Fungal Infections

We’re going to break fungal infections down to systemic (inside the body) and dermatologic (skin).

Systemically, they get it in the respiratory tract (coccidoidomycosis) quite often. Especially common in the Central Valley in California. Fungal infections could also get in the urinary tract and brain (meningitis).  Dermatologically, we have what’s commonly called Athlete’s Foot.

• Systemic
  • Respiratory (coccidioidomycosis)
  • Urinary
  • Meningitis
• Dermatologic
  • Athlete’s Foot

Amphotericin B

This is probably our mainstay drug in the hospital. It’s used intravenously or as bladder irrigation, meaning it goes straight into the bladder through a catheter, dwells in the bladder, and then it’s drained out. Our problem with it is that it precipitates in saline, so we have to administer it with dextrose. So for this we have no choice, even if the patient is diabetic, we must mix it with dextrose. This poses a problem with bladder irrigation because we don’t want to put sugar in the bladder because it will lead to a bladder infection. So our only other choice is water. When the pharmacy sends this bag up with water, it will have fluorescent stickers all over that say, “For bladder irrigation only.”  Blood has a tonicity of 300mosm. Water has a tonicity of 0mosm. If you accidentally ever used this bag intravenously, the patient will die because the red blood cells will explode (that’s called “lysis”).

We also need to protect the Amphotericin B IV bag from light, so we hang the bag in an amber colored bag so no light goes through. We must first give a test dose to see if they are okay with this and then gradually increase the dose.

Recap

• Intravenous and Bladder Irrigation
• Precipitates in Saline, therefore intravenous admixtures in Dextrose and bladder irrigation in water
• Protect from light
• Test dose is administered
• Dose is gradually increased
• Adverse Reactions
  • Headache, chills, fever
    • we typically premedicate with antipyretic (tylenol), steroids, and/or antihistamines
  • Thrombophlebitis (swelling of a vein caused by a blood clot)
    • premedicate with an anticoagulant
  • Hypokalemia (We may give them potassium)
  • Nephrotoxicity (reversible though when the drug is stopped)

Fluconazole

We treat them with an IV drug and then send them home with the oral medication. With amphotericin we don’t have that choice because we have only IV. So why don’t we use fluconazole? Well this is less effective than amphotericin.  There is a little bit of resistance to this one. The plus is that we have less side effects. Oral agent for systemic agents.  This is also an advantage used for vaginal yeast infection and it takes just one dose, one tablet.  It can be a very effective agent, if we don’t have resistance.

• Oral and Intravenous Therapy
• Less effective than amphotericin
• Less side effects
• Advantage: oral agent for systemic infections

Nystatin

This is commonly used for candida (thrush mouth) where fungus is growing in their mouth. This may happen cause they’re on antibiotic medication or orally inhaled steroids (for asthma) and didn’t rinse their mouth.

Usually it comes in a suspension and the instructions are to take a teaspoon and swish it around the mouth and then spit it out four times a day. Sometimes you’ll get an order that says swish and then swallow. We say that in case the infection has gone down the esophageal area.

• Oral and Topical
• Oral use for candida (thrush)
• Topical use for skin and vaginal infections

Flucytosine

This is an oral tablet that’s also used adjunctly for meningitis therapy (added together with one of the other antifungals like amphotericin B)

• Oral Use
• Adjunct therapy for meningitis

Miscellaneous

Miconazole: topical (athletes foot) and vaginal use. You can buy this OTC.

Griseofulvin: oral for dermatologic use and nail infections. Treating a fungal nail infection is not easy. The appearance of a fungal nail infection is it’s deformed and discolored/yellow.  It’s problematic to treat because nail is dead tissue so you can’t put a cream on it as there’s no active absorption going on. Historically they cut the nail off which was painful and didn’t cure it because the fungi was in the nail bed, not the nail. Treating a person with oral agents is not easy because the blood supply to the toenail bed is not very high so you can’t get high blood concentrations in the toe. However, we do try it and we try this therapy from 6 months to a year at the risk of liver damage. So you have to weight the differences.

Terbinafine: Used for nail infections. This one is also similar to griseofulvin except it takes months of therapy and causes liver damage.  So you have to ask yourself… deal with an ugly nail or liver damage? Hmmm?

Ketoconazole: dermatologic and oral infections, topically.