Microbes & Infection Model

Question 1

What are the key features of bacteria?

Answer 1

lack of membrane-bound organelles, unicellular, small

Question 2

What are the key features of viruses?

Answer 2

Enclosed in protective envelope
spikes = attach to the host cell
non-cellular
do not respire, do not metabolize, do not grow, do reproduce
protein coat = capsid, contains genetic material

Question 3

What are the key features of fungi?

Answer 3

multicellular, eukaryotic, heterotrophs = gain nutrition through absorption

Question 4

How are microorganisms classified?

Answer 4

Classified by taxonomy, name = genus + species

Question 5

List the micro-organisms in order of size

Answer 5

Prions, 
proteins, 
viruses, 
mycoplasma/clamydiae/rickettsiae, 
mitochondria, 
bacteria, 
eukaryotic cells (yeasts, protozoa, human cells), 
worms

Question 6

What is a prion?

Answer 6

Protein that causes brain degeneration e.g. CJD

Question 7

What microorganism is macroscopic?

Answer 7

Worms

Question 8

Describe the genetic material of viruses

Answer 8

Can be ss or ds, to replicate the genome viruses need to be inside a host cell to utilise their replication processes

Question 9

What does the baltimore classification of viruses tell us?

Answer 9

That there is a huge diversity of viruses

Question 10

Give an example of a ds non-enveloped DNA virus

Answer 10

Adenovirus = res tract infections

HPV = cervical cancer

Question 11

Give an example of a ds enveloped DNA virus

Answer 11

Epstein-barr virus

Question 12

What are the shapes of bacteria?

Answer 12

Coccus, spirillus, bacillus/rods

Question 13

What 2 arrangements can cocci be in?

Answer 13

Clusters or chains

Question 14

What makes a bacteria gram +ve or –ve?

Answer 14

peptidoglycan, in cell wall of Gram +ve bact

Gram +ve bact retain crystal violet dye, Gram -ve bact do not

Crystal voilet, iodine, alcohol washing, counterstain safranin, stain Gram -ve bact pink

Both Gram +ve and Gram -ve bact pick up counterstain but is unseen on Gram +ve bact due to darker crystal violet stain

Question 15

Outline the types of oxygen tolerances

Answer 15

Aerobes = survive in O2.

Anaerobes = survive in no O2.

Obligate = require for survival

Question 16

Outline some diff between eukaryotes and prokaryotes

Answer 16

E = multiple chromosomes, nucleus membrane bound, membrane bound organelles, no peptidoglycan.

P = circular DNA, plasmids, no nuclear envelope, no membrane bound organelles, cell wall has peptidoglycan

Question 17

What is the difference between an exotoxin and endotoxin?

Answer 17

Exotoxins are toxic substances secreted by bacteria and released outside the cell.

Endotoxins are bacterial toxins consisting of lipids that are located within a cell

Question 18

Outline the general areas of virulence

Answer 18

Host entry/exit
Adherence to host cell
Immunosupression 
Immunoevasion
Iron sequestration 
Toxins

Question 19

Outline the key stages in the model of infection

Answer 19

Patient meets pathogen, differing mechanisms of infection = infection followed by management then outcome

Question 20

Expand on the pt part of the infection model

Answer 20

Person: age, gender, physiological state, pathological state, social factors

Time: calendar time (seasons), incubation period.

Place: current, recent

Question 21

Expand the infection part of the infection model

Answer 21

infection –> attachment –> toxin prod/interaction with host defenses –> inflam = host damage

Question 22

Expand the management part of the infection model

Answer 22

History (for diagnosis)
Examination (for diagnosis)
Investigations (for diagnosis)
Treatment (specific or supportive)
Infection prevention

Question 23

What 2 areas can treatment be broken down into?

Answer 23

Specific = antimicrobials, surgery, drainage, debridement, dead space removal (hole after drainage/debridement infect can occur)

Supportive = symptom relief, physiological restoration

Question 24

Name the 7 mechanisms of infection

Answer 24

Contiguous (direct)
Inoculation
Haematogenous
Ingestion
Inhalation
Vector
Vertical