Infections and Superbugs

Question 1

What are the different types of microorganisms?

Answer 1

• Bacteria
• Viruses
• Fungi
• Protozoa
• Helminths

Question 2

Describe bacteria

Answer 2

• Prokaryotic DNA (no nucleus) and circular DNA
• Highly abundant
• Found in soil, water, plants and animals

Question 3

Describe viruses

Answer 3

• Smaller than bacteria
• Obligate intracellular (cannot survive outside host)
• DNA or RNA- no replication mechanism
• Humans have 3000 genes and HIV has 10 genes
• They have a protein coat and maybe envelope- no nucleus
• Found in animals and humans

Question 4

Describe fungi

Answer 4

• Eukaryotes
• Multi or unicellular
• Cell walls contain chitin
• Found in soil, animals and humans

Question 5

Describe protozoa

Answer 5

• Eukaryotic, unicellular animals
• Motile
• Found in water and animals

Question 6

Describe helminths

Answer 6

• Worms
• Eukaryotic parasites
• Found in soil water and animas

Question 7

Define pathogen

Answer 7

Organism that causes or is capable of causing disease

Question 8

Define commensal

Answer 8

Organism that colonises host but normally does not cause disease (symbiotic relationship)

Question 9

Define opportunist pathogen

Answer 9

Microbe that only causes disease if host defence is compromised (i.e. vulnerable people)

Question 10

Define virulence/pathogenicity

Answer 10

Degree to which a given organism is pathogenic (ebola and cholera have high virulence)

Question 11

Define asymptomatic carriage

Answer 11

When a phone is carried harmlessly at a tissue site where it causes no disease (vaccination to reduce asymptomatic carriage)

Question 12

Define pathobiont

Answer 12

Potentially pathological which lives as a non-harming symbiont

Question 13

Define tropism

Answer 13

When an organism is able to attach itself to tissue

Question 14

What are the different routes of acquisition and transmission?

Answer 14

• Skin
• Airway
• Alimentary tract
• Genital tract
• Inoculated into blood

Question 15

What microbes can be transmitted via skin?

Answer 15

Bacteria, fungi, virus and helminths

Question 16

What microbes can be transmitted via airway?

Answer 16

Bacteria, fungi and viruses

Question 17

What microbes can be transmitted via alimentary tract?

Answer 17

(usually leads to diarrhoea)

Bacteria, viruses, helminths and protozoa

Question 18

What microbes can be transmitted via genital tract?

Answer 18

Bacteria, viruses and protozoa

Question 19

What microbes can be transmitted through inoculation into blood

Answer 19

Bacteria, viruses and protozoa

Question 20

Describe bacterial nomenclature

Answer 20

Genus, species

Question 21

What are current mega problems

Answer 21

HIV, malaria, tuberculosis, antibiotic-resistant bacteria, hospital associated infections, respiratory viruses, viral haemorrhage fever and Zika virus

Question 22

What does flora mean?

Answer 22

Bacteria

Question 23

What does a gram stain tell us about bacteria?

Answer 23

Blue- gram positive- thick cell wall made of peptidoglycan

Pink- gram negative- bacteria held together by lipopolysaccharide

Question 24

Why are peptidoglycan and lipopolysaccharide harmful?

Answer 24

They are detected by the immune system because they are not found in animals, therefore they can cause sepsis

Question 25

What are the two shapes of bacteria?

Answer 25

- Rods and cocci - Cocci are small and round - Rods can be spiral (spirochete) or curved (vibrio)

Question 26

What is the Ziehl-Neelsen stain used for?

Answer 26

- Pink stain that tests for mycobacteria (genus that causes disease) - Acid is added to sample and mycobacteria holds pink stain (acid fast bacillae)

Question 27

What are the features of an ideal bacterial environment?

Answer 27

- Temperature- 80 (120 for spores) - pH- 4-9 - Water- 2 hours-3 months (>50 years for spores) - Bacterial growth is exponential - Dislike UV light

Question 28

What are endotoxins?

Answer 28

Component of the outer membrane of the bacterium

Question 29

What are exotoxins?

Answer 29

Secreted proteins of gram positive and gram negative bacteria (e.g. tetanus toxin inhibits nervous system)