Microbiology Flashcards
Order these for increasing complexity.
Fungi, Virus, parasite, bacteria
Virus –> Bacteria –> Fungi –> Parasite
What is a microbe?
A microscopic entity that can be unicellular, multi-cellular or acellular
What kind of pathogens are viruses?
Obligate intracellular pathogens
Virion
Single infectious unit, genome surrounded by protein capsid (and sometimes phospholipid membrane)
How are viruses classified?
By their genome structure, virion morphology and replication strategy
How are viral infections diagnosed?
By presentation and PCR
What is an active viral infection?
Replicating virus is causing symptoms of disease
Describe the possibilities of the viral genome.
Can be DNA, RNA, dsRNA
What is a chronic viral infection?
Low levels of viral replication without clinical disease
What is viral latency?
Virus is no longer causing disease but has not been eradicated and is dormant inside cells that are infected
What is viral re-activation?
A change in the immune system (stress, immune suppression) results in replication of a dormant virus
What is a prion?
Small infectious protein with no associated nucleic acid
How do prions replicate?
Intracellular “spreading” of misfolded protein
Why can these be difficult to treat?
They are often resistant to heat, chemicals and radiation
Bacteria
- # cells?
- Prokaryote or eukarote?
- Internal organelles present?
- Structure of nucleic acid?
- Method of reproduction?
- Unicellular
- Prokaryotes
- No nucleus or membrane bound organelles
- DNA is compact and circular
- Binary fission
The cell wall of bacetria may contain ______
Peptidoglycan
What is a gram positive bacteria?
The gram stain turns peptidoglycan purple, so gram positive appear purple due to presence of peptidoglycan in their cell wall.
What is gram negative bacteria?
They have a double plasma membrane with peptidoglycan between the 2 layers so the dye for gram stain cannot penetrate that membrane and stain peptidoglycan so they apper red on gram stain (no gram dye taken up)
What are 2 kinds of bacteria that do not gram stain either + or -?
Mycobacteria
Mycoplasma
How are bacteria classified?
Microscopic appearance
Growth
Metabolism
Genotype
Fungi
Eukaryotes with cell walls composed of chitin and cell membranes with ergosterol
What are the 2 basic forms of fungi growth?
Yeast (individual cells)
Mold (multicellular filaments)
Fungi are common in air and on surfaces in our lives. Why aren’t we constantly sick from them?
They’re generally only invasive and lead to disease in immune deficient patients
How are fungi classified?
Molecular biology
Growth (yeast, mold)
Patient presentation
Parasite
Broad spectrum of eukaryotic organisms (unicellular - protozoa) (multicellular - helminths)
Do all parasites cause disease?
No
How are parasites transmitted?
Insects or fecal-oral route
How is parasitic infection diagnosed?
Microscopic examination of blood smears or lesions
Microbiota
Diverse population of microbes that inhabit the skin and mucous membranes in a mutualistic relationship
What are important functions of the gut microbiota?
1) Metabolism and biosynthesis
2) Bacterial Interference
3) Immune maturation and homeostasis
4) Signaling to nervous system
Microbiota
- Residents
- Transients
- Carrier state
- Strains that have established niche at site and occupy indefinitely
- Acquired from environment and established briefly but then eliminated via competition from residents or immune defense
- Organisms known to be potentially pathogenic but are residents or transients without pathogenesis in host
Microbiota are ______ and can cause infection if they reach protected areas of body in sufficient number
Opportunists
How do pathogens cause disease (generally)
Pathogen is able to invade host tissue to due trauma or when host resistance is impaired –> in tissue, they multiply and secrete disease causing agents –> abnormal conditions arise in host that interrupt normal body function due to pathogen
Pathogenesis
Ability of oragnism to cause disease
Virulence factors
Qualities enhance ability of microbe to cause disease
What are the 3 means by which pathogens cause disease?
1) Invasion of host cell
2) Toxin production
3) Stimulate evading/immune response
What is the epidemiologic triad?
What is the chain of infection?
What is the natural history of disease?
What are contact precautions?
Clean hands, gown, gloves
Used to protect against tramission via indirect contact
Droplet precautions
Clean hands, surgical mask, eye protection
Used to protect against infections transmitted via air droplets / particles
Airbone precautions
Clean hands, N95 respirator, negative pressure room
Used to protect against microbes that stay in the air and travel
Sterilization
Complete killing or removal of all living organisms from a particular location or material
Disinfection
Destruction of mircobes by processes insufficient to be called sterile
