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InFocus: Part 2 in a Series

The Clinical Approach to Paronychia

Roberts, James R. MD

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Author Credentials and Financial Disclosure: James R. Roberts, MD, is the Chairman of the Department of Emergency Medicine and the Director of the Division of Toxicology at Mercy Health Systems, and a Professor of Emergency Medicine and Toxicology at at the Drexel University College of Medicine, both in Philadelphia, PA. Dr. Roberts has disclosed that he has no significant relationships with or financial interests in any commercial companies that pertain to this educational activity.

Learning Objectives: After reading this article, the physician should be able to:

  1. Identify the clinical appearance of common paronychia.
  2. Discuss unusual presentations that require additional therapy or referral and the general approach to treatment.
  3. Describe the bacteriology of most infections.

Release Date: September 2003

Paronychia is a rather common and often painful and annoying digit infection that frequently brings patients to the ED in search of relief. Most infections are minor and can be treated easily with rather conservative methods, but occasionally surgical intervention or other aggressive or prolonged therapies are required.

Importantly, the neglected or mismanaged case can end up a disaster. There are surprisingly few objective data in the medical literature dealing with the treatment of this common problem, probably reflecting the fact that most patients do quite well. I could not find a single prospective study that evaluated treatment protocols or outcomes, and even review articles or textbooks are often superficial or incomplete. I have been impressed, however, that some of my colleagues, and even often quoted textbooks, tend to recommend an overly aggressive approach to what is usually a simple problem with a simple solution. When dealing with a paronychia, as with any infection involving the hand, it is paramount for the clinician to know when to be aggressive and when to be conservative.

Paronychia, Randell P Aust Fam Physician 1985;14:377

Although brief and quite superficial, this is one of the few articles I could find written within the past 20 years that discusses the treatment of the common paronychia. A paronychia is an acute or chronic inflammation or infection of the periungual tissue. An acute paronychia generally begins as a red, hot, swollen, and tender area on the skin surrounding the proximal fingernail. It can quickly become quite painful.

The rapid onset of tenderness, soft tissue swelling, redness, warmth, and fluctuance under the eponychium is characteristic of a bacterial paronychia, left. This infection occurred in a man who had continual minor trauma to the fingertips. Sometimes only swelling and pain are present, but pus under the cuticle is obvious in this paronychia, right.

Clinically it first appears as a cellulitis, and if left untreated, can progress to an abscess. Once pus has localized, drainage can be accomplished relatively easily, and the patient experiences rapid relief of symptoms. Many cases seem to develop spontaneously, but some patients can recall an episode of trauma, such as a puncture wound. Children can develop a paronychia from sucking their fingers. The infection usually involves the fingers (especially the thumb and index finger), but the toes may be affected.

A chronic paronychia can develop, particularly in individuals whose hands have repeated exposure to moisture and repeated minor trauma. The chronic form involves slow progressive swelling of the lateral or posterial border of the nail folds and scarring associated with discoloration or physical changes of the nail. Unlike an acute bacterial paronychia that generally involves a single finger, the chronic infection can affect a number of fingers simultaneously. Often it has a fungal component.

Careful local treatment is generally curative. Patients with a chronic paronychia should be investigated for yeast infections. Once cured, attention to local nail care can help prevent a recurrence. Failure to cure a paronychia rapidly should prompt specialized culture techniques, proper referral, and occasionally a biopsy.

A chronic paronychia caused by fungal infections should always raise the possibility of immunosuppression. A paronychia can be mistaken for psoriasis or Reiter's diseases. Tumors, such as squamous cell carcinoma or malignant melanoma, cysts, the primary chancre of syphilis, warts, or foreign body reactions can occasionally mimic a paronychia.

Recently, paronychias, especially of the great toe and associated with ingrown toenails, have been linked to retroviral therapy. Both indinavir and lamivudine have been reported to cause painful periungual inflammations of several nails during treatment with these HIV drugs, developing months after starting treatment (Br J Dermatol 1999;140[6]:1165; Clin Infect Dis 2001;32[1]:140). Unlike a typical bacterial paronychia, this drug-induced condition would not require an invasive approach.

Comment: This is a superficial article that attests to the fact that this subject is neglected in the medical literature. Reading the current medical literature will leave the student with many unanswered questions and unproven therapeutic recommendations, and even can instill incorrect approaches. I could not find a single prospective study that compared various treatment modalities. Most of the articles in the literature are written by hand surgeons who see complicated or advanced cases, and base their treatment recommendations on their skewed experiences.

Figure. Av
Figure. Av:
oiding an actual skin incision, the eponychium is lifted up with a scalpel blade, 18-gauge needle, or tip of small scissors, left. A digital block is required and a finger tourniquet is suggested. The scalpel blade is held parallel to the nail and slid between the nail and eponychium. A blunt instrument, such as a hemostat, is then swept around the entire base of the cavity to break up loculations and facilitate further drainage, right. Copious drainage of pus usually results in a rapid cure.

In many instances, the rather benign paronychia is included with a discussion of much more serious and complicated hand infections, such as human bites, deep space infections, or purulent tenosynovitis. One need only peruse the literature quickly to conclude that many textbooks are overaggressive in their recommendations for therapy of a common garden variety paronychia.

Theoretically, there has to have been a break in the skin for a paronychia to develop, usually from a hangnail, puncture, or trauma, with local inoculation of bacteria. The infections are polymicrobial, and involve a number of aerobic and anaerobic organisms. Bacteria that normally inhabit the skin or mouth are usually found if the infection is cultured. Many patients with paronychias bite their nails, suffer repeated minor trauma, or have chronic skin conditions or occupational predisposition.

It's helpful to consider the common bacterial paronychia in two contexts. The first scenario would be the subacute infection where patients present with minor pain, swelling, redness, and tenderness in the periungual area without obvious fluctuance, drainage, lymphangitis, or adenopathy. The history is usually not specific for an etiology, and the process insidiously develops for no apparent reason. At this point, the process is basically a cellulitis, but sometimes pus drains spontaneously or the brave patient performs self-treatment, and the infection is already on the road to recovery. Patients in this category will likely respond to conservative treatment.

Although there are no data, most physicians defer drainage attempts unless there is obvious pus, and recommend three to four days of a broad spectrum antibiotic in addition to hot soaks. I have found it difficult to convince some patients to soak their fingers with enough regularity to ward off pus formation; nevertheless, when pus is absent, conservative home care is the most reasonable course.

In fact, there is no surgery to recommend unless pus is present; one is dealing with a simple cellulitis. I advise patients to soak their affected finger in a coffee cup filled with very hot tap water (not boiled water or sterile saline) for 10 minutes, four times a day. It sounds simple enough, but it's difficult to do religiously. If you give patients some betadine or similarly bright colored additive, it may increase compliance because it focuses attention on a bona fide “medical procedure” — soaking in an antiseptic. Because the skin is closed, the antiseptic should offer no great medical benefit over the local heat, but it can increase compliance because it focuses attention on the hot soaks.

Each time the finger is soaked — and it should be for 10 minutes by the clock — the patient should take an oral antibiotic. Long-acting antibiotics are usually more patient-friendly, but if one couples the antibiotic with the soaking, the soaking may be more likely. There are no data identifying the proper antimicrobial, but a short course (maximum 4 to 5 days) with an antibiotic with gram-positive coverage would be a reasonable approach (see following discussion). This may be curative in this early stage of cellulitis.

Many physicians, however, question the need for antibiotics at all at this stage, but I tend to prescribe them unless the process is obviously minor. After soaking the finger, an antibiotic ointment and gauze dressing or Band-Aid is applied. Follow-up is not scheduled and not required unless the condition worsens. X-rays, cultures, and lab tests are unnecessary, but tetanus prophylaxis is suggested.

The second scenario involves a more complicated or advanced condition where conservative measures fail or the patient presents with frank pus. In these cases, surgical treatment is indicated. I hesitate to use the word surgery, however, because this means skin incision to most physicians. In this case, however, initial drainage can be accomplished without an actual incision.

I was amazed to find that some textbooks recommend incising the skin rather than the more reasonable approach of draining this localized pus collection by simply lifting up the eponychium. It is important to realize that a paronychia is not an actual subcutaneous abscess like a boil or infected sebaceous cyst, but a skin cellulitis over a collection of pus under the cuticle. Incising the dorsal skin of the eponychium only compounds the injury, and is clearly not the way to drain pus from under the cuticle. Skin incisions should be avoided as the initial treatment.

I cannot understand why textbooks written for primary care physicians have diagrams involving skin incision or tissue removal as the initial treatment; it's downright absurd! Incising the skin in the fingertip of a diabetic can relegate them to four to six weeks of slow healing. Contrast this to the few days healing associated with a more conservative procedure that eschews actual skin incision. Likewise, removing the fingernail, as suggested by some authors, is gross over-treatment for the first visit. Pus from a paronychia rarely makes its way underneath the fingernail. The presence of a true subungual abscess is an indication for a nail removal, but this rarely occurs with a paronychia.

Some patients can tough out a gentle physician's lifting up of the cuticle, but I prefer to perform all drainage procedures under a digital block with long-acting bupivicaine. The only disadvantage of the long-acting anesthetic is that the finger should not be individually soaked in hot water until sensation returns to avoid thermal injury. (One can get around this by soaking an adjacent unanesthetized finger at the same time.)

Following digital block, the eponychium is separated from the underlying nail, exposing the potential space that is now filled with pus. This is done atraumatically by advancing a scalpel blade, scissors blade, or 18-gauge needle into the nail fold. The instrument is always kept parallel to the nail, so the skin is not actually incised. One gently lifts the eponychium until there is spontaneous flow of the pus that has collected in the nail fold. Once the eponychium is loose, a blunt instrument, such as a hemostat (and not the scalpel) finishes the job by being swept from side to side at the base of the infection to break up loculations. Irrigation of the cavity is probably not necessary.

Figure. F
Figure. F:
ollowing drainage, a loose gauze pack, such as betadine-soaked packing gauze, is inserted under the eponychium to fill the cavity left by draining the pus. Note that the finger tourniquet allows the clinician to better assess the adequacy of the drainage procedure because bleeding does not obscure the operative site.

A loose gauze pack is then placed in the eponychial fold to ensure continued drainage. I advise the patient to begin soaking (with the pack in place) as soon as they get home. I have discovered that many of my colleagues bandage this infected area, and tell the patient not to touch it for two days. In my opinion, this is a big mistake that only enhances skin maceration and bacterial growth.

Patients should be rechecked within 24 to 36 hours. The initial pack is then removed and the wound inspected. Packing can usually be removed without anesthesia after soaking in peroxide to soften the gauze. If the infection is well on its way to recovery, additional packing is not needed. If there is still considerable drainage, the nail fold may be irrigated, reopened, and packed a second time. This may require another digital block.

Some patients can remove the second pack themselves (after soaking at home) in another 24 hours, and follow-up is determined by clinical response or degree of patient anxiety. If the periungual skin has been under significant pressure, an outer layer of skin may blister or peel within 24 to 48 hours of drainage. This is not serious, but the dead skin should be debrided. Following removal of the packing, usually a small cavity remains open. It can be filled easily with an antibiotic ointment and covered with a large Band-Aid or dressing.

Soaking should continue for another two to three days after the pack has been removed. Once the paronychia has healed, the patient is advised to keep the periungual area dry and to use skin softeners to avoid cracking. I also advise against biting the fingernails or removing hangnails with the teeth.

X-rays, lab tests, and cultures are not generally necessary, even if pus is obtained. It's probably impossible to convince some physicians that abscess cultures are not necessary, but there's voluminous data to support this suggestion. Complete cure is expected in a few days. Further testing, cultures, and fungal scrapings may be warranted in the immunocompromised patient or in those who have poor response to therapy or suffer recurrences.

There is no evidence that oral antibiotics are necessary for the treatment of uncomplicated, easily drained paronychias in patients with normal immune systems. Although I may prescribe three to four days of antibiotic coverage to complement local care if there is significant induration proximal to the paronychia, 10 days of the newest third-generation cephalosporin or some similarly exotic recently introduced antibiotic is clearly unwarranted.

Plain old penicillin appears to be a reasonable first choice in most cases based on culture data (see following discussion), but in my experience patients seem to do well given any antibiotic. The antibiotic debate is unresolved, but the key is to use reasonable clinical judgment and not be dogmatic. If $25 of an antibiotic will prevent a revisit, the cost is certainly justified. Prescribing inexpensive penicillin or erythromycin is a theoretical acceptable compromise.

When the packing was removed at 36 hours post I&D, the outer layer of skin that was under pressure by the trapped pus was obviously nonviable and easily removed. Although initially disconcerting to the patient, this wound site was of no clinical consequence. At this point, hot soaks and bacitracin dressings were continued for a few days. This wound healed in one week without consequences.

Patients should be relatively asymptomatic in three to five days. Those who have recurrent problems or do not respond adequately, especially if pus was drained, should be considered to have complicated infections, a possible foreign body, or an unusual organism, and should be referred to a consultant. It's probably a mistake to follow patients with numerous members of an ED group for a number of weeks trying to cure a smoldering infection with each new doctor's favorite regimen. The recognized complications of a neglected paronychia are osteomyelitis or extension to the flexor tendon (tenosynovitis) or fat pad area (felon). Occasionally patients must be admitted for intravenous antibiotics or more extensive surgery, but such cases should be the exception.

Importantly, patients who fail to respond should be considered to have a herpes infection, termed the herpetic whitlow, or a fungal cause. These variations are usually clinically evident after a few days of no response. Herpetic infections will be discussed in detail next month, but suffice it to say that patients with herpetic infections of the mouth or genital area, concomitant with their paronychia, or a paronychia associated with vesicles on the periungual skin, should be considered to have this viral infection. Although it's of no great clinical consequence, herpetic infections are slower to resolve, and should not be treated with overly aggressive incisions or antibiotics. To emphasize, patients with skin infections that do not respond as expected should be investigated for unusual organisms, osteomyelitis, possible cancer, occult foreign bodies, or immunocompromise in the host (especially AIDS).

Aerobic and Anaerobic Microbiology of Paronychia, Brook I, Ann Emerg Med 1990;19:994

This report analyzes the microbiology of 28 patients who underwent surgical drainage for a paronychia of the finger. Patients ranged in age from 19 to 48 years, and there were 20 women and eight men. Aerobic and anaerobic cultures were obtained from the infected area by swabbing the wound or by directly aspirating fluid. Careful culturing techniques were done to ensure optimal anaerobic growth. A variety of culture media was used to ensure maximum recovery of fastidious organisms.

An average of 2.6 isolates per specimen was identified, with 72 separate organisms being recovered from the 28 specimens. A pure culture of a single anaerobic organism was present in only five (18%) patients, and a pure culture of a single aerobe in eight (29%). Mixed aerobic and anaerobic cultures were the norm, and were found in 54 percent. There was no consistent pattern or combination of organisms. In four cases, Candida albicans was cultured, and Eikenella corrodens was isolated in three patients.

Based on culture results, the authors conclude that paronychias are usually infected with a number of mixed aerobic and anaerobic organisms. The presence of aerobic bacteria is thought to be due to direct inoculation of the fingers with mouth flora, as can occur in biting the fingernails or sucking the fingertips. The organisms recovered were those that commonly colonize either the oral cavity or the skin. Interestingly, a few cases of E. corrodens were discovered. This organism accounts for some cases of human bite infections, and is normal flora of the mouth.

The author attempted to discuss the proper selection of antibiotics for these mixed infections, but could not recommend an ideal empiric choice. Most pathogens isolated should theoretically respond to clindamycin or amoxicilin/clavulanate. The presence of anaerobic bacteria, some Gram negatives, and E. corrodens makes first-generation cephalosporins a less than perfect choice. It is recommended that cultures be done if antibiotic therapy is contemplated.

Comment: Most textbooks state that staphylococci are the most common pathogen found in paronychias. However, staph (aureus orepidermidis) was isolated in this study in only two of 72 cultures. Clearly such infections are polymicrobial, including aerobes, anaerobes, and both gram positive and gram negative cocci and bacilli. In a related study of the bacteriology of paronychia in children by the same author (Am J Surg 1981;141:703), similar results were reported. Specimens from the paronychia of 33 children demonstrated a 20 percent incidence of pure anaerobic cultures, 27 percent pure aerobic cultures, and 46 percent mixed aerobic and anaerobic flora. In that report, there were 3.6 isolates per specimen. Numerous organisms were identified, including Candida albicans.

Certainly no single antibiotic will provide complete coverage for the array of bacterial and fungal pathogens cultured from paronychias. Because the vast majority is cured easily with simple drainage procedures and local treatment, systemic antibiotics probably play no role in the cure. In fact, antibiotics are unlikely to be curative if one considers the polymicrobial nature of the infection. Just because someone receives 10 days of treatment with an expensive antibiotic and the paronychia goes away, the favorable response does not prove that the antibiotics were helpful.

Because there are no prospective studies evaluating the true role of antibiotic treatment of paronychia and no antibiotic will cover 72 pathogens, I would interpret the data in this study to argue clearly against the routine use of antibiotics. Likewise, I see no reason to culture paronychial pus routinely; how does one interpret a report of three organisms, all with a different antibiotic sensitivity?

This infection is essentially an abscess, and there are good data demonstrating that antibiotics are of no value for the treatment of cutaneous abscesses that are adequately drained. In immunocompromised patients, particularly those with diabetics, peripheral vascular disease, or AIDS, cancer, or recurrent paronychia, a culture and antibiotics are warranted. It's also possible that antibiotics will short circuit an early paronychia that is still only a cellulitis and not yet a drainable abscess, so antibiotics may play a yet undefined role in the early phase of the infection.

I disagree with the authors of this study; I would not routinely culture a paronychia just because I was prescribing antibiotics. Unless one does aerobic, anaerobic, fungal, and viral cultures, the full benefit from this laboratory investigation will not be gleaned, so why be only half-scientific? It is impossible to choose prospectively or empirically the proper antibiotic in all cases, but it seems reasonable to choose penicillin, erythromycin, clindamycin or ampicillin/clavunate if one opts for treatment. Because anaerobes are so common, penicillin may not be a bad choice, but the data just are not available. There's always the concern that penicillin will not cover staph, but staph infections are rare, and anaerobes and strep species are more common isolates.

Evidence linking E. corrodens to a paronychia is interesting and thought-provoking. A gram negative rod that is normal oral flora, E. corrodens has been reported to cause nasty infections from human bites. This organism has an unusual sensitivity. It's sensitive to penicillin and ampicillin, but resistant to oxacillin, methicillin, nafcillin, clindamycin, and often to cephalosporins, perhaps another reason to choose penicillin. Suffice it to say that long courses of expensive antibiotics are not routinely required, and should never be substituted for drainage follow-up or further investigation. This area is ripe for prospective multicenter research from some energetic emergency physicians.

A chronic paronychia most often represents an occupational problem or a fungal infection. Repeated exposure to trauma, water, or irritating chemicals can prolong healing of a paronychia. C. albicans is the most common fungal pathogen. Candida can be cultured or diagnosed from a potassium hydroxide slide test, and it may cause physical changes in the fingernail. Consider underlying diabetes or immunosuppression in patients with proven Candida paronychia. Mycostatic cream is curative, but infections are difficult to eradicate and therapy must be used for a number of weeks. It's best to refer such patients to a dermatologist.

© 2003 Lippincott Williams & Wilkins, Inc.