Antimicrobial Therapy Flashcards
What is anesthesia’s role in antibiotic therapy?
The anesthetic provider plays an important role in timely administration of antibiotics
Contributes to our reimbursement for quality care
What are potential adverse reactions from antibiotic therapy?
Hypersensitivity reaction
Direct organ toxicity
Potential for superinfection
What is a common misconception regarding hypersensitivity reactions with antibiotics?
They are dose independent meaning you can give any amount (test dose or not) and still have a reaction
Why do we give antibiotics prophylactically?
The surgeon exposes and transects parts of the body that have bacteria all the time
Exposing certain parts of the body to flora that is not normal in that area
What antibiotic covers majority of the organisms we expose the body to?
Cefazolin
What antibiotics should be used with caution in pregnancy?
Aminoglycosides (ototoxicity) and Clindamycin (colitis)
What antibiotics are contraindicated in pregnancy?
Tetracyclines –> tooth discoloration in babies
How are antibiotics categorized?
Bactericidal
Bacteriostatic
What does it mean if an antibiotic is considered to have bactericidal properties?
It can kill the susceptible bacteria
What does it mean if an antibiotic is considered to have bacteriostatic properties?
It reversibly inhibits growth of the bacteria
If bacteriostatic drugs cannot kill bacteria how do they get rid of a bacterial infection?
They allow cellular and humoral defense mechanisms to eradicate the bacteria
What type of antibiotics are penicillins?
Bactericidal
What is the mechanism of action of penicillins?
They interfere with synthesis of peptidoglycans, which are components of bacterial cell wall
What type of antibiotics are cephalosporins?
Bactericidal
What is the mechanism of action of cephalosporins?
Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins
What class of antibiotics have the highest reported rate of allergy?
Penicillins (up to 10%)
What two types of reactions are associated with penicillin allergy?
Delayed = maculopapular rash Immediate = anaphylaxis
Why is there a high likelihood of cross sensitivity between penicillins and cephalosporins?
They share a common beta-lactam ring
What is a side effect of high dose penicillins?
Affect platelet aggregation
What superinfections can result with cephalosporin use?
Enterococci
Enterobacter
Candida
How many generations of cephalosporin drugs are there?
Four
What type of antibiotic is Vancomycin?
Bactericidal for most gram positive bacteria
What is the mechanism of action of Vancomycin?
Inhibits cell wall synthesis by inhibiting peptidoglycan synthetase
What infections is Vancomycin typically reserved to treat?
MRSA
Endocarditis due to strep, viridans or enterococci
Patients allergic to beta lactams
Why is it important to administer Vancomycin slowly?
To prevent a massive histamine leading to Red Man’s Syndrome
Why is it important to check the IV site prior to administering Vancomycin?
It is phlebosclerotic causing damage to the tissues if infiltration occurs
What organ systems can Vancomycin affect?
Kidneys, nephrotoxicity when given with other nephrotoxic drugs
Ototoxicity increased risk if giving with aminoglycosides
What symptoms usually accompany Red Man Syndrome?
Profound hypotension
Flushing
Why have aminoglycosides lost favor in patient administration?
It has an extensive list of significant side effects
What kind of antibiotic is Gentamicin?
Bactericidal Aminoglycoside
What side effects are typically seen with aminoglycoside use?
Ototoxicity
Nephrotoxicity
Muscular Weakness
What drugs used in combination with aminoglycosides can increase the risk of ototoxicity?
Lasix
Mannitol
What renal impairment are aminoglycosides known to cause?
Acute tubular necrosis
What mechanism causes muscle weakness in aminoglycoside use?
Aminoglycosides inhibit the prejunctional release of Ach and decreases post-synaptic sensitivity
Pre-exisitng musculoskeletal diseases may be potentiated by these efects
How would aminoglycoside use impact administration of neuromuscular blockade?
Aminoglycosides are associated with potentiation of Non depolarizing NMBA
Not effectively reversed by neostigmine
What other anesthetic drug is affected by aminoglycosides?
Lidocaine, it enhances the neuromuscular blocking activities
How would dose of NMBA be adjusted if the patient is currently taking aminoglycosides?
Decrease the amount given
What class of antibiotics are useful in patients with allergies to PCN and cephalosporins?
Macrolides
What two Macrolide antibiotics are commonly used?
Erythromycin
Azithromycin
What is the most common complaint with Macrolide use?
GI intolerance
How do Macrolides affect the GI tract?
Prokinetic effect on GI tract and increases the tone of the LES
What effect do Macrolides have on the cardiovascular system?
Prolongs cardiac repolarization (prolong QT)
Can cause Torsades and sudden cardiac death
What drug is most commonly used in female GU surgeries?
Clindamycin
Why is Clindamycin’s use so limited?
Severe GI complications limit its used to infections that are difficult to treat
What other antibiotic has an affect on neuromuscular blockade?
Clindamycin, produces pre and post junctional effects at the NMJ that cannot be readily antagonized
What ailments are fluoroquinolones useful in treating?
Respiratory infections
GI upset
Anthrax
What type of antibiotics are sulfonamides?
Antimicrobial
What is the mechanism of action of sulfonamides?
Prevent normal use of PABA by bacteria to synthesize folic acid
What antibiotic is used most often in pediatric patients for ear infections?
Sulfonamides
What is a negative effect of using sulfonamides?
High incidences of allergic reactions
What is a virus?
Obligate intracellular parasites
How do we target a virus without killing our own cells?
Some host cell surface receptors are unique for viruses and this gives a location for potential drug therapy
What is Acyclovir used to treat?
Used to treat herpes
What side effects can be seen with the use of Acyclovir?
May cause renal damage if infused rapidly
Thrombophlebitis
Headache
If a patient reports being on triple therapy what disease process are they more than likely fighting?
HIV
What are the six classes of HIV antiretrovirals?
Nucleoside/nucleotide reverse transcriptase inhibitors Protease inhibitors Fusion inhibitors CCR5 receptor antagonists Integrase inhibitors
What should the anesthetic provider be assessing in the operative patient on triple therapy?
Existence of adverse effects (organ damage, neuropathy, weakness)
Interactions with other medications (PPI and cimetidine) can affect CYP causing increased available medications leading to toxicity
If a healthcare worker is exposed to HIV with a high viral load what precautions should be taken?
Prophylaxis with three or more antiretroviral drugs (two if the patient had a low viral load)
How long should a healthcare provider be followed if exposed to HIV?
For at least six months after exposure
When does most mother to child transmission of HIV occur?
At the time of labor and delivery (both mom and baby should receive AZT every six hours for six weeks after birth)
What antiretroviral drug should the HIV positive mother receive after the first trimester of pregnancy?
AZT
What microbial agents do first generation cephalosporins have the greatest effect on?
Strep pneumoniae
Gram positives
(little effect on gram negative)
What microbial agents do second generation cephalosporins have the greatest effect on?
Equally effective against gram positive, gram negative and strep pneumoniae
What microbial agents do third generation cephalosporins have the greatest effect on?
Gram negative
Strep pneumoniae
(little effect on gram positive)
What microbial agents do fourth generation cephalosporins have the greatest effect on?
Gram negative
Strep pneumoniae
(moderate effect on gram positive)
What other drug is almost always used in combination with aminoglycosides?
Almost always used along with a cell wall synthesis inhibitor
What is the mechanism of action of aminoglycosides?
Irreversible inhibition of protein synthesis 30s (O2 dependent transport)
What pregnancy category are aminoglycosides?
C
What lab values should you base your dose of aminoglycosides on?
Creatinine
Serum concentration
What is significant about azithromycins half life?
The half life is three days, 1g dose provides 7 days of coverage
What is the mechanism of action of macrolides?
Bind to 50s and block translocation step in protein synthesis
What type of antibiotics are macrolides?
Bacteriostatic
How can macrolides affect metabolism of other drugs?
P450 Inhibitor, increasing the concentration of other drugs
Can also cause liver toxicity
What type of antibiotic is Clindamycin?
Bacteriostatic
If a sulfa allergy is present, what two drugs can be used to treat toxoplasmic encephalitis?
Clindamycin and pyrimethomine
What two GI disturbances can occur with Clindamycin use?
Cdiff
Enterocolitis
What is the mechanism of action of fluoroquinolones?
Inhibits DNA gyrase and topoisomerase
What type of antibiotic are fluoroquinolones?
Bacteriocidal
What pregnancy category are fluoroquinolones?
C
What are some adverse effects of fluoroquinolone use?
Tendon rupture QT prolongation seizure Dizziness Confusion Photosensitivity
Why shouldn’t children under 18 take fluoroquinalones?
Interferes with cartilage formation
How is cefazolin typically dosed?
Usually 1g, but increase to 2g when over 80kg
