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The Online Textbook of Bacteriology is a general and medical microbiology text and includes discussion of staph, MRSA, strep, Anthrax, E. coli, cholera, tuberculosis, Lyme Disease and other bacterial pathogens.
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Web Review of Todar's Online Textbook of Bacteriology. "The Good, the Bad, and the Deadly".

Tag words: bacteria, pathogen, pathogenesis, virulence, colonization, invasion, specific adherence, adhesin, invasin.











Kenneth Todar currently teaches Microbiology 100 at the University of Wisconsin-Madison.  His main teaching interest include general microbiology, bacterial diversity, microbial ecology and pathogenic bacteriology.

Bacillus cereus bacteria.Print this Page

Colonization and Invasion by Bacterial Pathogens (page 4)

(This chapter has 4 pages)

© Kenneth Todar, PhD

Toxins With Short-Range Effects Related to Invasion

Bacterial protein toxins which have adenylate cyclase activity are thought to have immediate effects on host cells that promote bacterial invasion. One component of the anthrax toxin (EF or Edema Factor) is an adenylate cyclase that acts on nearby cells to cause increased levels of cyclic AMP and disruption of cell permeability. One of the toxins of Bordetella pertussis, the agent of whooping cough, has a similar effect. These toxins may contribute to invasion through their effects on macrophages or lymphocytes in the vicinity which are playing an essential role to contain the infection. For example, since they use ATP as a substrate, they may deplete phagocyte reserves of energy needed for ingestion. Edema is seen as a pathology because the increase in cAMP in affected cells disrupts equilibrium.


Gelatinous edema seen in a cutaneous anthrax lesion. CDC.

The following table summarizes the activities of many bacterial proteins that are noted for their contribution to bacterial invasion of tissues.


TABLE 3. SOME EXTRACELLULAR BACTERIAL PROTEINS THAT ARE CONSIDERED INVASINS

Invasin

Bacteria Involved

Activity

Hyaluronidase Streptococci, staphylococci and clostridia Degrades hyaluronic of connective tissue
Collagenase Clostridium species Dissolves collagen framework of muscles
Neuraminidase Vibrio cholerae and Shigella dysenteriae Degrades neuraminic acid of intestinal mucosa
Coagulase Staphylococcus aureus Converts fibrinogen to fibrin which causes clotting
Kinases Staphylococci and streptococci Converts plasminogen to plasmin which digests fibrin
Leukocidin Staphylococcus aureus Disrupts neutrophil membranes and causes discharge of lysosomal granules
Streptolysin Streptococcus pyogenes Repels phagocytes and disrupts phagocyte membrane and causes discharge of lysosomal granules
Hemolysins Streptococci, staphylococci and clostridia  Phospholipases or lecithinases that destroy red blood cells (and other cells) by lysis
Lecithinases Clostridium perfringens Destroy lecithin in cell membranes
Phospholipases  Clostridium perfringens Destroy phospholipids in cell membrane
Anthrax EF  Bacillus anthracis One component (EF) is an adenylate cyclase which causes increased levels of intracellular cyclic AMP 
Pertussis AC Bordetella pertussis One toxin component is an adenylate cyclase that acts locally producing an increase in intracellular cyclic AMP




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Kenneth Todar has taught microbiology to undergraduate students at The University of Texas, University of Alaska and University of Wisconsin since 1969.

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