Microbiology Hockey Q's Flashcards
What are the characteristic features of gram positive bacteria?
+ve: (stain purple as thick peptidoglycan wall by crystal violet)
Single membrane
Thick, multilayered peptidoglycan : this is what makes gram positive stain purple.
Lipotechoic acid
What are the characteristic features of gram negative bacteria?
-ve
2 membrane
Thin peptidoglycan
Lipopolysaccharide: endotoxin
Which bacteria are harder to treat and why?
Negative
Double layer membrane
Antibiotics harder to penetrate
What is an endotoxin?
Component of gram negative bacteria
Made of lipopolysaccaride
WHAT GRAM ARE MOST COCCI?
Positive
By what test are stapholoccus differentiated and what are the bacteria from each result?
Give some examples of diseases that these bacteria are present in?
Coagulase test
If coagulase + clots
S. aureus
Septic arthritis, HAP (hospital aquired pneumoniae)
If coagulase -
S.epidermidis
Endocarditis on metal heart valves
How are streptococcus first diffentiated?
What are the colour results for each?
How could you further differentiate them?
Blood agar (CBA)
Alpha haemolytic
Green
Further differentiate by optochin
Beta haemolytic
Clear
Further differentiate by lancefield grouping
Non haemolytic
Strep mutans, strep milleri
How can you further differentiate alpha haemolytic?
What are the bacteria for the different results?
Give examples of diseases where these bacteria are?
Optochin
Sensitive
Strep pneumonia
RTI (respiratory tract infections)
Resistant
Strep viridins
Infective endocarditis
How can you further differentiate beta haemolytic bacteria?
What are the bacteria found?
Give examples of diseases where they are found?
Lancefield grouping
A
Strep pyogenes
Impetigo, cellutitis
B
Strep agalactae
Neonates
Give examples of gram positive bacilli?
Aerobic
Listeria monocytogenes, corneryabacteria diphtheria
Anaerobic
Clostridium difficile, tetani
WHAT GRAM ARE MOST BACILLI?
Negative
How can you differentiate between gram negative bacilli?
What colour do they each go?
Give examples of bacteria?
What diseases are they in most?
How can you differentiate?
Aerobic
Use MacConkey, CLED or XLD to determine if lactose fermenting or non-lactose fermenting
Lactose fermenting
Pink on macconkey
Yellow on CLED
E. coli (UTI), klebsiella pneumonia (RTI)
Non lactose fermenting
Clear on macconkey
Blue on CLED
Use the oxidase test to differentiate
How can you further diffentiate non lactose fermenting bacteria?
What colour will they go?
Give examples of the bacteria present?
What disease are they in?
Oxidase test
Oxidase positive
Purple
Pseudomonas
Atypical pneumonia characteristic in CF
Oxidase negative
No change
Enterobacteria
How are enterobacteria differentiated?
What are the results?
What are the bacteria present?
XLD plate
Red c black dots
Salmonella
Red
Shigella dysentriae
What is chocolate agar used for?
What tests do you do after chcolate agar?
What bacteria would you see in the results?
Chocolate agar (fastidious growth requirements) is used in aerobic bacilli:
If urease positive
H. pylori
10+5 positive
Haemophilus influenza
legionella pneumphilia
Bordatellpertussis (RTIs)
Campylobacter jejeni (Gullianbarre)
