Haemophilus influenzae
Grows in the blood. Infects the lungs of patients who are weakened by the viral flu infection, and infects children who are at the stage of developing their immune system.
- Virulence factors:
- Polysaccharide capsule, of which there are six types: a, b, c, d, e and f. Capsule b is associated with the disease in children. Bacteria lacking a capsule can only cause local infection.
- Child diseases (type b):
- Meningitis (late-onset).
- Acute epiglottitis, swelling and inflammation of the epiglottis.
- Septic arthritis, where usually only one joint is infected from bacteria in the bloodstream.
Haemophilus ducreyi
Causes the STD, chancroid.
Gardnerella vaginalis
Causes bacterial vaginitis with the presence of anaerobic vaginal bacteria.
Bordetella pertussis
Causes disease by toxin release, not bacteria-cell invasion.
- Exotoxins:
- Pertussis toxin - like most exotoxins, its B subunit binds to the target cell receptors and gain entry. The A subunit activates G protein in target cell membrane and, in turn, activates intracellular messengers such as cAMP. In the case of pertussis, this signal causes:
- Histamine sensitization
- Increased insulin synthesis
- Increased lymphocyte production and inhibition of phagocytosis
- Extra cytoplasmic adenylate cyclase - this toxin is taken up by host neutrophils, lymphocytes and monocytes. Adenylate cyclase synthesizes cAMP, and in this case, weakens the defense cells' ability to lyse and phagocytose.
- Filamentous hemagglutinin (FHA) - pili that are responsible for attachment to bronchi epithelium.
- Tracheal cytotoxin - destroys ciliated epithelial cells, causing more buildup of mucus and bacteria.
- Diseases:
Legionella pneumophila
Infection by airborne bacteria from contaminated water, but not person-to-person transmission. It survives phagocytosis and replicates intracellularly.
- Diseases:
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