Antimicrobials microbio
0.0 / 5
- Created by: Amh
- Created on: 22-03-16 10:39
Who founded chemotherapy
Paul Ehrlich, Trypan red and arsenic v syphilis
1 of 68
Who first observed Penicillin
Fleming in 1929
2 of 68
Who first purified Penicillin?
Florey and Chain in 1940, used clinically in 1944
3 of 68
What is an antbiotic
a A natural antimicrobial substance produced by a micro-organism
4 of 68
Give an example of antibiotics we use today and their natural source?
Fungi Penicillium spp - penicillin, and Cephalosorium - cephalosporin, Bacteria - Actinomycetes - streptomyces spp - gave us streptomycin
5 of 68
What are antimicrobials
Antibiotics and synthetic substances
6 of 68
Give an example of a synthetic antimicrobial
Sulphonamides, and Quinolones
7 of 68
What are some bacterial targets
Cell wall synthesiis, bacterial protein synthesis, Folic acid synthesis, Nucleic acid metabolism, bacterial cell membrane
8 of 68
How do Beta-lactams work
inhibit cell wall synthesis, bind to transpeptidases involved in cross linking NAG and NAM residues in cell wall - the unsupported cell wall ruptures and cell bursts
9 of 68
Where do Beta lactams get their name
they all have a beta lactam ring
10 of 68
What does the activity (effectiveness) depend on
The affinity for transpeptidases (Penicillin binding proteins) on target organsim
11 of 68
Give some examples of Beta lactams
Penicillin, Flucloxacillin Amoxicillin, Cephalosporins, Carbapenems
12 of 68
What is penicillin effective against
Streptococci
13 of 68
What is Flucloaxacillin effective against
Staphylococci
14 of 68
What is amoxicillin effective against
Gram negatives, streptococci, and eneterococci
15 of 68
What is Cephlosporins affective against
– 1 st Generation < +ve Gram -ve < 4th Generation
16 of 68
What are Carbapenems affective against
Multidrug resistant gram negatives
17 of 68
How do Glycopeptides work
Act on cell wall synthesis in Gram-positive bacteria, bind D-Ala-D-ala precursors of the cell wall syntheiss preventinf access of transpeptidases PBP)
18 of 68
What is some examples of Glycopeptidases?
Vancomycin, Teicoplanin
19 of 68
Do Glycopeptidases work against gram negative bacteria
No they are too big to penetrat gram neg membrane
20 of 68
how are Glycopeptidases given
Intravenously
21 of 68
When are the used
For patients with allergies or MRSA
22 of 68
What drugs target protein synthesis
Aminoglycosides, tetracylines, macrolides and lincosamides
23 of 68
Which of thes drugs targets the 30s subunit
Aminoglycosides and tetracyclines target the 30S
24 of 68
Which of thes drugs targets the 50s subunit
macrolides and lincosamides
25 of 68
How do aminoglycosides work
bind to 30s subunit on ribosome and disrupts the structure preventing initiation of protein synthesis
26 of 68
Give examples of aminoglycosides
Gentamicin, tobramycin, amikacin, streptomycin
27 of 68
What are Gentamicin, tobramycin, amikacin effective against
Gram-positive and Gram-negative bacteria
28 of 68
What is Streptomycin effective against?
Mycobacterium tuberculosis
29 of 68
How are Aminoglycosides given
Intravenously
30 of 68
what are some side effects of Aminoglycosides
Cause hearing loss and renal impairment at high dose (e.g. treating meningitis) – Requires therapeutic monitoring of serum levels
31 of 68
How do Tetracyclines work
Bind to the 30S subunit and prevent incorporation of amino acids resulting in Incomplete non-functional proteins
32 of 68
Give an example of tetracylcines
doxycycline / minocyclinev
33 of 68
How do Macrolides work
Bind to 50S subunit and prevent translocation of polypeptide chain along ribosome
34 of 68
Give an example of macrolides
erythromycin / clarithromycin / clindamycin
35 of 68
What in clindamycin (macrolide) effective against?
Anaerobes
36 of 68
Why are Macrolides and tetracyline similar
They are both bacteriostatic, achieve high intracellular conc in host (good against intracelluar pathogens) both interup protein syntheis
37 of 68
Which 2 classes of antibiotics inhibit nucleic synthesis
Quinolones, and Rifampicin
38 of 68
Give an example of Quinolones
Ciprofloxacin, and Levofloaxacin
39 of 68
How do quinolones work
Inhibit DNA synthesis by binding to • DNA gyrase (GyrA, GyrB) • DNA Topoisomerase (ParC, ParE)
40 of 68
Do they work against gram negatives?
Yes they work against gram negs and pos
41 of 68
How does Rifampicin work?
Inhibits RNA polymerase
42 of 68
How is Rifampicin used?
*** an adjunctive to other antibiotics (antibiotics that work close to DNA are morelikley to gain resistance)
43 of 68
Why is folate acid synthesis a target in bacteria
Humans do not synthesize their own folic acid - they obtain it form diet, whereas bacteria do, and folic acid is essential for bacteria
44 of 68
Which 2 drugs interfer with folic acid synthesis
Sulfonamides, and trimethoprim
45 of 68
Where do sulfonamides act
They inhibit PABA to DHF conversion by inhibiting dihydropterate synthase
46 of 68
How does Trimethoprim work?
It stops the conversion of DHF to THF by inhibitinf DHFR
47 of 68
What are membrane distrupting agents
Catinionic peptides such as polymyxinn B and some disinfectants
48 of 68
Why aren't Cationic peptides used
Toxic because of lack of selectivity
49 of 68
Why do we do sensitivity testing?
To see whether the therapy will be effective, to reduce sideeffects, to obtain data on prevalence of resistance, and to enable antimicrobial policies to be formed
50 of 68
What guidlines are there for susceptibility testing?
guidelines such as CLSI (US) or BSAC (UK) are used
51 of 68
What is MIC
Minimal inhibitory concentration of antibiotic required to inhibit growth
52 of 68
What are some methods of susceptibility testing?
Disc diffusion (BSAC), Agar dilution, broth microdilution, Gradient Etest, automated VITEK system, molecular detection of resistance mechanisms
53 of 68
What is the US reference method
Broth Microtitre Dilutions
54 of 68
How do Broth Microtitre Dilutions work
microtitre plates are filled with broth bacteria are added and varying conc of antibiotics are added, there are incubated at 35'c and then checked for turbidity MIC = 1st dilution with no visible signs of growth
55 of 68
What is the UK reference method
Agar dilutions
56 of 68
How do agar dilutions work
Uses Isosensitest agar supplemented with increasing concentrations of antimicrobial MIC = dilution of 1st plate on which no colony recovered
57 of 68
What is the disc diffusion test
Organisms is grown on media then discs of antibiotics are added, the plate is incubated overnight and zones of inhibition are measuread and compared either to a sensitive control or ‘zone diameter breakpoints’
58 of 68
What is the Etest method
Organsim is grown on plate then ***** js added, ***** has varying conc of antibacteria agent, allows you to see the exact conc required, you caan use multiple *****ts on plate to determine the most effective antimicrobial
59 of 68
What are some automated methods of antisuscptibillity methods?
– MicroScan WalkAway – Vitek – Phenoix, all use microdiultion cards and high resolution optical scanning for microbial growth
60 of 68
What is the MIC50 and the MIC90
MIC50 = Concentration required to inhibit 50 % of the population • MIC90 = Concentration required to inhibit 90 % of the population
61 of 68
What is the geometric mean of MIC
a measure of level of susceptibility of the species as a whole
62 of 68
How can you do Molecular Detection of Resistance Genes
PCR
63 of 68
What are some methods for carrying out this PCR
Dallene ultiplex, Voets multiplex,
64 of 68
How else can you determine resistance genes
DNA microarrays, Fluorescent in-situ hybridization (DNA probes with fluorescent tags)
65 of 68
Why are bactericidals important
They activley kill bacteria - needed for severe infections, and immunocomprimised
66 of 68
Is MIC a measure of bacterialcidials or bacterostatics
bacterostatics
67 of 68
**not finished ad pharmaco ****
and definitions
68 of 68
Other cards in this set
Card 2
Front
Who first observed Penicillin
Back
Fleming in 1929
Card 3
Front
Who first purified Penicillin?
Back
Card 4
Front
What is an antbiotic
Back
Card 5
Front
Give an example of antibiotics we use today and their natural source?
Back
Similar Biology resources:
0.0 / 5
5.0 / 5 based on 1 rating
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
0.0 / 5
3.0 / 5 based on 1 rating
0.0 / 5
Comments
No comments have yet been made