Microbial Infection Flashcards
What are the five main types of infectious agents?
Viruses, fungi, helminths, Protozoa and bacteria
What is the definition of a virus?
A obligate parasite
They are not ells in their own right
They contain RNA or DNA as genetic material
How do viruses reproduce?
By infecting a host cell and using their nuclear synthetic machinery
What can viruses infect?
All life forms, including bacteria
But they show host specificity
How do viruses divide?
by budding out of host cell, or cytolysis
What are some routes of infection for viruses?
various routes of infection
e.g., faecal-oral, airborne, insect vectors, blood borne
What does HIV (retrovirus) RNA genome require?
reverse transcriptase
What was used to treat polio virus?
Pressure machines, to make it easier to breath
What virus can cause cervical cancer?
papilloma virus
What type of cells are bacteria?
Prokaryotes
DO prokaryotes and eukaryotes have internal membranes?
No, photosynthetic bacteria are an exception
Eukaryotes have internal membranes that define organelles including nucleus, ER, mitochondria
Are prokaryotes/ eukaryotes haploid or diploid?
prokaryotes are haploid (single copy of chromosome)
eukaryotes can be haploid or diploid
What type of organisms are fungi?
Eukaryotes - Single cell
What type of organisms are protozoa?
Eukaryotes - single cells
What type of organisms are helminths?
Eukaryotes - multicellular
What type of genetic material do viruses contain?
RNA or DNA
What is an example of a virus and what type f genetic matter does it have?
HIV - Is a retrovirus so has RNA
what is the difference between eukaryotes and prokaryotes?
Prokaryotes do not have internal membranes and therefore do not have membrane bound organelles
What is the difference in cytoskeleton between eukaryotes and prokaryotes?
Prokaryotes cytoskeleton is poorly defined.
Eukaryotic cells have 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
What type of DNA do bacteria have?
Double stranded DNA
How does Shigella spread?
Faecal-oral transmission
How does shigella spread from cell to cell?
invades and destroys the cell by using host cell actin
Which bacteria causes meningitis?
Neisseria Meningitidis - when it infects the CSF
What is the result of septicaemia on the body?
Rapid progression, septic shock and a severe inflammatory response
How would you describe Neisseria meningitidis?
community acquired (multiple serogroups)
commensal to pathogen
What is another way to say hospital-acquired?
nosocomial
Which bacteria are commonly responsible for hospital acquired infections?
Clostridium difficile (forms spores which are hard to remove)
Methicillin Resistant Staphylococcus Aureus
Which bacteria causes peptic ulcers and gastric cancer?
Helicobacter pylori
How is mycobacterium tuberculosis spread?
Airborne
What is the top infectious killer in the world?
tuberculosis
How do bacteria evolve so quickly?
They have similar mutation rates to humans, however have a much shorter generation time - therefore reproduce much more often, so more mutations when the generation time is shorter
What three types of conditions can fungi cause?
Cuteanous, Mucosal or systemic mycoses
How do fungi occur as?
Yeasts, filaments or both
How do yeasts replicate?
They bud or divide
What is a cutaneous infection?
skin
What is an example of an infectious fungi?
CANDIDA ALBICANS
What are two characteristic features of filaments?
They have cross walls or septa
What do protozoa include?
Unicellular eukaryotic organisms
- include intestinal, blood and tissue parasites
How do protozoa replicate?
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
e.g., malaria and leishmaniasis
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?
Forms trophozoites inside the host cell
How is Malaria infection acquired?
Thrugh a mosquit 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
How does malaria replicate?
it is a blood and tissue parasite, by formation of trophozoites inside a cell
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 are helminths?
metazoa with eukaryotic cells
Are helminths visible to the naked eye?
Yes; multi-cellular
What are three examples of helminths?
Roundwords e.g., ascaris
Flatworms (flukes)
Tapeworms
What type of transmission do helminths exhibit?
Faecal-oral transmission
What disease do flukes cause?
Schistosomiasis
Where is the lifecycle of helminths?
outside the human host
What is a major health priority?
developing new strategies to prevent (vaccines) and treat (drugs) infection
What does effective treatment require?
knowledge of the causative agent
- its source and means of transmission
- how they cause damage and how the human body reacts
