Triple Sugar Iron Agar (TSI)

The TSI is a multiple test medium. Its a slanted medium with a deep butt that is used to further investigate Gram-negative microorganisms. It differentiates the microbes by their ability to ferment glucose, lactose and/or sucrose with or without the production of gas and production of hydrogen sulfide. The TSI medium contains three carbohydrates; 1.0% … Continue reading Triple Sugar Iron Agar (TSI)

The Gram Stain

Gram staining is the first step and common technique used to differentiate Gram-positive bacteria and Gram-negative bacteria. Bacterial cell walls contain the constituent peptidoglycan. In the photo above you'll see Staphylococcus aureus gram positive stained purple and Escherichia coli gram-negative stained pink. Bacterial cell walls lack membranes around their organelles. A major component of a … Continue reading The Gram Stain

No Organisms Were Recovered On Buffered Charcoal Yeast Extract Medium After 2 Days of Incubation

Serum samples collected from a patient with pneumonia demonstrate a rising antibody titer to Legionella. A bronchoalveolar lavage (BAL) specimen from this patient had a positive antigen test for Legionella but no organisms were recovered on buffered charcoal yeast extract medium after 2 days of incubation. What is the best explanation? First of all, Legionella is … Continue reading No Organisms Were Recovered On Buffered Charcoal Yeast Extract Medium After 2 Days of Incubation

Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is a generalized activation of homeostasis secondary to a systemic disease. There are multiple different diseases that can activate different homeostatic factors that can contribute to DIC. Conditions such as physical trauma and endothelial cell damage exposing tissue factor that finds its way into circulation; or being exposed to tissue factor … Continue reading Disseminated Intravascular Coagulation

Hemoglobin, What is it?

Function Hemoglobins main function is to carry oxygen to the tissues and cells of the body. Hemoglobin can bind and transport four molecules of oxygen. Hemoglobin is made up of 4 polypeptide globin chains, two alpha and two beta that forms a tetramer heme group with iron located within the tetramer. Globin is the protein … Continue reading Hemoglobin, What is it?