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POM > Antimicrobial therapies > Flashcards

Antimicrobial therapies Flashcards

1
Q

What class of antibiotic is prontosil?

A

Sulphonamide antibiotic.

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2
Q

How do sulphonamide antibiotics work?

A

Competitive inhibitors of folic acid synthesis in bacteria. Inhibits DNA replication.

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3
Q

What enzyme do sulphonamide antibiotics target?

A

Dihydropteroate synthase.

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4
Q

What are sulphonamide antibiotics used to treat?

A

UTI, RTI.

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5
Q

Are sulphonamide antibiotics bacteriostatic or bactericidal?

A

Bacteriostatic.

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6
Q

Why are gram negative bacteria harder to treat?

A

2nd membrane makes it harder to get antibiotics into the bacteria.

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7
Q

What drug class is penicillin and methicillin?

A

Beta-lactams.

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8
Q

Most commonly used antibiotic?

A

Beta-lactams.

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9
Q

How do beta-lactams work?

A

Bind to penicillin-binding proteins and inhibit peptidoglycan synthesis.

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10
Q

What are penicillin-binding proteins?

A

They catalyses a number of steps involved in the synthesis of peptidoglycan.

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11
Q

Why can use of an antibiotic result in resistance?

A

Antibiotics provide selective pressure. Resistant bacteria survive and go on to reproduce. High prevalence of AB resistant strains in patient population after non resistant have died and resistant have gone on to reproduce.

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12
Q

What are some of the problems associated with antibiotic resistance?

A

Use of expensive drugs. Use of more toxic drugs. Increased time in hospitals. Use of less effective antibiotics.

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13
Q

What gram positive bacterium is associated with Pseudomembranous colitis, antibiotic-associated diarrhoea?

A

Clostridium difficle.

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14
Q

What gram positive bacterium can cause a UTI?

A

Enterococcus spp (VRE).

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15
Q

What gram negative bacterium is common in cystic fibrosis lung infections and survives on abiotic surfaces?

A

Pseudomonas aeruginosa.

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16
Q

What gram negative bacterium can cause GI infect., neonatal meningitis, UTI?

A

E.coli

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17
Q

What gram negative bacterium can cause GI infect and typhoid fever?

A

Salmonella

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18
Q

What gram negative bacterium can cause UTI and pneumonia?

A

Acinetobacter baumannii.

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19
Q

What gram negative bacterium can cause gonorrhoea?

A

Neisseria gonorrhoeae.

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20
Q

Are aminoglycosides bactericidal or bacteriostatic?

A

Bactericidal.

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21
Q

How do aminoglycosides work?

A

They target protein synthesis, RNA proofreading and damage cell membranes.

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22
Q

What drug class are gentamicin and streptomycin

A

Aminoglycosides.

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23
Q

What is Rifampicin?

A

Bactericidal that targets RNA polymerase.

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24
Q

What drug class if Rifampicin?

A

Ansamycin.

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25
Q

What is vancomycin?

A

Bactericidal. Targets lipid II component of cell wall synthesis, as well as wall crosslinking.

26
Q

What drug class is vancomycin?

A

Glycopeptide.

27
Q

What is linezolid?

A

Bacteriostatic. Inhibits initiation of protein synthesis by binding to the 50s ribosomal RNA subunit. Only works on gram positive.

28
Q

What drug class is linezolid?

A

Oxazolidinones.

29
Q

What is daptomycin?

A

Bactericidal. Targets bacterial cell membrane. Only works in gram positive.

30
Q

What drug class is daptomycin?

A

Lipopeptides.

31
Q

What allows for selective toxicity for antibiotics?

A

Antibiotics only target processes that occur in bacteria.

32
Q

What are the 4 mechanisms of antibiotics resistance?

A

Altered target site. Inactivation of antibiotic. Altered metabolism. Decreased drug accumulation.

33
Q

How can alternative target site in bacteria arise?

A

Alternative gene or a gene that encodes a target modifying enzyme.

34
Q

What is the resistance mechanism in MRSA?

A

MRSA encodes an alternative penicillin binding protein with low affinity for beta-lactams.

35
Q

What is the resistance mechanism in streptococcus pneumoniae?

A

Acquires gene that encodes an enzyme that causes Methylation of AB target site in 50s ribosomal subunit leads to resistance to erythromycin.

36
Q

How does inactivation of antibiotic work?

A

Enzymatic degradation or alteration leading to antibiotic being ineffective.

37
Q

How does beta lactamase cause penicillin to be ineffective?

A

Breaks bond in beta lactam ring in penicillin.

38
Q

How can altered metabolism in bacteria work as a form of resistance?

A

Increased production of enzyme substrate can outcompete antibiotic inhibitor. Can also increase loads more of target which means a greater dose of drug is required. Bacteria can also switch to other metabolic pathways.

39
Q

How does decreased drug accumulation work in bacteria?

A

Reduced permeability to antibiotic. Increase efflux of antibiotic out of cell.

40
Q

How do macrolides work?

A

Target 50s ribosomal subunit preventing amino-acyl transfer and thus truncation of polypeptides.

41
Q

What kind of drug is erythromycin and azithromycin?

A

Macrolides.

42
Q

How do quinolones work?

A

Bactericidal. Target bacterial enzymes involved in DNA. Leads to DNA damage.

43
Q

What are the three sources of antibiotic resistance genes?

A

Plasmids. Transposons. Naked DNA (DNA from dead bacteria released into the environment).

44
Q

Why can bacteria go from being not resistant to very resistant?

A

Plasmids contain lots of resistance genes. One plasmid can be transferred and bacteria can gain lots of resistance genes.

45
Q

What are transposons?

A

Can be integrated into chromosomal DNA. Allows transfer of genes from plasmids to chromosomal DNA.

46
Q

Three ways AB resistance genes can be shared?

A

Transformation, transduction, conjugation.

47
Q

Reasons for why antibiotic course may fail?

A

Presence of AB resistance within commensal flora. Inappropriate dose. Bacterial spores.

48
Q

Why is antibiotic resistance common in hospitals?

A

Hospitals provide strong selective pressure. High doses of antibiotics given and lots of infected people.

49
Q

Risks factors for HAI?

A

Lots of ill people. Crowded wards. Broken skin (surgical wound/iv catheter.

50
Q

How to deal with antibiotic resistance?

A

Knowledge of local strains / resistance patterns. Reduce use of broad spectrum antibiotics. Quicker identification of infection caused by resistant strains. Combination therapy

51
Q

Name two sulphonamide antibiotics?

A

Prontosil and sulfa-methoxazole.

52
Q

How does chloramphenicol acetyl transferase work?

A

Transfers acetyl group from acetyl CoA to chloramphenicol. Chloramphenicol can’t bind to ribosomes.

53
Q

What is transformation?

A

Uptake of naked DNA from environment.

54
Q

What is transduction?

A

DNA is transferred from one bacteria to another by a virus (bacteriophage).

55
Q

What is conjugation?

A

Transfer of genetic material from one bacteria to another by direct contact.

56
Q

What are mycoses?

A

Fungal infections.

57
Q

Classes of mycoses?

A

Superficial, cutaneous, subcutaneous or systemic.

58
Q

What are Mycotoxicoses?

A

Ingestion of fungi and their toxic products

59
Q

Antifungal treatment targets?

A

Cell membrane - Fungi use ergosterol instead of cholesterol. Cell wall (mammalian cells don’t have).

60
Q

Gram positive antibiotics?

A

Linezolid, Daptomycin.

POM (41 decks)

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