Lec1 Flashcards
Antimicrobial Spectrum types and examples
Narrow spectrum e.g. isoniazid against mycobacterium tuberculosis.
Broad spectrum e.g. tetracycline, flouroquinolones, carbapenems.
Extended spectrum e.g.Ampicillin against gram-positive and some gram-negative bacteria
What is preferred among the drug spectrums
Usually narrow spectrum is preferred though it target a specific pathogen.
Some times the board spectrum drugs is preferred if the pathogen is not yet identified.
Bactericidal
Able to kill bacteria
What does the bactericidal do? Give an example
Block activities that are essential for bacterial survival E.g., Penicillins
Bacteriostatic
Able to slow the growth of bacteria but does not kill them
What does bacteriostatic drug do? Give an example
Inhibit a metabolic reaction needed for bacterial growth but is not necessary for survival. E.g., Tetracyclines
Concentration-dependent drug example
Aminoglycosides
minimum inhibitory concentration (MIC)
is the lowest antimicrobial concentration that prevents visible growth of an organism after 24 hours of incubation.
Time-dependent effect drug associated with ………………..example ………………..
1drugs inhibiting cell wall
2β-lactams
Post antibiotic effect (PAE)
The PAE is a persistent suppression of microbial growth that occurs after levels of antibiotic have fallen below the MIC
Antimicrobial drugs exhibiting a long PAE example
aminoglycosides and fluoroquinolones
Drugs that inhibit bacterial cell wall synthesis:
β-Lactam Antibiotics
Glycopeptide Antibiotics
β-Lactam Antibiotics(Camp)
[1]Penicillins, [2]Cephalosporins,
[3]Monobactams, [4]Carbapenems
Glycopeptide Antibiotics:
[1] Vancomycin, [2] Bacitracin
Drugs that Inhibit Bacterial Protein synthesis:(MCAT)
[1] Macrolides, [2] Clindamycin, [3] Tetracyclines, [4] Aminoglycosides
Drugs that Inhibit Bacterial Nucleic Acid Synthesis:
[1] Quinolones, [2] Rifampicin
The difference between Beta Lactam antibiotics and non beta Lactam antibiotics
Beta Lactam antibiotics contains beta Lactam ring others not
Beta Lactam antibiotics are very powerful but the other is less powerful
Penicillins Mechanism of action
Bactericidal
They inhibit cell wall synthesis by preventing the formation of peptidoglycan in actively multiplying bacteria → inhibit bacterial cell wall synthesis
Penicillin-binding proteins
enzymes involved in peptidoglycan biosynthesis
Peptidoglycans
are polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall
Penicillin is given
orally , IV, or IM
Penicillin have poor entry to………..
Ce rebrospinal fluid (CSF)
Penicillin Dose reduction is necessary in……………..
severe renal failure
Penicillin Adverse drug reactions (DIC)
1.Immediate hypersensitivity(0.05%) urticaria-to-life threatening anaphylactic response.
2.delayed hypersensitivity (0.5%) manly as rashes.
3.Diarrhoea
4.CNS irritation & seizures(by high doses or renal failure)
Penicillin Drug–drug interactions (TAP)
1.Aminoglycosides produce synergism with penicillins (not
combine in same syringe)
2.Tetracyclines reduce bactericidal effects of penicillins
3.Probenicid decrease excretion and prolong duration of
penicillins
Cephalosporins Mechanism of action
Bactericidal their mechanism of action is
like penicillins
Ce phalosporins The Concept of Generations
As the generation increases the resentence increases.
Cephalosporins route of administration
IV or IM
Cephalosporins drug that is used in meningitis and why
Cefotaxime is used cuz of adequate CSF penetration to treat meningitis)
Cephalosporin route of excretion
Primary rout is kidney
Cephalosporins Adverse drug reactions
1Hypersensitivity reaction; rash, fever, bronchospasm, anaphylaxis
2Cephalosporins should be avoided or used with caution in individuals with penicillin allergy.
A small proportion (0.5 - 6.5%) of patients with an IgE medicated penicillin allergy will also be allergic to cephalosporins
3Increase risk of bleeding ( thrombocytopenia )
4Diarrhoea and dizziness
Cephalosporins Drug – drug interactions 🐄
With Aminoglycosides: increased risk of nephrotoxicity
With Warfarin: increased risk of bleeding
β-Lactam: Monobactams example 👨🚀
Aztreonam
Monobactams Mechanism of action
Bactericidal like penicillins
Against gram-negative pathogens, including H.influenzae and P. aeruginosa ,It lacks activity against gram positive organisms and anaerobes
administration route of Monobactams
IV OR IM
Monobactams can accumulate in patients with………………
renal failure (relatively nontoxic)
Monobactams Adverse drug reactions
Phlebitis, skin rash and, sometimes, abnormal liver function tests
Monobactams drugs are safe alternatives for treating patients who are allergic to other penicillins, cephalosporins, or carbapenems, why?
Cuz it Has a low immunogenic potential, and it shows little cross-reactivity with antibodies induced by other β-lactams.
β-Lactam : Carbapenems example 📢🚗
Example: Imipenem, Meropenem
Carbapenems Mechanism of action & spectrum
Bactericidal mechanism of action like penicillins
Extremely broad spectrum: including aerobic and
Anaerobic G+ve and G-ve microorganisms: used in
multi-drug resistant nosocomial infections
Carbapenems Adverse drug reactions
In addition to the side effects of all penicillin-like drugs, imipenem does lower seizure threshold
Vancomycin mechanism of action
Glycopeptide Antibiotic, Bactericidal, inhibits synthesis of bacterial cell wall phospholipids as well as peptidoglycan polymerization (targeting the end of peptidoglycan) → inhibit bacterial cell wall synthesis
Dose of vancomycin is adjusted based on…………….
renal function and serum trough levels
Vancomycin route of administration
IV
Vancomycin Oral administration is limited to….
treatment of severe antibiotic associated Clostridioides difficile colitis
Vancomycin Normal Half life
6-10 hours
Vancomycin IV infusion time
60 to 90 min
Vancomycin therapeutic uses
-treatment of life-threatening MRSA Infections
-Used in case of prosthetic heart valves, especially in those hospitals wherethere are high rates of MRSA
MRSA
Methicillin-resistant Staphylococcus aureus
Vancomycin adverse drug reaction (HARD)
§ Hypotension
§ Red man syndrome (histamine release by rapid infusion)
§ Dose-related ototoxicity & nephrotoxicity
Vancomycin Drug – drug interactions
With aminoglycosides: increased nephrotoxicity& ototoxicity
Bacteriacin mechanism of action
Glycopeptide Antibiotics § Bactericidal § Bacitracin interrupts the flow of peptidoglycan precursors to the site of cell-wall synthesis, weakening the cell wall and eventually leading to bacterial death→ inhibit bacterial cell wall synthesis.
Bacteriacin active against ……………….
Many gram-positive organisms
Bactericin Route of administration and why
Used topically, coz if used systemically it’s toxic
Why Bacteriacin is used?
It’s mostly used for the prevention of skin infections after burns or minor scrapes
Bacteriacin is used in combination with……………… and used as …………… for ………….. in…………….
Polymixin and neomycin
Topical ointment
Mixed bacterial infections
Skin eye and ear
Polymixin
Bactericidal,active against gram- negative bacteria
