Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology 2. A topics > 17. Penicillins and beta-lactamase inhibitors > Flashcards

17. Penicillins and beta-lactamase inhibitors Flashcards

1
Q

Structure of penicillins

A

Beta-lactam ring (that can be cleaved by beta-lactamase) and thiazolidine ring. Two chains that are responsible for pharmacokinetics and antimicrobial spectrum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does structure influence pharmacokinetic properties of penicillins?

A
  • If Na/K -> water-soluble -> can be given IV. 2-3h
  • if procaine -> bad water solubility, relatively long action. Is not usually given alone. Up to 24h
  • Benzatine -> least water-soluble. Very long action. Up to 72 hours
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the target of penicillins?

A

PNP - penicillin binding proteins: transpeptidase and carboxipeptidase - enzymes responsible for last step of bacterial cell wall synthesis - tranpeptidation.

Beta-lactam drugs have similar structure to peptide chain -> PBP will bind beta-lactam drugs and not the bacterial peptide chain -> IRREVERSIBLE INACTIVATION of PBP -> cross-linking doesn’t happen -> weak cell wal -> collapsing of the cell wall and death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is peptidoglycan? What is its structure?

A

= Murein. Layer of bacterial cell wall. Is important for cell wall integrity especially in Gram+ bacteria.
N-acetyl-muranic acid (NAM) and N-acetyl-glucose amine chain (NAG) make long chains that are connected to each other by transpeptide bonds. For formation of these bonds PBP (protein binding proteins) are responsible.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Mechanism of action of penicillins

A

Inhibition of synthesis of the peptidoglycan layer of bacterial cell wall. Irreversible inactivation if PBP (penicillin binding proteins) -> cross-linking (transpeptidation) does not happen -> collapse of cell wall and death of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Mode of action of penicillins

A

BACTERIACIDAL. Time-dependent. Also hav PAE (postantibiotic effect) 4-8h.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why penicillins should NOT be used with bacteriostatic drugs?

A

Penicillins work against cell wall synthesis => against dividing bacteria.
Bacteriostatic drugs INHIBIT division of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Against what type of bacteria penicillins are most effective? Why?

A

Against Gram+ bacteria because

  1. huge part of their cell wall is peptidoglycan -> very sensitive to beta-lactam antibacterial drugs.
  2. PBPs are locate between cell wall and cell membrane an it’s much easier for drug to penetrate cell wall of Gram+ bacteria than Gram- (in gram- it can come only through PORINS)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Types of resistance against penicillins

A
  1. Ab ovo (primary). Never effective against pathogen
  2. Beta-lactamase production
  3. PBP-gene mutation (e.g. MRSA, MRSP)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Examples of ab ovo resistance to penicilins

A
  • Mycoplasma - absence of cell wall. (resp tract infection in poultry and swine)
  • acid-fast bacteria - penicillin cannot penetrate and reach the target (Mycobacteria)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Against what bacteria were penicillinase stable penicillins created?

A

Against Staphylococcus. Gram+ bacteria that produces beta-lactamase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What bacteria produce beta-lactamase?

A

all gram– and Staphylococci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the ways to avoid beta-lactamase resistance?

A
  1. To use clavulonic acid
  2. To change structure of the drug
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens if bacteria modifies its PBP? Can we apply penicillins?

A

If PBP is changed - NONE of beta-lactam antibacterial drugs will be efficient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

MRSA - ?

A

Methicillin resistant Staphylococcus aureus.
Staphylococci produce beta lactamase -› penicilinase resistant penicillins were created with slightly different structure (methicillin, oxacillin, cloxacillin) -› PBPs mutated and changed structure -› none of beta-lactam antibacterial drugs is anymore resistant against MRSA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

MRSP -?

A

Methicillin Resistant Staphylococcus pseudintermedius

17
Q

What are the types of antibacterial spectrum of penicillins?

A
  1. Narrow spectrum bacteria
  2. Penicilinnase stable penicillins
  3. Extended spectrum penicillins
  4. Penicillins acting against Pseudonomas spp.
18
Q

Narrow spectrum penicillins act against …

A

Most of gram+ bacteria, fastidious gram- + Leptospira, Borrelia, anaerobes

19
Q

What are the drugs belonging to narrow spectrum penicillins?

A
  • benzylpenicillin - Na/K (water-soluble)
  • benzylpenicillin - procaine
  • benzylpenicillin - benzathine
  • phenoxymethyl-penicillin (acid-stable, can be given orally)
  • penethamat (can cross blood-milk barrier)
20
Q

What bacteria are fastidious gram- ?

A
  • Pasteurella
  • Haemophilus
  • Actinobacillus
  • Mannheima

mainly cause respiratory tract infections

21
Q

Narrow spectrum penicilins are the first choice of trearment of: …

A
  1. swine erysipelas (diamond skin disease) Erysipelothrix rhusiopathiae
  2. anthrax - Bacillus anthracis
  3. tetanus - Clostridium tetani
  4. necrotic enteritis of poultry - Clostridium perfringens
  5. streptococcosis (mastitis, dermatitis, pharyngitis)

respiratory infections - not the first choice but can be treated

22
Q

What narrow spectrum penicillin can be absorbed orally?

A

phenoxymethyl-penicillin

23
Q

What is the distribution of narrow spectrum penicillins (PK)?

A

Distribution is poor. Hydrophilic. Can’t enter the cells -› not effective against intracellular organisms.

Most of penicillins can’t cross special biological barriers (exception: penethamat - can cross blood-milk barrier)

24
Q

What is the metabolism and excretion of narrow spectrum penicillins (PK)?

A

Metabolism is minimal. Can be given to patience with liver failure.

Excretion mainly via kidney. In active form and also concentrated.

25
Q

What are side effects of narrow spectrum penicillins?

A
  • allergy, non-immunological anaphylactic reaction (because of histamine release from mast cells). If adminestered IV then even more severe
  • dysbacteriosis (esp. in HORSES and RODENTS)
  • the most toxic nar. sp. pen. - procaine-penicilin (because of procaine) - restlessness, tremor. PIGLETS and FOALS are esp. sensitive. Doping drug.
26
Q

Can respiratory infections be treated by narrow spectrum penicillins?

A

Yes. But mostly not the first choice

27
Q

What narrow spectrum penicillins are often used together?

A

benzylpenicillin-procaine and benzylpenicillin-benzathine to increase duration of action

28
Q

Against what bacteria were penicillinase stable penicillins invented for?

A

Against Staphylococci and Streptococci mostly causing mastitis and dermatitis

29
Q

Are penicillinase stable penicillins effective against gram- bacteria?

A

NO

30
Q

What drugs belong to the penicilinase stable penicillins?

A
  • methicillin (now only historical significance. first kind of this kind)
  • Oxaciline
  • Cloxacillin
  • Dicloxacillin
  • Flucloxacillin

usually used as intramammary infusion in case of mastitis.

31
Q

Extended spectrum penicillins act against what type of bacteria?

A

Most of gram+ bacteria and several gram- bacteria

32
Q

Extended spectrum penicillins are important because they can act against…

A

E. coli and Salmonella

33
Q

Drugs belonging to broad spectrum penicillins

A
  • amphicillin (outdated: bad oral absorption, feed reduces it even more)
  • amoxicillin
34
Q

Why amphicillin considered outdated drug

A

Relatively bad oral absorption and fee reduces it even more. Instead amoxicillin is used

35
Q

Broad spectrum penicillins are used in case of:

A
  • same as narrow spectrum penicilllins and in case of respiratory infections are more effective
  • urinary tract infections
  • GI infection
  • Dermatitis, soft tissue infections
  • Lyme-disease
  • Osteomyelitis
  • Oral cavity infection, bite wounds
  • Septicaemia, bacteraemia
36
Q

Penicillins acting against Pseudonoas spp. Drugs:

A
  • Piperacillin (+tazobactam)
  • Ticarcillin (+ clavulonic acid)
37
Q

To what group of AMEG classification do penicillins acting against Pseudonomas spp. belong?

A

A. Avoid => only in small animals

Pharmacology 2. A topics (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions