections of a blood agar plate containing bacitracin discs for 24 hours at 37 oC. A coagulase test was then performed following the observation of bacitracin resistance in the bacteria. This test was performed to detect the production of enzyme coagulase by adding a loop full of the bacteria to tubes containing rabbit plasma and incubating for 24 hours at 37 oC. The coagulase negative samples were further tested for novobiocin susceptibility by incubating the bacteria in plates containing novobiocin antibiotic disks at 37 oC for 24 hours. Novobiocin test is usually used to distinguish between S. epidermidis and S. saprophyticus.

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