Infection of a finger is a common problem and can range from mild and treatable at home, to a serious problem requiring urgent surgical intervention. Failure to properly treat these infections in an appropriate and timely fashion can result in permanent disability or loss of the finger.
Early recognition of finger infections will help prevent most of the serious outcomes. These infections come in several characteristic forms:
Paronychia: A paronychia is an infection of the finger that involves the tissue around the edges of the fingernail. This infection is usually superficial and localized to the soft tissue adjacent to the fingernail. This is the most common bacterial infection of the hand, and is frequently associated with a simple hangnail that the person attempts to bite off permitting bacteria of the skin or mouth to gain a foothold. Paronychia are characterized by swelling, redness, pus formation, and pain in the soft tissue around, and possibly extending under, the nail plate. In chronic paronychia, the responsible organism may be a yeast or fungus.
Felon: A felon is an infection of the soft pad, or pulp, of the fingertip. This infection is located in the fingertip pad and soft tissue associated with it, and is usually the result of a puncture wound. The fingertip is reinforced with connective tissue walls, or septae, that stabilize the pad. During infection, swelling or pus is trapped in these small compartments under pressure; this provokes extreme throbbing & discomfort. There is firm swelling, redness, heat, and an accumulation of pus may be visible.
Herpetic whitlow: A herpetic whitlow is an infection of the fingertip area caused by the herpes virus and is the most common viral infection of the hand. This infection is often misdiagnosed as a paronychia or felon. Small fluid filled vesicles or blister like lesions develop, and these are often more painful than would be expected from the physical presentation.
Cellulitis: This is a superficial infection of the skin and underlying tissue. It usually does not involve deeper structures of the hand or finger.
Infectious flexor tenosynovitis: This infection involves the tendon sheaths surrounding the tendons, which flex, or bend, the digits. Pus can be trapped within these sheaths, and serious damage can occur endangering future motion and even loss of the digit.
The diagnosis will start with a detailed history and physical exam. Coexisting problems such as diabetes or circulatory problems can complicate the infection and the treatment. Specific information may help pinpoint the type of finger infection:
Paronychia: A history of nail biting may aid the diagnosis.
Felon: A history of a puncture wound or cut will aid the diagnosis. This would include a plant thorn. The doctor may obtain an x-ray to look for involvement of the bone or possible foreign body.
Herpetic whitlow: A history of contact with body fluids that may contain the herpes virus will aid the diagnosis. The diagnosis can often be made from the history and the appearance of the lesions. The presence of a clear fluid from the wounds may indicate a viral infection rather than a bacterial infection. A sample of the fluid may be analyzed by a Tzank smear, which will identify certain cells, indicating a viral cause.
Cellulitis: The doctor will need to consider other causes that may look similar such as gout, various rashes, insect sting, burns, or blood clot before the final diagnosis is made. An x-ray may be obtained to look for a foreign body or gas formation that would indicate a type of serious cellulitis.
Flexor tenosynovitis: A history of a puncture wound or cut will aid the diagnosis. The presence of the 4 Kanavel signs is a strong diagnostic aid.
A small, simple paronychia may respond to frequent warm water soaks and elevation of the hand. However, if no improvement is noticed in 1–2 days, you should see your doctor at once.
The mainstay of treatment for finger infections is antibiotics and proper wound care. The proper wound care varies for each of the different infections. This can range from a simple incision and drainage of the wound to an extensive surgical exploration of the wound to remove as much infected material as possible.
Some of the infections can be treated as an outpatient, but several may require inpatient treatment and IV antibiotics. Because the organisms that cause these infections are similar, many of the same types of antibiotics may be used.
Paronychia: If a collection of pus is present, it will need to be drained. This may be done in several different ways. A small incision can be made directly over the collection, the cuticle can be raised, or a portion of the nail can be removed if need be. The procedure should be largely pain free, or a local anesthetic can be used where needed. Typically, an oral antibiotic will be prescribed along with instructions for wound care.
Felon: Often incision and drainage is required because the infection is trapped under pressure within the multiple compartments of the fingertip pad. Usually an incision will be made on one or both sides of the fingertip. The doctor will then insert an instrument into the wound and break up the compartments to aid in the drainage followed by generous fluid flushing, and often a small drain will be placed into the wound to aid the initial drainage. These infections will require antibiotics. The wound will then require specific home care as prescribed by your doctor.
Herpetic whitlow: Antiviral drugs such as acyclovir (Zovirax) may shorten the duration of illness. Pain medication is often needed. The wound must be properly protected to prevent a secondary bacterial infection and to prevent you from infecting other sites on your body or other people. Incision and drainage is not recommended as it may actually delay healing.
Cellulitis: This infection is superficial, and oral antibiotics are usually sufficient. If the area is extensive or your immune system is weakened, then you may be treated in the hospital with IV antibiotics.
Flexor tenosynovitis: This is a surgical emergency and will require rapid treatment, surgical decompression and irrigation, and early treatment with IV antibiotics. Because of the intricate nature of the fingers and hands, a hand surgeon will usually perform this procedure. After surgery, several days of IV antibiotics will be required followed by a course of oral antibiotics
If these infections are treated early and properly, the prognosis for full recovery is good. However, if treatment is delayed, or if the infection is severe, the prognosis can be much less optimistic.
-- Lee, MD