Types of infectious agents

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Lecture 001 I&D

Inanimate proteins able to cause pathology

What are prions?

It is inanimate - only a protein
It has no DNA

Why is a prion unable to replicate on its own? (2)

They can not replicate on their own (are inanimate)

Why can prions not be cultured?

Host derived glycoproteins (e.g. Cellular prion protein, PrPc)

What are prions derived from?

PrPc - Cellular protein prion

Give an example of a prion.

The abnormal form of PrPc - PrPsc

What is the infectious agent of a prion?

The abnormal, infectious form of PrPc

What is PrPsc?

Enzymes
Heat
Radiation
Disinfection

What is PrPsc resistant to? (4)

Phenol
NaOH
Hyperchlorite

What is PrPsc susceptible to? (3)

<100nm

What is the average size of PrPsc?

Induces the conversion of PrPc on a cell to PrPsc (acts as a template)
Cell replicates and precipitates more PrPsc

How does PrPsc replicate?

It induces a change in a cell protein to cause the cell to make more PrPsc rather than using DNA

Why is PrPsc replication non conventional?

Transmissible spongiform encephalopathies
Bovine spongiform encephalopathis - Mad cow
Ceutzfeldt-Jakob disease

What diseases does PrPsc cause? (3)

Brain tissue
Neural tissue

What main tissue groups does PrPsc affect? (2)

Tiny holes appear in cortex - causes mental and physical abilities to deteriorate

What is transmissible spongiform encephalopathy?

Degenerative neurological disorder

What is Creutzfeldt-Jakob disease?

Transmissible spongiform encephalopathy

What group of diseases is Creutzfelt Jakob disease a part of?

Illness that causes gradual deterioration of organs and cell
Leads to loss of function

What does degenerative mean?

Infectious agent made up of nucleic acid and a protein coat which is too small to be seen using a light microscope

What are viruses?

Protein
Nucleic acid

What types of molecule make up a virus? (2)

DNA or RNA in centre
Nucleic acid surrounded by protein coat
(Sometimes protein coat is surrounded by lipid envelope)

What are the components of a virus? (3)

The capsid

What is the protein coat of a virus called?

The protein coat that surrounds the nucleic acid of a virus

What is a capsid?

Nucleic acid type (RNA or DNA)
Single or double stranded
Presence of an envelope
Symmetry

What is the process of classification of viruses? (4)

Parvovirus

Give an example of a single stranded DNA virus.

Destroys RBC

How does the parvovirus cause pathology?

Severe diarrhoea

What is the main symptom of a child infected with rotavirus?

Faeco-oral route

How is rotavirus transmitted?

Herpes
Hep B
Adenovirus
Papilloma virus

Give an example of a double stranded DNA virus? (4)

Herpes simplex (HSV)
Varicella zoster (VZV)
Cytomegalovirus (CMV)
Epstein Barr virus (EBV)
Human Herpes Virus (HHV)

What are the 5 main types of herpes virus?

Genital herpes

What does type 2 herpes simplex virus cause?

Type 2 herpes simplex virus

What causes genital herpes?

Type 1 herpes simplex virus

What causes cold sores?

Cold sores

What does type 1 herpes simplex virus cause?

Chicken pox
Shingles

What does varicella zoster virus cause? (2)

Varicella zoster virus

What causes chickenpox?

Varicella zoster virus

What causes shingles?

Cold-like symptoms

What does cytomegalovirus cause in immunocompetent people?

Oesophagitis
Gastroenteritis
Retinitis
Pneumonia

What does cytomegalovirus cause in immunocompromised patients? (4)

Infection of the oesophagus

What is oesophagitis?

Infections of the stomach or intestines

What is gastroenteritis?

Infection of the eye

What is retinitis?

Infection of the lungs

What is pneumonia?

Infectious mononucleosis

What does the Epstein Barr virus cause?

Abnormally high number of mononuclear white blood cells in the blood

What is mononucleosis?

Fever
Malaise
Sore throat
Lymphadenopathy
Atypical lymphocytes

What are the symptoms of infectious mononucleosis? (5)

Infected blood
Hypodermic needles
Tattooing needles
Unprotected sex

How is Hepatitis B transmitted? (4)

Headache
Fever
Chills
General weakness
Jaundice (after 1-6month incubation period

What are the symptoms of a hep B infection? (5)

Interferon - and other antivirals

What is the main treatment of hepatitis B?

Infections of upper respiratory tract

What does adenovirus cause?

Rota virus

Give an example of a double stranded RNA virus.

Picorna virus
Rubella virus
Hep C virus
SARS
Influenza
Measles virus
Mumps virus

Give an example of a single stranded RNA virus. (7)

Cox sackie viruses
Polio viruses
Rhino viruses

What are some of the subtypes of picornaviruses? (3)

Respiratory diseases
Neurological diseases
Muscular diseases

What do coxsackie viruses cause in humans? (3)

In the GI tract

Where do cox sackie viruses multiply?

Poliomyelitis

What does polio virus cause?

Paralysis
Because it affect the CNS

What does poliomyelitis cause? ...Why?

German measles

What does the rubella virus cause?

Enlarged lymph nodes
Headache
Sorethroat
Slight fever
(Later) Rash with pink spots

What are the symptoms of german measles? (5)

Fatigue
Sore bones
Dryness of eyes

What are the symptoms of an infection with Hep C virus? (3)

Interferon

What is used to treat hepatitis C infections?

Severe acute respiratory syndrome

What does SARS stand for?

The respiratory system

What system does the influenza virus affect?

Coughing
Sneezing

How is influenza transmitted? (2)

Headache
Fever
Loss of appetite
Aches and pains

What are the symptoms of an infection with influenza? (4)

Blotchy pink rash
Koplicks spots

What are the main symptoms of measles? (2)

Small red spots with white centre on the inside of cheeks

What are koplicks spots?

Pneumonia
Middle ear infections

What are people infected with the measles virus susceptible to? (2)

Fever
Headache
Vomiting
Swelling of parotid salivary glands

What are the symptoms of mumps? (4)

Infectious parotitis

What us mumps also known as?

They are inanimate - so cannot replicate on their own

Wy do viruses need a living host?

Prokaryotic, single celled

What type of organism are bacteria classed as?

70S

What type of ribosome is found in bacteria

Cell wall
(Capsule)
Flagella
DNA in nucleid
Plasma membrane
Pili
Plasmid

What are the main components of a bacterial cell? (7)

The basal bodies they are attached to?

What causes the flagella of a bacterium to move?

Movement
Attachment

What are the main functions of pili? (2)

Movement - chemotaxis

What is the main function of flagella on bacteria? (1)

A nucleoid

What is the DNA of a bacterium found in?

Irregularly shaped region in a prokaryotic cells that
contains the genetic material
It is not surrounded by a nuclear membrane

What is a nucleiod?

Rods
Spheres
Spirals

What are the three general shapes of bacteria?

Cocci

What is another word for describing bacteria that have a spherical shape?

Spirochete

What is another word for describing bacteria that have a spiral shape?

Culture conditions
Shape
Staining reactions
Sensitivity to oxygen
Genetic similarity

What characteristics are used in bacterial classification? (5)

Streptococci

What is the most common gram positive cocci?

Listeria

What is the most common gram positive rod?

Neiserria

What is the most common gram negative cocci?

E. Coli

What is the most common gram negative rod?

Genus name
Speices name

What is the naming of bacteria based on? (2)

Organisms that feed on organic matter

What is a fungi?

The moulds
The yeasts

What are the 2 forms of funig?

The filamentous form of a fungi

What is a mould?

Myecelium

What do filamentous fungi form?

Networks of Hyphae

How doe filamentous fungi form a myecelium?

100 microns

What is the length of a hyphae?

2-8 microns

What is the diameter of a hyphae?

A unicellular form of mould

What is a yeast?

2-20 microns long

What is the range in size of yeasts?

Eukaryotic, unicellular or multicellular

What type of organism is a fungi?

Budding and division

How do yeast cells multiply?

Growth form
Type of infection

How are yeasts classified? (2)

Myocoses

Superficial and deep

What types of infections do fungi cause? ...What are the subtypes of this type of infection?

Epidermophyton
Microsporum
Trichophyton
Sporothrix

What types of fungi cause superficial mycoses? (4)

Aspergillus
Blastomyces
Canadida
Coccidiodes
Cryptococcus
Histoplasma
Paracoccidiodes

What types of fungi cause deep myocoses? (7)

Eukaryotic, single cellular

What type of organism are protozoa?

Free-living (extracellular)
Parasitic (intracellular)

What types of existences can protozoa have?

Active
Inactive

What are the two forms of free living protozoa?

Trophozoite

What is an active, free living protozoa called?

A cyst

What is an inactive, free living protozoa called?

Entameoba
Leishmania
Trypanosome

What are the three meain genera of protozoa that affect humans?

Infected food
Infected water
Insect vectors

What are the most common ways a protozoa is acquired? (3)

Malaria

What s the most common protozoan disease?

A parasitic worm

What is a helminth?

An organism that lives in or on another organism that benefits by depriving nutrients at the hosts expense

What is a parasite?

Eukaryotic, multicellular

What type of organism is a parasite?

Round worms
Flat worms
Tape worms

What are the three common shapes of parasitic worm?

Nematode

What are roundworms also known as?

Trematode
Fluke

What are flat worms also known as? (2)

Cestodes

What are tape worms also known as?

Acaris
Shistosoma
Teania

What parasites are particularly important in human disease? (3)

Organism with an exoskeleton made of chitin

What are arthropods?

Eukaryotic, multicellular

What type of organism is an arthropod?

Directly
As vectors - for other microorganisms

How do arthropods cause disease? (2)

Mites
Ticks
Bugs
Lice
Flies
Mosquitoes

What arthropods are important medically? (6)

Lyme disease
Malaria
Plague
Yellow Fever

What human diseases are spread via arthropods? (4)

An inflammatory disease
Tick borne
Caused by borrelia bacteria

What is Lyme disease?

Borrelia bacteria

What is Lyme disease cause by?

Via ticks

How is Lyme disease transmitted?

A tropical, viral, haemorrhagic disease that causes fever and jaundice (affects kidneys and liver)

What is yellow fever?

Kidneys
Liver

What organs does yellow fever affect? (2)

Fever
Jaundice

What are the main symptoms of yellow fever?

Through female mosquitoes

How is yellow fever transmitted

Accompanied/Produced by haemorrhage

What does haemorrhagic mean?

2 organisms living in close association without much interaction

What is commensalism?

2 organisms living in close association each benefitting from the other (reciprocal benefit)

What is mutualism?

2 organisms living in close association, one doing damage to the other for its own benefit - unilateral benefit

What is parasitism?

Symbiosis

What is another word for mutualism?

Toxin production
Invasion
Immune mechanisms

How do microbes causes disease? (3)

Travel to sites that are normally sterile

Why commensal organisms found the the human body sometimes cause disease?

On epithelial surfaces

Where are commensal organisms found int the body generally?

Ability to make toxins
Ability to invade cells/tissues
Ability to outcompete normal commensal organisms

What are the virulence characteristics of pathogenic organisms? (3)

Staph aureus
Staph epidermidis
Diptheroids
Streptococci

What normal commensal bacteria are found in the nose? (3)

Strep mutans
Becteroides
Fusobacterium
Streptococci
Actinomyces

What normal commensal bacteria are found in the teeth? (5)

Pneumocyctis jirovecii

What normal commensal bacteria are found in the lungs? (1)

Staph epidermidis
Diptheroids
Streptococci
Gram negative rods

What normal commensal bacteria are found in the urethra/vagina? (4)

Strep viridians
Strep pyogenes
Stre pneumoniae
Neisseria
Staph epidermidis
Haemophilis influenzae

What normal commensal bacteria are found in the throat? (6)

Strep mitis
Candida
Trichomonas tenax

What normal commensal bacteria are found in the mouth? (3)

Staph epidermidis
Staph aureus
Diptheroids
Streptococci
Pseudomonas
Aeruginosa
Anaerobes
Candida
Torulopsis
Pityrosporum

What normal commensal bacteria are found in the skin/feet/scalp/groin/perineum? (10)

pH
Humidity
Attachment/retention
Oxygen tension
Host inhibitors
Nutrients

What factors influence how many/which types of bacteria grow in certain areas of the body? (6)

A macrophage phagocytosing bacteria

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