Haroons Flashcards

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1
Q

Gram stain - diff between gram negative and positive
Come in and stain

A
  1. Crystal violet
  2. Iodine
  3. Acetate/ alcohol
  4. Safrin counterstain
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2
Q

Colours for bacteria and stain

A

Gram negative pink - decolourise and turn pink due to safrin counterstain
Gram positive purple - retain crystal violet

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3
Q

What are gram positives and gram negatives mainly

A

G + Cocci - balls
G - Bacili - rods

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4
Q

Gram positive bacili

A

C difficile
Listeria

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5
Q

Gram negative diplococci

A

Meningitidis
Neisseria gonorrhoea

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6
Q

Blood agar

A

Sheep and horse blood

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7
Q

Chocolate agar

A

Blood agar cooked for 5 minutes at 80 degrees which will release nutrients that are required for some bacteria to grow
Needed for fastidious organisms

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8
Q

Fastidiious organisms require what to grow

A

Factor X and Y
Known as fastidious require more than normal bacteria

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9
Q

Cled agar

A
  • Differentiate lactose fermenting and non lactose fermenting gram negative bacteria
  • Show E.coli as yellow
  • Salmonella and shigella as blue
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10
Q

3 main gram negative bacteria

A

E. Coli - lactose fermenting
Shigella - non lactose fermenting
Salmonella - non lactose fermenting

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11
Q

Macconkey agar

A
  • Shows E coli as pink
  • Salmonella and shigella as yellow or colourless
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12
Q

Gonoccus agar

A

For neisseria culture

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13
Q

XLD agar

A
  • After macconkey
  • Going to differentiate salmonella and shigella
  • Salmonella - red with black centres
  • Shigella - Red only
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14
Q

Sabouard agar

A

For fungal cultures
e.g candia albicans or aspergillos

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15
Q

Lowenstein Genson medium

A

Culuture medium used to grow tuberculosis

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16
Q

How do we identify Gram positive

A
  • Catalase test
  • Positive in Staph - clusters - bunch of grapes
  • Negative in Strep - chains - strep
17
Q

What do you do to differentiate different types of staph

A
  • Coagulase test
  • Coagulase: enzyme produced
    by bacteria that clots blood plasma.
18
Q

Coagulase Positive and Negative - test for Staph

A

Positive - S. Aureus
Negative - Other staph - saprophyticus. epidermis

19
Q

How do you differentiate strep?

A
  • Haemolysis on Blood agar
  • Blood agar medium and appy different bacteria to differnt discs - throw the disc in the medium and you measure how much haemolysis occurs
  • Very little haemolysis/ Gamma - typically enterococcus
  • Alpha - Partial haemolysis - green - AS WHEN rbcS BROKEN DOWN THE PRODUCTS OF THAT are bilirubin and iron so it looks rusty - haemolysis is incomplete
  • Beta - full haemolysis - Group
20
Q

Alpha haemolytic strep test

A
  • Optochine test - see if theres a zone of inhibition or not
  • If theres zone of inhibition - optochine sensitive - Strep pneumoniae -
  • If not optochin resistant - no zone of inhibition - Strep viridians - IE and poor dental hygiene
21
Q

Beta haemolysis

A

Lancefield grouping
A - S. pyogenes
B. S. agalectiae

A - affects nasopharyngeal area and skin
B - implicated in neonatal sepsis - children who are under 3 months old

22
Q

How do you differentiate Staph second way other than coagulase

A
  • Culture on blood agar
  • Staph aureus - appear gold - aureus means gold
  • Other staph are colourless or white
23
Q

Sterile sites of body (parts of body that should never have bacterial pathogens)

A

Blood - sepsis
CSF - meningitis
Pleural fluid - pericarditis, pleural effusion
Peritoneum - SBP
Joints - septic arthritis
Urinary tract - UTIs
Lower resp tract - TB + Pneumonia

24
Q

Negative flow chart - lactose fermentation

A
  • Use maconkey
  • Lactose fermentation - E. Coli/ klebsiella
25
Q

Negative flow chart non lactose fermenrts

A

oxidase positive and negative
Oxidase positive - pseudomonas aeruginosa
Oxidase negative - Salmonella and Shigella

26
Q

How do you differentiate between salmonella and shigella

A

XLD
Salmonella - red with black centres
Shigella - only red

27
Q

Gram positive have what type of cell wall

A

Single thick peptidoglycan cell wall
Produce exotoxin - specific action

28
Q

What does exotoxin do

A

Produced inside cell and secreted

29
Q

Gram negative cell wall

A

Double thinner cell wall - smaller peptidoglycan cell wall - less peptidoglycan
Release endotoxin/ LPS - non speecific action

30
Q

Which antibiotics are used for cell wall destruction

A

Beta lactam - penicillin. cephalosporins
Good against gram positive

31
Q

For MRSA what do you give

A

Vancomyocin
ALSO VANCOMYOCIN FOR PENICILLIN ALLERGY

32
Q

aNTIBIOTICS THat inhibit dihydrofolate reducttase

A

Methotrexate - stops processing of normal folate production -

33
Q

Folate inhibitors

A

Nitrofurantoin + trimethoprim

34
Q

DNA gyrase antibiotics

A

Fluroquinolones - ciprofloxacin

35
Q

RNA polymerase antibiotics

A

Rifampicin