Infectious Disease Flashcards
Sensitive staph (MSSA): IV and ORAL Tx
IV: oxacillin/nafcillin or cefazolin (first gen cephalosporin)
Oral: dicloxacillin or cephalexin ( first gen cephalosporin)
What microbe most commonly affects Bone, heart, skin and joints.
Staph Aureus
Resistant staph (MRSA): Severe infection treatments?
Severe infection: Vancomycin, linezolid, daptomycin, ceftaroline, tigecycline, or telavancin.
Linezolid causes thrombocytopenia.
Daptomycin causes myopathy and a rising CPK.
Resistant staph (MRSA): Minor nfection treatments?
Minor infection: Trimethoprim/sulfamethoxazole (TMP/SMX), clindamycin, doxycycline
Tx of Staph Aureus in a pt with Penicillin allergy?
– Rash: Safe to use cephalosporins
– Anaphylaxis: Macrolides (azithromycin, clarithromycin) or clindamycin
– Severe infection: Vancomycin, linezolid, daptomycin, telavancin
– Minor infection: Macrolides (azithromycin, clarithromycin), clindamycin,
TMP/SMX
Fact! Telavancin is a vancomycin derivative with similar
efficacy.
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Fact! If the organism is sensitive, oxacillin and nafcillin are superior to vancomycin.
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How to treat Strepococcus?
Use the same drugs as Staph. Medications that are specific for Streptococcus: ·· Penicillin ·· Ampicillin ·· Amoxicillin
Gram-negative bacilli (rods)?
Escherichia coli, Enterobacter, Citrobacter, Morganella, Pseudomonas, Serratia
Treatment for Gram-negative bacilli (rods):
All of the following medications are essentially equal in their efficacy for gram negative bacilli.
1) Cephalosporine
2) Penicillins
3) Monobactam: Aztreoman
4) Quinolones
5) Aminoglycosides
6) Carbapenems
Cephalosporine examples?
Cefepime
Ceftazidime
Penicillins examples?
Piperacillin
Ticarcillin
Quinolones examples?
Ciprofloxacin
Levofloxacin
Moxifloxacin
Gemifloxacin
Aminoglycosides examples?
Gentamicin
Tobramycin
Amikacin
Carbapenems examples?
Imipenem
Meropenem
Ertapenem
Doripenem
Mechanism of Beta-lactam Abx
The 4 beta-lactam antibiotics all inhibit the cell wall by binding the penicillin-binding protein. The 4 classes are:
•• Penicillin
•• Cephalosporins
•• Carbapenem
•• Monobactam (the only one is aztreonam)
Treatment of Gastrointestinal anaerobes (Bacteroides)
- Metronidazole is the best medication for abdominal anaerobes.
- Carbapenems, piperacillin, and ticarcillin are equal in efficacy for abdominal anaerobes compared to metronidazole.
- Cefoxitin and cefotetan (in the cephamycin class) are the only cephalosporins that cover anaerobes.
Treatment of Respiratory anaerobes (anaerobic strep)
Clindamycin is the best drug for anaerobic strep
Medications with no anaerobic coverage
Aminoglycosides, aztreonam, fluoroquinolones, oxacillin/nafcillin, and all the cephalosporins except cefoxitin and cefotetan
Tx of herpes simplex, varicella zoster.
Acyclovir, valacyclovir, and famciclovir: All 3 of these agents are equal in efficacy
Tx of cytomegalovirus [CMV]
Valganciclovir, ganciclovir, and foscarnet
These are essentially equal in efficacy. They also cover herpes simplex and varicella. Valganciclovir is the best long-term therapy for CMV retinitis.
Adverse effect of Valganciclovir and ganciclovir:
Neutropenia and bone marrow suppression
Adverse effect of Foscarnet
Renal toxicity
oral agents used to tx chronic hepatitis C
Telaprevir, boceprevir, simeprevir, sofosbuvir: None is used as a single agent. Sofosbuvir does not need to be combined with interferon.
Influenza A and B tx
Oseltamivir and zanamivir (neuraminidase inhibitors):
Hepatitis C (in combination with interferon), respiratory syncytial virus (RSV) treatment
Ribavirin
Ribavirin causes anemia
Chronic hepatitis B tx
Lamivudine, interferon, adefovir, tenofovir, entecavir, and telbivudine
Mechanisms of Oral Hepatitis C Medications.
1)Sofosbuvir. 2) Simeprevir, boceprevir, and telaprevir
- Sofosbuvir: RNA polymerase inhibitor
- Simeprevir, boceprevir, and telaprevir: Protease inhibitors that prevent viral maturation by inhibiting protein synthesis
Fluconazole treats
Candida (not Candida krusei or Candida glabrata), Cryptococcus, oral and vaginal candidiasis as an alternative to topical mediations
Itraconazole treats
Largely equal to fluconazole but less easy to use; rarely the best initial therapy for anything
Voriconazole treats
Covers all Candida; best agent against Aspergillus. Adverse effect:
– Some visual disturbance
Posaconazole treats
Also covers mucormycosis or Mucorales
Echinocandins (caspofungin, micafungin, anidulafungin) treats
- Excellent for neutropenic fever patients.
- Does not cover Cryptococcus.
- Better than amphotericin for neutropenia and fever (less mortality).
- Adverse effect—Echinocandins have no significant human toxicity because they affect/inhibit the 1,3 glucan synthesis step, which does not exist in humans.
Mechanism of Antifungal Medications
Azole antifungals inhibit conversion of lanosterol to ergosterol. Ergosterol is the major component of the cell wall of fungi. Disrupting ergosterol damages the cell membrane and increases its permeability, resulting in cell
lysis and death.
Amphotericin treats
Effective against all Candida, Cryptococcus, and Aspergillus:
– The last 2 main indications for amphotericin are Cryptococcus and mucormycosis.
Best meds to treat Aspergillus
Voriconazole superior to amphotericin
Best to treat neutropenic fever
Caspofungin superior to amphotericin
Fact! Fluconazole vs amphotericin in the tx of candida
Fluconazole is equal to amphotericin to treat candida but has far fewer adverse effects.
Adverse effects of amphotericin
renal toxicity (increased creatinine); hypokalemia; metabolic acidosis; fever, shakes, chills
Mechanism of Renal Toxicity of Amphotericin
Amphotericin is directly toxic to the tubules. Distal tubule toxicity results in renal tubular acidosis. Distal RTA gives excess potassium and magnesium loss and hydrogen ion retention. When renal toxicity is described, the answer is
“Switch to liposomal amphotericin.”
