Chapter 9 Flashcards
What does bacterial Pathogenesis depend on? (3 points)
Host immune status
Nature/ Virulence of species/strain
Organisms number in the initial exposure
What are the 4 bacterial classifications?
Saprophytic
Non-pathogenic
Opportunistic
Pathogenic
Where is Saprophytic present in?
Nature
Where can Saprophytic be found in?
3 points
Air
Water
Soil
Describe Non-pathogenic bacteria
Harmless
What are the 2 Non-pathogenic bacteria?
Normal flora
Commensals
Where do Non-pathogenic bacteria live in?
Humans
Where can Non-pathogenic bacteria be found in humans?
Skin
Gut (GIT)
What are the 3 non-pathogenic bacteria which are found on the Skin?
Staphylococcus aureus
S. epidermidis
Propioni-bacterium acnes
What are the 2 non-pathogenic bacteria which are found in the Gut (GIT)?
Bacteroides
Enterobacteriaceae
Where can Opportunistic bacteria be found in?
Immuno-compromised patients
What does the opportunistic bacteria exploit in an immuno-compromised patient?
Weakened defenses
What can the opportunistic bacteria cause?
Infectious diseases
Give an example of an opportunistic bacteria that causes infectious
diseases
Normal flora
When does Normal flora cause infectious diseases?
When it enters bloodstream
When would it enter the bloodstream?
After surgery
What does Pathogenic bacteria cause?
Disease
Where can Pathogenic bacteria cause disease in?
Humans
What does the outcome of an infection depend on? (2 points)
Pathogen’s virulence
Effectiveness of host defense mechanisms.
Define Superinfection
The occurrence of a new infection after a pre-existing infection
What can Superinfection complicate?
Antimicrobial therapy course
When can Superinfection complicate Antimicrobial therapy course?
When the organism causing the new infection is resistant to the drugs being used to treat the first infection.
Give an example where Superinfection can occur
Viral respiratory disease
From where are most bacterial infections obtained?
External sources
What are the 6 stages of bacterial pathogenesis?
Transmission Escape Colonization Disease symptoms Responses Disease progression/resolution
Between what are bacteria transmitted?
External source to entry portal
What are the 6 modes of bacterial transmission?
Inhalation Contact Ingestion Injection Trans-placental Sexual contact.
What does bacteria escape from?
Host defense mechanisms
Define Colonization
Bacterial growth at entry site
What causes the symptoms of the disease?
Toxins production
Invasion
Inflammation
From where does a response come from?
Host
What does the host response triggers?
Immune response
What are the 2 determinants of bacterial pathogenesis?
Pathogenicity
Virulence
Define Pathogenicity
Host organism ability of disease production
Define Virulence
Microbe pathogenicity degree
What are the 2 ways in which Virulent bacteria produce disease in humans?
Microbe adherence
Invasion and intercellular survival
What does the microbe adhere to?
Cell surfaces
What are the two factors that are involved in microbe adherence to cell surfaces?
Receptor
Adhesion
Where is the receptor found on?
Tissue cell
Where is the adhesion found on?
Bacteria
Define tissue tropism
Receptor and adhesion interaction
Describe the interaction of the Receptor and the Adhesion? (2 points)
Complementary
Specific
Give an example of by how does a microbe adhere to cell surfaces
Fimbriae (pili)
What does the microbe do to facilitate its invasion? (2 points)
Produce extracellular substances
Inhibit phagocytic engulfment/adsorption
What are these extracellular substances produced?
Enzymes
What are the enzymes produced by the microbe? (11 points)
Hyaluronidase Collagenase Neuraminidase Streptokinase Staphylokinase 3 enzymes that cause hemolysis/leucolysis Protease Deoxyribonuclease Coagulase
Describe Hyaluronidase
The original spreading factor
What does Hyaluronidase break down?
Hyaluronic acid
Where is Hyaluronic acid present in?
Connective Tissue
Which bacteria produces Hyaluronidase?
Streptococci
What does Collagenase break down?
Muscles collagen
What does Collagenase facilitate?
Infection
What does Collagenase cause when produced?
Gas gangrene
Which bacteria produces Collagenase?
Clostridium
What does Neuraminidase break down?
2 points
Neuraminic acid
Sialic acid
Describe Neuraminic acid/Sialic acid
Intercellular cement
Where is this intercellular cement found in?
Intestinal mucosal epithelium
Which bacteria produces Neuraminidase?
Haemophilus influenzae
What do Streptokinase and Staphylokinase convert?
Inactive Plasminogen to Plasmin
What does Plasmin digest?
Fibrin
What does Plasmin prevent?
Blood clotting
What are the 2 bacteria that produce Streptokinase and Staphylokinase?
Streptococci
Staphylococci
What are the 3 enzymes that cause hemolysis/leucolysis?
Lecithinases
Hemolysins
Leukocidins
What do these enzymes usually act on?
Cell membrane
What does Lecithinases breaks down?
Cell membrane lecithin
What does Hemolysins break down?
RBCs
What does Leukocidins break down?
Leucocytes
Phagocytes
What is an example of Protease?
Immunoglobulin
What does Immunoglobulin Protease break down?
IgA
What does Deoxyribonuclease break down?
DNA
What does Coagulase convert?
Fibrinogen to Fibrin deposit
Where will Fibrin deposit be found?
Around bacteria
What does Fibrin deposit protect bacteria from?
Phagocytosis
Which bacteria produces Coagulase?
Staphylococcus aureus
What are the 5 substances which bacteria carry that inhibit phagocytic adsorption or engulfment?
Cell wall proteins Capsule Coagulase Ig A proteases Intercellular survival ability
Where are these bacterial substances found?
On its surface
What are the 2 cell wall proteins?
M
A
Which type of bacteria have cell wall proteins?
Gram positive cocci
What is the group of protein M which is present in gram positive cocci?
A
Which bacteria has protein M of group A?
Streptococci (S.pyogenes)
Which bacteria has protein A?
Staphylococcus aureus
What does Capsule prevent?
Phagocytes attachment to bacterial cells
What are the 2 bacteria that have Capsule?
S. pneumoniae
Haemophilus influenzae
What are their Capsule made of?
Polysaccharide
What is involved in the Intercellular bacterial survival ability?
Phagosome
How does the bacteria react to the Phagosome?
Escape
Which bacteria escape Phagosome?
Listeria
What does the bacteria do to the Phagosome fusion?
Inhibit it
Which bacteria inhibit Phagosome fusion?
Mycobacteria
What are the 2 types of toxins that bacteria produce?
Exotoxins
Endotoxins
What are Exotoxins made of?
Protein
Which bacterial cells release Exotoxins?
Living
Which type of bacteria mainly release Exotoxins?
Gram positive
Which type of bacterial certain species release Exotoxins?
Gram negative
What are the genes that code for Exotoxins located?
Plasmid
Bacteriophage
Describe the level of toxicity of Exotoxins
High
Describe the antigenicity of Exotoxins
High
Describe the action of Exotoxins
Specific
What is the site in which Exotoxins act at?
Tissue
What is the site in which Exotoxins don’t act at?
Bacterial growth
What converts Exotoxins?
Formalin
What does Formalin convert Exotoxins into?
Toxoid
When are Toxoid used in?
Active Immunization
What are Toxoid used as?
Vaccine
What feature of Exotoxins is lost when converted?
Toxicity
Which feature of Exotoxins is retained when converted?
Antigenicity
Give 2 examples of bacteria that release Exotoxins?
C.diphtheria
Clostridium tetani
At what temperature are Exotoxins labile?
60 °C
Where are the genes that code for Exotoxins are found in, C.diphtheria?
Phage
Where are the genes that code for Exotoxins are found in, in Clostridium tetani?
Plasmid
What are Endotoxins made of?
Lipopolysaccharides
Describe Endotoxins
Cell wall structural components
Which bacteria release Endotoxins?
Disintegrated
Which type of bacteria release Endotoxins?
Gram Negative
What type of cells also release Endotoxins?
Lysed
What are the causes of Endotoxins production by lysed cells? (2 points)
Effective host defense
Certain antibiotics activities
Give an example of an effective host defense
Lysozyme
Give 2 examples of antibiotics of certain activities
Penicillin
Cephalosporin
Where is the gene that codes for Endotoxins?
Chromosomes
Describe the level of toxicity of Endotoxins?
Low
Describe antigenicity of Endotoxins?
Poor
Describe the action of Endotoxins?
Non-specific
What does the action of Endotoxins cause?
2 points
Fever
Shock
At what temperature is Endotoxins stable?
100 °C
For how long are Endotoxins stable at this temperature?
1 hour
Give an example of a bacteria that releases Endotoxins?
Meningococci
Describe this release
Sepsis
