Clinically Relevant Gram Positives Flashcards
What is peptidoglycan?
A sugar network composed of two major sugars (N-acetylmuramic acid
and N-acetylglucosamine.).
Which gram cell wall is more complex?
Gram negative cell walls.
Name some features of the cell wall which is specific to the gram negative cell wall.
Contains-
- lipoproteins
- lipids & porins, to get materials in and out of the cell.
What does peptidoglycan form the basis of?
A very simple staining method used to classify bacteria.
What colour does bacteria stain?
Pink or purple.
Purple bacteria are?
Gram positive.
Pink/red bacteria are?
Gram negative.
What kind of microscope do you need in order to view bacteria?
Light microscope.
Why does gram positive bacteria stay purple?
Because of the thick layer of peptidoglycan.
Crystal violet is able to form complexes within the peptidoglycan so stain is retained.
Why soes gram negative stain pink?
Because of the thin layer of peptidoglycan.
Unable to retain crystal violet stain.
List the advantages of using gram staining.
- Quick, simple, cheap way to classify clinically important organisms.
2.Provides an early indication of which genus of bacteria is causing the infection.
What do anaerobic/aerobic mean in terms of bacteria?
Whether or not bacteria need oxygen in order to grow.
Name the bacteria which can be anaerobic or aerobic.
Cocci or bacilli.
Name the two forms that aerobic cocci can take.
Chains- streptococci.
Clusters- staphylococci.
What are streptococci determined by?
Their haemolysis- appearance on the blood agar.
Name the three types of haemolysis streptococci can have.
Alpha haemolytic- partial haemolysis.
Beta haemolytic- full haemolysis.
Non-haemolytic.
Give an example of of a disease which each of the following represent-
Alpha haemolytic- partial haemolysis.
Beta haemolytic- full haemolysis.
Non-haemolytic.
- Pneumonia
- Neonatal infections
- UTI
What are staphylococci determined by?
If they produce the enzyme coagulase or not.
Name the two kinds of staphylococci.
Coagulase positive.
Coagulase negative.
Give an example of a disease which the following represent-
Coagulase positive.
Coagulase negative.
Coagulase positive-sepsis
Coagulase negative-device related infections.
How can you differentiate between types of bacillus?
Shape- either large or small.
Name two small bacilli.
Corynebacterium or listeria.
Name one large bacilli-
Bacillus.
Name a disease which can be represented by-
Corynebacterium
Listeria.
Bacillus
- Diphtheria
- Sepsis or gastroenteritis
- Gastroenteritis
Give an important example of coagulase positive staphylococci.
Staphylococcus aureus.
Where is Staphylococcus aureus commonly found?
Nose, axilla and perineum.
What kind of diseases can Staphylococcus bring about?
Wide range-
boils to abscesses, soft tissue infections, osteomyelitis, septicaemia.
What do antibiotics NOT cure?
Abscesses- need drained.
Staphylococcus aureus is resistant to what type of drug?
Penicillin as produces enzyme penicillinase.
Methicillin- type of synthetic penicillin.
Name one characteristic of coagulase negative staphylococci..
Forms biofilms (bacertia adheres to surface and forms complex microbial community).
What is the main issue w biofilms?
Bacteria are protected and very difficult to treta.
Name a common example of coagulase negative staphylococci.
S.Epidermis.
What does alpha haemolytic bacteria do the blood agar?
Turns it green.
What does beta haemolytic bacteria do to blood agar?
Turns it clear.
What does non haemolytic bacteria do to blood agar?
No difference.
Name one type of alpha haemolytic bacteria.
Streptococcus pneumoniae.
How is Streptococcus pneumoniae protected from the immune system?
Has a capsule which protects it.
How are beta haemolytic bacteria identified?
By carbohydrate surface antigens.
What groups of beta heamolytic bacteria do you get?
Groups A-G
Which groups of beta haemolytic bacteria are most important?
Groups A, B, F and D
Name the group A bacteria responsible for flesh eating bugs.
Streptococcus Pyogenes.
Name a classic representative bacteria of Group B of beta haemolytic bacteria.
Streptococcus Agalactiae.
What does Streptococcus Agalactiae usually cause?
Neonatal sepsis
Responsible for sepsis in older adults with underlying health issues.
Group D streptococcus is…?
Less harmful than groups A and B
Often non-haemolytic.
Found in the gut.
What can Group D streptococcus cause?
UTI’s
Infective endocarditis.
Give an example of a clinically important gram positive bacillus.
Clostridiodes difficile.
Is clostridiodes difficile aerobic or anaerobic?
Anaerobic.
Discuss colonies of bacteria.
Colonies are groups of bacteria found within humans bt are usually harmless.
What does clostridiodes difficile cause?
Diahorrea.
Associated w production of toxins and potentially fatal.
What can increase risks of clostridiodes difficile?
Increased exposure to antibiotics as disrupts normal gut flora, allowing bacteria and other organisms like clostridiodes difficile to proliferate.
How is clostridiodes difficile transmitted?
Via spores.
Name another key gram positive bacillus.
Clostridium perfringens
What does Clostridium perfringens typically cause?
Gas gangrene.
Where is Clostridium perfringens found?
In soil.
Found in the gut and faeces of animals and humans.
C.tetani causes?
Tetanus through toxin production.
What can happen in those with C.Tetani?
Uncontrolled muscle spasms due to loss of inhibition at neuromuscular junctions.
C.Tetani can be prevented…how?
Use of vaccines.
Biological spore warfare involves use of bacteria for what?
Botox
