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Flashcards in Scenario 15 Deck (102)
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1

What are the 3 classes of microorganisms?

Viruses, prokaryotes (bacteria/ mollicutes), eukaryotes (fungi, protozoa, nematodes, ectoparasites)

2

What is the difference between a parasite and commensal?

Both live in/ on another organism but commensal does not injure the organism

3

What colour is gram positive?

Purple/blue

4

What colour is gram negative?

Red

5

What classification are mycobacteria?

Gram positive but dont take up aq gram stain- walls made up of waxy my colic acid (use ziehl nelson stain)

6

What are the properties of gram positive bacteria?

survive well on drying some produce spores/ toxins and have teichoic acids in their cell wall

7

What are the properties of gram negative bacteria?

dont survive drying, no spores, have endotoxin in their cell wall (LPS)

8

Is staph aureus gram negative or positive?

Gram positive coccus which forms clusters

9

What are some distinguishing factors of staph aureus?

Grow readily on blood agar, golden colonies after 48 hours, coagulase and DNAase production

10

What are the virulence factors of staph aureus?

Protein A- anti-phagocytic and secretes coagulase and exotoxins

11

Where is it found/ transmitted?

Normal human flora, transmission from some carriers and close contact

12

What infections does staph aureus cause?

Skin and soft tissue, ENT, pneumonia, bone and joint, sepsis, infective endocarditis, implanted prosthetics

13

What toxin mediated problems does it cause?

Staphylococcal toxic shock and food poisoning

14

What do you use to treat s aureus?

NOT penicillin- 90% resistant sue to beta lactamase, can use fluoxacillin or co-amoxiclav or macrolides (erythromycin) for MRSA use vancomycin

15

How do you classify streptococcus pyogenes?

gram positive cocci in chains, grows readily on blood agar

16

What are the virulence factors of s.pyogenes?

M protein in cell wall and endotoxins

17

Where is it found and how is it transmittes?

In nose and throat of 1-5% of population and transmitted by close contact

18

What infections does s.pyogenes cause?

pus forming, ENT and RT, skin and soft tissue (impetigo), puerpal fever, blood stream, streptococcal toxic shock

19

What are some post infecitve manifestations of s.pyogenes?

non suppurative sequalae, acute rheumatic fever, acute glomerulonephritis

20

How do you treat s.pyogene?

PENICILLIN OR AMOXICILLIN erythromycin, vancomycin if allergy

21

How do you distinguish streptococcus pneumonia?

Gram positive cocci in pairs/short chains up to 4 cells long, produced pheumolysin in alpha haemolysis on blood agar

22

What are the virulence factors of s. pneumo

pneumococcal teichoic acid c-polysaccharide and polysaccharide capsule which is anti-phagocytic

23

Where is it found?

Commensal URT flora in humans, transmission by resp secretions

24

What infections does s.pneumo cause?

URTIs, LRTIs, CNS (meningitis), sepsis, peritonitis, endocarditis

25

What is the treatment for s.pneumo?

2 vaccines in UK, penicillin (90%), erythromycin (not in meningitis), ceftriaxone in meningitis

26

What are some other gram positive bacteria?

Coagulase-negative staphylococci (normal skin flora, implanted prosthetics), Clostridium (spore forming rods, commensals in GIT produce endotoxins, difficile, tetani, botulinum, perfringens) Bacillus (rods, anthrax and cereus), cornyebacterium species (non spore forming rods, skin commensals)

27

What are the distinguishing factors of E coli?

gram negative bacilli, grow on blood agar, fements lactose, cell wall contains LPS, proteins and porins, motile (flagellae, fimbiae)

28

What are the virulence factors of E coli?

LPS, iron binding proteins, small polysaccharide capsule, fimbiae or pili, endotoxin priduction

29

Where is it found and how is it transmitted?

normal colonic flora, contaminated food/water, ascending infection

30

What infections does e coli cause?

UTI, diarrhoeal illness, intraabdominal infection, sepsis, pneumonia, meningitis