Chapter 14: Pathogensis of Infectious Diseases (Incomplete)

Receptor and Integrin

• general terms used to describe molecule on the surface of a host cell that a particular pathogen is able to recognize and attach to

Adhensin and ligand

• the general terms used to describe a molecule on the surface of a pathogen that is able to recognize and bind to a particular receptor

Fimbrae

• considered to be virulence factors because they enable bacteria to attach to surfaces including various tissues within the human body

Obligate Intracellular Pathogens

• must live within host cells to survive and multiply

Rickettsias and Chlamydias

Example of an Obligate Intracellular Pathogen:

Facultative Intracellular Pathogen

• capable of both an intracellular and extracellular existence

Capsules

• considered to be virulence factors becayse they serve as an antiphagocytic fucntion

Flagella

• considered to be virulence factors becase they enabe motile bacteria to invade aqueous areas of the body that nonmotile bacteria are unable to reach

Exoenzymes

• The major mechanisms by which pathogens cause disease are certain______ or toxins that they produce

Nectrotizing enzymes

• many pathogens produces exoenzymes that destroy tissues

Coagulase

• is a virulence factor that causes clotting

Kinases

• also known as fibrinolysins

• are exoenzymes that dissolves clots

Streptokinase and Staphylokinase

• two types of kinases - produced by streptococci and staphylococci respectively.

Hyaluronidase

• “spreading factor”

• enables pathogens to spread through connective tissue by breaking down hyaluronic acid

Hyaluronic acid

• the polysaccharide “cement” that holds tissue cells together

Collagenase

• produced by pathogens that breaks down collagen

• this enables pathogens to invade tissues

Hemolysins

• are enzymes that cause damage to the host’s red blood cells (erothrocytes)

Lecithinase

• an enzyme produced by C.perfringes, that breaks down phospholipids that are collectively referred to as lecithin.

Endotoxins

• integral parts of the cell walls of Gram-negative bacteria

• can cause a number of adverse physiologic effects

Exotoxins

• toxins that are produced within the cells and then released from the cells

Septicemia

• a very serious disease consisting of chills, fever, prostration, and the pressence of bacteria or their toxins in the bloodstream

Pyrogens

• substances that cuases fever

Septic shock

• the type of shock that results from Gram-negative sepsis.

Exotoxins

• poisonous proteins that are secreted by a variety of pathogens

Neurotoxin

• most potent exotoxin

• affects the central nervous system (CNS)

Clostridium tetani and Clostridium botulinum

• they produce neurotoxins

Enterotoxins

• are toxins that affects the gastrointestinal tract, often causing diarrhea and sometimes vomitting

Exfoliative toxin

• causes the epidermal layers of skin to slough away

• leads to a disease known an Scalded Skin Syndrome

Erythrogenic Toxin

• produced by some strains of S.pyogenes that causes scarlet fever

Diphtheria toxin

• produced by toxigenic strains of C. Diphteriae, inhibits protein synthesis

• kills mucosal epithelial cells and phagocytes and adversely affects the heart and nervous system