Bacterial Virulence Factors Flashcards
Virulence Factors
Specialized structures or characteristics that improve the ability of an organism to cause invasion. (Actions or toxins)
Adherence
Attachment to host cell’s surfaces, using adhesin proteins and pili.
Bacterial infection vs adherence
Adherence is not infection, the bacteria must colonize tissues and remove material from host cells for it to be infection.
Examples of adhesion infections
Meningitis (Neisseria meningitidis)
Pneumonia (Streptococcus pneumoniae
Hyaluronidase in bacterial invasion
This enzyme digests hyaluronic acid, a glue-like substance that holds cells together in some tissues, allowing bacteria to invade.
Coagulase
Enzyme that causes blood clotting, which protects the infecting bacteria from immune system.
Streptokinase
Enzyme that dissolves blood clots, allowing entry/exit of infecting bacteria.
Toxigenicity
The capability of microbes to produce toxins,
Types of bacterial toxins
Endotoxins - Part of outer membrane of gram negative bacteria, released into host tissue when bacteria die out or divide.
Exotoxins - Soluble substances produced inside some bacteria that are secreted into the host tissues.
Endotoxin structure
Consist of lipid A in a lipopolysaccharide complex. These are normally weak unless release in large doses.
Exotoxin strucutre
Mostly polypeptides and enzymes, and be be cytotoxic, neurotoxic or enterotoxic.
Hemolysin
Protein that causes lysis in red blood cells.
Neurotoxin
These block neuromuscular signaling, such as botulin (botox) blocks acetylcholine activation in the face, and tetanus, prevents acetylcholine release in muscles.
Bacterial skin diseases
Erysipelas - lesions form on skin and spread caused by haemolytic streptococci sp.
Impetigo - highly contagious staphylococci sp, causes open sores on mouth and nose.
Acne
Caused by propionibacterium acnes, feeds on sebum produced by sebaceous glands leaving sores.
Bacterial eye infections
Ophthalmia neonatorum - conjunctivitis in newborns, caused by neisseria gonorrhea and chlamydia trachomatis.
Pinkeye - caused by s. aureus.
Wound infections
Gangrene - mix of two or more bacterial infections. Muscle carbohydrates are fermented and gases produced destroy and distort tissue, turning it blue/green.
Whooping cough
Caused by Bordetella pertussis infection in respiratory tissues.
Pneumonia
Caused by Streptococcus pneumoniae leaving fibrin deposits in lungs.
