L1: Microbial ecology & transmission (Dr Edet E Udo)

Question 1

What is microbial ecology?

Answer 1

The study of interactions between microbes and their environment.

Question 2

What generates an environment for microorganisms to interact with the body?

And what is this interaction called?

Answer 2

Human or animal’s skin and mucous membranes generate an environment for microorganisms to interact with the body.

• This interaction between the host and the organism is referred to as symbiosis.

Question 3

Two forms of symbiotic relationships can occur at an anatomical level:

Answer 3

1. Commensalism: friendly relationship, the interaction benefits both parties
2. Parasitism: one is benefiting and the other is getting harmed

Question 4

Any disease or infection occur due to several element:

Answer 4

1. The pathogen: the organism causing the infection
2. The host: the infected person or animal
3. The entry: the method the pathogen uses to enter the
   body of the susceptible host
4. Transmission: how the pathogen is transferred from
   host to susceptible host
5. The environment: the environment in which
   transmission of the pathogen takes place.
6. The exit: the method the pathogen uses to leave the body of the host

Question 5

What are pathogens?

Answer 5

organisms that have the potential to produce a

disease (pathogenicity)

Question 6

What are the types of pathogens?

Answer 6

1. Primary pathogens: cause a disease mn il bdaya

2. Opportunistic pathogens: resident/transient flora that can cause a disease under certain conditions

Question 7

What are examples of primary pathogens?

Answer 7

E.g., Vibrio cholerae, M. tuberculosis, Treponema pallidum

Question 8

What are examples of opportunistic pathogens?

Answer 8

Staphylococcus aureus, Escherichia coli, etc

Question 9

What determines the ability to cause a disease (potential pathogenicity)?

Answer 9

The ability to cause disease is determined by factors such as

• the number of pathogens,
• their virulence
• and the nature and magnitude of host defenses

Question 10

What are virulence factors?

Answer 10

The factors that allow micro organism to cause diseases

Question 11

“A microorganism will not be able to invade unless it overcomes an animal’s or individual’s host defenses.”

• Specific host defenses may
include:

Answer 11

• Skin and mucosal secretions 
• Non-specific local responses
(e.g., pH)
• Non-specific inflammatory
responses
• Specific immune responses
(e.g., lymphocytes)

Question 12

What are the different types of carriers?

Answer 12

Question 13

What is a vector?

Answer 13

A live animal that transmits an infectious agent from

one host to another.

Question 14

What is zoonoses?

Answer 14

A disease that occurs primarily in animals and can be transmitted to humans

Question 15

What are examples of zoonoses?

Answer 15

1. SARS virus anthrax
2. Rabies
3. Brucellosis
4. Salmonellosis
5. Lyme disease
6. Pneumonic plague

Question 16

What types of animals are considered vectors?

Answer 16

Arthropods and larger animals (birds bats etc)

Question 17

What is phytosis?

Answer 17

A disease caused by a plant

Question 18

What are biological and mechanical vectors?

Answer 18

Biological vector: participates in the pathogen’s life cycle/ basically means il disease already kann primarily mawjood bl vector

Mechanical vector: not necessary to the life cycle of the infectious agent.

Question 19

What are examples of nonliving reservoirs?

Answer 19

Soil: harbors pathogens such as: clostridium botulinum, cl. Tetanu, fungi

Water: may be contaminated with human and animal faeces and act as reservoir for several pathogens (cholera)

Question 20

What are the control measures directed towards reducing or eliminating the source or reservoir of infection?

Answer 20

1. quarantine and isolation of cases and carriers
2. destruction of animal reservoir of infection
3. treatment of sewage to reduce water contamination
4. therapy that reduces or eliminates infectivity of the individual

Question 21

What are the control measures designed to break the connection between the source of infection and susceptible individuals?

Answer 21

1. chlorination of water supplies,
2. pasteurization of milk
3. supervision and inspection of food and people who handle food
4. destruction of vectors by spraying with insecticides

Question 22

What are the Control measures to reduce the number of susceptible individuals and raise the general level of herd immunity:

Answer 22

Vaccination

1. Passive immunization: temporary vaccine following the exposure to the pathogen
2. Active immunization: protects individual from the pathogen and the host population from epidemic (covid)

Question 23

What are benefits of nonpathogenic microorganisms?

Answer 23

Question 24

What are transient flora?

Answer 24

Microorganisms present for a short period of time

Question 25

Hand washing only gets rid of?

Answer 25

Transient microorganisms not permanent ones

Question 26

How does normal flora protect us from invasion and proliferation of pathogenic ?microbes

Answer 26

by competing for space and

nutrients.

Question 27

What are the benefits of normal flora?

Answer 27

Question 28

As the first teeth erupts what becomes dominant?

Answer 28

Anaerobes then streptococcus

Question 29

What part of the body is usually free of microorganisms?

Answer 29

Upper genitourinary tract

Question 30

What is dominant in the adult female genital tract? W shesawoon?

Answer 30

The acid tolerant lactobacilli, and lactobacillus acidophilus

They maintain the pH of the vagina at the cervical orfice at between 4.4 and 4.6

Question 31

What mo are usually present in the distant portion of the urethra?

Answer 31

S. epidermidis,
E. faecalis and
Corynebacterium spp