MMP 201: Bacteria of Medical Importance and Antigens

Staphylococcus aureus Biochemical Tests

Characterized as Catalase-positive and Coagulase-positive, which distinguishes it from other Staphylococci.

Escherichia coli EMB Agar Appearance

Produces a metallic green sheen on Eosin Methylene Blue (EMB) agar due to lactose fermentation.

Neisseria gonorrhoeae Morphology

A Gram-negative diplococcus often described as kidney or coffee-bean shaped.

Salmonella Typhi Characteristic Symptom

Presents with Rose spots, which are faint pink spots found on the trunk of the body.

Shigella dysenteriae Infectious Dose

Requires a very low infectious dose of only 10 to 100 organisms to cause disease.

Vibrio cholerae Toxin Mechanism

Secretes Cholera Toxin (CT), causing hypersecretion of water and electrolytes into the intestinal lumen, leading to rapid dehydration.

Clostridium tetani Morphology

Appears as "drumsticks" under a microscope due to the presence of terminal spores.

Tetanospasmin Function

A potent neurotoxin that blocks the release of inhibitory neurotransmitters such as GABA and Glycine.

Lockjaw (Trismus)

A characteristic symptom of tetanus involving muscle spasms and stiffness that often starts with the chewing muscles.

Epitope

The specific site on an antigen (antigenic determinant) that is recognized and bound by an antibody.

IgM (Immunoglobulin M)

The first class of antibody produced by the immune system during an initial infection.

IgG (Immunoglobulin G)

The most abundant antibody in the body; it provides long-term immunity and is the only class that crosses the placenta.

IgA (Immunoglobulin A)

An antibody found primarily in mucosal secretions such as saliva and breast milk.

B-lymphocyte Function

Responsible for tagging intruding antigens and differentiating into plasma cells to secrete specific antibodies.

Cytotoxic T-cells (CD8^+)

Immune cells that directly target and kill infected host cells.