Microbial Infection Flashcards
What are the 5 types of microbial infection?
- Viruses
- Bacteria
- Fungi
- Protozoa
- Helminths
What are viruses?
Obligate parasites
Why are viruses not cells?
Replicate using host-cell machinery
How do viruses divide? (2)
- Budding out
- Cytolysis
What are the 4 routes of viral infection?
- Faecal-oral
- Airborne
- Insect vectors
- Blood borne
Are viruses host specific?
Yes
What are 4 important examples of viral infections?
- HIV
- Small pox
- Polio
- HPV
What type of virus is HIV and why?
Retrovirus
- Reverse transcriptase required to turn RNA to DNA before DNA replication
Which virus was the first to be eradicated?
Small pox
Why could smallpox be eradicated? (3)
- Easily detected by rash
- Obligate —> only survive in humans
- Good vaccine
Which virus are we close to eradicating?
Polio
What type of cell are bacteria and why? (5)
Prokaryotes
1. No internal membranes
2. Haploid
3. Poorly defined cytoskeleton
4. Peptidoglycan cell wall
5. Binary fission
What are bacterial cell walls made of?
Peptidoglycan
How do bacteria divide?
Binary fission
Why are mutations more likely to have a phenotypic effect in bacteria? (2)
Haploid
What are the 8 parts of a bacterial cell?
- Nucleoid
- Cytoplasm
- Ribosomes
- Plasma membrane
- Cell wall (peptidoglycan)
- Capsule (not all)
- Pilus
- Flagella
What are 7 important examples of bacterial infections?
- Shigella
- Neisseria meningitidis —> meningitis
- Clostridium difficile
- MRSA
- Mycobacterium tuberculosis —> TB
- Helicobacter pylori
- E.coli
What part of the body does shigella effect?
GI tract
How is shigella transmitted?
Faecal-oral
What is the infectious dose of shigella?
10-100
How does shigella travel round the body?
Cell-to-cell spread using host actin
(No flagella)
What does shigella do in the body?
Destroy GI tract epithelium —> dysentery
What is the main symptom of neisseria meningitidis?
Meningitis
What does neisseria meningitidis cause in the body? (5)
- Septicaemia
- Septic shock
- Meningitis
- Severe inflammatory response
- Petechiae (purple/red spots)
What proportion of people already have neisseria meningitidis as commensal bacteria?
20%
What are hospital acquired infections called?
Nocosomal
What are the 2 common nosocomial infections?
- Clostridium difficile
- MRSA
Why is learning about tuberculosis important?
No1 infectious killer after Covid
How long does treatment take for those with drug-resistant vs non-resistant TB?
- Non-resistant —> 6 months
- Resistant —> 9-12 months
What bacteria causes tuberculosis?
Mycobacterium tuberculosis
How is TB treatment/prevention developing? (3)
- New drugs to combat resistance
- Better vaccines
- Better diagnosis tools
What scan is used to identify TB?
PET-CT
Why is there FDG uptake in TB PET-CT scans?
Lots of immune response —> high metabolic activity
—> see heat
What does helicobacter pylori cause in the body? (2)
- Peptic ulcers
- Gastric cancer
What is unique about helicobacter pylori?
Multiple flagella
When is E.coli present in the body?
Always in non-pathogenic gut
When does E.coli become pathogenic?
Mutated
What is the generation time of E.coli?
20 mins
What is the generation time of mycobacterium tuberculosis?
20 hours
What are the point mutation rates for humans, bacteria and viruses?
- Human —> 10-8
- Bacteria —> 10-8
- Viruses —> 10-4
Why do bacteria evolve so quickly?
- Short generation time
- Haploid
What are the 3 eukaryotic microbial infectious agents?
- Fungi
- Protozoa
- Helminths
What type of cells are fungi?
Eukaryotic
What do fungi cause in the body?
Mycoses
1. Cutaneous
2. Mucosal
3. Stystemic
What are fungi present as? (2)
- Yeast
- Filaments
How does yeast fungi replicate?
- Bud
- Divide
What are present in fungi filaments?
Cross walls/septa
What is an important example of a fungal infection?
Candida albicans
What are 3 infections caused by candida albicans?
- Oral thrush
- Vaginal yeast infection
- Bloodstream infections
What are protozoa?
Unicellular eukaryotic organisms
How do protozoa replicate? (2)
- Binary fission
- Trophozoite formation
Which 3 parts of the body do protozoa parasites infect?
- Intestinal
- Blood
- Tissue
How are protozoal infections acquired?
Insect vector or by contact with an infected substance/surface
What is involved in the life cycle of a protozoa?
2 hosts
What are 2 important examples of protozoal infections?
- Malaria
- Leishmaniasis
Which vectors transmit malaria?
Plasmodium
How do plasmodium protozoa replicate?
Trophozoite formation
Which 2 parts of the body do malaria parasites infect?
- Blood
- Tissues
How are cells infected with malaria indicated on a blood film?
Large with lots of granule-looking spots inside
Which genus of protozoa cause leishmaniasis?
Leishmania
Which vector transmits leishmaniasis?
Sandfly vector
Which 2 parts of the body do leishmaniasis parasites infect?
- Blood
- Tissues
How do leishmania protozoa replicate?
Trophozoite formation
How is leishmaniasis indicated on a blood film?
Very distinct —> look at picture
What are the symptoms of leishmania? (3)
- Skin lesions
- Ulcers
- Facial disfigurement
What are the symptoms of malaria?
- Fever
- Cognitive impairment
- Anaemia
- Jaundice
What type of disease does leishmaniasis cause? (2)
- Cutaneous
- Visceral
What are helminths?
Multicellular eukaryotic cells (metazoa)
What is special about the life cycle of helminths?
Outside human host
What are 3 important examples of helminths?
- Roundworms - ascaris
- Flatworms - flukes
- Tapeworms
How are helminth infections transmitted?
Faecal-oral transmission
What type of helminth causes schistosomiasis?
Flukes
What are the 5 steps in the life cycle of flukes?
- Egg
- Miracidium
- Snail intermediate host
- Cercaria —> burrows in skin —> blood
- Adult pair
What are the symptoms of schistosomiasis?
- Fever
- Intestinal/bladder/urogenital issues
- Malnutrition
- Genital lesions
