Antibiotics Flashcards
Vancomycin
Glicopeptide
Gram positive only
Clinical use: especially effective against multidrug-resistant organisms
Broad-spectrum coverage against gram-positive bacteria only
Methicillin-resistant Staphylococcus aureus (MRSA)
S. epidermidis
Enterococci
Clostridium difficile
Adverse effects
Nephrotoxicity
Ototoxicity/vestibular toxicity
Rapid infusions are associated with anaphylactoid reactions (“red man syndrome” or “red neck syndrome”)
Thrombophlebitis
Neutropenia
Carbapenems (eg meropenem0
Carbapenems Drugs IV imipenem (+ cilastatin) IV meropenem IV ertapenem IV doripenem Clinical use: broad-spectrum antib iotics with intrinsic beta-lactamase resistance Gram-positive cocci Gram-negative bacilli Anaerobes Adverse effects: considered a “last resort” drug because of its significant adverse effects Secondary fungal infections Can lower seizure threshold (especially imipenem) Gastrointestinal upset Rash Thrombophlebitis “I'm a pen” that crosses out allthe bacteria.
What are beta lactam antibiotics?
A large group of antibiotics that includes penicillins, carbapenems, aztreonam, and cephalosporins
How do beta lactams work?
Inhibit cell wall synthesis by blocking peptidoglycan crosslinking
Bacterial death as a result of an inability to synthesize new cell wall during replication
Which commonly used beta lactam antibiotic has good CNS penetration?
Ceftriaxone (3rd generation)
Describe uses of Ceftriaxone
Severe gram-negative infections that are resistant to other beta-lactams (e.g., Enterobacteriaceae)
Ceftriaxone (good CNS penetration) is used in disseminated Lyme disease, meningitis, gonorrhea, and for perioperative prophylaxis against wound infection
What is cefazolin
1st generation cephalosporin
What are the first generation cephalosporins
Cephalexin (oral)
Cefazolin (IV, IM)
WHy is gentamycin (an Aminoglycoside) often give n with a beta lactam antibiotic?
Aminoglycosides (eg gentamycin) have a Synergistic effect when combined with beta-lactam antibiotics: Beta-lactams inhibit cell wall synthesis → facilitate entry of aminoglycoside drugs into the cytoplasm
What antibiotics are completely contraindicated in renal failure
Tetracyclines eg Oral doxycycline
What are the aminopenicillins?
Aminopenicillins
Drugs
Oral or IV amoxicillin (± clavulanate)
IV or IM ampicillin (± sulbactam)
Structures are similar to penicillin, therefore are susceptible to beta-lactamase degradation.
Clinical use: broader spectrum of activity than penicillin
Some gram-positive aerobes and gram-negative bacilli
What are beta- lactamase inhibitors?
Beta-lactamase inhibitors
Bacteria often develop resistance to β-lactam antibiotics by synthesizing a β-lactamase, an enzyme that attacks the β-lactam ring. To overcome this resistance, β-lactam antibiotics can be given with β-lactamase inhibitors such as clavulanic acid.[6]
Beta-lactamases, which are usually produced by gram-negative and anaerobic organisms, can split the beta-lactam ring and render certain beta-lactam antibiotics ineffective.
Beta-lactamase inhibitors increase the spectrum of antibiotic activity.
Drugs
Clavulanic acid (combined with amoxicillin = co-amoxiclav)
Sulbactam (combined with ampicillin)
Tazobactam (combined with piperacillin)
How do beta lactams work?
A large group of antibiotics that includes penicillins, carbapenems, aztreonam, and cephalosporins
Mechanism of action
β-lactam antibiotics are antibiotics that contain a beta-lactam ring in their molecular structure. This includes penicillin derivatives, cephalosporins, monobactams, carbapenems and carbacephems.
Inhibit cell wall synthesis by blocking peptidoglycan crosslinking
The beta-lactam structure mimics the D-ala-D-ala residue of bacterial peptidoglycan
Irreversibly binds to penicillin-binding proteins (transpeptidases responsible for peptidoglycan crosslinking), stalling the catalytic reaction because the beta-lactam cannot be cleaved
Bacterial death as a result of an inability to synthesize new cell wall during replication
Activate autolytic enzymes
Beta-lactam antibiotics are bactericidal
