Therapy for Staph and Strep II Flashcards
What type of compound is vancomycin?
Glycopeptide
Vancomycin mechanism of action?
Prevents cell wall synthesis, binds to d-ala-d-ala, prevents elongation and cross linking.
Resistance to vancomycin?
D-Ala-D-Ala turned into D-Ala-D-Lactate, Vanco can’t bind. Also, thickened cell wall.
What types of organisms does vancomycin affect?
Only gram positive organisms
Is vancomycin bactericidal or bacteriostatic?
Slowly bactericidal, but bacteriostatic against enterococci
What is vancomycin the drug of choice to treat?
MRSA and penicillin-resistent pneumococcus
Why is the oral formulation used to treat C. diff?
Because it isn’t absorbed, so it doesn’t work systemically, only in gut lumen.
Toxicity of vancomycin?
Nephrotoxicity, hypersensitivity (red man syndrome).
Red Man syndrome
Histamine response to rapid vanco infusion. Huge widespread rash.
What type of compound is daptomycin?
A cyclic lipopeptide
What type of organisms does daptomycin treat?
Gram positive organisms (MRSA, MSSA, Enterococci, VRE). NO gram negative activity
VRE
Vancomycin resistent enterococci.
Does daptomycin have gram negative activity?
No!
How does daptomycin work?
Binds to the cytoplasmic membrane using Ca and causes rapid depolarization, leading to intracellular ion release. Rapid bactericidal action, concentration dependent mechanism.
What type of infections is daptomycin used for?
Skin and soft tissue infections. MSSA, MRSA, bloodstream infections. VRE.
What isn’t daptomycin used for pneumonia?
It is inactivated by pulmonary surfactant.
Adverse effects of daptomycin
Musculoskeletal pains, weakness, rhabdomyolysis
Who is at increased risk for rhabdomyolysis when taking daptomycin? What to do to monitor?
Those on statins! Check CPK (creatine phosphokinase) levels and monitor muscle strength.
Inhibitors of protein synthesis in gram positive cocci
Linezolid, doxycycline, clindamycin. These drugs are bacteriostatic.
Inhibitors of protein synthesis
Linezolid, Doxycycline, Clindamycin. These drugs are bacteriostatic.
What type of compound is doxycycline?
A tetracycline
What organisms does doxycycline treat?
Gram positive and gram negative bacteria, also useful against INTRACELLULAR BACTERIA
What is doxycycline used for?
Skin and soft tissue infections
Where is doxycycline absorbed?
In the GI tract
What is something tricky about taking doxycycline?
Avoid dairy, forms nonabsorbable chelates with Ca, Mg, Fe, Al
Where does doxycycline concentrate?
In the liver, kidney, skin, and spleen. Large Vd.
Adverse effects of doxycycline?
Binds to calcifying tissues like teeth and bones. GI discomfort, hepatoxicity, photosensitivity.
Metabolism of Doxycycline
Hepatic metabolism, renal excretion
What can clindamycin treat?
Potentially active against strep and staph. Anaerobic bacteria and non-enterococcal gram positive cocci. NO activity against enterococcus
Does clindamycin reach therapeutic levels in CSF/urine?
No.
Side effects of clindamycin?
Rash – potentially C.Diff
How to treat enterococcus?
Penicillin/ampicillin. Vancomycin (most is susceptible)
How to treat vancomycin resistant enterococci?
Linezolid
What is special about linezolid?
100% bioavailability, so oral is great.
Problems with prolonged use of linezolid?
Thrombocytopenia and neuropenia, lactic acidosis, serotonin syndrome when taken with SSRIs.
Serotonin syndrome
Cognitive: Mental status changes
Autonomic: fever, hypertension, tachycardia
Somatic: hyperreflexia, myoclonus, tremor
Folic Acid antagonists
Trimethoprim-Sulfamethoxazole (TMP-SMZ, bactrim)
Why is folate important?
Needed to synthesize DNA, RNA
Is TMP-SMZ bactericidal or bacteriostatic?
Bacteriostatic
What is TMP-SMZ used to treat?
MRSA/MSSA, but primarily UTIs, also treats listeria in the setting of beta lactam allergy.
Where is TMP-SMZ absorbed?
Intestines, large Vd including CSF
Why isn’t TMP-SMZ given to neonates?
Causes kernicterus (bilirubin deposition, causes movement disorders and developmental delays).
What is the drug of choice for MRSA?
Vancomycin
What is rapidly bactericidal and can be used for strep and staph infections, but not pneumonia?
Daptomycin
What is potentially active against strep and staph?
Clindamycin
What should not be given to children or pregnant women?
Doxycycline
What is associated with many side effects, so patients must be monitored closely?
Linezolid
What drug does not have reliable streptococcal coverage?
TMP-SMZ
