Introduction To Medical Microbiology

Question 1

Importance of microorganisms

Answer 1

• Bacteria and fungi help to break down wastes and dead organisms and return the raw materials to the environment
-inhabit all types of environments and contribute to the life cycle

Question 2

Normal flora

Answer 2

used when referring to the diverse species of microorganisms that consistently inhabits the bodies of healthy animals

Question 3

Disease

Answer 3

state is when the interaction between a microorganism and the host (human) leads to a situation where the interaction is detrimental to the host (human).

Question 4

Infection

Answer 4

The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites this often leads to a disease.

Question 5

Pathogenic

Answer 5

Microorganisms that have the ability to cause diseases

Question 6

Virulence

Answer 6

provides a quantitative measure of the pathogenicity or the likelihood of causing disease.

Question 7

Virulence factors

Answer 7

refer to the properties (gene products) that enable a microorganism to establish itself on or within a host of a particular species and enhance its potential to cause disease.
•
Virulence factors include
• Bacterial toxins, cell surface proteins that mediate bacterial attachment,
• Cell surface carbohydrates and proteins that protect a bacterium
• Hydrolytic enzymes that may contribute to the pathogenicity of the bacterium.

Question 8

Classification of microorganisms

Answer 8

1. Bacteria(Bacteriology)
2. Viruses (Virology)
3. Fungi(Mycology)
4. Parasites(Parasitology)a.Helminths(Helminthology)b.Protozoa (Protozoology)
5. Algae (Phycology or algology ) Non microbial sources of infection:
6. Toxins
7. Prions(infectiousproteinaciousparticles)

Question 9

Bacteria

Answer 9

• Simplest single celled organism (0.5 – 4μm) • Capable of independent replication.
• Multiply by cell division
• Many different species.
• 3 basic shapes • Cocci
• Bacilli • Spiral.
• Some live singly, some cluster into pairs or groups • Live independently or as parasites
• Most common cause of disease in humans.
• Only 1% of bacteria cause human disease

Question 10

Viruses

Answer 10

• Smallest infectious agent (20 - 300 nm). Simplest microbe
• Not capable of independent replication. Hijack host cell machinery
• Many different species.
• 4basicshapes • Polyhedral
• Spherical • Helical
• Complex
• Obligate parasites
• Vaccines are available for many but not all

Question 11

Algae

Answer 11

• 1 μm to several cms
• Unicellular or multicellular
• Reproduce asexually
• Only a few unicellular species cause human disease
• Some produce toxic substances

Question 12

Parasites

Answer 12

• Are unicellular.
• Smallest animals 2 – 200 μm
• Reproduce asexually and sexually
• 4 groups: ciliates, amoeba, flagellates and sporozoans • Live independently or as parasites
• A few cause human disease
• Are a leading cause of death in developing countries
(In 2019, 229 million cases of malaria occurred worldwide with 409, 000 deaths down from 219 million cases of malaria 435 000 deaths in 2017 (WHO, 2020)

Question 13

Fungi

Answer 13

• Large complex organism
• Reproduction mainly asexual, some sexual
• Two types
• Unicellular - yeasts
• Multicellular - moulds and mushrooms
• A few infect humans (mycosis) • Source of antibiotics and toxins

Question 14

Prions

Answer 14

• Proteinaceous infectious particles
• No nucleic acid
• nv-CJD (when abnormal prions infect humans, the resulting disease is known as (new) variant CJD (nvCJD))
• Cannot be cultured and no immune response elicited
• Difficult to diagnose early stages of disease using
conventional means
• No vaccine currently available
• Experimental treatment options and vaccine underway

Question 15

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Answer 15

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