Microbial Infection

Question 1

Micro-organism

Answer 1

Microscopic organisms, includes all unicellular organisms - bacteria/protozoa

Question 2

Koch’s Postulates

Answer 2

4 Postulates

1. The suspected pathogen must be present in all cases of the disease and absent from healthy animals.
2. The suspected pathogen must be grown in pure culture.
3. Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal.
4. The suspected pathogen must be reisolated and shown to be the same as the original.

Question 3

What are some limitations of Koch’s postulates ?

Answer 3

Some human diseases cannot be replicated in animal hosts.

Cannot be fulfilled for viruses that do not replicate in cell culture.

Question 4

Infection

Answer 4

A disease caused by a pathogen

Question 5

What is meant by normal microbiota ?

Answer 5

Microorganisms that are in every human being.

These are not harmful to humans; some are even beneficial and most help maintain our health.

Question 6

Physical Barriers

Answer 6

Skin, Mucous

Question 7

Chemical Barriers

Answer 7

Lysozyme, Sebum

Question 8

Phagocytic Cells

Answer 8

Macrophages
Monocytes
Dendritic Cells
Mast Cells
Basophils
Eosinophils
Neutrophils

Question 9

Commensal

Answer 9

A micro-organism which forms part of the normal host microbiota.

Question 10

Pathogen

Answer 10

Micro-organism that can invade the body and cause disease

Question 11

Pathogenicity

Answer 11

The ability to cause disease. (Qualitative)

Question 12

Pathogenesis

Answer 12

The development of a disease

Question 13

Virulence

Answer 13

A pathogen’s power to cause severe disease. (Quantitative)

Question 14

What are the 7 virulence factors ?

Answer 14

Toxin secretion
Pilus formation
Adhesion factors
Capsule
Iron transport systems
Enzymes
Antibiotic resistance

Question 15

What do virulence factors do ?

Answer 15

Help to :

1. Invade the host
2. Cause disease
3. Evade host defences

Question 16

What are the 2 types of pathogen ?

Answer 16

Obligate
Opportunistic / Conditional

Question 17

Obligate pathogen

Answer 17

Almost always associated with disease
e.g. HIV

Question 18

Opportunistic pathogens

Answer 18

Don’t always cause disease, but if given the chance can.

Immune-compromoised host
HAI
e.g. Staph A
e.g. Cryptococcus neoformans

Question 19

Stages of Infection

Answer 19

Recognition
Attachment & Entry
Multiplication
Evasion of host defences
Shedding
Damage

Question 20

Endogenous infections

Answer 20

Disease arising from a pathogen already present in the body but previously asymptomatic.

Question 21

Exogenous infections

Answer 21

Disease arising from a pathogen not normally present in the body and comes from the environment.

Question 22

Tissue tropism

Answer 22

The cells and tissues of a host that support growth of a particular virus or bacteria.

Question 23

Transmission

Answer 23

The means by which contagious, pathogenic microorganisms are spread from one person to another.

Question 24

Types of transmission

Answer 24

HUMAN TO HUMAN
Respiratory / Salivary spread
Fecal / Oral spread
Venereal spread

ANIMAL TO HUMAN
Vector
Vertebrae reservoir
Vector-Vertebrae reservoir

Question 25

Fomite transmission

Answer 25

A fomite refers to inanimate objects that can carry and spread disease and infectious agents.

Question 26

Examples of HAI’s

Answer 26

Staph A
C-Difficile

Question 27

HAI

Answer 27

Hospital Acquired Infections

Question 28

Are bacteria pathogenic ?

Answer 28

Most bacteria ARE NOT pathogenic

Question 29

Examples of bacterial infection

Answer 29

Tuberculosis
Bubonic Plague
Staph A

Question 30

Name 5 micro-organisms

Answer 30

Bacteria
Protozoa
Helminths
Fungi
Viruses

Question 31

Name 2 protozoal infections

Answer 31

Malaria
Giardiasis

Question 32

Name 2 fungal infections

Answer 32

Candidiasis
Cryptococcus neoformans
(Infection of the lungs and brain)

Question 33

Name 2 helminth infections

Answer 33

Schistosomiasis
Trichuriasis / Whipworm infection