4.1 Microbial Infection Flashcards
What are the five main types of infectious agents?
Viruses, bacteria, fungi, helminths, protozoa
What is the definition of a virus?
Obligate intracellular parasite
How do viruses reproduce?
By infecting a host cell and using their nuclear synthetic macheinery
What can viruses infect?
All life forms, including bacteria
What type of cell is a virus?
They are not cells in their own right
What type of cells are bacteria?
Prokaryotes
What type of organisms are fungi?
Eukaryotes - single cell
What type of organisms are protozoa?
Eukaryotes - single cell
What type of organisms are helminths?
Eukaryotes - multicellular
What type of genetic material do viruses contain?
RNA or DNA
How do viruses divide?
By budding out of the host cell or by cytolysis
What are the four routes of infection that viruses can show?
Faecal-oral, airborne, insect vectors, blood borne
What is an example of a virus and what type of genetic material does it have?
HIV – retrovirus so has RNA
What do RNA genomes require in order to replicate?
Reverse transcriptase enzyme
What is the difference between eukaryotes and prokaryotes?
Prokaryotes do not have internal membranes and therefore do not have membrane bound organelles
Which bacteria has membrane bound organelles despite being a prokaryote?
Photosynthetic bacteria
What is the genetic makeup of a prokaryotic organism?
Haploid – single copy of chromosome
What is the difference in cytoskeleton between eukaryotes and prokaryotes?
Prokaryotes – cytoskeleton is poorly defined
Eukaryotes – well developed cytoskeleton
What does the prokaryote cell wall contain?
Peptidoglycan
How do prokaryotes divide?
Binary fission
What structure of bacteria allows them to move?
Flagellum
How does shigella spread?
Faecal-oral transmission
How does shigella move around in the host?
Using host cell actin
Which bacteria causes meningitis?
Neisseria Meningitidis when when it infects the CSF
What is the result of septicaemia on the body?
Septic shock and a severe inflammatory response
Which bacteria are commonly responsible for hospital acquired infections?
Clostridium difficile
Methicilin resistant staphylococcus aureus
Which bacteria causes peptic ulcers and gastric cancer?
Helicobacter pylori
How is mycobacterium tuberculosis spread?
Airborne
How do bacteria evolve so quickly?
They have similar mutation rates to humans, but reproduce more often, thus having a shorter generation time
What three types of conditions can fungi cause?
Cuteanous, mucosal or systemic mycoses
How do fungi occur as?
Yeasts, filaments or both
How do fungi replicate? (yeasts vs filaments)
Yeasts bud or divide
Filaments undergo fragmentation
What is an example of an infectious fungi?
Candida albicans
What are two characteristic features of filaments?
They have cross walls or septa
How do protozoa replicate?
In the host by binary fission or by formation of trophozoites inside a cell
How is a protozoa infection acquired?
Infection is acquired by ingestion or through a vector
How many hosts does the protozoa life cycle involve?
2
Where can protozoa pathogens be found?
Intestines, blood and tissue
How does the pathogen which causes malaria replicate?
Plasmodium forms trophozoites inside the host cell
How is Malaria infection acquired?
Mosquito vector
What is the malaria belt?
The belt around the equator line in which the incidence of malaria is the highest – corresponds with high temperatures
What condition does Leishmania species cause?
Leishmaniasis
How is Leishmaniasis infection acquired?
Via sandfly vector
How does the Leishmania species replicate to cause Leishmaniasis?
Formation of trophozoites inside a cell
What type of disease is leishmaniasis?
Cutaneous and visceral
What are three exmples of helminths?
Roundwords
Flatworms
Tapeworms
How do helminths replicate?
Sexually via eggs
Some are hermaphroditic (have both male and female reproductive organs)
What type of transmission do helminths exhibit?
Faecal-oral transmission
Which bacterial pathogen are metazoa?
Helminths – multicellular
What type of worm are flukes?
Flatworms
What disease do flukes cause?
Schistosomiasis
Is there a vaccine against helminths?
Treatable, but no vaccine
