Bio 220: Lecture 28

Front 1

symbiosis

Back 1

two organisms living together

Front 2

What are the three types of symbiosis?

Back 2

commensalism, mutualism and parasitism

Front 3

commensalism

Back 3

two organisms living together where one is benefited and the other is neither harmed nor benefited. The normal skin flora represents this type of symbiotic relationship where the microorganism is benefited and the host is unaffected.

Front 4

mutualism

Back 4

two organisms living together where both gain benefit. The classic example would be the lichen. The algal component is photosynthetic and manufactures glucose, while the fungus provides root support and draws in minerals and water. The intestinal flora in the human gut also illustrates this type of symbiotic relationship. These bacteria gain nutrients from the intestines and also provide the human host with vitamin K and some of the B vitamins.

Front 5

parasitism

Back 5

one organism is benefited while the other is harmed.

Front 6

Interactions Between Microbe and Host
Colonization by normal flora

Back 6

the newborn is first colonized by microorganisms as it moves down the vaginal canal. Contact with air, water, food, soil and all exposures to the outside environment complete this process.

Front 7

Interactions Between Microbe and Host
Infection

Back 7

defined as microorganisms living in or on the body of the host. If the infectious agent causes harm and now exists as a parasite, the homeostatic balance of the host becomes altered. This is now referred to as a disease.

Front 8

Interactions Between Microbe and Host
Infestation

Back 8

macroscopic parasites in or on the body of the host. Examples include ticks, lice, fleas, tapeworms, flukes etc.

Front 9

Interactions Between Microbe and Host
Disease

Back 9

any departure from the healthy state (a shift away from normal homeostatic balance). This can be an altered physiologic state or an altered structural state. A disease can be non infectious or infectious. Examples of non infectious diseases include genetic, metabolic, nutritional, degenerative, immunologic and psychogenic diseases. Infectious diseases are caused by infectious agents such as bacteria, viruses, fungi etc. The traditional infectious bacterial disease starts with the incubation period. This represents a time prior to the first signs or appearance of infection. Next, we see the prodromal period. This represents the first signs of infection. Perhaps the first tickle in the throat or the subtle suggestion of a headache. The illness period follows where the classic signs and symptoms of the infectious agent are apparent. If the patient survives there is a decline period where the major symptoms go away. The convalescence period is a time where the patient recovers their strength and is restored to pre-disease health.

Front 10

Infectious diseases are caused by infectious agents such as ...

Back 10

bacteria, viruses, fungi etc

Front 11

The traditional infectious bacterial disease starts with the ___ period.

Back 11

incubation
This represents a time prior to the first signs or appearance of infection

Front 12

What occurs in the prodromal period?

Back 12

This represents the first signs of infection. Perhaps the first tickle in the throat or the subtle suggestion of a headache.

Front 13

What are the 4 periods of disease?

Back 13

1. incubation
2. prodromal period
3. illness period
4. decline period
5. convalescence

Front 14

What occurs during the Illness period?

Back 14

The illness period follows where the classic signs and symptoms of the infectious agent are apparent.

Front 15

What occurs during the decline period?

Back 15

If the patient survives there is a decline period where the major symptoms go away.

Front 16

What occurs during the convalescence period?

Back 16

The convalescence period is a time where the patient recovers their strength and is restored to pre-disease health.

Front 17

Interactions Between Microbe and Host
Pathogen

Back 17

any agent capable of producing disease. Pathogenicity depends upon factors of both the host and the microorganism. It is the potential ability of the infectious agent to enter the host and cause disease. Microbial competition and mutual inhibition contribute to a normally balanced ecosystem in or on the body and may prevent invasion by pathogens. Virulence is the degree of pathogenicity as defined by the organism alone to produce disease. Two factors influence virulence. They are invasiveness and toxigenicity.

Front 18

pathogenicity

Back 18

depends upon factors of both the host and the microorganism. It is the potential ability of the infectious agent to enter the host and cause disease. Microbial competition and mutual inhibition contribute to a normally balanced ecosystem in or on the body and may prevent invasion by pathogens.

Front 19

virulence

Back 19

is the degree of pathogenicity as defined by the organism alone to produce disease. Two factors influence virulence. They are invasiveness and toxigenicity

Front 20

What are the factors and influence pathogenicity?

Back 20

1. dose
2. method of transmission
3. portal of entry

Front 21

Factors influencing pathogenicity
Dose

Back 21

an increase in the numbers of organism will increase the probability of disease.

Front 22

Factors influencing pathogenicity
Method of Transmission

Back 22

(communicability)

Front 23

Factors influencing pathogenicity
Portal of Entry

Back 23

the organism must gain access through the correct route. Presence of the organism does not necessarily result in disease. Eating Clostridium tetani spores will not cause tetanus. Placing these spores in an open wound however, will cause disease. Mycobacterium tuberculosis must gain access into the respiratory passages to cause tuberculosis. Salmonella typhi placed upon the skin is not problematic. This organism in the G. I. however, can cause typhoid fever.


Pathogenicity involves the interaction of the organism and the host together. The probability that an organism will cause disease within a host takes into account the microbial strengths (virulence) and the host strengths (resistant state or immune system of the host).


Front 24

Vertical Method of Transmission

Back 24

from parent to progeny. These are all directly transmitted.

Front 25

Horizontal Method of Transmission

Back 25

from one member of one species to another member of that species.

Front 26

What are some examples of direct contact?

Back 26

venereal disease, nonsocimial transmission, latrogenic transmission

Front 27

What are some examples of indirect contact?

Back 27

air, food, water, arthropod borne, fomites

Front 28

Direct Contact
Venereal Disease

Back 28

gonorrhea, syphilis, trichomoniasis, AIDS etc.

Front 29

Direct Contact
Nosocomial Transmission

Back 29

derived in hospital or clinical setting.

Front 30

Direct Contact
Latrogenic Transmission

Back 30

derived from a physician.

Front 31

Indirect Contact
Air

Back 31

tuberculosis, pneumonia, flu, common cold etc.

Front 32

Indirect Contact
Food

Back 32

Staphylococcal food poisoning, salmonellosis (causing gastroenteritis) etc.

Front 33

Indirect Contact
Water

Back 33

Shigellosis, typhoid fever, cholera etc.

Front 34

Indirect Contact
Arthropod borne

Back 34

mosquitoes, ticks, fleas, lice etc.

Front 35

Indirect Contact
Fomites

Back 35

inanimate objects.