Pathogenesis Of Bacterial Infection

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1

Pathogenesis

Creation Of Disease

2

Virulence

Ability to cause disease

3

Virulence Factors

  • Transmissibility
  • Adherence to Host Cells
  • Persistence/ Evade The Host I.S
  • Toxins
  • Antimicrobial Resistance
  • Enzymes
  • Secretion Systems
  • Protein Complexes/ Channels
  • Biofilm Formation
4

Phomite

Non-Living thing that transmits disease

ex. MOP

Spores

5

Spores

Non Active Bacterial Formation

6

Can get C. Diff From

  1. Misuse Of Antibiotics --> Wiping out Normal Flora
  2. Environment --> Through Spores
7

Koch's Postulates Definition

How Bacteria Can Cause A Disease

How Likely It Was From That Organism

8

Koch's Postulates

  1. The Microorganism causing this disease should be found in all cases
  2. Microorganism should be grown in pure culture in vitro for several generations --> prove microorganism is viable **
  3. When pure culture inoculated into animal species, typical disease must result **
  4. Microorganism then must again be isolated
9

Koch's Postulates MODs

** We Can't Always Culture Easily

  • Anaerobic Bacteria
  • Viruses
  • Prions

** Host Can Be Inoculated But No Disease Shows B/C:

  • Carries, Dormant/ Latent Virus
  • Sub Clinical Symptoms
10

Sub Clinical Symptoms

Typical Symptoms Dont Result

11

Microorganism classifications

  1. Non Pathogens
  2. Opportunistic
  3. Pathogens
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Non Pathogens

Normal Flora

Friendly Bacteria

Everywhere (Skin, Gut, GU Tract)

*Can Become Pathogenic*

13

Opportunistic Pathogens

Take Advantage of I.S

Can Become Pathogenic

ex. E.coli --> Gun shot moves it into blood stream

occurs when bacteria is displaced

I.S compromised

14

Bad Immune System:

HIV, Chemo from Cancer, Transplant

15

Chemo leads to poor immunity because

Block Cell Cycle of Rapidly Dividing Cells

Tumor Cells AND I.S Cells Are Rapidly Diving

Blocks Good and Bad Cell Production

16

Transplant Patients have poor immunity because

Drug Suppresses I.S to Not Reject An Organ

17

Pathogens

Primary Pathogens Always Cause Disease When Introduced In Body

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Transmission Of Infection

Bacteria can Adapt to a Variety of External Enviro:

  1. Soil, Water, Organic Matter
  2. Internal Milieu
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Internal Milieu

Insect Vectors

Animals

Humans

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Insect Vectors

Pathogens Transmitted By Insects

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Zoonotic Infection

From Animals To Humans

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Zoonotic Infections Examples

Pasteurellosis

Giardiasis

Food Poisoning

Anthrax

Lyme Disease

23

Pasteurellosis

Organism: Pastuerella Muctocida

Main Reservoirs: Dogs/Cats

Transmission Mode: Bites/ Scratched

*** Most Common**

Normal Flora In dogs and cats mouth but cause infection in human

24

Giardiasis

Organism: Giardia Lamblia

Main Reservoirs: Wild Life

Transmission Mode: Waterborne

**Scranton**

25

Food Poisoning

Organism: Salmonella

Main Reservoirs: Poultry, Cattle, Sheep, Pigs

Transmission Mode: Foodborne

26

Anthrax

Organism: Bacillus Anthracis

Main Reservoirs: Live Stock * N.F In Sheep*

Transmission Mode: Direct Contact, Ingestion

*Biological Weapon*

27

Lyme Disease

Organism: Borrelia Burgdorferi

Main Reservoirs: Ticks, Deer, Small Mammals

Transmission Mode: Tick Bite

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Clostridium Spores

Spores Protect Against UV Light, Desiccation, Chemical Detergents and pH Extremes

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Botulism

Via raw honey

Can cause disease in people w/ weak I.S --> Babies

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Disease Promoting Transmission

  1. Diarrhea --> Fecal/ Oral
  2. Genital Discharge --> STD
  3. Cough --> Airborne
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Leading Cause of Transmission of Disease

DIRTY HANDS!!

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Portals of Entry

  • Where mucous membrane meets skin (Mouth, Nose)
  • Respiratory
  • GI (Mouth)
  • Genital
  • Urinary Tract
  • Breaks In Skin
33

Once Bacteria Inside Body

  1. Attach to host cells --> Generally epithelial
  2. Multiply and Spread
    • Directly
    • Systemic**
34

Direct Spread

Via Tissue

35

Systemic Spread

Via Lymphatic System or Blood

More SEVERE Infection

36

Pneumococcal Pneumonia

cultured from nasopharynx of healthy people

If aspirated into lungs + lack of antibodies

--> Enter lungs and spread to blood: SYSTEMIC 50% Fatal

37

Cholera

Ingestion of V. Cholera (Gram (-) Rod)

Chemotactic Attraction of bacteria to gut epithelium

Motile

Penetration of mucous later of gut

Adhesion by Pilli ---> Introduced to Cholera Toxin

  • Influx of Cl- and H2O
  • Massive Diarrhea + Electrolyte Imbalance

*Earthquake in Haiti*

38

In Bacteria, Genes:

  1. Clonal
  2. Can Pass Virulence Genes from Generation to Generation
39

Bacterial Clonal

Flu

Heamophilus Influenza

40

Heamophilus Influenza

Many Types

Only Type B is Pathogenic (Respiratory Infection)

--> Children vaccinated for it

41

Passing Virulence Factors by:

Mobile Genetic Elements:

  • Plasmids
  • Transposons
  • Bacteriaphages/phages
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Plasmids

Extrachromosomal Pieces of DNA

capable of replication

43

Transposons

Mobile Segments of DNA

Move from one part of DNA to another

44

Phages

Virus that replicated in a bacteria

45

Plasmid Encoded

  • E. Coli Enterotoxins
  • Bacillus Anthrax Caps
  • Shigella Species Adherent Factors
46

Phage Encoded

  • Botulism Toxin
  • Diphtheria Toxin
  • Cholera Toxin
47

Botulism Toxin not a problem in US b/c

Good Food Proccessing

48

Diphtheria Toxin Not A Problem In US B/C

Vaccination

49

Cholera Toxin Not A Problem In US B/C

Clean Water

50

Adherent Factors

First Step to Infection once bacteria in host

*Hydrophobic bacterial surfaces adhere greater to cells by:

  • Pilli
  • Fimbraie

Can lead to host cell conformation changes allowing organism uptake by cell

51

Exotoxins

Proteins that are excreted from bacteria cell

Made by bacteria

  • Excreted By Living Cell
  • Gram (+) and (-)
  • Highly Antigenic --> Can Stim. anything that wont neutralize it
  • Highly Toxic
  • Do Not Produce HIGH Fever
52

Endotoxins

Lipid Molecules that are components of bacterial cell membrane

  • Integral Part of Lipid Cell Wall
  • ** GRAM (-) ONLY
  • Weakly immunogenic --> No Strong Immune Response
  • Moderately Toxic
  • Produce Fever
53

Enzymes: Virulent Factors

Tissue Degrading Enzymes

Cytolysins

IgA Proteases --> Deactivates IgE

54

Secretion Systems, Protein Complexes/ Channels as Virulent Factors

Ensure Transport of Structure and Toxigenic Proteins through bacterial cell

55

Biofilm Formation as Virulent Factor

From Bacterial interaction

can be persistent and lead to difficult to treat infections

  • contact lenses
  • dental plaque
  • central venous catheter infection from stapylococcus (bio films can enter blood)
  • Prosthetic Joint Infection
  • Cystic Fibrosis --> Hyper Prolif. of Mucous