How To Detect And Treat Tinea Pedis

Author(s): 
By Barry Blass, DPM

   Fungal infections of the foot represent the fourth most common problem that we see in podiatric practice.1 Approximately 26.5 million people are affected annually.2 Nearly half of these people will suffer from multiple episodes for years. Treatment varies from home remedies and OTC preparations to a large variety of topical and oral medications. While tinea pedis is certainly is not the most challenging condition we treat, eliminating a longstanding, annoying and embarrassing condition can make the practitioner a hero in the eyes of his or her patient.    I will leave the in-depth discussion of the categories of tinea infections of the foot to the dermatology textbooks. However, as a brief reminder, there are four basic presentations.    Chronic squamous or papulosquamous tinea presents with dry, thick scales, frequently with fissuring on the plantar surface. The classical presentation is in a moccasin-type distribution. Interdigital tinea presents with maceration, scaling and itching between the toes. It frequently spreads to the plantar surface proximal to the web spaces. Acute vesicular or vesiculobullous tinea usually appears in non-weightbearing areas such as the longitudinal arch. It usually displays small vesicles and bulla on erythematous bases. Acute ulcerative tinea classically involves larger areas with desquamation of layers of tissue, foul odor and drainage.    Although all tineas can lead to secondary infection, the acute ulcerative tinea is the most likely presentation to do so. This is a matter of increased concern for patients with diabetes, those with vascular disease and immunocompromised individuals.

How Diagnosis Of The Condition Has Evolved Over The Years

   When I was a student, I recall spending hours peering into a microscope looking for hyphae. We would take a scraping from the involved area and dissolve it in a dilute solution of potassium hydroxide. After the chemical dissolved the epithelial tissue, we examined the specimen for evidence of fungal organisms. Although we were always elated when we found those strands and buds, the search was not always easy. In many cases, obvious fungal infections eluded this KOH technique both in the hands of students and many clinical laboratories. Was the collection faulty or was the observer not tenacious enough? I do not know.    As I started to visit podiatry offices and as I later discovered in my own office, it was common to have rows of bottles of culture media with an array of colors and contents that rivaled the neglected refrigerators of college students. Practitioners ordered DTM (dermatophyte test media) tests by the dozens. Not only did the DTM change color from orange to red in the presence of dermatophytes, the DTM also came with a handy color chart that guided the practitioner through a specific diagnosis of the causative organism. For years, Medicare mandated the testing for various CPT codes and insurance companies paid for the work. We had never heard of the Clinical Laboratory Improvement Amendment (CLIA) and our staff could handle most of the task.    I no longer see young practitioners listing a microscope as essential in their list of equipment priorities. Although the bottles of media are not gone, their numbers have decreased drastically with an increase in the paperwork required to use them. In many cases, the practitioner relies on his or her clinical knowledge to make the diagnosis. When specific proof is needed, the PAS stain is now the preferred test. However, when one sends a sample to an outside lab, it is a good idea to ensure the lab has individuals well versed in the test. The PAS stain is rapid (unlike DTM), dependable (unlike KOH) and universally well accepted. With the broad spectrum of the medications I will discuss, it has become less important to identify the specific species.    During a series of lectures on podiatric dermatology at the APMA Annual Meeting, Bradley Bakotic, DPM, DO, discussed the under use of shave and punch biopsies. A dermatopathologist, Dr. Bakotic presented cases demonstrating skin pathology that appeared simple and proved to be aggressive skin lesions. Practitioners are well advised to ensure that the presenting dermatological condition is a tinea. A biopsy that proves nothing unusual is far better than facing the prospect of missing an important diagnosis.

Assessing The Impact Of Topicals

   Although we would like the population to realize we are the foot experts and the best providers of treatment for pedal conditions, this is clearly not always the case. There are a large number of individuals who are ready to treat the itching, peeling and scaling of what they know as athlete’s foot. These well meaning people include the old wife (the source of old wives’ tales), coaches, pharmacists and their assistants, nurses, physicians’ assistants and physicians other than podiatrists. The numbers are quite surprising. Approximately 7.6 million OTC topical antifungal treatments are recommended by pharmacists every year.3 More than 2 million prescriptions for antifungal creams were written in 2003 by individuals who were not podiatrists.4    In the case of some medications, it is easy for practitioners to feel OTC preparations cannot be as efficient as the drugs in our armamentarium. However, this is difficult when it comes to treating tinea. Many of the drugs that we wrote prescriptions for in past years are now easily available to the population without our help. Pharmaceutical companies are glad to directly promote a product to patients through television ads or print media. Early NSAIDs are now available in lower dosage form without prescription. Drugs such as Lamisil AT and Lotrimin, which required prescription not so long ago, are now readily available without our intervention. This means that many patients suffering from tinea pedis will never make it into our offices. However, it also means that many of the patients who do seek our care may have already tried other forms of treatment, whether or not they are willing to share that use with us in the patient history. In short, they are expecting something better and different from the foot specialist.    The symptoms of tinea pedis arise from growth of the organism. Many products, including some OTC preparations, inhibit this growth and the patient may see his or her symptoms disappear rapidly. However, if individuals have not been educated on the nature of this condition, they assume it is gone and stop using the drug. The fungus has merely retreated and formed spores. As soon as the patient stops the medication, the symptoms may return. This results in relapse and chronic tinea pedis. Since it can take up to four weeks for epithelial tissue to turn over, one may have to use OTC preparations for the same period of time.    Practitioners should know the strengths and weaknesses of the different products for tinea pedis, and use what he or she feels will work best for a given patient. However, when one consults the Physician’s Desk Reference, the number of prescription drugs for treating tinea pedis is smaller than one might think.    Econazole nitrate (Spectazole®, Ortho-McNeil) and ciclopirox (Loprox®, Medicis) are two of the remaining prescription antifungals. Unless the prescriber indicates otherwise, the prescriptions are likely to be filled with the generic product. While these two products are effective, one must remind patients to apply these topicals twice a day and caution them to avoid overusing the product but apply it properly in order to ensure adequate absorption. These products are best used for 28 days. In my experience, I have found a reduced recurrence of infection when patients use these medications for at least two weeks after symptoms resolve. A new topical entry into the market is sertaconazole nitrate (Ertaczo®, OrthoNeutrogena).    When it comes to topicals for tinea pedis, my personal favorites are oxiconazole (Oxistat®, Glaxo Smith Kline) and naftifine (Naftin®, Merz), which are prescription only. Oxistat has the advantage of once-a-day application. I also prefer treatments that have a “reservoir” effect, which ensures some continuing effect of the previous application if the patient misses a day. Naftin and Loprox have the advantage of being available as a gel whereas Oxistat comes in lotion and cream formulations. Anecdotally, I have found that interdigital tinea responds best to a combination of oral and topical medications. This has been supported by the literature.5    It is important to remember that patients who present with tinea pedis may have tried a topical that failed. Was it the fault of the drug or compliance? Is the patient capable of reaching his or her feet and rubbing in a medication? Does arthritis or obesity hamper or prevent them from applying a topical medication? Is there a family member who will commit to at least one month of the task? Will the patient or family member apply the topical twice a day? If the symptoms clear, does the patient avoid the expense of refilling the drug for an additional two weeks as I noted earlier? Is there a large area of involvement that requires treatment, necessitating multiple tubes of topicals? I find that topicals are more effective when there is a smaller area of involvement and reliable patient involvement is greatest.

Off-Label Use Of Oral Antifungals For Tinea Pedis: Is It Appropriate?

   There is a great amount of promotion of oral antifungal drugs. Terbinafine (Lamisil®, Novartis) and itraconazole (Sporanox®, Janssen) have become very familiar to our profession. These drugs are very effective for the treatment of onychomycosis. However, a review of the indications reveals that these drugs are for onychomycosis and not for tinea pedis. Yes, there is anecdotal support that they may work, but the package insert does not support their use for tinea pedis. Fluconazole (Diflucan®, Pfizer) might also clear tinea pedis, but it is not indicated for this condition.    I am not against using drugs off label but I usually do not do so if another equally effective and indicated drug is available. It is hard to defend a complication of off-label drug use, especially if the practitioner had an indicated alternative.

What You Should Know About Griseofulvin

   Fortunately, an indicated oral antifungal is available and has been for the 30 years of my practice and somewhat longer. That drug is griseofulvin (Gris-PEG®, Pedinol). I admit to being old enough to remember when we were scared of this drug. We ran blood tests regularly and the dosage was high, mostly because the first formulation available just did not dissolve well. Penicillin allergy was a contraindication. Fortunately, pharmaceutical science marches forward.    The original formulation has undergone considerable improvement in the form of reduced particle size. The ultramicrosize formulation of griseofulvin allows for a dosing of 250 mg twice a day. I usually prescribe it for 30 days and evaluate the patient again at about three weeks. Occasionally, I will write a second prescription for 30 days if necessary. (Be aware that Grifulvin V®, a microsize particle, is frequently mistaken for Gris-PEG.)    One can also use the ultramicrosize formulation to treat children older than 2 years of age (3.3 mg per pound per day). Pediatricians commonly use the drug for tinea capitis, a testament to the safety of the drug.    As far as contraindications, Gris-PEG is category C for pregnancy. One cannot use this drug when patients have liver disease. It is also contraindicated in patients who have porphyria. It can cause photosensitivity so I advise patients to wear sunscreen and sunglasses. The drug can also reduce the effectiveness of coumadin. If this comes up in the patient history, I contact the patient’s primary care physician. It can also decrease the effectiveness of oral birth control drugs. These precautions are certainly no more stringent than those of the oral medications for onychomycosis.    Employing an oral antifungal medication certainly improves patient compliance. One can monitor compliance by simply having patients bring the bottle to the office and counting the days and tablets. Cross sensitivity to penicillin is not reported in the literature I have read. However, when penicillin sensitive patients present with tinea pedis, I will start them on a very small piece of a tablet and monitor for any adverse reaction before proceeding with the indicated dosage.

Why Patient Education Is Invaluable In Reducing The Risk Of Recurrence

   For years, I have been a consultant to insurance companies, the Florida state board and attorneys who may be involved in defending a podiatrist’s practice from a patient complaint or lawsuit. In my efforts to defend doctors, I have noticed a repetitive depressing scenario. Many doctors do not spend enough time talking to their patients. While feeling for pedal pulses, I tell the patient what I am doing. I explain the rationale behind my treatment and the risks, and I enlist the patients’ help in treating their condition. It takes more time but I do not have patients misunderstanding my actions or doing things that are counterproductive to their care (with the possible exception of the female patient who is intent on wearing severe pumps). In the case of tinea pedis, the patient’s actions or lack of the same can make all the difference between cure and recurrence.    It is important to educate and remind patients that fungus loves wet. One must stress careful daily drying, especially between the toes. If the patient cannot reach his or her feet, I suggest using a hair dryer on low or medium setting. Daily powdering is strongly advised for individuals who are prone to tinea pedis. The patient can line the bottom of a box with powder and simply place his or her foot into it before donning socks or hose. Whenever possible, patients should avoid wearing the same shoes two days in a row. Work and sports footwear especially requires time to dry out after a day of use. Emphasize to patients that wearing two pairs of shoes on alternate days helps the shoes last longer as opposed to wearing two pairs consecutively. Also encourage them to avoid walking barefoot in moist areas, especially soil, and to use shower shoes or thongs when using public shower and locker facilities.    Granted, it may take a few extra minutes to discuss compliance and preventive measures with patients, but it turns you into a practitioner they talk about to their friends as seeming to be more interested in their care.

Case Study: When OTC Topicals And Recommended Prescriptions Fail

   Approximately one year ago, a 37-year-old male patient presented to the office for the first time. He noted a history of bouts with “athlete’s foot” on and off for as long as he could remember. He initially tried treating himself with some of the original OTC products. Each cleared the problem only temporarily. Pharmacists had recommended some of the newer drugs, which had recently been removed from prescription, but the patient still only found only temporarily relief.    Subsequently, he received a likely drug for onychomycosis from a podiatrist. Shortly afterward, the patient’s primary care physician criticized the podiatrist for not running liver function tests (LFTs) prior to even one or two weeks of use. A dermatologist wrote a prescription for Diflucan. The patient did not fill that prescription when his wife explained the condition for which she used the drug. Now, in the patient’s mind, it was my turn to fail.    I wrote a prescription for ultramicrosize griseofulvin and it cleared his condition that covered more than 75 percent of the plantar surface of both feet. However, what impressed him the most was the time I took to teach him methods to try to avoid recurrence.    He called me about a month ago to say that he had foolishly stayed in wet shoes all day and the condition had returned. He wanted to know if I would just call in some of those pills he used before if he promised to follow my advice in the future.

In Conclusion

   The information shared here is based on my daily podiatric experience. Treating tinea pedis requires little or no display of manual dexterity and it certainly will not buy you that new plasma television. However, it is an ever present part of the practice of podiatry. We cannot hold ourselves out to be the specialists in foot care if we are not aware of the most efficient, safe and indicated methods of treating the patient’s foot complaint, no matter how mundane. You might even save a leg. You will definitely make a friend. Dr. Blass is in private practice in Tampa, Fla. He is on the Credentials Committee of the University Community Hospital in Tampa, Fla., and is a regular lecturer with the Florida Podiatric Medical Association.
 

 

References:

1. 2000 Survey of Attitudes Toward Foot Care. American Podiatric Medical Association Department of Public Relations.
2. Handbook of Nonprescription Drugs, 12th edition.
3. Pharmacy Times, June 2002, OTC Supplement 2002.
4. IMS Health.
5. Zaias N, Battisini F, Gomez-Urcuyo F, et. al. Cutis 1978;22:197-199.
Recommended Reading
1. Garcia Rodriguez LA, Duque AA, et al. A cohort study on the risk of acute liver injury among users of ketoconazole and other antifungal drugs. Br J Clin Pharm 1999;48:847-852.
2. Chien, Rong-Nan, et al. Hepatic injury during ketoconazole therapy in patients with onychomycosis: a controlled cohort study. Hepatology. January 1997; 103-107.
3. Bioavailability of Microsized and Ultramicrosized Griseofulvin Products in Man. J Pharmacol and Biopharmacol 1980;8(4):347-362.
4. Kidawa AS. A comparison of Gris-Peg and Fulvicin-U/F in the treatment of tinea pedis. JAPMA 1981;71:323-327.

 

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