ToB S4 - Bacteria and Viruses

Question 1

What is infection?

Answer 1

The multiplication of a pathogen microbe on/in a susceptible host with associated dysfunction/damage

Question 2

Outline the Henle-Koch’s Postulates

Answer 2

Proving the bacteria is the causation of the disease

1) Agent must be shown to be present in every case of the disease by isolation in pure culture
2) The agent must not be found in cases of other diseases
3) Once isolated, the agent must be capable of reproducing the disease in experimental animals, and must be recovered from the experimental disease produced

Question 3

What colour do gram positive bacteria stain?

Answer 3

Blue

Question 4

What colour do gram negative bacteria stain?

Answer 4

Red

Question 5

Explain the significance of genome composition when classifying and detecting viruses

Answer 5

RNA viruses are more likely to mutate as RNA is less stable

Question 6

Explain the terms Pathogen and Non-Pathogen

Answer 6

A pathogen is a bacterium, virus, or other microorganism that can cause disease whereas a non-pathogen is a bacterium that doesn’t cause disease. Many non-pathogens perform essential ecological roles

Question 7

Why is acid fast staining used?

Answer 7

• Allow us to detect the bacteria causes of tuberculosis and leprosy (mycobacteria)
• These bacteria cannot be identified by gram staining

Question 8

Explain the significance of envelope presence when classifying and detecting viruses

Answer 8

If a virus has an envelope it’s more easily sterilised as if holes are punched in the envelope the virus cannot survive

Question 9

Explain the significance of Replication strategy when classifying and detecting viruses

Answer 9

RNA viruses can use reverse transcriptase (HIV), DNA viruses can use cell machinery (HPV), or a virus can carry its own replication enzymes

Question 10

Name a DNA enveloped Virus

Answer 10

Any from: - Hepatitis B - Inflamed liver - Herpes - Oral/genital warts - Smallpox - smallpox

Question 11

Name a DNA non-enveloped virus

Answer 11

HPV - Warts, cervical cancer

Question 12

Name a RNA enveloped virus

Answer 12

Any from: - HIV - AIDS - Rubella - Rash, congenital rubella syndrome - Rotovirus - Diarrhoea - Coronavirus - SARS

Question 13

Gram positive bacteria?

Answer 13

Staphylococcus, streptococcus and Clostridium

(Gram negative = everything else Acid fast - mycobacterium)

Question 14

What is the target for the β -lactams class of antibiotics? Eg Amoxicillin, Penicillin

Answer 14

Cell wall

Question 15

What is the target for the glycopeptide class of antibiotics? Eg Vancomycin

Answer 15

Cell wall

Question 16

What is the target for the macrolide class of antibiotics? Eg Erythromycin

Answer 16

Protein synthesis

Question 17

Define “carriage” in the context of infection

Answer 17

Passage taken by microorganism

Question 18

Define “normal flora” in the context of infection

Answer 18

non-pathogenic bacteria naturally found in our bodies e.g. the gut

Question 19

Define “Commensal” in the context of infection

Answer 19

Symbiotic relationship where one species derives benefit (microbe) and the other is unaffected (host). This is the time when the microbe may be replicating or waiting for the immune system to become compromised