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PAMS- Antimicrobials > Antibacterials > Flashcards

Antibacterials Flashcards

1
Q

What is the structure of a bacteria ?

A

They are unicellular prokaryotes that have a cell wall with absent organelles and a disorganised nuclear material.

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2
Q

What are the shapes of bacteria ?

A

Cooci, Bacilli, Vibrios, Spiralla( H.Pylori), and spirochates.

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3
Q

What is the difference between gram - and gram + bacteria ?

A

Gram negative poorly gram stains because they absorb little stain due to their cell wall structure that consist of an outer cell membrane with lipopolysaceride projections, a thin peptidoglycan and an inner cytoplasmic membrane. Whereas, gram positive absorbs the stain well because it only has thick peptidoglycan and an inner cytoplasmic membrane.

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4
Q

What are the two different ways of classifying antibiotics ?

A

Based on action- bacteriocidal or static.
Based on therapeutic spectrum: broad or narrow.

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5
Q

What are the most common bacteriostatic antibiotics ?

A
  • Tetracyclines.
  • Spectinomycine
  • Sulphonamides
  • Macrolides
  • Chloramphenicole
  • Trimethoprime.
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6
Q

What are the most common bacteriocidal antibiotics?

A
  • Penicillins
  • Cephalosporins
  • Fluroquinilones.
  • Glycopeptides
  • Monobactums
  • Carbapenims.
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7
Q

What are the 3 most common bacterial cell wall synthesis inhibitors ?

A

Penicillins, Cephalosporins, and Vacnomycine. They are bacteriocidal.

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8
Q

What are the most common mRNA transcription inhibitors ?

A

Tetracycline, erythromycin, streptomycin, and chloramphenicol

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9
Q

What is an inhibitor of DNA replication ?

A

Quinolones.

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10
Q

What are the four types of drugs that contain beta lactam rings ?

A

– Penicillins
– Cephalosporins
– Monobactams
– Carbapenems
They are useful against both gram + and - bacteria.

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11
Q

What is the action of beta lactam drugs ?

A

They inhibit bacterial cell wall synthesis by binding to penicillin binding protein transpeptideses which prevents cross linking of peptidoglycans leading to bacterial death.

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12
Q

What is the action of bacterial beta lacamase enzyme ?

A

Beta lactamse is a lytic enzyme produced by the bacteria to protect itself from beta lactam antibiotics by hydrolysing the beta lactam rings of the drugs.

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13
Q

what is an example of beta lactmase resistant drug ?

A

Carbapenems

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14
Q

What is the penicillin used for the Tx of bacterial meningitis ?

A

High dose IV benzylpenicillin.

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15
Q

What is the penicillin used for bone and joint infections with Steph Aureus ?

A

flucloxacillin

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16
Q

What are the penicillins for skin and soft tissue infections with Streptococcus pyogenes or S. aureus ?

A

benzylpenicillin ,
and flucloxacillin

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17
Q

What is the penicillin of choice for animal bite ?

A

Amoxicillin -clavulanate

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18
Q

What is the penicillin used for the tx of pneumonia, bronchitis, and UTI with E.coli ?

A

Amoxicillin.

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19
Q

Amoxicillin and probenicide are used in combination to treat what infection ?

A

gonorrhea

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20
Q

What is the drug of choice for Syphilis ?

A

procaine benzylpenicillin

21
Q

What is the Tx of endocarditis with Streptococcus viridans or Enterococcus faecalis ?

A

High-dose intravenous
benzylpenicillin sometimes with an aminoglycoside.

22
Q

What is the Tx of serious infections with Psuedomonas aeruginosa?

A

ticarcillin , piperacillin .

23
Q

What is the pharmacokinentcis of Penicillins ?

A

They have poor oral bioavailability, hence are given IV or IM. They have wide body fluid and compartment distribution. However, they do not enter the mammalin cell as they are lipophobic. They only cross blood brain barrier, if the meninges are inflamed. They are rapidly eliminated by renal excretion.

24
Q

What are the side effects of penicillins ?

A
  • They have no direct toxic effect.
  • Hypersensitivity reactions by the degradation products of penicillin, which combine with host protein and become antigenic.
  • Skin rashes and fever are common
  • Rare side effects are serum sickness and anaphylaxis.
25
Q

What is the main unwanted side-effect of oral penicillin ?

A

Pseudomembranous colitis.

26
Q

What are MRSA ?

A

These are strains of Steph aureus which are resistance to b-lactam antibiotics due to them having mutated Penicilin Binding Protein known as PBP2a which has no affinity for beta lactams.

27
Q

What are Cephalosporins
& Cephamycins?

A

They are first isolated from Cephalosporium acremonium in 1945 and has Similar profile and mechanism of action as penicillins.

28
Q

What are monobactams ?

A

They are resistant to most β-lactamases and are Effective only against Gram-negative aerobic bacilli such as pseudomonas species, N meningitidis and H influenzae.

29
Q

What is the main monobactam in use ?

A

aztreonam

30
Q

What is the action of carbapenems ?

A

They have a very broad spectrum activity and resistant to
beta lactamase enzyme. Hence, active against many aerobic and
anaerobic Gram-positive and Gram-negative organisms.

31
Q

what are the main carbapenems?

A

Imepenem and Meropenem

32
Q

What is the main side effect of carbapenem ?

A

Seizuregenic at high doses

33
Q

what are the most concerning drug interactions of beta lactams ?

A

Reports of drug–drug interactions with the beta-lactams are relatively rare. The main ones are :
decreased effectiveness of oral contraceptives ,
methotrexate toxicity due to renal tubular competition that reduce the excretion of methotrexate and increased elemenation of
valproic acid leading to sub therapeutic effect.

34
Q

What is the main use of glycopeptide drug Vancomycin ?

A

It is only effective against gram positive organisms and is the main stay of treatment for MRSA.

35
Q

What is the action of vancomycin ?

A

It makes the bacteria susceptible to osmotic pressure and death by inhibiting cell wall synthesis by binding to to amino acid tails of peptidoglycan.

36
Q

What are the side effects of Vancomycin ?

A
  • Fever, rashes and local phlebitis
  • Redman syndrome
  • Ototoxicity and Nephrotoxicity
37
Q

How doe drugs such as Tetracyclines, Macrolides
Aminoglycosides work ?

A

They inhibit mRNA translation or ribosomal protein synthesis.

38
Q

What is the structure and action of tetracycline & doxycycline?

A

They have four fused cyclic rings and binds to 55s, 39s and 28s bacterial ribosmal sub-units and inhibit protein synthesis. Thus, are bacteriostatic.

39
Q

What is the pharmacokinetcis of tetracyclines ?

A
  • They are administered PO or IV
  • Minocycline and doxycycline are completely absorbed.
    *Absorption of other tetracyclines is irregular and incomplete but is improved in the absence of food.
40
Q

Why tetracyclines should not be given to children, pregnant
women or nursing mothers ?

A

Tetracyclines chelate (bind) Ca+ they are deposited in growing bones and teeth which causes them to have yellow-brown color.

41
Q

How does Quinolones and fluoroquinolones works ?

A

They inhibit DNA replication.

42
Q

What are the most common fluoroquinolones ?

A

broad-spectrum agents such as ciprofloxacin , levofloxacin , ofloxacin , norfloxacin and moxifloxacin.

43
Q

What is the example of a commonly used Quinolone ?

A

Nalidixic acid, a narrowspectrum drug used in urinary tract infections.

44
Q

What is the action of fluoroquinolones ?

A

They inhibit bacterial DNA gyrase topoisomerase II which is an enzyme that produces a negative
supercoil in DNA, essential for DNA replication.

45
Q

What is the pharmacokinetics of Quinolones and fluoroquinolones ?

A

FQ are well absorbed orally and accumulates in kidney, prostate and lung. Most fail to cross the blood brain barrier. Aluminium and magnesium antacids interfere with absorption
of quinolones.

46
Q

What are the side effects of Quinolones and fluoroquinolones ?

A

GI symptoms, skin rashes, arthropathy in young individuals, CNS symptoms, headache and dizziness.

47
Q

What is the clinically relevant drug interaction of fluoroquinolones ?

A

The interaction between ciproflaxin and theophylline which can lead to theophylline toxicity.

48
Q

What are the two types of anti-microbial resistance ?

A

-Natural Resistance
-Acquired Resistance

49
Q

What are the mechanisms of anti-microbial resistance ?

A
  • Increase active eflux of the drug.
  • Inactivation of the drug by phosphorylation.
  • Presence of plasmid proteins
  • modification of cell wall proteins taht prevent the entry of drug into the bacteria.

PAMS- Antimicrobials (3 decks)

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