Microbial infection Flashcards
What type of microbe is a virus?
Obligate intercellular parasites
What type of genetic material do viruses have?
How do they replicate and divide?
Contain RNA or DNA
replicate using host machinery and divide via budding and cytolysis
What are the routes of infection for a virus?
Faecal oral
airborne
Vectors (insects)
Blood-borne
Give three examples of viruses
HIV - retrovirus (uses reverse transcriptase)
Small pox - variola
Polio - iron lungs
HPV - can cause cervical cancer
What type of cells are bacteria?
Give some features of bacteria
Pro-karyotes single circular chromosome - mutation immediately expressed poorly defined cytoskeleton cell wall - peptidoglycan flagella for transport
How do bacteria divide?
binary fission
What colour do gram positive and gram negative bacteria appear as under a gram stain?
Bacteria are identified by how they look under the microscope, and how they Gram stain.
If it’s blue, it’s Gram +ve;
pink = Gram –ve.
This is because the outside cell membrane of the Gram –ve bacteria blocks the stain from penetrating the cell wall
Give some examples of bacteria.
shigella - faecal-oral transmission, uses host actin to move and wrecks the GI tract
Neisseria meningitidies - usually harmless (commensal) septicaemia, meningitis, septic shock, fatality
C. diff and MRSA - HAIs
Tuberculosis - top infectious killer - difficult to diagnose
Helicobacter pylori - peptic ulcer disease and gastric cancer
Pathogenic e. coli - GI infections, usually fine but can become pathogenic as they mutate easily
What type of a microbe is fungi?
Unicellular eukaryotic organisms
How do fungal infections replicate/spread
Yeast - Bud or divide
filaments/hyphae cross walls or septa
How can you tell where TB is on a Pet-ct scan?
shows where there are high amounts of metabolic activity so we can see where the immune response is and therefore where the TB is
What are some types of fungal infections?
Allergic reactions - ABPA
Mycotoxicosis - aflatoxin
Athlete’s foot (tinea pedis
Cutaneous, mucosa or systemic mycoses
How are mycoses infections classified?
Level of tissue affected
Superficial - skin
cutaneous - mucosal
Subcutaneous - systemic
What are the targets for antifungal therapy?
Cell membrane -ergosterol is what they use
DNA synthesis
Cell wall - have a cell wall
What type of microbe is a protozoa?
Where are they found?
Unicellular eukaryotic
Intestinal, blood, tissue parasites
How do protozoa replicate?
How is infection aquired?
Binary fission or formation of trophozoites (active replication stage)
Often have two hosts - infection acquired by ingestion or a vector
What type of protozoa cause malaria?
How do they function?
Plasmodium species
acquired via mosquito vector
Blood and tissue parasites - trophozoites inside cell
Fevers in malaria are associated with parasites bursting from cells and going into the bloodstream which gives you periodic fevers as it goes through the life cycle
What causes leishmaniasis?
How does it function?
Acquired by a sandfly vector
Blood and tissue parasites
formation of trophozoites inside a call
cutaneous or visceral - swelling
What type of microbe are helminths?
What type of transmission occurs?
Macroscopic multicellular eukaryotes (metazoa)
Faecal-oral
What is unique about helminths lifecycle and give examples of them.
Life cycle is outside the human host
Roundworms - ascaris
Flatworms (flukes) - schistosomiasis
tapeworms
Are there vaccines for helminths?
Treatable but no vaccine
How do flukes work?
Schistosomiasis
• Small intermediate host snails take up miracidia which burrow into the snail.
• Replicate in the snail and develop into adult infectious cercaria and release into water
• These burrow into the feet and enter the blood stream
• Migrate to the hepatic portal vein and replicate and release eggs which migrate to the gut.
