Bacterial pathogenicity

Question 1

What is a pathogen

Answer 1

An organism capable of causing disease

Question 2

What is a commensal

Answer 2

An organism that is part of the normal flora

Question 3

What is pathogenicity

Answer 3

The ability to cause disease

Question 4

What is virulence

Answer 4

The ability to cause severe disease

Question 5

What is the simple life cycle of a parasite

Answer 5

Enter​
Attach​
Colonise​
Evade host immunity​
Produce harmful proteins​
Disseminate​
Release from host​

Question 6

What are the subdivisions of microorganisms

Answer 6

Bacteria​
Fungi​
Viruses​
Prions​
Parasites ​

Question 7

What is microbiology

Answer 7

The study of microscopic organisms; sub-disciplines include virology, mycology, parasitology, and bacteriology

Question 8

What are some flora found in the nasopharynx

Answer 8

Streptococci
Candida
Neisseria

Question 9

What normal flora are found on skin

Answer 9

Streptococci
Staphylococci
Yeasts

Question 10

What flora are found in the lower bowel

Answer 10

Bacteroides
Clostridium

Question 11

What flora are found within the vagina

Answer 11

Candida
Lactobacilli
Corynebacteria

Question 12

What is colonisation

Answer 12

When microbes find a new host and start to multiply

Question 13

What is an endogenous infection

Answer 13

An infection caused by the patient’s own flora

Question 14

What is an exogenous infection

Answer 14

Infection from external flora

Question 15

What is the difference between primary and opportunistic pathogens

Answer 15

Microbes that always cause disease in a new susceptible human are called primary pathogens while microbes that cause disease only in immunocompromised patients are called opportunistic pathogens

Question 16

What is the carrier state

Answer 16

The continued presence of an organism (bacteria, virus, or parasite) in the body that does not cause symptoms, but is able to be transmitted and infect other persons

Question 17

What is bacterial colonisation

Answer 17

The presence of bacteria on a body surface (like on the skin, mouth, intestines or airway) without causing disease in the person

Question 18

What is the germ theory of disease

Answer 18

The microbe must be present in every case of the disease​

The microbe must be isolated from the diseased host and grown in pure culture​

The disease must be reproduced when a pure culture is introduced into a susceptible host​

The microbe must be recovered from an experimentally infected host​

Question 19

Who created the germ theory of disease

Answer 19

KOCH’S POSTULATES (1890)

Question 20

How can diseases be spread

Answer 20

Person-to-person​
-Contaminated blood or other bodily fluids​
-Touch​
-Saliva​
-Air​

​Fomites​
Insects​
Water​
Food​

Question 21

What features pf a prokaryotic cell are usual

Answer 21

Cell envelope
DNA
Cytoplasmic membrane
Ribosomes

Question 22

What MAY be present in a prokaryotic cell

Answer 22

Capsule
Inclusion granules
Frimbriae (pilli) (gram -ve)
Flagellum
Membranous invagination

Question 23

Defence against UTIs

Answer 23

Main defence is flushing action of urine

Tamm-Horsfall protein helps bind specific Escherichia coli strains and remove them

Question 24

What are some encapsulated infections

Answer 24

Meningitis, pneumonia, otitis media and sinusitus

Question 25

What is the function of a bacterial capsule

Answer 25

Mediate adhesion​

Immune evasion​

Protection from desiccation​

Reserves of carbohydrate​

Encapsulated bacteria give rise to smooth colonies​

Capsule material gives rise to ‘capsular antigens’​ - strep infections

Question 26

What are endotoxins

Answer 26

Produced inside mostly Gram -ve bacteria as part of their growth and metabolism

They are secreted and released following lysis into the surrounding medium

Question 27

What are endotoxins

Answer 27

Part of the outer portion of the cell wall or Gram -ve bacteria

They are liberated when bacteria die and the cell wall breaks apart

Question 28

What is the point of LPS (endotoxin)

Answer 28

Promotes production of platelets, clotting factors, mast cells, macrophages, inflammatory response etc

These responses when uncontrolled can lead to hypertension and toxic shock which can result in death

Question 29

Lethal bacterial proteins (exotoxins)

Answer 29

Botulinum 0.6x10-8 (mouse)

Tetanus 4x10-8 (mouse)

Shigella toxin 2.3x10-6 (rabbit)

Question 30

Difference between endo and exo toxins

Answer 30

ENDO
Lipopolysaccharide
Outer membrane
Not very potent
Low specificity
Pyrogenic

EXO
Protein
Extracellular (diffusible)
Highly potent
Very specific
Occasionally pyrogenic

Question 31

Virulence factors

Answer 31

Fimbriae (pilli)
-adhesion

Capsule
-protection/camouflage

Flagella
-Chemotaxis, Penetration

LPS/Endotoxin
-endotoxic shock/ inflammation