Antimicrobials Flashcards
What are some of the adverse reactions seen with antibiotic administration?
Hypersensitivity reactions (anaphylaxis), Direct organ toxicity, Potential for superinfections, Drug-Drug reactions
What is the most common antibiotic given in surgery and what is the dose?
Ancef. 1-2 grams.
What antimicrobials are safe in pregnancy?
Penicillins, Cephalosporins, Erythromycin
Which antimicrobials should you use with caution in pregnancy and why?
Aminoglycosides (ototoxicity to mom and baby) Clindamycin (colitis in mom)
Which antimicrobials are contraindicated in pregnancy and why?
Tetracyline (tooth discoloration in baby)
What are the two antibiotic categories and how are they different? Which is preferred?
Bactericidal: they kill the bacteria
Bacteriostatic: they reversibly inhibit the growth of bacteria
Bactericidal is preferred but many factors may dictate the use of bacteriostatic
What is a criteria for the use of bacteriostatic antibiotics?
The duration of therapy must be sufficient to allow for cellular and humoral defense mechanisms to eradicate the bacteria
Which antibiotics fall under the bacteriostatic category?
Chloramphenicol, Clindamycin, Macrolides, Sulfonamides, Tetracyclines, Trimethoprim
Which antibiotics fall under the bactericidal category?
Penicillins and Cephalosporins, Isoniazid, Metronidazole, Polymyxins, Rifampin, Vancomycin, Aminoglycosides, Bacitracin, Quinolones
What category of antibiotic is PCN and how does it work?
They interfere with synthesis of peptidoglycans (cell wall component of bacteria) They are bactericidal
People are most commonly allergic to which antibiotic?
PCN. 10%
What are some of the allergic reactions from PCN?
Maculopapular rash (delayed) Anaphylaxis (immediate)
PCN has a cross sensitivity with which other type of antibiotic? Why?
Cephalosporins (8%)
They share a common beta-lactam ring
High doses of PCN have an effect on what in the body?
Platelet aggregation
What is the problem with PCN these days?
Many are developing resistance to this class of antibiotics
What category of antibiotic is Cephalosporins and how do they work?
Bactericidal. They bind to penicillin binding proteins. They are resistant to penicillinases, but not Cephalosporinases.
How are Cephalosporins cleared?
Renal excretion
What are some side effects of Cephalosporins?
Hypersensitivity reactions (cross-hypersensitivity with penicillins 1-3%), Superinfections: enterococci, Enterobacter and candida
Which generation of Cephalosporin has the best coverage for Gram Negatives, Strep Pneumoniae, and Gram Positives collectively? First, Second, Third, or Fourth?
Fourth Generation. +++,+++,++ (respectively to bacteria mentioned) But go with first generation if treating just Gram positive (+++)
What category of antibiotic is Vancomycin and how does it work?
Bactericidal (for most gram-positive bacteria.) It inhibits cell wall synthesis by inhibiting peoptidoglycan synthetase.
What are the indications for use of Vancomycin?
MRSA, Endocarditis due to Strep. viridans or enterococci, Patients allergic to B-lactams.
What is Vancomycin usually reserved for?
Typically reserved for Rx of bacterial infections resistant to other antibiotics, or patients with sever hypersensitivity to other indicated antibiotics
What are the pharmacokinetic properites of Vancomycin?
Very poor absorption upon oral administration. IV administration (slowly over 1 hour). Renal excretion by glomerular filtration (80-90% in 24 hrs). Slow CSF penetration unless there is meningeal inflammation
What are side effects of Vancomycin?
What happens if the Vanc is infused to quickly?
Phlebosclerotic (irritating to tissue), Nephrotoxic (rare with current preparations; increased risk if giving with aminoglycosides). Ototoxicity (rare) (increased risk if giving with aminoglycosides. Hypersensitivity (maculopapular skin rash)
Hypotension and Red Man Syndrome (flushing due to systemic histamine release if given IV in less than 1 hour.)
Why do Aminoglycosides have limited use?
Because of the extensive list of side effects
What are the side effects of Aminoglycosides?
Ototoxicity: dose dependent and increased in patients with renal dysfunction. Lasix and mannitol can increase risk
Nephrotoxicity: cause acute tubular necrosis (sometimes reversible)
Muscle weakness: inhibit the prejunctional release of ACh and decreases post-synaptic sensitivity (impact on patients with neuromuscular pathology)
Aminoglycosides are commonly used on what type of surgeries?
Female surgeries??? I’m guessing when the lower bits are involved??? ;)
Which antibiotic has cross reactivity with NMBA’s and what happens?
Aminoglycoside IV administration is associated with potentiation of Non-depolarizing neuromuscular blocking drugs.
What else can Aminoglycosides potentiate?
The neuromuscular blocking action of lidocaine.
Are aminoglycosides effectively reversed by neostigmine?
No
What is the common aminoglycoside that is used?
Gentamicin
What is the mechanism of action of Aminoglycosides as far as NMBA potentiation is concerned?
MOA is the same as intrinsic muscle relaxant effects.
What are the common Macrolides that are used?
Erythromycin, Azithromycin
What category of antibiotic are Macrolides?
Bacteriostatic
What is the indication for Macrolides?
Useful for patients with sensitivities to PCN and cephalosporin drugs
What is a common side effect of Macrolides?
GI intolerance is the most common complaint. It has a prokinetic effect on GI tract = diarrhea
What is an adverse side effect of Macrolide admin?
Prolongs cardiac repolarization (dose/plasma concentration dependent) lead to increase risk of torsades de pointes AND sudden cardiac death
What is the most common combination of antibiotics for female GU surgeries.
Gentamicin and Clindamycin
What limits Clindamycin’s effectiveness in treating infection?
The severe GI complications that it can cause
What is the Fluroquinolone that it used?
Cipro
Fluroquinolones side effect profile?
Mild side effect profile (light sensitivity)
Fluroquinolones are helpful in treating…?
Respiratory infections, GI upset (montezuma’s revenge), Anthrax
What is the MOA of Sulfonamides?
Antimicrobial activity is due to the ability of these drugs to prevent normal use of PABA by bacteria to synthesize folic acid.
Do sulfonamides have a higher or lower incidence of allergic reactions?
Higher. Consider cross-sensitivity to drugs in class
What are sulfonamides used to treat in the pediatric population?
Ear infections (otitis media)
What are viruses?
Intracellular parasites which are difficult to kill without killing the host cell.
How do some antiviral medications find their intended target?
Some host cell surface receptors are unique for viruses and this gives a location for potential drug therapy
What is used to treat Herpes (pre-C-section)
Acyclovir
What are potential complications with Acyclovir?
Renal damage if infused rapidly, Thrombophlebitis, headaches during IV infusion
What type of antibiotic therapy is used to treat HIV?
Triple therapy. Drugs are chosen from 6 classes
What classes of drugs are used in triple therapy for HIV?
Nucleoside/nucleotide reverse transcriptase inhibitors (NRTI’s), Protease inhibitors, Fusion inhibitors, CCR5 receptors antagonists, Integrase inhibitors
What should CRNA’s note when taking care of patients on antiretrovirals?
Existence of adverse effects (liver toxicity, peripheral neuropathy, nephro-toxicity, neuromuscular weakness), Interactions with other medications (PPI, cimetidine)
What are the treatment guidlines of HIV infection in healthcare workers?
Needle stick injury: concern for transmission to health care worker
HIV high viral load: recommend a post-exposure prophylaxis protocol with 3 or more antiretroviral drugs
HIV low viral load: 2 drug protocol (combination of zidovudine and lamuvudine) given for 4 weeks
Follow up of HIV testing for possible seroconversion for at least 6 month after exposure
What are the treatment guidelines for HIV treatment during Pregnancy?
Consider delaying treatment till 10 to 12 weeks in the absence of symptoms. After first semester, pregnant women with HIV should receive at least AZT.
When does most transmission of HIV from mother to baby occur?
During labor and delivery, so it is crucial for mother to be receiving treatment at this time.
True/False. Highly active antiretroviral therapy (HAART) is recommended even for HIV-infected pregnant women who do not need treatment for their own health. And should include AZT.
True. And during labor and delivery, the mother should receive intravenous (IV) AZT and the baby should take AZT (in liquid form) every 6 hours for 6 weeks after birth.
