Antimicrobial Flashcards
Group 1: parenteral penicillin
Benzyl penicillin
Procaine penicillin (long acting)
Group 2: Oral penicillin similar
Penicillin
Group 3: Anti-staphylococcal penicillin
Cloxacillin
Group 4: Extended-spectrum penicillin
Active against Enterobacteriacea except Pseudomonas
Ampicillin
Amoxicillin
Group 5: penicillin active against Pseudomonas aeruginosa
Piperacillin
Group 6: β-lactamase-resistant penicillin
Active only against Gram-negative
Temocillin
Penicillin …… Toxicity and Side effects
Hypersensitivity reaction Mild like skin rash or fatal
Anaphylactic reaction ( rare, rapid reaction within minutes, nausea, vomiting , dyspnea and coma, fatal)
Purities and urticarial reaction (develop within 1-3days )
Skin eruptions usually maculopapular rashes (commonest)
Hemolytic anemia and thrombocytopenia
Neurotoxicity with high doses (rare)
Cephalosporin
Have a 6-membered dihydrothiazine ring fused to a β- lactam ring
They are derivative of 7- aminocephalosporanic acid (7-ACA)
The additional carbon affect the pharmacokinetic and antibacterial activity
Cephalosporin
The principal target is like penicillin (Transpeptidase)
Cephalosporin
Have advantages over penicillin in that they are:
More stable to enzymes ( Staphylococcus penicillinases)
Broader spectrum
Less prone to cause hypersensitivity
Oral and parenteral preparations
*** Less active against Enterococci
Classification of Cephalosporin
1 2 3 4
First generation
First generation
Cephalexin
Cephazolin
Wide range of Gram-positive and negative except (Pseudomonas and Haemophilus)
active against Streptococcus, Staphylococcus, Enterobacteriac
Second generation
Cefuroxime
Cefoxitin
Wide range of Gram-positive and negative including Haemophilus and
anaerobes
Cefuroxime: like cephalexin plus active against Haemophilus and S. pneumoniae
Third generation
Cefotaxime
Ceftriaxone
Third generation
Ceftazidime (antipseudomonal)
3rd generation
Wide range but more anti-Gram-negative than second generation
Cefotaxime
active against Enterobactericae, Haemophilus and S. pneumoniae and not active against Pseudomonas spp
4th generation
Narrow
4th generation
Cephepime
Anti-Gram-negative
cephepime: active against Enterobacteriacae and Pseudomonas
Cephalosporin … Toxicity and
Side Effects
Local pain and thrombophlebitis at site of injection
Hypersensitivity reaction in 0.5-10% of patients (10% cross
reaction with penicillin allergy)
Hepatotoxicity Elevates liver enzymes
Gastrointestinal disturbance
Thrombocytopenia
Pseudomembranous colitis
β- lactam
Monobactams
Monobactams
Monocyclic β- lactam antibiotics,
Monobactams
Aztreonam
Aztreonam
Narrow spectrum (anti-Gram-negative aerobic bacilli)
Bactericidal
Stable to bacterial enzymes
Carbapenem
β- lactam
Carbapenem
Isolated from Streptomyces’s
Carbapenem
Potent activity against a broad range of Gram-positive and
negative bacteria
Carbapenem
Resistant to lysis by β-lactamases
Carbapenem
2 important antibiotics
Imipenem
Meropenem
Carbapenem : Imipenem
Not stable, it need to be combined with cilastatin to be more stable Safe
Broad spectrum
Seizures and transient changes in liver enzymes are main side effects
Carbapenem : Meropenem
Stable and broad spectrum
Side effects .. Similar to imipenem
Glycopeptides
Vancomycin & Teicoplanin
Glycopeptides
Mode of action
Act on cell wall synthesis at a stage prior to B-lactams
Not act on PBP & not inactivated by B-lactamases enzymes
*Very big molecule and can’t take it orally *Used mainly for severe cases.
Glycopeptides
Spectrum and Toxicity
Activity is restricted to Gram-positive bacteria only
Poorly absorbed from GI
IM injections are painful
Nephrotoxic Reversible
Ototoxic Irreversible
Reversible neutropenia and thrombocytopenia
Teicoplanin is less nephrotoxic
The level of vancomycin should be monitored in the blood
Glycopeptides
Clinical use
MRSA Methicillin resistant staphylococcus aureus
Patient allergic to penicillin or cephalosporin with Staphylococcus or Streptococcal infections
Inhibition of nucleic acid
synthesis:
Inhibit DNA synthesis directly or indirectly
Inhibit DNA synthesis directly or indirectly
Sulphonamides & Trimethoprim indirectly inhibit DNA synthesis
Inhibition of NA synthesis
Quinolones directly inhibit DNA-gyrase
Inhibition of NA synthesis
Nitrofurantoin bindtobacterialribosomeandinhibitproteinsynthesis
Inhibition of NA synthesis
Rifampicin inhibit DNA dependent RNA polymerase
Nitrofurantoin
For uti only!
Nitrofurantoin
Mode of action is complex
Nitrofurantoin
Act on bacterial mRNA, ribosomal proteins
Well absorbed orally
Used for UTI
Nitrofurantoin
Side effects:
Nausea and vomiting
Peripheral neuropathy
Hemolysis in patients with G6PD deficiency
Quinolones
Form a large group of synthetic compounds
Have dual ring structure
Quinolones
Act by inhibiting DNA gyrase (topoisomerase) this will inhibit DNA replication
Quinolones
The 4-quinolones like naladixic acid
Fluoroquinolones (new like Ciprofloxacin)
More potent
Broader spectrum (UTI, Osteomyelitis, STD, Pneumonia)
Better absorption and distribution (oral & parenteral)
Quinolones …. Toxicity
Side effects: GI ( nausea, vomiting & diarrhea) Pseudomembranous colitis Skin rash CNS (benign intracranial hypertension) and psychosis Thrombocytopenia
Metronidazole
A 5-nitroimidazole
Metronidazole
Exert its effect by reduction of the nitro group to amine under
low redox potential
(anaerobic atmosphere)
Metronidazole
Active against obligate anaerobes & helicobacter and
Protozoa (T. vaginalis, Giardia, E. histlolytica)
Rapidly and completely absorbed form GI
Metronidazole
Side effect: CNS, confusion and seizures Peripheral neuropathy GI (nausea, vomiting & diarrhea) Neutropenia (reversible) Metallic taste Rash and pruritis
