Pathogens

Question 1

Describe bacteria and 2 types

Answer 1

Single cell prokaryotes
Gram+ (purple) PM, PS, Petidoglycan wall
Gram- (red) additional outer membrane, PS

Question 2

Describe fungi and an associated disorder

Answer 2

Multicellular eukaryotes (mould)
Unicellular yeast
Fusarium Keratitis ~ corneal ulcers (rare)

Question 3

Describe Protozoa

Answer 3

Single cell eukaryote
Moves via flagella/cillia/amoebae
Parasitic or free living symbionts

Question 4

Explain toxoplasmosis and how it can be contracted

Answer 4

T. Gondii (fatal in brain)
Sporocysts (Cat faeces)
Bradyzoites (ingest undercooked meat)
Tachyzoites (active prolif. In tissue damage/inflammmation ~ transplacental spread to foetus)

Question 5

Explain congenital toxoplasmosis and symptoms

Answer 5

Retinochoroiditis
Deaf/Blind
strabismus
Convulsions

Refer if recurrent

Question 6

What is a virus?

Answer 6

DNA/RNA core with protein coat that reproduces within hosts - classed by host, size, appearance, structure

Question 7

Explain herpes simplex keratitis

Answer 7

Corneal ulcer infections (green lines)

Question 8

Explain adenovirus

Answer 8

Removal of adenoid tissue

Question 9

Which pathogens cause chickenpox/shingles?

Answer 9

CP: Varicella Zoster, Shingles: Herpes Zoster
Infection via mucosa in resp. tract

Question 10

Explain Herpes Zoster Ophthalmicus diseases

Answer 10

Keratitis, glaucoma, ptosis
Vesicles in face/waist/chest/back

Question 11

Explain togavirus and cytomegalovirus

Answer 11

Toga: rubella, skin rash, light fever (birth defects ~ deaf/cataracts) resp. tract

Cyto: AIDs causing retinitis

Question 12

Explain acanthomoeba and it’s disorder

Answer 12

trophozoites, feed on bacteria/nutrients

Acanthomoeba keratitis: rare lethal associated with water/CLs ~ blindness

Question 13

What are helminths and what can they cause?

Answer 13

Tape/round worms (dogs)

Toxocara (Canis rundworm) ~ blindness

Vitritis/Papilitis/Retinitis/Atrophy

Question 14

What are prions and their most common disease in humans?

Answer 14

Infection proteins (hard to inactive - use on disposable GAT heads/RGP trial CLs)
Scrapie can cause BSE

Creutzfeld-Jakob (85%) via nerve tissue transplants/surgery

Question 15

Name 6 types of pathogen transmission

Answer 15

Vector
Direct
Indirect
Inoculation
Inhalation
Ingestion

Question 16

How do exotoxins differ from endotoxins?

Answer 16

Exo: effect far from inf. response
Except proteins (from gram+) very toxic, destroyed in heat

Endo: fever, diarrhoea, shock, death
Dead Gram- bacteria liberates lypopolysaccharides
Toxic in big dose, stable in heat

Question 17

Explain sterilisation

Answer 17

Eliminate all vegetative microorganisms from inanimate equipment in sterile body area/skin contacts

Question 18

Explain disinfection

Answer 18

Eliminate all vegetative microorganisms from inanimate objects except bacterial/fungal spores

Question 19

Explain 5 physical control methods of decontamination

Answer 19

Heat: Dry (increase oxidation) Moist (boiling/autoclaving) both to denature enzymes
Cold: inhibits organism growth (kills most bacteria not viruses)
Radiation: (UV/gamma)
Filtration: remove microbes from lipids (small spores ~ 0.3 micrometers)
Drying: no H2O so no growth (doesn’t work for bact. endospores/viruses)

Question 20

Explain 7 chemical control methods of decontamination

Answer 20

Cl/I compounds: bleach (func. group oxidised ~ inactive enzyme)
H2O2: disinfect CLs, avoid corneal burns
Heavy metals: (ZnCl mouthwash/AgN newborn eye drops)
Surfactants: (non)-ionic, CL care
Alcohol: mediwipes, denatures proteins
Aldehydes: formaldehyde (inactivated proteins ~ cross link func. group)
Ph Compounds: disrupts membranes, good on lipids (same as OH)