Lecture 1

Question 1

Oppurtunistic pathogen

Answer 1

Cause disease in compromised hosts

• immunocompromised
• break in physical innate barrier
• break in normal flora
• candida albicans, pneumocysits jirovec

Question 2

What are the points of entry of a microbe into the host

Answer 2

Skin

Mucous membranes

Question 3

Opportunistic pathogenic bacteria

Answer 3

Can cause disease in people with immunosuppression

Pseudomonas aerugonisa

Question 4

Challenges for eradication of disease

Answer 4

• Intracellular infections
• Multiple host organisms
• Genetic plasticity e.g. Influenza A; antigenic shift and drift

Question 5

Old friends hypothesis- Rook

Answer 5

An alternative to the hygiene hypothesis
It is believed that the immune system depends on certain microbes that evolved with humans
Their absence can cause abnormal function of the immune system

Question 6

Incidence

Answer 6

The number of new cases of a disease in a given area

Question 7

The enterotypes that make up the gut microflora

Answer 7

prevotella
bacteroides
ruminococcus

Question 8

Pathogen

Answer 8

An organism that causes disease

Question 9

Virulence

Answer 9

The degree of severity of disease

Continuos variable

Question 10

How is virulence determined

Answer 10

By adherence, invasiveness, toxicity and persistence

Question 11

How is virulence measured

Answer 11

LD50
the number of microbes required to kill 50% of infected hosts
the fewer the number of microbes required to cause disease, the more virulent

Question 12

What are virulence factors

Answer 12

Virulence genes

Pathogenicity islands

Question 13

Hygiene hypothesis outlined by Dr David Strachan

Answer 13

a lower incidence of infection in early childhood could be an explanation for the 20th century rise in atopic diseases by suppressing the natural development of the immune system

Question 14

Health care associated infection HCAI

Answer 14

MRSA
Clostridium difficile
Norovirus
Seasonal influenza (flu) 
Escherichia coli

Question 15

Yersinia pestis

Answer 15

Causes the bubonic plague

Question 16

morbidity rate

Answer 16

The incidence of a disease across a population and/or geographic location during a single year

Question 17

Obesity

Answer 17

Reduction in bacteriodetes and an increase in firmicutes

Increase in firmicutes = an increase in the breakdown of polysaccharides

Question 18

4 bacterial phyla in gut

Answer 18

actinobacteria
firmicutes
bacteroidetes
proteobacteria

Question 19

Bacterial genus in the gut

Answer 19

Bacterioides, clostridium, faecalibacterium, eubacterium, ruminococcus, peptococcus and bifidobacterium

Question 20

Probiotics

Answer 20

lactobacillus

bifidobacterium

Question 21

Primary pathogen

Answer 21

Causes disease when it enters the body

Question 22

ID50

Answer 22

The number of microbes required to infect 50% of the population

Question 23

What could influence ID50 and LD50 values of a pathogen

Answer 23

The host
Immunological status
Physiological status
Route of infection

Question 24

Virulence genes

Answer 24

encode factors allowing pathogen to cause disease (adherence, invasion, nutrient acquisition, modulation of immune system)

• toxins
• attachment proteins
• capsules

Question 25

Pathogenicity islands

Answer 25

Section of genome, may contain multiple virulence genes, often encode related functions (protein secretion system, toxin production)

Question 26

Pathogenic bacteria

Answer 26

``` The bacteria that can cause infection Myobacterium tuberculosis Streptococcus Shigella Campylobacter Tetanus ```

Question 27

Koch's postualtes

Answer 27

Establish a causative relationship between microbe and disease

Question 28

Endogenous infection

Answer 28

An infection caused by an infectious agent that is already present in the body

Question 29

Intracellular parasite, bacteria

Answer 29

They have the ability to grow and replicate inside other cells Intracellular pathogenic bacteria: salmonella, neisseria, myobacterium,

Question 30

Bacterial pathogen examples

Answer 30

Bacterial vaginosis- the bacteria that change vaginal microbiota caused by overgrowth of bacteria that crowd out the Lactobacilli species Bacterial meningitis- bacterial inflammation of the meninges UTI- Escherichia coli Bacterial gastroenteritis- caused by enteric pathogenic bacteria

Question 31

Gram negative bacterial pathogens

Answer 31

E.coli Pseudonomas aerugionas Neisseria goorrhoeae Neisseria meningitis Beta proteobacteria There are 12 serogroups of N. meningitis

Question 32

Gram positive bacterial pathogens

Answer 32

Colstridium Streptococcus pneumoniae Corynebacterium diptheriae

Question 33

Requirements for a disease

Answer 33

1. Portals of entry 2. Establishment 3. Avoid host defences 4. Damaging the host

Question 34

Portals of entry

Answer 34

How do pathogens gain access to host tissues ``` Adherence Adherence factors that help the attachment of microbial pathogens to host tissues Capsules Adherence proteins Lipoteichoic acid Fimbrae ```

Question 35

Mucous membranes

Answer 35

Antimicrobial secretions protect against infection - Fe not available (is needed for microbial growth) - Long chains of fatty acids in acidic secretion of the skin (lethal to bacteria) - Lactenin, proteins present in breast milk that are selectively bacteriocidal for Streptococcus pyogenes