Microbial Infection Flashcards
What are the five groups of infective agents?
Viruses
Not cells
Bacteria
Prokaryotes
Fungi
Single cell eukaryotes
Protozoa
Single cell eukaryotes
Helminths
Multicellular
What are some facts about viruses?
Obligate parasites
Contain RNA or DNA as genetic material
Replicate using host cell
Show host specificity (but infect most life forms including bacteria)
Divide by budding out of hosts, or cytolysis
Various routes of infection (fecal oral, blood borne, insect vector, air borne)
What are some facts about HIV?
Contains RNA Also reverse transcriptase to make DNA Retrovirus Enveloped virus They bud
What is the o ly infectious disease to be eradicated by vaccination?
Smallpox in 1977
Bacteria are prokaryotes what are some facts about these?
No internal membranes (such as around mitochondria)
All have a single copy of a chromosome (haploid)
Poorly defined cytoskeleton
Cell wall contains peptidoglycan
Divide by binary fission
What are some features of bacterial cells?
Pilli
How they adhere to surfaces
Capsule
Can hinder phagocytosis
Flagellum
Helpful in swimming
What is special about shigella?
Bacterial
Can move without flagella
Bacterial cells nuclear energy host cell actin at the tail, this pushes them round the cell and into neighbouring cells
Infects the GI tract
What is the difference between hospital acquired infections and community acquired infections?
Hospital
Show more antimocrobial resistance
Eg c diff and MRSA
Community
Eg neisseria meningitidis
viruses evolve very quickly how do they do this?
They have very higher mutation rates
Point mutation rates:
Human( 10^-8)
Bacteria(10^-8)
Viruses(10^-4)
Bacteria replication is very error prone
They are haploid, so only one gene needs to mutate to have an effect not two
Also very short replication times
Fungi can be separated into three groups based in the location they infect, what are these?
cutaneous mycoses
Mucosal mycoses
Systemic mycoses
Eg candida Albicans
In what forms do fungi occur as?
Yeasts
Filmaments
Both
How do fungi divide?
Yeasts Bud
What arse some featurss of Protozoa?
Unicellular eukaryotic
Include intestinal, blood and tissue parasites
Replicate by binary fission or by formation of trophozoites
Many have complicated life cycles involving two hosts
Infection by ingestion or through a vector
Include malaria and leishmaniasis
What are some facts about plasmodium species?
5 that can infect humans
All go through a mosquito vector
They form trophozoites in cells to make progeny
Lots of drug resistance to antimalarials
What are some facts about helminths?
Metazoa
Have differentiated Cells that form organs
Multicellular
Visible to the naked eye
Complex life cycles in and out of human hosts
Transmitted by the faecal oral route
Eg flat worms, round worms, tape worms
