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Flashcards in Antimicrobials 1 + 2 Deck (53)
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1

What is the goal of antimicrobial therapy?

Eliminate infectious organism without toxicity to host

2

What is the most important thing to try and augment when treating bacterial infection?

Natural defence mechanism

3

Give 3 examples of natural defences and when these may be compromised

- mucociliary escalator (cystic fibrosis)
- flushing effect of urination (catheter placement)
- normal gut flora (gut dysbiosis)

4

What are the 4 quadrants targetted by the antimicrobial spectrum? What else may "4 quadrants" of microbes also refer to?

1. G+ aerobes/ G- aerobes/ Obligate anaerobes (G+-)/Penicillinase producing staph
2. G+/G- aerobes/ G+/G- anaerobes

5

Give 4 examples of G+ aerobes

- Strep (B haemolytic)
- Enterococcus
- Pnumococcus
- Bacilli (lactobacillus, corynebacterium, listeria, erysopalathrix, arcanobacterium)

6

Give 6 examples of G- aerobes

- E. Coli
- Klebsiella
- Helicobacter
- Campylobacter
- Pastuerella
- Psuedomonas

7

Give 5 examples of staph

- aureus
- saphrophyticus
- epidermis
- haemolyticus
- capitis

8

Give 4 broad examples of anaerobes

- G+ spore forming clostridium (perfringens, botulinum, tetani)
- G+ bacilli (actinomyces, lactobacillus, bifdobacterium)
- G- bacilli (fragillis or not fragillis)
- Cocci (peptococcus niger)

9

Give 6 examples of atypical bacteria

- Rickettsia (not uk disease)
- Mycoplasma
- Chlamydia
- Borrelia
- Bartonella
- Mycobacterium

10

Where are many antimicrobial substances derived from?

Fungus

11

Give conditions when rational antimicrobial use can be justified

- bacterial infection definitively diagnosed
- OR highly likely
- disease will progress without medical therapy
- would casue critical illness if occourred and not recognised/treated

12

What essentially useless treatment should be given inlieu of prescribing antibiotics as a placebo because you don't know what else to do?

Vitamin injection

13

Give some clues of bacterial infection

- heat, redness, swelling
- pyrexia (could also be viral/fungal/neoplasia)
- neutrophilia (stress leukogram)
- bacterial cause COMMON?!

14

Give 3 examples where ABx are commonly prescribed but a bacterial aetiology is rare

1. V+ D- = acute gastritis due to eating rubbish etc. No bacteria casues V+D-! except helicobacter but v. rare
2. Hameaturia in young cat <10y = idiopathic cystitis usually due to stress, will resolve within 5-7d. In DOGS haematuria indicates UTI but cat urine so concentrated these are RARE.
3. Haemotochezia = no evidence of need for antimicrobials unless signs of sepsis seen

15

What 5 factors influence the success rate of ABx Tx?

- what bugs live where?
- bacterial susceptibility
- Pharmacokinetic phase - getting the drug to the infection
- Pharmacodynamic phase - Local conditions
- Client comlpliance

16

Give the 3 main sources of infection with egs.

1. Environment
- mycobacteria, tetanus, contaminated food (campylobacter, E. Coli)
2. Other animals
- Bordatella
3. Internal
- GI (E. Coli, G-s, Anaerobes)
- Skin (Staph - S. Aureus, Strep in horses )

17

How does previous ABx Tx affect the decision making for rational ABx use?

changes susceptibility profile of bugs

18

How do horses differ from SAs with wound infection risks?

Strep ^ risk in horses than staph/

19

What bacteria usually causes mastitis in cattle?

Staph

20

How should sepsis of unknown origin be treated?

Cover all 4 bacterial quadrants

21

What is the common cause of pneumonia?

Difficult to predict bacteria

22

What is the common cause of endocarditis, arthritis or discospondylitis?

Staph -> systemic infection from the skin

23

What is the exception to the rule of bacteria which are resistant to a drug in vitro being resistant in vivo?

- stats based on blood concentration of drug
-> resistence may be overcome by high concentrations achieved in urine/topically

24

Define MIC. How is this used clinically?

Minimum inhibitory concentration
- lowest concentration of a drug to inhibit bacterial growth
- MIC90 used as therapeutic dose (conc that inhibits 90% bacterial isolates of a specific species eg. e coli, s. pseudointermedius)

25

Give 3 antimicrobials that inhibit cell wall synthesis

- penicillins
- cephalosporins
- bacitracin (usually used for eyes and ears)

26

Give 4 antimicrobials that inhibit cell membrane function. What are their usual usage?

- polymixins (eyes)
Usually antifungals:
- amphotericin B
- imidazoles
- nystatin

27

Give 5 antimicrobials that inhibit protein synthesis

- chloramphenicol
- macrolides
- lincosamides
- tetracylinces
- aminoglycosides (good for ears)

28

Which antimicrobial class have an ^ risk of side effects and why?

Protein synthesis inhibitors (chloramphenicol, macrolides, lincosamides) as act on element of bacterial cell that is similar to mammalian.

29

Give 5 antimicrobial classes that inhibit nucleic acid synthesis

- sulphonamides
- trimethoprim
- quinolones (enrofloxacin etc.)
- metronidazole
- rifampin (used rarely)

30

Is distinguishing bacteriostatic and bacteriocidal drugs clinically relevant?

Not really - just know that bacterioSTATIC = effect reversible once drug removed, and during Tx MIC should be maintained at site of infection throughout dosing interval -> specific dosing schedule and strict instructions necessary. Can work as bactericidal if dose is sufficiently high/prolonged.
- BacterioCIDAL = preferred when concern about site of infection or host defences as technically body defence not necessary. Killing action may be both TIME and CONCENTRATION dependent