Beta Lactams Flashcards
List the natural antibiotics
Penicillin, tetracycline, cephalosporin, streptomycin
List the synthetic antibiotics
Fluoroquinolone, sulfonamides
List the bacteriostatic drugs
(T..)
TCS=
Tetracycline
Chloroamphenicol
Sulphonamides
Concentration dependent bacteriostatic drugs:
Macrolides, Tetracyclines, clindamycin
List the bactericidal drugs
PICAR=
Penicillin
Ioniazid
Cephalosporin
Aminoglycosides
Rifampicin
Concentration-dependent:
Metronidazole
Aminoglycosides
Quinolones
T…for bacterisostatic
Differentiate between time-dependent and concentration-dependent efficacy
Time-dependent:
- Concentration should be above the MIC for a long period of time
- Slow bactericidal action
- Moderate post-antibiotic effect
- Penicillins and Beta Lactams
Concentration-dependent
-Outcome dependent on the peak concentration relative to the MIC
- Strong post-antibiotic effect
Bactericidal: MAQ= Metronidazole, aminoglycosides and quinolones
Bacteriostatic: MTC= Macrolides, tetracyclines and clindamycin
Classify the antibiotics into 3 categories
- Inhibition of cell wall synthesis
- Inhibition of ribosomal protein synthesis
- Inhibition of nucleic acid synthesis
List the drugs part of the inhibition of cell wall synthesis
- Penicllins
- cephalosporins or cephamycins
- Monobactams
- Carbapenems
- Glycopeptides
Describe the mechanism of action of penicillin
- Penicillin interferes with the transpeptidation reactions. The cell wall is comprised of NAM and NAG cross-linked together by D alanine, synthesis of cell wall
- Interference with transpeptidation can result in rupture due to osmotic pressure
- Loss of cell wall integrity, cell lysis and death
- Bactericidal, time-dependent killing
- Binds to the penicillin-binding protein
- Inactivate an inhibitor of autolytic enzyme in the cell wall
Classify penicllins
- Narrow spectrum beta lactamase sensitive
- Broad spectrum beta lactamase sensitive
- Beta lactamase resistant
- Extended spectrum
List the penicillin groups and the antimicrobial activity
- Benzyl Penicillin/Penicillin G
- Streptococci penicillin
- Gram + with some gram -
- Little activity against gram - rods
- Tx. of choice for many infections
- Streptococci and pneumococcal pneumonia
- Endocarditis
- Anthrax, syhillis, clostridia and diptheria
- Meningococcal meningitis - Penicllin V:
- less potent than Penicllin G
- Oral preparation
- Strep Pharyngitis - Benzathain Penicllin
- Strep Pharyngitis
- syphillis - Procain Penicillin
- Gonorrhea
- Pneumococcal pneumonia
Discuss the broad spectrum beta-lactamase sensitive drugs
- Examples
- Antimicrobial activity
- Clinical use of ampicillin
- Side effects
- use of beta lactamsae inhibitors
e.g. Amoxycillin, ampicillin
SESH:
Some gram -ve bacteria
Enterococci
Streptococci
H. Influenza
- Ineffective against P. aeruginosa
- Spectrum similar to benzyl penicillin but greater activity against gram -ve bacteria
- Ampicllin= Meningitis, oral abscess, pneumonia
- Associated with C. difficile
- Comnination with beta lactamase inhibitors to protect beta lactamase
1. Clauvanic acid + Amxoycillin= co-amoxyclav
2. Ampicillin + Salbactam= Ampicillin-Salbactam
describe the beta-lactamase resistant penicillins
- examples
- Antimicrobial activity
- Antistaphylococcal penicllins
- Dicloxacillin, Cloxacillin, Oxacillin
- Limited to staph and strep infections
- Not effective against anaerobic bacteria, enterococci and gram -ve rods or cocci
C for examples….C in speCtrum
Describe the Extended Spectrum
- examples
- Antimicrobial activity
- Beta lactamse inhibitors
- Anti-pseudomonal penicllins
- CAPT= Cabernicillin, Azolocillin, piperacillin and ticarcillin
- Spectrum similar to broad spectrum penicillins plus pseudomas and proteus species
- Beta lactamase inhibitors can be combined:
1. Clauvanic acid + Ticarcillin
2. Salbactam + piperacillin
Discuss the pharmacokinetics of penicillins
- well absorbed orally
- Interference with food. Need to eat 1-2 hours before or after
- Benzyl penicillin IV> IM, local irritation at site
Benzathaine and procaine= IM - Excretion via the kidneys
What are the adverse reactions with penicillins?
What do males want to alwasys do?
SHAG=
Super infections: Pseudomonas, staph, yeasts. Pseudomembranous collitis (treated with Vancomycin or metronidazole)
Hypersensitivity Reactions:
Rash
Urticaria
Angioedema
Acute anaphylactic shock
Interstitial Nephritis
Alteration to the GIT bacterial flora
GIT disturbances: Nausea, vomiting, diarrhoea
Discuss the clinical uses of penicillin in dentistry
- Orofacial infection= Amxoycillin + Penicllin V
- Periodontal infection= Amoxycillin + Metronidazole
- Beta lactamase producing: Beta lactamase resistant, or erythromycin/ clindamycin
Explain the antimicrobial activity, characteristics and MOA of cephalosporins and cephamycins
- Similar MOA to penicllins
- More stable against beta lactamses except for strains of E.coli and Kliebsellia
- Not effective against enterococci ***
- Time dependent killing
Discuss the generations of cephalosporin, examples, antimicrobial activity, clinical uses
1st generation:
e.g. Cefazolin, Cephalexin
- gram + cocci= Streptococci, methicillin-sensitive staph aureus
Some gram - bacilli
- Klebsiella pneumoniae and proteus mirabilis
Clinical uses: Oral agents for urinary tract infections
Cefazolin: Surgical prophylaxis, Alternative to antistap penicllin in allergic patients (I.e. beta lactamase resistant penicillin)
2nd Generation:
e.g. Cefaclor, Cefuroxime
- First generation coverage (Staph and strep, kliebsellia and proteus–(extended spectrum) plus H. Influenza (Broad spectrum beta lactamase sensitive)
- Extended gram -ve coverage
clinical uses: sinusitis, LRTI, Otitis
3rd generation:
Cefixime, Ceftazidime, Cefttriaxone
- Second generation PLUS expanded gram negative coverage
- Greater stability against beta-lactamases
- Greatest activity against P. aeruginosa
‘antipseudomonal cephalosporins’ *** Ceftazidine especially
- Less active against staphylococci
Clinical uses: Meningitis, pneumonia and sepsis
(Pneumonia and meningtis was also covered by ampicillin)
4th Generation:
e.g. cefepime
- More resistant against Beta-lactamases
- Good activity against P. aerginosa, staph aureus, S. Pneumonia enterbacteraciea e.g. E.coli
- High activity against Nesseria and Haemophillus
Skin and soft tissue infections
5th Generation
Ceftaroline Fosamil
- MRSA
sporeins = sperm
Discuss the adverse effects of cephalosporins
SHAG=
Super infections= canida albicans
Hypersensitivity reations
Rare ADVERSE effects: nephrotoxicity, thrombocytopenia
GIT: Diarrhoea
Explain how bacteria resist Penicillins and Cephalosporins
- Lack of a cell wall e.g. mycoplasma
- Alteration in the permeability of the cell wall (gram -v)
- Alteration of the penicillin binding site (methicillin resistant staph)
- Efflux pump
- Production of beta lactamases e.g. Staphylococci
Carbapenems
Explain the Carbapenems in terms of example, antibacterial coverage, characteristics, clinical uses, side effects and the diadvantage
e.g. imipenem
- Broadest spectrum of all the antibiotics
- gram + and gram - aerobic and anaerobic bacteria
- Effective against P aeruginosa **more potent than 3rd generation e.g. cefixime, ceftzaidine, cefttriaxone
- resistant to hydrolysis by beta-lactamases
- Acquired resistance uncommon
- Septecemia of renal origin, intra-abdominal infection and noscomial pneumonia (carba- carbohydrates =intrasabdominal)
- renal function impaired
Side effects: blood disorders, confusion, convulsion, allergic rxn
- Has to be given with cilastatin (prevents inactivation and toxicity) Inhibits dihypropeptidase i
Discuss the characteristics of Meropenem and its advantage
- This is a carbapenem
- Similar to imipenem
- Doesn’t have to be given with cilastatin
- Not associated with nausea or convulsions
Discuss the characterisitcs and MOA of vancomycin
- glycopeptide, bactericidal
- different site of action from beta-lactams
- Inhibits transglycosylase—> prevents elongation and cross linking
- Bactericidal against clostridia
- effective against all strains of S. aureus
- Gram + bacteria
red deaf alibi
Discuss the clinical uses and side effects of vancomycin and an alternative agent
- MRSA
- Collitis
-In combination with cephalosporins (meningitis)–> 3rd generation
Side effects:
Auditory damage
Allergic reactions
Red person syndrome- maculopapular rash
Metronidazole
