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Flashcards on Fundamental Biomedical Techniques Lecture 7 (Week 8)
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Pathogen
Biological agent that causes disease or illness to its host.
Helicobacter pylori
Gastric ulcers are caused by this bacteria, not stress or spicy food.
Animals and insects
Infectious diseases can be spread by these organisms
Mosquitoes
Murray Valley Encephalitis, Ross River virus, Zika virus
Birds
Bird flu, Psittacosis, Salmonella and Campylobacter (chickens)
Leading causes of death in 2000
Ischaemic heart disease, Stroke, Chronic obstructive pulmonary disease
Leading causes of death in 2019
Ischaemic heart disease, Stroke, Alzheimer's disease and other dementias
Healthy life expectancy at birth
Average number of years that a person can expect to live in 'full health' from birth.
Physical barriers to resist infection
Tough outer layers of skin.
Chemical defense to protect inner tissues
Acid in the stomach
Intrinsic defenses of individual human cells
Cells aggressively degrade double-stranded RNA (viral)
Types of Pathogens
Bacteria, Viruses, Fungi, Protozoa, Helminths, Prions
IgM
Primary infection triggers this initial antibody
IgG
Repeat infection triggers this initial antibody
Bacteria
Unicellular organisms without a nucleus.
Virus
Non-cellular infectious agent that replicates in living cells.
Fungi
Eukaryotic simple organisms, that can grow single-celled or as thread-like filaments.
Protozoa
Unicellular eukaryotic organism
Helminths
Multicellular complex organisms living in or on a host.
Prions
A protein as a standalone infectious agent.
Microorganism (microbe)
Microscopic organism that comprises either a single cell (unicellular) or cell clusters.
Microorganisms
Bacteria, fungi, archaea, and protists; microscopic plants (green algae)
Archaea and Bacteria
Lack a cell nucleus and the other membrane bound organelles; unicellular
Eukaryotes
Membrane bound ('true') nuclei containing their DNA.
Prokaryotes Nucleus Description
A DNA/protein complex in the cytosol (nucleoid) which lacks a nuclear envelope.
Primary Pathogens
They can breach barriers and survive in host locations where other microorganisms cannot.
Examples of Primary Pathogens
Bubonic plague – Yersinia pestis; Smallpox / Variola vera – Variola major or V. Minor; Mononucleosis - Epstein–Barr virus; TB - Mycobacterium tuberculosis
Pathogenicity
Ability of an organism to cause disease (i.e., harm the host).
To survive and multiply, a successful pathogen must:
Colonize the host; Find a nutritionally compatible niche in the host’s body; Avoid, subvert, or circumvent the host’s immune responses; Replicate, using host resources; and Exit and spread to a new host.
Opportunistic pathogens
Cause disease under some circumstances
Examples of opportunistic pathogens
Candidiasis – Candida albicans; Staphylococcus aureus
Microbiome
The totality of microorganisms and microbial genomes that constitute a host’s normal microbiota.
Common bacteria shapes
Coccus/cocci (plural), Bacilli (Rods)
Food Poisoning
Due to contaminating microorganisms in food that have not been killed, and that can invade your gastrointestinal tissues.
Invasiveness
The ability to colonise
Ability to produce toxins (toxigenesis)
Some of these toxins are released from the living bacteria. These toxins (exotoxins) are very potent.
Ability to produce toxins (toxigenesis)
Some of these toxins are part of the outer cell wall and these are released when the bacteria are lysed (endotoxins).
How do we diagnose bacterial infections?
Agar plates, physical (staining) and growth characteristics (what they like to grow on, what they don’t like to grow on, which carbohydrates they can use to grow)
Other method used to diagnose bacterial infections
Flow cytometry, PCR
Multidrug resistant (MDR)
Multidrug resistant (MDR) is a condition enabling disease-causing microorganisms to resist distinct anti-microbial agents (antibiotics) of a wide variety of structure and functional targets.