1. sulfamethoxazole (with trimethoprim, which eliminates bacteria that cause UTIs)
What are some common "other" antibiotics used to treat drug-resistant bacteria?
1. imepenem/cilastatin (cilastin keeps impenem from being inactivated in the kidneys)
3. quinupristin/dalfopristin (for staph/VRE)
4. daptomycin for injection
What is a common natural product with antibacterial properties?
What are the 5 mechanisms of action of antibiotics?
1. Inhibit bacterial protein synthesis
2. Inhibit bacterial DNA synthesis
3. Disrupt bacterial metabolism
4. Bind to and depolarize bacterial plasma membrane
5. Other mechanisms
What are 3 ways bacteria become resistant to antibiotics?
1. Inactivate or degrade the drug with bacterial enzymes.
2. Prevent the drug from reaching its target inside the bacteria.
3. Change the bacterial target site.
What are 3 side effects that are shared among ALL antibiotics?
1. Hypersensitivity reactions
2. GI effects
What 2 side effect are shared by many antibiotics, and which ones do NOT cause each side effect?
1. CDAD (C-difficile colitis): NOT caused by lincomycins
2. Stevens-Johnson Syndrome: NOT caused by macrolides, lincomycins, aminoglycosides.
What decreases tetracycline and fluoroquinolone absorption? What would you teach patients who are taking this medication?
Dairy, calcium, antacids, etc. Do not take them with dairy/milk/calcium-containing products.
What pharmacokinetic properties of sulfanomides can cause interactions with other drugs?
Sulfonamides and their metabolites are highly protein bound. This can increase the plasma levels of other highly protein bound drugs, which may intensify their effects/side effects (ie, warfarin).
What do erythromycins do the activity of the hepatic P450 enzymes?
It inhibits cytochrome P450, which can cause it to have a rapid effect on other drugs that are metabolized by the CP450 system.
What is Cytochrome P450?
The cytochrome P450 family of enzymes are present in most cells of the body, in the mitochondria & rough ER. They are responsible for the metabolism and bioavailability of many drugs (up to 75% of all drugs reactions).
If a drug inhibits the CYP-mediated metabolism of another drug, the second drug may accumulate within the body to toxic levels.
Which antibiotics can increase the risk for pregnancy? How does this happen?
They suppress the enterohepatic circulation (liver ->bile -> intestines ->liver ->repeat; influenced by endogenous bacteria) of estrogen-containing oral contraceptives, which decreases the amount of circulating contraceptive.
Which antibiotics can cause bleeding? What increases this risk?
This risk is increased by combining the antibiotic with other drugs that cause bleeding (ie, salicylates (asprin)
If a person is allergic to penicillins, what other types of antibiotics should they avoid? What do these drugs have in common?
3. carbapenems (impenemem)
They all have a beta-lactam ring structure, which inhibits synthesis of the bacterial cell wall.
Which antibiotics can cause ototoxicity, nephrotoxicity, and neuromuscular blockade (paralysis)?
2. aminoglycosides (Advise against if pt has impaired hearing, neuromuscular disease, infants, and older adults.)
What are symptoms of ototoxicity? What other drugs should be avoided if they're taking these antibiotics?
2. hearing loss
Avoid salycilates (asprin).
What are symptoms of nephrotoxicity? What other drugs should be avoided if they're taking these antibiotics?
Watch for this with lincomycins
Monitored by creatine-clearning urine tests or BUN (blood urea nitrogen) levels.
Should be avoided in patients with renal impairment.
Avoid NSAIDs (like ibuprofen).
Which antibiotics can cause crystalluria? How can it be prevented?
Fluoroquinolones and sulfonamides.
Can cause crystalluria (because drug precipitates in the urine, which may cause renal damage)
Recommend pt drink lots of water, and possibly monitor urine output.
What other drugs should be avoided with potentially hepatotoxic antibiotics?
Other hepatotoxic drugs, such as alcohol, NSAIDs, and isoniazid.
What antibiotics can cause photosensitivity?
Tetracyclines, fluoroquinolones, and sulfanomides.
What natural product should be avoided when taking antibiotics that can cause photosensitivity?
St. Johns Wort, and other substances that can cause photosensitivity.
What antibiotics can cause a disulfiram-like reaction? What are the signs and symptoms?
Cephalosprins PLUS alcohol.
Metronidazole (commonly used to treat C. difficile colitis. (VERY COMMON reaction)
Symptoms include flushing, sweating, tachycardia, headache, nausea, vomiting, weakness.
<Note: disulfiram is used to treat alcohloism by making you feel like CRAP if you drink alcohol>
What's the difference between "bactericidal" and "bacteriostatic"?
Bactericidals kill bacteria; bacteriostatic inhibit bacterial growth or replication, which allows the immune system to kill the bacteria.
Which antibiotics are bactericidal by inhibiting bacterial protein synthesis?
Which antibiotics are bacteriostatic by inhibiting bacterial protein synthesis?
Which antibiotics are bactericidal by inhibiting synthesis of the bacterial cell wall?
Also some Lincomycins
Which antibiotics are bacteriostatic by interfering with bacterial metabolism?
Sulfonamides (via stopping folic acid synthesis)
Which antibiotics are bacterisidal by interfering with bacterial DNA synthesis?
What are 3 mechanisms by which bacteria become resistant to antibiotis?
1. Inactivating or degrading the drug with enzymes (EXAMPLE: beta lactamases break beta-lactam ring)
2. Preventing antibiotic from reaching its target site (EXAMPLE: pumping antibiotic out of the bacteria)
3. Changing the bacterial target site
(EXAMPLE: changing target proteins so antibiotic can't bind.)
Which types of antibiotics are Pregnancy Category D?
What are 3 conditions that should be taken into account before prescribing ALL antibiotics?
Renal impairment (may reduce dose)
Should penicillin be taken with food or drink?
Take on an empty stomach with a full glass of water. DO NOT take with acidic foods/drinks (orange juice). Both can decrease absorption.
Which antibiotics are generally administered parenterally? Why? When can this be a benefit?
They are poorly absorbed from the GI tract (which also makes them good for bacteria in the gut.)
Which antibiotic is mainly excreted in the bile after being metabolized in the liver?
Where are most antibiotics distributed?
All over, cross placenta, enter breast milk, most minimally enter CSF.
What are symptoms of a hypersensitivity reaction? What should a pt do if this occurs?