Infectious Diseases Flashcards
Name the 2 ways in which infectious diseases can be transmitted.
- Direct contact (i.e, hand to hand touching)
2. Indirect contact (i.e, hand, to a surface, to a person)
List 5 infectious agents
- Bacteria
- Viruses
- Fungi
- Protozoa
- Parasites
Diseases may be caused by micro-organisms (microbes) or ______ _______ organisms.
Multi-cellular organisms
Name an infection caused by protozoa
- Malaria
- Dysentary
Why do infectious agents always try to create a colony?
Because in doing this they have more chance to overcome your immune system
Why are bacteria very good at replicating at speed and creating colonies in a very short space of time?
Because are very basic / simple organisms with very few cell structures.
Microbes can be _______ or non- _______
Pathogenic or non-pathogenic
What does pathogenic mean?
Disease causing
Many microbes are symbiotic. What does this mean?
They live together, at no detriment to either of them.
There are ____ times as many bacterial cells as human cells in the body.
10 times
What are pathogens?
Disease-causing microbes / infectious agents.
Describe a commensal relationship.
A symbiotic relationship between organisms whereby one benefits (i.e, gets nutrients), and the other is unaffected.
Where in the body might we have a commensal relationship with bacteria?
On the skin, in the intestines.
Name an organism that is usually commensal but can very easily become opportunistic (pathogenic).
Candida
Describe a mutualistic relationship.
A symbiotic relationship between organisms whereby both benefit.
Give an example of a mutualistic relationship
E.coli in the intestines gets nutrients and an attachment point, but makes vitamin K for us
Name a type of bacteria that helps makes vitamin K for us in the intestines.
E.coli
Name a bacteria that is usually mutualistic in the gut but is pathogenic if found in the reproductive system.
E.coli
Describe a parasitic relationship.
A symbiotic relationship between organisms whereby one benefits at the other’s expense.
Give an example of a parasitic relationship
Head lice, intestinal worms.
Describe an opportunistic relationship.
A symbiotic relationship between organisms which is initially commensal or mutualistic but then becomes pathogenic (i.e, candida)
What does symbiotic mean?
A relationship between organisms
What is significant about Anton van Leeuwenhoek?
He invested the microscope (in the 1670’s) and started to document microbes.
What did Dr Semmelweis discover in 1847?
That washing hands reduced disease spread in hospitals (maternity care).
Who discovered antibiotics in the 1900’s?
Alexander Fleming
Who came up with Germ Theory?
Louis Pasteur
What is Louis Pasteur famous for?
Germ theory and inventing the process of pasteurisation
Explain the ‘germ theory’ of disease
Germ theory states that all germs are bad and cause disease.
Who came up with Terrain Theory?
Antoine Bechamp
Explain the ‘terrain theory’ of disease
Terrain theory states that germs are opportunistic in nature and live with us symbiotically, not always becoming pathogenic.
Which theory of disease advocates not to kill germs but to promote health (i.e, through diet and exercise), to prevent illness?
Terrain theory
Which theory of disease states that the only way to prevent illness is to kill all germs?
Germ theory
Describe pasteurisation.
A process whereby a substance (i.e, milk) is rapidly heated to a high temperature to kill any microbes.
Describe why pasteurisation could be responsible for the rates of lactose intolerance that we see in society today?
Because the process of rapidly heating the milk to kill microbes also damages / kills the enzyme lactase. It can also kill the nutrients.
Most whole, micro-organisms can been seen with a ______ microscope.
Light microscope
Name a type of organism that is too small to be seen under a light microscope, and name the more advanced laboratory equipment used instead to view it.
Viruses are too small to be seen under a light microscope. Instead, an electron microscope is used.
Name a type of organism that requires an electron microscope to be seen.
Viruses
Are bacteria prokaryotic or eukaryotic?
Bacteria are prokaryotic cells.
This means the cell structure is very simple - they have no nucleus or membrane-bound organelles.
Do bacteria have DNA?
Yes, Bacteria have a single loop of DNA.
Name a cell organelle that bacteria have.
Ribosomes
What is the name given to rod-shaped bacteria?
Bacilli
i.e, E.Coli
What is the name given to round-shaped bacteria?
Cocci
i.e, streptococci
What are spirochetes?
Bacteria that are spiral-shaped
Bacteria have one of 2 types of cell wall, which can be identified via a process called _____ staining.
Gram staining
What is the purpose of gram staining?
To identify what type of cell wall a bacteria has.
Which type of bacteria stain purple with Gram’s method?
Gram positive bacteria (thick cell wall)
Which type of bacteria stain pink with Gram’s method?
Gram negative bacteria (thin cell wall)
Describe the difference between Gram positive and Gram negative bacteria.
Gram positive bacteria have a thick cell wall and stain purple with Gram’s method. They are made up of peptidoglycans (proteins & carbohydrates).
Gram negative bacteria have a thin cell wall and stain pink with Gram’s method. They are made up of lipopolysaccharides (LPS - fats & carbohydrates).
When Gram ______ bacteria die they can release ______ from their cell wall which can cause harmful effects in the body.
Gram negative bacteria
Can release lipopolysaccharides (LPS)
Which type of bacteria can release LPS from their cell wall when they die?
Gram negative bacteria
By which process to bacteria reproduce / grow / multiply?
Binary fission (asexual)
How quickly can the bacteria E.Coli divide and replicate?
Within 20 minutes.
What are spores?
Live structures (‘coats’) around bacteria, created to protect them from harsh environments.
Spores form part of the life cycles of which 3 infectious agents / micro-organisms?
Bacteria, fungi, protozoa
_______ are a dormant life form that serve to protect several micro-organisms from harsh environments.
Spores
Bacteria exert their harmful effects by releasing one of two toxins. Name these two toxins.
- Endotoxins
2. Exotoxins
Which micro-organism releases endotoxins or exotoxins, and invasive enzymes?
Bacteria
What are invasive enzymes?
Enzymes released by certain bacteria to help them invade a host.
e.g, haemolytic streptococci release enzymes that breakdown RBC’s in Scarlet Fever
Bacteria release either endotoxins or exotoxins. Which are more toxic / harmful?
Exotoxins
Which types of bacteria release exotoxins?
Gram positive AND Gram negative bacteria release exotoxins, but only whilst they are alive.
What type of toxins are released by a living bacteria?
Exotoxins
Which toxic, protein toxins have a variety of effects on human body functions?
Exotoxins
Botox is an example of an _________
Exotoxin
Which type of toxins are released from the cell wall only after a bacteria dies?
Endotoxins
Which type of bacteria release endotoxins?
Gram negative bacteria
Lipopolysaccharides (LPS) molecules released from the cell walls after gram negative bacteria die are also called ______toxins.
Endotoxins
Give an example of an endotoxin-releasing bacteria.
Salmonella (Gram negative)
Give an example of an exotoxin-releasing bacteria.
E.Coli (Gram positive)
Define ‘microflora’.
Naturally occurring micro-organisms (mostly bacteria) inhabiting the healthy human body.
List 4 places in the body where microflora should be present.
- Intestines (mostly large intestine)
- Vagina
- Skin
- Mouth
- Nasal cavity
- Perineum
List 4 places in the body where microflora should NOT be present (because they should be sterile).
- Blood
- Cerebrospinal fluid (CSF)
- Lungs
- Stomach
- Uterus
- Ovaries
- Bladder
- Kidneys
In which 2 circumstances could organisms within the microflora become pathogenic?
- If the environment changes in a negative way
2. If the immune system becomes compromised
Most cystitis is caused by _______
E.Coli
What are antibiotics?
Conventional drugs that kill bacteria
Antibiotics can be broadly categorised as being ______ spectrum, or _____ spectrum.
Broad or narrow spectrum
Which type of antibiotics can have devastating effects on the body’s microflora?
Broad spectrum antibiotics
List 3 side effects of antibiotics.
- Depletion of beneficial gut flora & dysbiosis
- Excessive growth of candida
- Impaired immunity
- Inflammatory bowel diseases
- Susceptibility to autoimmune diseases
_______ are obligate intracellular parasites. They need a living host cell for survival and replication.
Viruses
Which infectious agents are known as intracellular parasites?
Viruses
What is a capsid?
The hard protein coat that surrounds the DNA or RNA strand in a virus.
Which type of infectious agents don’t have their own metabolism, a nucleus or organelles?
Viruses
Which are the smallest microbes (so small that they can’t be seen with a light microscope)?
Viruses
What makes viruses unique?
They are only able to multiply inside the cells of other living things.
Give 2 examples of DNA viruses.
- Varicella zoster virus (chicken pox, shingles)
- Herpes simplex (cold sores, genital warts)
- Smallpox
Give 2 examples of RNA viruses.
- Measles
- Mumps
- HIV
Describe how viruses reproduce.
They reproduce by injecting their DNA or RNA strand into a living host cell and use the host cell’s apparatus (i.e, its ribosomes) for reproduction.
Viruses are incredibly specific and will each only infect certain host cells (i.e, muscle cells or nerve cells). True or false?
True
When a virus binds with a cell, it only allows entry of genetic material and the ________ remains outside.
Capsid
What generally happens to a host cell, once the virus leaves it?
The host cell bursts
List 4 reasons why it’s very difficult for our immune system (and allopathic anti-viral agents & drugs) to identify and destroy viruses.
- Viruses can hide and remain latent.
- Viruses don’t have their own metabolism /enzymes
- They don’t have many structures of their own
- They can mutate
What is viral lysis?
When viral particles burst out of the host cell, resulting in the death of the host cell.
What is viral budding?
When a virus takes a small piece of the host cell outer membrane as it leaves the host cell and uses it as an envelope / shield for itself.
Name a virus that utilises viral budding
HIV
Describe the latent stage of viral replication.
The stage of infection where the disease/virus is present but is hidden and inactive, in order to avoid a stronger immune system.
Viruses can remain in a latent state for decades.
Name 2 viruses that typically remain latent for a long time, until the immune system is compromised.
- Herpes Simplex (cold sores)
- Varicella zosta (chicken pox and shingles)
What type of organisms are fungi?
Eukaryotic
Whereabouts in fungi would you find melanin?
In the cell wall
Why do fungi have melanin in their cell walls?
To protect them from UV light
Where are fungus found?
Everywhere!
In soil, medicine, food, mould
Filaments of fungi are called ________, whilst a mass of fungi is called a __________.
Filaments = Hyphae
Mass of fungi = Mycelium
What is a mycosis?
A fungal infection
What is another name for a fungal infection?
Mycosis
Fungal infection (mycosis) usually results from 3 forms of fungi. Name them.
- Yeasts - single celled fungi (i.e, candida)
- Moulds - multi cellular fungi
- Dermatophytes - fungus causing skin disease
What is the name for fungi that cause skin disease?
Dermatophytes
Dermatophytes are fungus which cause ______ disease.
Skin disease
Where do dermatophytes obtain their nutrients?
From keratin in skin
Where do dermatophytes (fungus) colonise in the skin?
In the stratum corneum - the layer of dead cells on top of the skin.
Which type of fungus is the only type dependant on humans?
Dermatophytes
Give an example of a dermatophyte fungus.
Ringworm, or Tinia (athletes foot).
Name a common single-celled fungus that reproduces by budding.
Candida albicans
Give an example of how moulds are used in medicine.
To make some antibiotics, such as penicillin.
What are hyphae?
Fungal filaments
What is mycelium?
A ‘mesh’ of intertwined fungal filaments
List 4 things that promote fungal growth.
- Warmth
- Moisture
- Rich nutrition
- Acidity
Fungi can reproduce both asexually and sexually. Is this true or false?
True
Name a type of infectious agent that can reproduce both sexually and asexually.
Fungus
Are protozoa prokaryotic or eukaryotic?
Protozoa are eukaryotic
Name 3 infectious organisms that are eukaryotic.
Fungus, protozoa, helminths.
Describe the structure of protozoa
Single-celled organisms with no cell wall (just a cell membrane). They live in moist/wet environments and can move in various ways.
Explain the 3 ways in which protozoa can move.
- Via flagella
- Via Cilia
- Using vectors for transmission (i.e, mosquitos)
What is a vector? Give an example.
An intermediate carrier of protozoa.
i.e, mosquitos are vectors for the protozoa that causes malaria.
How are protozoa formed?
Through binary fission and budding.
They can also be formed sexually, but ONLY when the environment is unfavourable.
Under what circumstances would protozoa form cysts?
When the environment is very harsh (so that they can survive).
What are helminths?
Parasitic worms
What is another name for parasitic worms?
Helminths
Describe helminths.
Multi-cellular, eukaryotic, macroscopic organisms.
They can live in intestines, blood or tissues.
Many helminths are intestinal parasites
Examples are roundworm, tapeworm, pinworm
Give an example of a macroscopic organism
Helminths
Describe the lifecycle of helminths.
Egg > Larva > Adult
What type of organism is associated with roundworm, tapeworm and pinworm?
Helminths
Where are most helminths found?
In the intestines
Describe ‘infection’.
The invasion of a host by a pathogen, causing disease .
What is a large outbreak of a particular disease called?
An epidemic
What is an epidemic?
A large outbreak of a particular disease
What is a worldwide outbreak of a particular disease called?
A pandemic
What is a pandemic?
A worldwide outbreak of a particular disease.
What is the name given to an infectious disease that is spreading around a specific geographical area?
Endemic
Give an example of an endemic disease.
Malaria
In relation to infectious diseases, what is a reservoir?
The location where the pathogen comes from, where it has reproduced and the point from which it will spread to a new host.
What is the name given to the location where a pathogen comes from, where it has reproduced and the point from which it will spread to a new host?
The reservoir
In relation to infectious diseases, what is a carrier?
An infected individual who is asymptomatic
What is the name given to an intermediate carrier which transports pathogens from reservoir to host?
A vector
In relation to infectious diseases, what is a host?
An infected individual (person or animal)
Give an example of an infectious disease whereby the vector is also a host.
Malaria. The mosquito is both vector and host.
List 5 ways in which infectious diseases can be transmitted.
- Direct contact
- Droplet transmission
- Indirect contact
- Via a vector
- Nosocomial
What is a nosocomial infection?
An infection acquired from a medical setting (i.e, a hospital)
What is the most common type of nosocomial infection?
Urinary tract infections (UTI’s).
Catheterisation is a contributor to this.
List 4 examples of nosocomial infections.
- Pneumonia
- Ulcers & sores
- UTI’s
- Surgical site infections
List the 4 stages of infection.
- Incubation period
- Prodromal period
- Acute period
- Chronic infection
What is the incubation period?
Stage 1 of infection. The time between the initial exposure to the infecting organism and the appearance of the first signs/symptoms it produces.
What is the prodromal period?
The period between the start of vague, non-specific symptoms of infection, until the more specific symptoms of that particular infection begin.
(The time when you feel a bit unwell and as if you are coming down with something).
Describe the acute period of infection.
The point at which the pathogen peaks in population. This is when the very pronounced symptoms specific to the disease are experienced.
Describe chronic infection.
Infection with an insidious or slow onset over a long duration.
List 3 ways to reduce the spread of infection.
- Washing hands
- Sterilisation
- Stop droplet transmission (i.e, cover the mouth when coughing)
What is sterilisation?
A form of infection control which destroys all micro-organisms and their spores.
List 4 forms of infection control.
- Sterilisation (also kills spores)
- Antiseptics
- Disinfectants
- Pasteurisation
List 3 natural agents that can be used to help control infections.
- Tea tree oil
- Eucalyptus oil
- Colloidal silver
Explain what is meant by an epidemic.
A large outbreak of a disease
Describe the structure of a virus.
A structure that contains DNA/RNA surrounded by a protein coat known as a capsid.
Define the term ‘sterilisation’.
A procedure whereby all microbes and spores are destroyed, using either hot air or steam.
What is sepsis / septicaemia?
Sepsis occurs when a pathogen has infected the blood. The body’s own immune response against the infection can cause serious damage to organs and even multi-organ failure.
List 3 signs of an infection.
- Redness
- Warmth
- Pain & swelling
List 3 symptoms of an infection.
- Fever
- Fatigue
- Headache
- Nausea
How might we test for the presence of an infectious agent in our patients?
- Culture/staining
- Blood tests
- Stool tests
- Radiography (i.e, tuberculosis granulomas in the lungs)
