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35 Cards in this Set
- Front
- Back
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Flora |
A population of microbes inhabiting the outside or inside surfaces of people and other animals |
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Resident Flora |
Organisms that colonize for months or years (gut flora) |
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Transient Flora |
organisms that colonize the host only temporarily (dont cause harm) |
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Symbiosis |
Flora living on or within the host, neither are harmed or both receive equal benefits |
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Pathogen |
Flora living on or within the host that harms the host (cause disease) |
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Normal Flora |
Microbes commonly found in body sites of healthy people (symbiotic only) |
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Pathogenicity
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an organisms ability to invade host tissue, alter the hosts health and cause disease
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Virulence |
the degree of pathogenicity of an organism |
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Virulence factors |
properties of an organism that cause disease |
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Opportunists
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organisms considered part of the usual flora which under certain circumstances can cause disease
- habitat is damaged - habitat is disturbed or changed - host immune system is weakened or compromised (HIV, diabetes) |
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Phagocytosis |
Neutrophils are drawn to the site of infection by a chemical signal, attach to the organism, ingest the organism and kill it with cytokines like hydrogen peroxide |
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Epidemiology |
the study of how infectious disease is spread in a community |
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Origin of human microbial flora |
The fetus is in a sterile environment before birth, within the first few days of life, the exposure to microorganisms begins the establishment of normal microbial flora within the infant |
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# of organisms colonizing the human body |
- 100 trillion organisms colonize human at any given time
- hundreds of different species - 3 pounds of body weight is due to bacteria - 25% of deaths per year, due to infectious disease (malaria, cholora, tuberculosis) |
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4 stages of disease progression |
1. Incubation period - asymptomatic, don't know you are sick 2. Prodromal phase - vaguely aware of sickness, starting to feel "under the weather" 3. Acme period - bad symptoms, seek medical treatment, antibiotics 4. Period of decline - begin to feel better, symptoms begin to cease |
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Roles of Normal Flora |
- stimulates antibody production in the host
- competes with pathogens for nutrients, keeping pathogens suppressed
- help in synthesis of vitamins (vitamin k)
- aid in normal metabolism |
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Development of disease |
1. Pathogen makes contact with host tissue - will colonize or deteriorate 2. Immune system determines if infection progresses - Immunity lines of defense 3. Disease becomes acute and short lived - body heals self 4. Disease becomes chronic (ex. - C-diff.) 5. Infection is evaded |
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Immunity lines of defense |
1st - mucus, pH, etc.
2nd - phagocytosis
3rd - antibodies |
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Fatty Acids |
lower the pH of skin |
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Natural Immunity |
physical and chemical barriers, blood proteins, phagocytosis |
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Adaptive Immunity |
lymphocytes and antibodies |
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Routes of Disease Transmission |
- Inhalation - Ingestion - Close contact - Injection |
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Inhalation (Route of disease transmission) |
* Airborne/droplet transmission * Sneezing, coughing, talking * Viral disease - influenza, rhinovirus (common cold) * Bacterial disease - Strep. pneumonia (most common), tuberculosis |
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Ingestion (Route of disease transmission) |
* Most common from contaminated food/water (fecal-oral route) * Damages lining of GI tract with toxins, or by invading tissue/outnumber normal flora * Bacterial toxin producers --Clostridium botulinum --Bacillus cereus --Staph. aureus * Viruses -- Hepatitis A * Parasites -- Cryptosporidium |
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Close Contact (Route of disease transmission) |
* Passage by salivary, skin, and genital contact
-- Salivary: Herpes simplex virus, Epstein-Barr virus (infectious mononucleosis)
-- Skin/Genital: Human Papillomavirus (HPV), Syphilis, Chlamydia (most common STD, 900k per year), HIV, Neisseria gonorrhoeae, Trichomonas |
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Injection (Route of disease transmission) |
* Cuts (broken glass), punctures (needlesticks), bites
- Bites: --Plasmodium (malaria from mosquito) --Pasteurella multocida (normal in dogs, dangerous to humans) --Eikenella spp. (human bites) -- HIV and Hepatitis B (viral, blood transmission)
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Hyaluronidase |
Enzyme that breaks down collagen (tissue cement), allows bacteria to spread easier |
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Streptokinase |
Enzyme that dissolves clots, allowing pathogen to spread easier.
Strep A - strep throat |
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Leukocidins |
Enzyme that destroys neutrophils and macrophages.
Staph. aureus |
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Beneficial roles of microorganisms on the environment |
- bacteria break down dead tissue - fungi break down decaying vegetation - metabolic activities affect plants and animals - useful in food production and biotechnological processes
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Harmful roles of microorganisms on the environment |
water contamination - 7 cholera pandemics - bacterial, viral, parasitic
food contamination |
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Saprophytic |
lives on decaying matter - penicillin |
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3 types of water pollution |
Physical (sand and soil) - phosphates
Chemical (copper and acids) - pesticides
Biological - human and animal waste or dead things |
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Biofilm |
community of bacteria living together that act as a whole. These easily transmit information to one another and can be VERY resistant and resist phagocytosis. - share metabolic pathways, by-products and nutrients |
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Quorum sensing |
when chemical signals are produced that alter gene activity. - allows bacteria to transmit resistance strategies to other members of the biofilm |
