An Overview of Paronychia

Symptoms, Causes, and Treatment of Nail Infections

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The hand is a wonderful instrument wherein form and function are intricately related. With such detailed anatomy, there are plenty of compartments, spaces, and folds where bacteria can hide and fester.

Although you may be unfamiliar with the term, you might have experienced a paronychia in the past. Paronychia is a nail infection that affects the lateral nail fold and perionychium (the tissue surrounding the nail). In other words, a paronychia is an infection of the soft tissue bordering the nail itself and usually affects either the vertical portions of the nail or the horizontal portion of the nail.

Symptoms

Paronychia typically begins with a few days of pain, tenderness, and swelling of the finger. followed by a collection of pus under the surface of the skin and/or nail. This will eventually form an abscess from which pus can be drained.

Causes

You can get a paronychia secondary to a minor injury like biting your nails, pulling a hangnail, biting a hangnail, or pushing the cuticles back during a manicure—in short, any type of trauma that introduces bacteria into the fleshy part of your finger.

It may come as a surprise that the most infections originate from the human mouth; thus, bacteria isolated from paronychia often include all types of bacteria, both aerobic and anaerobic. Chief among these bugs are species of Staphylococcus aureus and Streptococcus species.

Paronychia is typically painful and can occur in healthy people. However, immunocompromised people (such as those with HIV) may experience hard-to-treat chronic paronychia. Furthermore, people with diabetes can get chronic paronychia caused by fungi like Candida albicans. Dishwashers and housekeepers frequently develop chronic paronychia when ongoing exposure to cleaning solutions and moisture compromises the nail and allows for infiltration by fungi.

Diagnosis

The diagnosis of paronychia is based on a physical exam. Cultures aren't usually needed. Sometimes an X-ray may be used to look for a foreign body or evidence of bone infection (osteomyelitis), the latter of which may occur when paronychia is caused by a chronic fungal infection.

Treatment

Paronychia is typically treated with antibiotics, although milder acute cases can often resolve on their own without treatment.

The antibiotics most commonly used to treat paronychia are Bactrim (TMP/SMX) and a cephalosporin named Keflex (cephalexin). If anaerobic bacteria is suspected, Evoclin (clindamycin) or Augmentin (amoxicillin-clavulanate) may be given with Bactrim. Bactrim is especially effective against drug-resistant bacteria, including methicillin-resistant Staphylococcus aureus. 

In severe cases, a physician can elevate the hardened bit of skin bordering the nail itself (eponychium) so that pus can be drained. Alternatively, the doctor can directly slice into the fluctuant portion of the infection; this procedure is no different from draining any other type of abscess or boil.

Because paronychia are pretty superficial, anesthesia is unnecessary to drain most infections of pus. In fact, anesthetizing the area will likely result in added pain with little benefit.

Sometimes paronychia can extend under part of the nail. In these cases, either part or all the nail needs to be removed. A paronychia that is left untreated can sometimes surround the entire nail margin and result in a "floating" nail.

After a paronychia is drained of pus, there is usually no need for antibiotics. However, if the paronychia is accompanied by localized cellulitis or skin infection, then antibiotics are needed to treat the skin infection.

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