Microbiology Flashcards
How can bacteria sneak in after eating?
Food particles can temporary increase the pH in the stomach, making it more basic so that bacteria can sneak through with a meal.
What is prokaryote?
A microscopic, single celled organism which lacks a distinct nucleus and specialised organelles.
What is syphilis cause by?
Bacterium treponema Pallidum
Before antibiotics what was used to treat syphilis?
Malaria fever
What pH is skin?
Acidic= 5
Which are the immune privileged sites?
- The brain and CNS
- The eyes
- Genitial areas
- The fetus
- The inner ear
Viruses causing common cold prefer a temperature of…?
33 degrees celcius
Majority of micro organisms are beneficial give some examples of how
- Help in digestion by helping to break down food
- Help in the production of enzymes and drugs like insulin
- Used to produce foods like cheese, yogurt, bread, wine.
Which type of yeast is used to make wine and leaven bread?
Saccharomyces cerevisiae
Name the taxonomy classifications
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What are the two microorganisms that aren’t classified?
Viruses and Prions
Why do we need the knowledge of microbiology?
To protect the vulnerable
To avoid iatrogenic infection
What shapes can bacteria take?
Bacillus (rod)
Coccus (Sphere)
Spiralla
Which bacteria is important in medical science?
Gram positive - Most ocular diseases
Gram negative - Disease from CL
How is the structure different between gram +ve and -ve?
+ve = Multi layered cell wall
-ve = One layered cell wall
Describe the gram stain technique
- Crystal violet 30 secs
- Wash off
- Iodine solution 1 min
- Organic solvent (ethanol) 15 sec
- Counter stain (safranin- pink)
- Gram negative appears pink, because has more permeability to organic solvent.
Name 3 gram positive bacteria
Staphylococcus aureus
Streptococcus Pneumoniae
B-haemolytic streptococci
Give an example of an eye disease caused by fungi?
Fusarium keratitis
What is toxoplasmosis? What is it caused by?
Toxoplasma gondii causes toxoplasmosis.
Toxoplasma gondii is an intracellular protozoa.
How can humans develop toxoplamosis?
- Ingestion of sporocysts due to accidental contamination of hands when disposing cat litter trays
- Ingestion of undercooked meat containing bradyzoites
- Transplacental spread of parasites (tachyzoites) to foetus.
What are the 3 forms of parasite which causes toxoplasmosis?
Sporocyst - cat faeces
Bradyzoite - Encysted in tissures
What do you need to recommend to people who use contact lenses?
- Dont swim with CL on
- Use dry hands when handling CL
- Clean with solution
- Clean dry the CL case
- Don’t shower with CL on
-Don’t go in sauna with CL on
What is the meaning of iatrogenic?
Infection caused by clinical practice.
E.g. not sterilising equipment.
If a patient is bedridden and if the professionals don’t turn the patient, the patient would develop sores
What eye disease are linked to protozoa?
- Congenital Toxoplasmosis
- Acanthamoeba keratitis
How to classify viruses?
By their:
- Host
- Size
- Appearance
- Structure
Give an example of eye disease caused by multicellularanimal parasites?
Toxocara
Give an example of eye disease caused by prions
Creutzfeld Jakob disease (vCJD)
How has prions changed how UK optoms practice?
- Tonometer head now disposable
- Disinfect CL trial sets with sodium hypochlorite solution.
What are the physical requirements for microbial growth?
-Moisture levels
- pH - most prefer neutral
- Temperature - most prefer 37
- Oxygen - some aerobic and some anaerobic
What chemical adaptation does the body have?
- Bile salts in intestines
- Skin fatty acids from sweat
- Lysozyme in tears, mucus, saliva
What are the overall factors that affect survival of microbes?
- Physical requirements
- Chemical toxicity
- Nutrient availability
- Competition
What are the first line defences of the eye?
The mechanical defences:
1. Eyelids
2. Orbit
3. Eyelashes
4. Skin
5. tear flow
6. mucus
Give example of 3rd line of defence
Immunoglobin A (IgA)
What is immune privilege?
Specific organs don’t become inflamed like normal organs. This is to prevent loss of function.
What is the function of the tear film?
- Lubrication
- 1st line of defence
- Smooth optical surface to help with optical performance
- Immuno-protection
What are the signs of inflammation and why?
- Calor- warm- blood vessels dilated
- Rubor- red - more blood at site
- Dolor - Pain- sending signals to brain via nerves
- Tumour - swollen - due to more plasma + blood.
What is the major histocompatibility complex?
A group of genes that code for proteins found on the surface of cell that help the immune system recognise foreign substances.
What is ACAID?
Immune tolerance
What are fungi?
Eukaryotic organisms which can be single (yeast) or multicellular (fungus seen on bread).
They dont carry out photosynthesis and so feed by absorbing organic material
What are protozoa and how are they classified?
Single celled eukaryotic microbes.
They are classified by how they move.
How can protozoa move?
- Amoebae move by pseudopods
- Others have flagella or cilia.
Give an example of an amoeba and explain it
Acanthamoeba keratitis
Can exist in vegetative states (metabolically active feeding on its environment) or as trophozoite (able to move around and infect).
It is a rare, devastating eye disease leading to blindness.
Why in the UK is there a 11% more chance to get acanthamoeba keratitis that the rest of Europe?
This is because of the way water is kept in tanks on roofs, and these tanks or more likely to have living acanthamoeba.
As acanthamoeba thrive in water.
Thus it is important to tell the patient not to use tap water to clean their CL or to not get water on their CL.
What are viruses?
Tiny packages with a simple structure of DNA or RNA within a protein capsid. Inject their DNA into host cells to replicate.
How much do viruses contribute to the amount of human infections?
Viruses cause majority of diseases in humans, 60% of human infections.
e.g. influenza, AIDS, polio, rabies, some cancers, hepatits, chicken pox
How to treat viruses?
special anti viral drugs or vaccines
What is herpes simplex (HSV)?
Virus causing cold sore lesions on skin
What are adenovirus?
Virus which causes problems to the glands, mucus membranes, conjuctiva and cornea
What is Herpes zoster?
Viracella virus. It lies dormant in the trigeminal nerves and then can reactivate later as shingles. Cold sores all over the trigeminal nerve. Vesicles found on waist, face, chest, back. Can cause ptosis (droop of upper eyelid), glaucoma, keratitis.
What are the 3 branches of trigeminal nerve?
- Ophthalmic nerve - Forehead and upper lid and globe
- Maxillary nerve - Lower lid and cheek
- Mandibular nerve - Jaw and chin
Features of togavirus?
e.g. rubella - skin rash, light fever.
Causes birth defects when contracted in early pregnancy.
Features of cytomegalovirus?
AIDS
Can cause retinitis
What are multicellular animal parasites?
Parasitc worms
What are helminths?
Type of multicellular anima parasites.
Tapeworms and roundworms which can cause lesions in the back of the eye at retina.
E.g. Toxocara canis rundworm:
-Usually from dog faeces.
What are prions?
Even simpler than viruses.
