Intro to Antibiotics Flashcards
Bactericidal
Directly kill bacteria (doesn’t require functioning immune system from the host for antibiotic to work appropriately)
Inhibitors of cell wall synthesis, cell membrane disruptors, aminoglycosides, DNA gyrase inhibitors
Bacteriostatic
Arrest the growth or replication of bacteria. Host immune system then eliminates the pathogens. (slow down infection, but require host immune system for it to work)
Non-aminoglycoside inhibitors of protein synthesis (i.e. macrolides), antifolate drugs
agents that inhibit cell wall synthesis
Penicillins Cephalosporins Cycloserine Vancomycin Bacitracin
Agents that act directly on the cell membrane of the microorganism affecting permeability and leading to leakage of intracellular compounds.
Detergents
Polymyxin
Agents that interfere with protein synthesis by Interaction with bacterial ribosomes
Chloramphenicol Tetracyclines Macrolides Clindamycin Streptogramins Ketolides
The antimetabolites—blocking bacterial folic acid pathway
Trimethoprim
Sulfonamides
When do you use antibiotics as empirical therapy?
before you get lab results and know which specific infection you’re treating. You know there’s infection but you don’t know which bacteria you have yet.
Goal: Broad spectrum- want to cover as many bacterium as possible.
what are some of the reasons resistance to antibiotics occurs?
1) drug fails to reach target
2) Drug is inactivated- Beta lactam antibiotics.
3) Target is altered (change in binding site)
4) Adaptations that bypass need for binding site
Examples of multiple drug-resistant bacteria:
Methicillin-resistant Staphylococcus aureus (MRSA)
Mycobacteria tuberculosis
Beta Lactam compounds
Penicillins: --Natural Penicillin (G and V) --Aminopenicillins --Penicillinase Resistanct Penicillins --Extended Spectrum Penicillins (Anti- pseudomonal) Cephalosporins: --First Generation --Second Generation --Third Generation --Fourth Generation --Fifth Generation Others: --Carbapenems --Monobactams --Beta lactamase inhibitors
Beta-lactam antibiotics are generally…
Bactericidal- because these are destructors of the cell wall
Most active against growing organisms (if you inhibit organisms growth by adding bacteriostatic, these wont work—general rule)
What are the “natural penicillins?”
Penicillin G or V.
Narrow spectrum, PCN G acid labile—breaks down in acid (have to administer non-oral route), penicillinase sensitive (same as beta lactamas sensitive)
Highly active against sensitive strains of gram positive cocci (except staphylococcus)
Streptococcus, Enterococcus faecalis, Listeria monocytogenes (rod)
What are some anaerobes and gram negative bacteria that “natural penicillins” work against?
Anaerobes such as Bacteroides species and Fusebacterium species
Some gram negative such as E. coli, H. influenzae, N. gonorrhoeae, Treponema pallidium
What are some infections that natural penicillins treat?
infections of upper and lower respiratory tract, throat, skin, GU tract
In what cases are natural penicillins used as prophylaxis?
Prophylaxis for rheumatic fever, dental procedures for those at risk of endocarditis*** (IV drug user at huge risk), gonorrhea or syphilis exposure (so pt that has a partner that’s infected with gonorrhea or syphilis)—but don’t want to pass out penicillin to everybody…just when you have a SPECIFIC concern.
What are the Aminopenicillins?
Ampicillin and amoxicillin
What bacteria Aminopenicillins treat?
Activity of Pen G plus improved coverage of gram-negative cocci and Enterobacteriaceae
Not active against Treponema sp. or Actinomyces sp. (which we did see w/ natural penicillins)
What are the therapeutic uses of aminopenicillins?
URI (otitis, sinusitis), uncomplicated UTI, meningitis, salmonella infections
Depends on resistance patterns in your area
Resistance has lead to combinations with beta- lactamase inhibitors
Augmentin = amoxicillin + clavulanic acid
Ampicillin + Sulbactam (Unasyn)
Better coverage against H. influenzae and Klebsiella sp.
What are the Penicillinase-Resistant Penicillins?
Also called “Antistaphylococcal Penicillins”
Nafcillin, Oxacillin, Dicloxacillin
Methicillin and cloxacillin no longer available in US but left up here because represents class of drugs (MSSA specific!! in MRSA pts, none of these will work. Methicillin resstant means Nafcillin, Oxacillin and Dicloxacillin won’t work)
What are Penicillinase-Resistant Penicillins used to treat ?
Used in treatment of staphylococcal infections with high beta-lactamase production
Cellulitis, endocarditits
Not active against gram-negative or anaerobic organisms
Specifically treats MSSA!!
Antipseudomonal Penicillins
Piperacillin, ticarcillin, carbenicillin (PO)
Which bacteria do antipseudomonal penicillins work against?
Maintain activity of Pen G (so still have coverage of strep, enterococcus) plus greater gram negative coverage including pseudomonas
coverage against H. influenzae and Klebsiella sp.
No coverage against Treponema palladium or Actinomyces sp. (lose this coverage from penecillin G)
Gram-negative infections in combo with aminoglycosides (to target some gram – infections. Can begin therapy w/ something like this. Broad spectrum)