Microbiology Quiz 7

Disease causing microorganism

Development of disease

Ability to cause disease by evasion (escaping or protecting) from the host defenses

An abnormal state in which the body is not functioning normally

Disease caused by a pathogen

Study of the cause of a disease

Agent causing a disease

May be present for days, weeks, months, and then disappear

Permanently colonize the host; is normal; doesnt cause disease in healthy individual

Microbes don't cause any disease in healthy individual, but under other conditions

Competition among microbes (observed b/w normal microbiota and pathogens) for common factors required for growth

1. Reducing avaliability of nutrients/ growth factors2. Occupying receptors on host tissue3. Changing pH/ O2 Concentrations4. Producing toxins for pathogens

Presence of pathogen in body when it is normally not there

1. Entry of pathogen in teh body (infection)2. Adhesion of pathogen to host tissue3. Survival or pathogen against hot defense and invasion: virulence and virulent factors4. Development of diease

Location: Respiratory tract, urogenital tract, conjuntiva of eye, GI tract

2nd most common portalentry through pore, hair follicle, digesting keratin layer of skin w/ enzymes, burrow in skin (some helminths)

Some viruses (HIV)Some bacteria, some protozoa Check mother's antibodies to seeSome infection --> mental retardation, miscarriage

Direct entry of pathogen in teh blood or deep in the tissueThrough cuts/ wounds, damaged physical barrier, contaminated blood transfusion, contaminated needles, bites of insects/ animals

Strength of a pathogen, ability for it to escape from host defenses

the number of pathogens required to infect 50 percent of test population, lower value= more virulent

Attachment of pathogen to the receptors of host tissue

Forms blood clots (prevents bacteria from host defenses)

Dissolves blood clots (invasion/ spread of pathogen inside the body)

Dissolves collagen (helps bacteria invasde)

Immunoglobulin A (antibodies) Help recognize pathogen. Proteases dissolve protein (destroys IgA antibody) mechanism for some pathogens to escape the immune system (protection)

Dissolves keratin (invasion)

Hyauronic acid helps epithelial cells stick together; this enzyme destroys these cells and helps in invasion

Ability of microbe to produce toxin

Produce inside mostly gram positive bacteria s part of their growth and metabolism. Secreted/ release followed lysis into surronding medium.

part of outer portion of the cells wall (lipid A) of GM- bacteria. They are liberated when the bacteria die and the cell wall breaks apart (lysis of cell wall)

Exo- Gram Positive Endo- Gram negative

Endo- Lipid A)

Exo- heat labile (less stable, easily destroyed by heat) Endo- heat stable

Endotoxins (pyrogen)

Exo- very high LD 50, endo- ow lethal dose; potency of toxic is inversely porportional to LOD50