Microbiology Flashcards Preview

Phase 2a > Microbiology > Flashcards

Flashcards in Microbiology Deck (260)
Loading flashcards...
1

Why do we culture blood?

to look for bacteraemia - it is normally bacteria free without bacteria flora

2

How can blood be contaminated?

patient's skin, surface of the items used to take the culture, fingers of the person taking the blood, laboratory

3

How long does it take for a blood culture to identify an organism?

1 day to do gram stain and coccsu/bacillus
2-3 days to identify organism and assess whether this is likely to be a contaminant

4

Why are contaminants a problem?

give wrong treatment, waste of money, side effects for patients, unnecessary equipment, increased length of stay, mislead clinicians, not always able to identify whether it is a contaminant or not, don't meet contamination targets

5

What organism is resistant to all B lactams?

MRSA

6

Disadvantage of using B lactam antibiotics?

can predispose to C.difficile and colonization with resistant bacteria e.g. MRSA, many people report allergies to this group, especially penicillin

7

What is the most widely used class of antibiotics and how do they work?

B lactams which includes penicillins, cephalosporins, carbapenems and combinations - bind to cell wall and inhibit cells wall sunthesis

8

Two main types of penicillins?

amoxicillin, flucloxacillin

9

What antibiotic is used for enterococci and H.influenzae?

amoxcillin - but most enterobacteria are resistant to it

10

What is flucloxacillin used for?

anti staphylococcal agent as stability to penicillinase

11

What are B lactamase inhibitors used for?

bacteria resistance is through B lactamase production, so these antibiotics prevent this resistance, so use combinations e.g. co-amoxiclav, tazocin

12

What are monobactams used for?

e.g. Aztreonam, for gram negative bacilli, including pseudomonas and preferably aerobes, safer for C.diff

13

What are carbapenems used for?

e.g. imipenem for very broad spectrum hospital acquired infections

14

Disadvantages of carbapenems e.g. imipenem?

expensive, CI in CNS disorders and can predispose to C.diff

15

What are cephalosporins used for?

e.g. cefotaxime, ceftazidime for gram negative activity, good CNS penetration and good anti pseudomonal

16

What are glycopeptides used for?

e.g. vancomycin for gram positive only and reserved for serious, resistant ones e.g. MRSA (Iv only and toxic)

17

What are macrolides used for?

e.g. erythromysin, clarithromycin for staph and strep activity, used to soft tissue and throat infections if allergic to penicillins (no gram negative cover)

18

What are lincosamindes used for?

e.g. clindamycin for staph, strep and anaerobes and C.diff and PMC good bone concentrations and well absorbed orally

19

What are tetracyclines used for?

mild MRSA infections and chlamydias

20

What are aminoglycosides used for and how do they work?

e.g. gentamicin for enterobacteriaceae, pseudomonas and staphylococci, synergy with cell wall antibiotics against streptococci and enterococci - inhibit ribosomal activity and protein synthesis

21

Disadvantages of aminoglycosides?

more toxic than glycoproteins so nephro and oto toic levels must be monitored carefullly

22

What is fusidic acid used for?

serious anti staphylococcal agents e.g. osteomyelitis, only used in combination

23

What is oxazolidinone used for and how does it work?

grampositive including MRSA and VRE - inhibits bacterial protein synthesis and blocks initiatio complex formation

24

Disadvantages of oxazolidinone?

only 1 class e.g. linezolid and are expensive and can cause bone marrow suppression if used for >2 weeks

25

What are nuclei acids/quinolones used for and how do they work?

e.g. ciprofloxacin - UTIs, enterobacteriacease pseudomonas and staph - inhibitt DNA gyrase

26

What is rifampicin used for and how do they work?

TB and general Staph's and meningitis prophylaxis - must be used in combination - interfere with nuclei acid synthesis or function

27

What is metronidazole used for?

anti anaerobic for bacteria and protozoa

28

What likely organisms are seen in UTIs?

e coli, staph sparophyticus, enterococci

29

Antibiotics for UTIs?

trimethoprim, amoxicillin, clavulanate, cephalosporin

30

Likely organisms to cause COPD?

Hinfluenzae, pneumococcus, Moraxella catarrhalis