Infectious Disease -- Intro

Question 1

Infectious due to endogenous bacteria are usually secondary to _______

Answer 1

some other alteration in tissue structure/function

Question 2

Examples of mechanisms for normal flora causing disease

Answer 2

Perforation of the intestine
Obstruction of draining pathways with overgrowth
(ear, sinus, obstructive pneumonia)
Alteration in host defenses (Candida)

Question 3

What four bacteria should always be considered with pneumonia

Answer 3

Strep pneumoniae
Haemophilus influenzae
Staph Aureus
Moraxella catarrhalis

Question 4

Bacterial respiratory infections with normal flora often follow….

Answer 4

viral infections causing swelling and obstruction

ex. OM, Sinusitis, Pneumonia

Question 5

95% of bacterial pneumonias are

Answer 5

Strep pneumoniae

Question 6

List three common disease causing bacteria that are not commonly found in mouth, nose, oropharynx

Answer 6

S pyogenes
H. influenza (type B)
Neisseria meningitidis

Question 7

Why does the site of propagation matter in exogenous flora?

Answer 7

In part, it determines the effectiveness of immune mechanisms

Question 8

What immuno-evasive manuever to the major causes of meningitis all share?

Answer 8

Capsules

Question 9

What is an exotoxin?

Answer 9

A soluble, secreted toxin

Question 10

What is an endotoxin

Answer 10

An insoluble component of the invading organism (LPS)

Question 11

What are the most common causes of meningitis?

Answer 11

N. Meningitidis
S. pneumo
E coli
H. influ (type B)

Question 12

How do capsules help bacteria cause meningitis

Answer 12

They prevent complement binding to the bacteria, allowing it to have a better chance of successfully migrating through the blood into the CSF, where Adaptive Immune response will play a minimal role

Question 13

Three special host features that may play an essential role in diagnosis

Answer 13

Age
Immune Status
Concurrent or Pre-Existing Disease

Question 14

Is S. aureus normal flora?

Answer 14

Yes, skin and mucosal surfaces

Question 15

How does S. aureus propagate?

Answer 15

Extracellular

Question 16

Staph aureus toxins?

Answer 16

Exotoxins –> Toxic Shock and Food Poisoning

Question 17

S. aureus immune response

Answer 17

Mostly neutrophils

Question 18

Non-toxin virulence factors of S aureus

Answer 18

Coagulase

Question 19

Four ways for a human to be infected by an organism

Answer 19

Come into contact
Colonizing organism gets past barrier
Changes in local condition cause overgrowth
Some combination

Question 20

Inability to produce immunoglobulin – increased susceptibility to…

Answer 20

Encapsulated organisms

Question 21

Lack of cellular immunity – increased susceptibility to…

Answer 21

Intracellular Organisms

Question 22

Lack of neutrophil fxn – increased susceptibility to…

Answer 22

Staph and Strep

Question 23

Lack of phagocytic clearing mechanism – increased susceptibility to…

Answer 23

Encapsulated organisms

Question 24

Concept of contagion is based on two principles…

Answer 24

Limiting Exposure to virulent organisms

Not allowing virulent organisms to grow where they don’t belong

Question 25

What is a nosocomial infection

Answer 25

Disease originating in a hospital

Question 26

Organisms commonly found in the mouth, nose, and oropharynx

Answer 26

``` S. aureus S. epidermidis Peptostreptococcal sp. alpha and non-hemolytic streptococci anaerobic streptococci, bacteriodes Candida albicans ```

Question 27

Koch's Postulates

Answer 27

1. Organism is regularly found in the lesion of the disease 2. Organism can be isolated as single colonies on solid medium 3. Inoculation of this culture causes lesions in experimental animal 4. Organisms can be recovered from lesions in the animal

Question 28

Difference betwen a high and low virulence pathogen

Answer 28

High -- Causes disease in a normal host | Low -- Causes disease only in hosts with low resistance or impaired defenses

Question 29

Five things that determine pathogenicity

Answer 29

1. Ability to establish infection/reproduce in host 2. Generation of products which directly damage host 3. Induction of host-cellular responses 4. Changes in virulence of org 5. Changes in host

Question 30

Changes in host that are most prone to cause pathogenicity changes

Answer 30

Alteration of tissue environment (obstruction of tube) | Changes in immune status

Question 31

Six famous examples of exotoxins

Answer 31

``` Diptheria Pseudomonas Streptococcus Vibrio cholera Clostridia Staphylococcus ```

Question 32

Endotoxins are assocaited with what negative symptoms

Answer 32

DIC, Septic Shock

Question 33

Describe the tissue seen in Suppurative inflammation

Answer 33

Exuberant Neutrophillic Response, Possible Abscess Bacterial products aid in chemotaxis+activation Exotoxins enhance inflamm resp Fibrinopurulent exudates in the presence of epithelial necrosis can cause pseudomembranes

Question 34

What is a granulomatous response

Answer 34

A specialized cell-mediated type 4 reaction to chronic intracellular infection

Question 35

Example of a caseous granuloma? | Non-caseous?

Answer 35

Cas -- TB | Non -- Histoplasmosis, Blastomycosis

Question 36

What happens in necrotizing inflammation | Examples?

Answer 36

Organisms have VFs that directly destroy cells. Few inflammatory cells seen in response to necrosis. C. perfringens, Entamoeba histolytica

Question 37

Most virulent organisms have evolved some specific strategy for bypassing natural barriers and/or subverting the immune system. Give examples

Answer 37

More encapsulated organisms with no Igs More intracellulars with lack of cellular immunity More staph, strep with diminished neutrophil function More encapsulated organisms - lack of clearing mechanisms (like spleen)

Question 38

The price of the failure to comply with the concept of contagion

Answer 38

Nosocomial Infections

Question 39

Sterile technique is used any time...

Answer 39

a natural barrier may be breached

Question 40

Four things you may need to do in therapeutic intervention in infectious disease

Answer 40

Treat the underlying disease Prevent contagious spread shore up natural barriers Alter the immune response