Antiboitcs - Cell Wall Inhibitors Flashcards
Explain Classification of Antibiotics drugs ( Cell water inhibitors) , penicillin’s mechanism of action , resistance of Penicillin, pharmacokinetics
—Classification of Cell wall inhibitors
1-Penicillin
2-Cephalosporin
3-Monobactams
4-Carbapenems
5-Glycopeotides
— Penicillin mechanism :
The mechanism is for all penicillins groups is the same , Penicillin bind to (PBP - Penicillin binding protein ) on the bacterial cell wall and inhibits the transpeptidse enzyme which is inhibite the transpeptades reaction , which is synthesis the walls of the cell , then it’s activates the autolytic enzyme called autolysin leading to cell rapture which is result of of cell wall inhibition and autolysis
-NB! The penicillin mechanism requires proliferation microorganisms, have no effect of bacteria that not dividing
—Penicillin resistant:
Enzymatic hydrolysis of the beta-lactam ring results in loss
of antibacterial activity. The formation of beta-lactamases
(penicillinases) by most staphylococci and many Gram-negative
organisms is a major mechanism of bacterial resistance. Inhibitors of these bacterial enzymes (eg, clavulanic acid, sulbactam, tazobactam) are often used in combination with penicillins to prevent their inactivation. Structural change in target PBPs is another mechanism of resistance and is responsible for methicillin resistance in staphylococci and for resistance to penicillin G in pneumococci (eg, PRSP, penicillin resistant Streptococcus pneumoniae)
and enterococci. In some Gram-negative rods (eg, Pseudomonas
aeruginosa), changes in the porin structures in the outer cell wall membrane may contribute to resistance by impeding access of penicillins to PBPs
1-MRSA ( methilin resistant staphylococcus aureus )
2-Some E-Coli
3-Psudomons
4-some streptococci
—- Penicillin Pharmacokinetics:
-Some penicillin should be Givin :
IV , IM , orally
-distribution: penicillin normally is non-ionised but once it reach the blood PH 7,47 become ionised and can’t pass BBB except in case which is meningitis due to tight junction gets dilated duo to inflammation so the Penicillin can reach the BBB
- penicillin can cross placenta but its not tetroginc bcs the fetal tissue has no Transpeptidase enzyme / PBP
-Excretion : mostly renal
classification of Penicillin drugs
-Natural :
1- Benzylpenicillin ( Penicillin G) short acting -Parenteral
2-Phenoxymethylpenicillin
(penicillin V) Orally - Short acting
3-Benzathine BenzylPencillin ( long acting per 7d - IM)
-Semi - Synthetic :
1-Anti Staphylococci Penicillin: Oxacilln
2-Extended Spectrum Penicillin:
Ampicillin - Amoxicillin
3-Antipsudomonal Pencillin :
Piperacillin , Ticarcillin
Explain BenzylPenicillin , Spectrum , list of bacteria , disadvantage
-Drug : Benzylpenicillin amp 1mlion ED
-Its the original Penicillin
-Spectrum : Narrow spectrum duo to targeting few Gram + bacteria only such as :
1-Streptococci
2-P.Coccai
3-Some staphylococci which is not producing B-Lactamse
4-Gono coccai : Gonnoria : Gram-
5-Treponin pellidum ( Sophylis) gram-
-disadvantage:
1-Cant be orally bcs HCL
2-Half life 2-4h ( shorty acting )
3- B-lactamse enzyme sensitivity
4-Narrow spectrum
Explain Phenoxymethylpenicillin ( Penicillin V)
-Drug : Phenoxymethylpenicillin Tab0.25 Penicillin V
-Its the same as Penicillin G , But its acid stable , Also short acting , and narrow spectrum
Explain Benzathine Benzylpenicillin ,
-Its the same as penicillin G but with modification which makes it last longer 7-14 days
- its most used in prophylaxis and treatment of syphalis during pregnancy
Explain Anti-Staphylococcal, Drug , spectrum, resistance,
-Drug : Oxacillin Tab/Amp 0,25/0,5
-they are effective against B-Lacatmes producing Staphylococci , But they have no effect or low activity against
other Gram- and Gram+ bacteria: Narrow spectrum .
-They most used against Stephyloccocai only
Explain Extended Spectrum penicillin , antibiotic drugs , B-Lcatamse inhibitors drugs , Spectrum, List of bacteria , ROA , resistance, Combination with B-Lcatamse inhibitors, , mechanism of Gram- ,
-Antibiotic drugs : , B-Lctms inhbt
1-Ampicillin + Sulbactam Amp 0,5/0,25
2-Amoxicillin + Clavulanic Acid Tab 0,25/0,6
-Spectrum : they are narrow/moderate spectrum duo to coverage of G+,G- Such as :
1-Slamonila
2-H.influenza
3-Protus
4-Shigella
-ROA : they are acid stable so they can be orally
-resistant: they are sensitive to B-Lactamse , and thats why we give them in combination with B-Lactamse inhibitors
-Mechanism of acting on Gram- :
The ampicillin/Amoxicillin have NH2 group : Amino acid,so it can pass the pores of the outer membrane as nutrients, and destroy the Cell wall and activate Autolysin
Explain the difference between Ampicillin and Amoxicillin
-Ampicillin:
1-oral absorption: +
2-distribution :+
3-Diarrhoea : +++ bcs its not absorbed 100% so it kills the bacteria in the GI
4-Spectrum : shigella , H.influenza
———
Amoxicillin :
1-oral absorption: ++
2-distribution :++ more in lung
3-Diarrhoea :+
4-Spectrum : Salmonila/typhoid fever ,
H,Pylori , Streptococcus pneumonia
Explain Anti-Pesudmonal penicillin, Drugs , spectrum, resistance
-Drugs :
1-piperacillin , Ticarcillin Amp
-Spectrum: they are targeting pseudomonal (Mainly) , Also G+ and G- also anaerobic bacteria, so they are broad spectrum
-resistant: they are B-Lactamase sensitive thats why we should combine it with Sulbactam ( b lactamse inhibitor )
What are the uses of Penicillin
1-Streptococcal infection: wound spesis , tonsillitis, sub endocrdaitis
2-P.Coccoi : pneumonia
3-Syphalis , Gonnoria
4-Minigialcoccai : meningitis
5-Typhoid fever
6-Pesudomons
7-Actinomycosis ,Anthrax , H.Influenza
Explain side effect of penicillin and drug interactions
—Side effect :
1-Allergic reaction : it occurs with all types of penicillin, and its not duo to penicillin it self but to degradation products common to all penicillin it more commonly in parental
2-Diarrhea: disruption of the balance of intestinal
microorganisms. It occurs to a greater extent with those
agents that are incompletely absorbed and have an
extended antibacterial spectrum. Pseudomembranous
colitis from Clostridium difficile may occur with penicillin use
3-Nephritis
4–Neurotoxicity: The penicillins can provoke seizures if injectedintrathecally or if very high blood levels. Epileptic patients are particularly at risk due to the ability of penicillins to cause GABAergic inhibition
– Drug intractions :
1-bactriostatics : bcs the penicillin need prolofration to act
2-Anti-pesudomonal with aminoglycosides : bcs they are diffreant in charge puting them in one syrngist they will make complex and antagonise each other
Explain the cephalosporin, structure,generation,,Pharmacokinetics,
-Cephalosporin Also a B-lactamse ring have similar mechanism of action As penicillin
-Each newer generation increasingly resistant to B-Lactamse .
-Pharmacoinatic :
-Distribution:They are widely distributed,But 3rd ,4th,5th generation can Penetrate CSF
-Ceftriaxone 3rd gen , are mainly excreted by bile
Classification of cephalosporin generation drugs .
1-Generation : Cefazolin Amp ,Cefalexin tab
2-Generation: Cefuroxime Tab/Amp
3-Generation:
- Cefotaxime , Ceftriaxone,Cefetazidime amp
-Cefixime ,Ceftibutene Caps
4-Generation:
-Cefepime amp
5-Generation:
-Ceftaroline
Explain 1st generation of Cephalosporin, Spectrum,Resistance,BBB,allergy
-Drugs :
1-Cefazolin amp 0.5 2-Cefalexine tab
-Spectrum: narrow spectrum, duo to covering G+ same as Penicillin G with some G- ( E coli klebsiella )
-resistant: Sensitive to B-Lactamse
-BBB : Dont pass
-Allergy : Cross allergy with Penicillin
Explain 2nd generation of Cephalosporin, Drugs , spectrum,Resistance,BBB,allergy
-Drugs : Cefuroxime Tab/Amp
-Spectrum : Covering G+ and some G- such as ( H.Influenza,Neaseria , Proteus ) but not Pesudomons , Narrow spectrum
-Resistant : Reletavly resistant to B-Lactamse
-BBB: only Cefuroxime Can pss
-Allergy : Cross allergy with penicillin
