Pathogenics of Microbioloy

Q: Ammensalism

Host is harmed, microbe does not benefit or get harmed.

Q: Resident microbiota

Permanently colonize the host (normal flora).

Q: Transient microbiota

Temporarily colonize the host (normal flora).

Q: T or F: Normal flora produce disease under normal conditions.

False, no disease under normal conditions.

Q: Distribution & composition of normal flora is determined by following factors:

1. Nutrients - product of cells, bodily fluids, food in GI. 2. Physical + chemical factors - temp, pH, O2, CO2, salt, sunlight. 3. Mechanical factors - chewing, peristalsis, action of resp. system. 4. Other "host" factors - age, nutritional status, disability, stress, hygiene, lifestyle, geography.

Q: Facts about resident microbiota of Upper Respiratory Tract.

- Nose is cooler than rest of tract, has unique microbiota. - Nose/mouth has more than trachea/bronchi. - Alveoli have no natural microbiota.

Q: Facts about resident microbiota of Upper Digestive Tract.

- Microbes colonize surface of teeth, gingiva, cheek lining & pharynx. - Large amt in saliva. - Dozens of species have never been identified.

Q: Facts about resident microbiota of Lower Digestive Tract.

- Bacteria are mostly strict anaerobes. - Some facultative anaerobes.

Q: Facts about resident microbiota of Female Urinary + Repro. System.

- Microbiota change as acidity of vagina changes during period.

question

Interactions between a microbe and host ...

answer

Few are actually pathogenic, many microbes benefit the host or colonize host without causing disease.
-- 10 trillion human cells < 100 trillion bacterial cells.

question

Do host factors greatly influence relationship between microbe and the host?

answer

Yes

question

Saprophytic mycobacteria - live on secretions & sloughed-off cells causing no benefit or harm to host.

answer

Commensalism

question

E. coli in large intestine synthesizing Vitamin K; large intestine provides ___ to E. coli.

answer

Mutualism

question

Tuberculosis bacteria in human lung.

answer

Parasitism

question

Ammensalism

answer

Host is harmed, microbe does not benefit or get harmed.

question

Resident microbiota

answer

Permanently colonize the host (normal flora).

question

Transient microbiota

answer

Temporarily colonize the host (normal flora).

question

T or F: Normal flora produce disease under normal conditions.

answer

False, no disease under normal conditions.

question

Distribution & composition of normal flora is determined by following factors:

answer

1. Nutrients - product of cells, bodily fluids, food in GI.
2. Physical + chemical factors - temp, pH, O2, CO2, salt, sunlight.
3. Mechanical factors - chewing, peristalsis, action of resp. system.
4. Other "host" factors - age, nutritional status, disability, stress, hygiene, lifestyle, geography.

question

Facts about resident microbiota of Upper Respiratory Tract.

answer

- Nose is cooler than rest of tract, has unique microbiota.
- Nose/mouth has more than trachea/bronchi.
- Alveoli have no natural microbiota.

question

Facts about resident microbiota of Upper Digestive Tract.

answer

- Microbes colonize surface of teeth, gingiva, cheek lining & pharynx.
- Large amt in saliva.
- Dozens of species have never been identified.

question

Facts about resident microbiota of Lower Digestive Tract.

answer

- Bacteria are mostly strict anaerobes.
- Some facultative anaerobes.

question

Facts about resident microbiota of Female Urinary + Repro. System.

answer

- Microbiota change as acidity of vagina changes during period.

question

Facts about resident microbiota of Male Urinary + Repro. System.

answer

- Urine flow prevents extensive colonization of urinary bladder or urethra.

question

Facts about resident microbiota of Eyes + Skin.

answer

- Live on outer, dead layers of skin & hair follicles/pores of glands.
- Deeper layers (dermis / hypodermis) are axenic.
- Tears cleanse eyes, so few compared to skin.

question

Microbial Antagonism

answer

Normal flora benefits host by preventing growth of pathogenic microbes.

question

How does microbial antagonism occur?

answer

- Competes with pathogen for nutrients.
- Produces substances harmful to pathogen.
- Manipulates host environment by inc/dec pH or O2 levels.

question

When balance between normal flora + pathogenic microbes are altered...

answer

disease can occur. AKA microbial antagonism fails.
- May be caused by age, changes in hygiene, nutritional status, etc...

question

Bacteriocins

answer

Proteins produced by E. coli that inhibit growth of closely related species of bacteria (ie: Salmonella, Shigella).

question

The presence of ___ ___ in large intestine inhibit growth of C. diff.

answer

normal flora

question

C. difficile causes

answer

GI problems (mild diarrhea to severe-fatal colitis).

question

This allows for an environment conducive to C. diff growth, resulting in disease.

answer

Antibiotic-mediated destruction of GI normal flora.

question

Opportunistic infections occur when: (3)

answer

1. Microbes from normal flora move from their normal habitat - causing disease.
2. Immunocompromised or weakened.
3. Changes occur in composition of host normal flora (shift of abundance of NF).

question

A. Damage of Host Cells
B. Contact + Exposure
C. Evasion of Host Defences & Penetration
D. Adherence.
E. Transmission.

answer

B, D, C, A, E

question

Contact + Exposure:
3 Portals of Entry [for pathogen to enter body]

answer

1. Mucous Membranes (tracts, eyes)
2. Skin (natural openings)
3. Direct deposition beneath membranes + skin (trauma, surgery).

question

Adherence (pathogenesis)

answer

How pathogen attaches to host tissues at portal of entry.

question

What are adhesins?

answer

Cell surface molecules located on pathogens that bind to receptors on host tissue cells.
(Host specific + tissue-specific).

question

P-fimbriae [pili / flagella] on pyelonephritogenic E. coli adhere to ...

answer

specific galactose disaccharide found on surface of uroepithelial cells (cause 90% of UTIs).

question

What 3 mechanisms aid with pathogen adherence?

answer

1. Bacterial structures (flagella, cili).
2. Adherence proteins (M-protein, Opa protein).
3. Glycocalyx (capsule - firmly attaches to cell wall, slime layer - loosely attaches).

question

When a colony of bacteria are adhered to surface via extracellular slime layer (ie: teeth).

answer

Biofilms.

question

T/F: Biofilms make bacteria easy to disinfect.

answer

False. Biofilms make microorganisms highly resistant to disinfectants & antibiotics. Shelter them from host defences. (Sx intervention is a tx.)

question

Mechanisms of adhesion _____ to evasion of host defenses.

answer

contribute

question

4 mechanism that contribute to host defense evasion.

answer

1. Capsule
2. Cell wall
3. Coagulase
4. Kinase

question

How does coagulase contribute to evasion from host defenses?

answer

- Coagulate fribrinogen in blood to form fibrin.
- Fibrin clots protect bacteria from phagocytosis + isolate microbes from host defence.
- Produced by some Staph spp.

question

How does kinase contribute to evasion from host defenses?

answer

- Degrades fibrin, digest clots formed by body to isolate wound + bacterial clots as protection from phagocytosis.
- Facilitate microbes ability to evade defenses + enter host.

question

Facultative intracellular bacteria can survive INSIDE immune cells by: (4)

answer

1. Escaping phagosomes before fusing with host lysosomes.
2. Preventing phagosome-lysosome fusion.
3. Reducing effectiveness of toxic compounds with lysosomes.
4. Producing cell walls resistant to lysosomal proteases.

question

How does HYALURONIDASE contribute to penetration of host tissues?

answer

Degrades hyaluronic acid (holds host cells together) and allows bacteria to penetrate deeper into host tissues.

question

How does COLLAGENASE contribute to penetration of host tissues?

answer

Degrades collagen fibres at base of superficial tissues & allows bacteria to move further into the host.

question

Invasins

answer

Rearrange actin-filaments in epithelial cells of intestinal lumen.

question

T/F: Some bacteria enter host cells that are NOT phagocytic.

answer

True.
(Some can rearrange filaments, induce an inflammatory response or membrane ruffling).

question

How to pathogens benefit from penetration of tissues (move from blood into tissues)?

answer

- Lots of nutrients.
- Protected from immune system.
- Partial protection from antibiotics.

question

4 mechanisms that cause host cell damage after further penetration into tissues:

answer

1. Appropriating host nutrients.
2. Directly damage tissues surrounding invasion site.
3. Produce toxins.
4. Induce hypersensitive rxns.

question

Microbial iron deficiency

answer

Occurs when pathogenic bacteria deplete iron from iron-transport proteins in blood.

question

Siderophores

answer

Secreted by invading bacteria, bind to iron more tightly than host iron-transport proteins.
- Binding releases toxins that kill host cells + release Fe.

question

Exotoxins

answer

Enzymatic proteins made inside some living pathogenic bacteria as normal part of growth.
- rapidly transported thru host.
- secreted into surroundings or released during lysis.

question

Ingestion or exposure to endotoxin-producing bacteria may cause

answer

disease

question

A-B Toxins

answer

A & B polypeptides.
A = active ez.
B = binding component.

question

Membrane-Disrupting Toxins

answer

Induce cell lysis via formation of protein channels or disruption of phospholipid layer of cell membrane.

question

Superantigens

answer

Provoke intense immune response.
- Not processed inside macrophages, bind directly to macrophage surface.
- Results in excessive IL-2, TNF, TF production.
[Fever, N&V, diarrhea, shock, sometimes death].

question

Endotoxins -- Lipid A

answer

Released when Gram-Neg (PINK) bacteria are killed or multiply - caused by cell wall lysis.

question

Disseminated intravasacular coagulation [DIC]

answer

Obstructive clots in capillaries inducing tissue death.

question

Meningitis is caused by which group of toxins?

answer

Endotoxins

question

Botulism is caused by ingestion of which group of toxins?

answer

Exotoxins

question

Exotoxins do not cause fever, because an exotoxin - not a bacteria - has been ingested.
What is the one exception?

answer

Superantigens

question

Toxin increase cAMP in respiratory epithelial cells, causes increased mucous production + coughing.

answer

Bordetella pertussis

question

T/F: Different endotoxins produce different signs and symptoms with each pathogen.

answer

False: Common mechanism of action causes all endotoxins to have the same signs/symptoms, regardless of pathogen.

question

Increased production of TF activates the extrinsic + intrinsic coagulation cascade, causing...

answer

DIC

1 of 58

question

Interactions between a microbe and host ...

answer

Few are actually pathogenic, many microbes benefit the host or colonize host without causing disease.
-- 10 trillion human cells < 100 trillion bacterial cells.

question

Do host factors greatly influence relationship between microbe and the host?

answer

Yes

question

Saprophytic mycobacteria - live on secretions & sloughed-off cells causing no benefit or harm to host.

answer

Commensalism

question

E. coli in large intestine synthesizing Vitamin K; large intestine provides ___ to E. coli.

answer

Mutualism

question

Tuberculosis bacteria in human lung.

answer

Parasitism

question

Ammensalism

answer

Host is harmed, microbe does not benefit or get harmed.

question

Resident microbiota

answer

Permanently colonize the host (normal flora).

question

Transient microbiota

answer

Temporarily colonize the host (normal flora).

question

T or F: Normal flora produce disease under normal conditions.

answer

False, no disease under normal conditions.

question

Distribution & composition of normal flora is determined by following factors:

answer

question

Facts about resident microbiota of Upper Respiratory Tract.

answer

- Nose is cooler than rest of tract, has unique microbiota.
- Nose/mouth has more than trachea/bronchi.
- Alveoli have no natural microbiota.

question

Facts about resident microbiota of Upper Digestive Tract.

answer

- Microbes colonize surface of teeth, gingiva, cheek lining & pharynx.
- Large amt in saliva.
- Dozens of species have never been identified.

question

Facts about resident microbiota of Lower Digestive Tract.

answer

- Bacteria are mostly strict anaerobes.
- Some facultative anaerobes.

question

Facts about resident microbiota of Female Urinary + Repro. System.

answer

- Microbiota change as acidity of vagina changes during period.

question

Facts about resident microbiota of Male Urinary + Repro. System.

answer

- Urine flow prevents extensive colonization of urinary bladder or urethra.

question

Facts about resident microbiota of Eyes + Skin.

answer

- Live on outer, dead layers of skin & hair follicles/pores of glands.
- Deeper layers (dermis / hypodermis) are axenic.
- Tears cleanse eyes, so few compared to skin.

question

Microbial Antagonism

answer

Normal flora benefits host by preventing growth of pathogenic microbes.

question

How does microbial antagonism occur?

answer

- Competes with pathogen for nutrients.
- Produces substances harmful to pathogen.
- Manipulates host environment by inc/dec pH or O2 levels.

question

When balance between normal flora + pathogenic microbes are altered...

answer

disease can occur. AKA microbial antagonism fails.
- May be caused by age, changes in hygiene, nutritional status, etc...

question

Bacteriocins

answer

Proteins produced by E. coli that inhibit growth of closely related species of bacteria (ie: Salmonella, Shigella).

question

The presence of ___ ___ in large intestine inhibit growth of C. diff.

answer

normal flora

question

C. difficile causes

answer

GI problems (mild diarrhea to severe-fatal colitis).

question

This allows for an environment conducive to C. diff growth, resulting in disease.

answer

Antibiotic-mediated destruction of GI normal flora.

question

Opportunistic infections occur when: (3)

answer

1. Microbes from normal flora move from their normal habitat - causing disease.
2. Immunocompromised or weakened.
3. Changes occur in composition of host normal flora (shift of abundance of NF).

question

A. Damage of Host Cells
B. Contact + Exposure
C. Evasion of Host Defences & Penetration
D. Adherence.
E. Transmission.

answer

B, D, C, A, E

question

Contact + Exposure:
3 Portals of Entry [for pathogen to enter body]

answer

1. Mucous Membranes (tracts, eyes)
2. Skin (natural openings)
3. Direct deposition beneath membranes + skin (trauma, surgery).

question

Adherence (pathogenesis)

answer

How pathogen attaches to host tissues at portal of entry.

question

What are adhesins?

answer

Cell surface molecules located on pathogens that bind to receptors on host tissue cells.
(Host specific + tissue-specific).

question

P-fimbriae [pili / flagella] on pyelonephritogenic E. coli adhere to ...

answer

specific galactose disaccharide found on surface of uroepithelial cells (cause 90% of UTIs).

question

What 3 mechanisms aid with pathogen adherence?

answer

1. Bacterial structures (flagella, cili).
2. Adherence proteins (M-protein, Opa protein).
3. Glycocalyx (capsule - firmly attaches to cell wall, slime layer - loosely attaches).

question

When a colony of bacteria are adhered to surface via extracellular slime layer (ie: teeth).

answer

Biofilms.

question

T/F: Biofilms make bacteria easy to disinfect.

answer

False. Biofilms make microorganisms highly resistant to disinfectants & antibiotics. Shelter them from host defences. (Sx intervention is a tx.)

question

Mechanisms of adhesion _____ to evasion of host defenses.

answer

contribute

question

4 mechanism that contribute to host defense evasion.

answer

1. Capsule
2. Cell wall
3. Coagulase
4. Kinase

question

How does coagulase contribute to evasion from host defenses?

answer

- Coagulate fribrinogen in blood to form fibrin.
- Fibrin clots protect bacteria from phagocytosis + isolate microbes from host defence.
- Produced by some Staph spp.

question

How does kinase contribute to evasion from host defenses?

answer

- Degrades fibrin, digest clots formed by body to isolate wound + bacterial clots as protection from phagocytosis.
- Facilitate microbes ability to evade defenses + enter host.

question

Facultative intracellular bacteria can survive INSIDE immune cells by: (4)

answer

question

How does HYALURONIDASE contribute to penetration of host tissues?

answer

Degrades hyaluronic acid (holds host cells together) and allows bacteria to penetrate deeper into host tissues.

question

How does COLLAGENASE contribute to penetration of host tissues?

answer

Degrades collagen fibres at base of superficial tissues & allows bacteria to move further into the host.

question

Invasins

answer

Rearrange actin-filaments in epithelial cells of intestinal lumen.

question

T/F: Some bacteria enter host cells that are NOT phagocytic.

answer

True.
(Some can rearrange filaments, induce an inflammatory response or membrane ruffling).

question

How to pathogens benefit from penetration of tissues (move from blood into tissues)?

answer

- Lots of nutrients.
- Protected from immune system.
- Partial protection from antibiotics.

question

4 mechanisms that cause host cell damage after further penetration into tissues:

answer

1. Appropriating host nutrients.
2. Directly damage tissues surrounding invasion site.
3. Produce toxins.
4. Induce hypersensitive rxns.

question

Microbial iron deficiency

answer

Occurs when pathogenic bacteria deplete iron from iron-transport proteins in blood.

question

Siderophores

answer

Secreted by invading bacteria, bind to iron more tightly than host iron-transport proteins.
- Binding releases toxins that kill host cells + release Fe.

question

Exotoxins

answer

Enzymatic proteins made inside some living pathogenic bacteria as normal part of growth.
- rapidly transported thru host.
- secreted into surroundings or released during lysis.

question

Ingestion or exposure to endotoxin-producing bacteria may cause

answer

disease

question

A-B Toxins

answer

A & B polypeptides.
A = active ez.
B = binding component.

question

Membrane-Disrupting Toxins

answer

Induce cell lysis via formation of protein channels or disruption of phospholipid layer of cell membrane.

question

Superantigens

answer

question

Endotoxins -- Lipid A

answer

Released when Gram-Neg (PINK) bacteria are killed or multiply - caused by cell wall lysis.

question

Disseminated intravasacular coagulation [DIC]

answer

Obstructive clots in capillaries inducing tissue death.

question

Meningitis is caused by which group of toxins?

answer

Endotoxins

question

Botulism is caused by ingestion of which group of toxins?

answer

Exotoxins

question

Exotoxins do not cause fever, because an exotoxin - not a bacteria - has been ingested.
What is the one exception?

answer

Superantigens

question

Toxin increase cAMP in respiratory epithelial cells, causes increased mucous production + coughing.

answer

Bordetella pertussis

question

T/F: Different endotoxins produce different signs and symptoms with each pathogen.

answer

False: Common mechanism of action causes all endotoxins to have the same signs/symptoms, regardless of pathogen.

question

Increased production of TF activates the extrinsic + intrinsic coagulation cascade, causing...

answer

DIC

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