What is Blistering Distal Dactylitis?
Blistering distal dactylitis (BDD) is an infection caused by bacteria, which shows up as liquid-filled bumps mainly on the fingers. This is commonly seen in children. Typically, BDD appears on the soft underside of the tip of the fingers, presenting as medium-to-large painless blisters filled with thin, white fluid. When this fluid is tested, the most commonly found bacteria is a type called Group A beta-hemolytic Streptococcus.
What Causes Blistering Distal Dactylitis?
Bullous impetigo is usually caused by an infection with a specific type of bacteria known as group A beta-hemolytic Streptococcus. However, there are also other kinds of bacteria, such as Group B Streptococcus, Staphylococcus aureus, and a tougher strain of Staphylococcus aureus that’s resistant to certain antibiotics (known as MRSA), that can cause this condition.
The bacteria generally get into the skin through open wounds. These could be from bug bites, cuts, scrapes, burns, or abnormal skin around nails. In some cases, bullous impetigo can be caused by a combination of different bacterial and viral infections.
Based on the symptoms and bacteria involved, some experts categorize bullous impetigo as a version of another skin condition called bullous impetigo. The presence of several fluid-filled blisters (or “bullae”) is a sign that the Staphylococcus aureus bacteria is the cause.
Risk Factors and Frequency for Blistering Distal Dactylitis
Children between the ages of 2 and 16 are usually the ones who get BDD. However, there have been cases of BDD in children younger than 1 and also in adults. People with weakened immune systems like those with HIV, and people with diabetes have also been reported to get BDD.
Signs and Symptoms of Blistering Distal Dactylitis
Dactylitis refers to the swelling of a finger or toe. This condition can arise from various factors, which may be inflammatory, infectious, or noninfectious. Sometimes, this inflammation affects not just the fingers, but also the toes and the surfaces of the hand closer to the wrist, in which case, it’s often referred to as “blistering dactylitis.” The inflammation can solely impact the bone, as seen in cases like sickle cell dactylitis and syphilitic dactylitis, or it can affect the bone, soft tissues, and skin, like in tuberculous dactylitis and sarcoid dactylitis. Blistering Dactylitis, on the other hand, affects only the skin. Interestingly, blistering dactylitis can be due to the presence of extra-thick skin on palms and soles.
The medical history of the patient can provide clues to identify the cause of this condition. For instance, a history of thumb sucking, insect bites, or exposure to chemicals or heat could potentially differentiate other conditions from blistering dactylitis. There was one documented case of blistering dactylitis appearing after an animal bite. The condition manifests as a single, or sometimes multiple, oval-shaped blisters filled with a cloudy fluid on a red base, usually on the inside part of the finger. These blisters may spread to include the sides of the fingernail.
The size of these skin lesions can vary from 10 mm to 30 mm. Before the blisters appear, a darkening of the skin might be noticed. Generally, there is no evidence of lymphangitis (inflammation of the lymph vessels), lymphadenopathy (abnormally enlarged lymph nodes), and fever. However, some patients may report pain and tenderness in the affected area and may have a fever. Over time, these blisters develop into bullae (large blister-like lesions) with central skin erosions or simply erode with layers of skin sticking to it.
In some cases, accompanying bacterial infections of the eye, upper respiratory tract, and gastrointestinal or genitourinary tract have been reported, which underscores the need for systemic antibiotic treatment.
Testing for Blistering Distal Dactylitis
If you have a blister, the doctor may choose to collect some fluid from it by either pricking it or removing the top. This fluid is then examined under a microscope, and a test known as a bacterial culture is done to identify the bacteria present. Based on the results, the most suitable antibiotics can be selected for your treatment.
The main types of bacteria they will be looking out for are Staphylococci and Streptococci. They are both categorized as gram-positive cocci, which means they appear blue or purple under a special dye in the lab. An interesting difference between them is their form; Staphylococci make little clumps, while Streptococci form long chains. To tell them apart, a test called the catalase test is used, as only the Staphylococci bacteria can produce an enzyme called catalase.
Treatment Options for Blistering Distal Dactylitis
If you have a tense, sore blister (or bulla), your doctor might suggest draining the fluid from it. This is typically done by making a small cut or using a sterile needle to deflate the blister, then applying a wet dressing for healing. It is important to keep the top layer of the blister intact as it acts like a natural bandage.
Using wet compresses can also help speed up the healing process. After applying the compress, a topical antibiotic is typically applied to the blister to fight off any potential infections.
There’s a chance that your blister might not be an isolated issue and could be linked to a hidden bacterial infection in your respiratory or digestive system. Due to this possibility, your doctor may recommend taking antibiotics to treat the infection and the blister.
In most cases, using only over-the-counter antibiotics isn’t enough. Prescription antibiotics are usually necessary to stop new blisters from forming, prevent the infection from spreading to other parts of the body, and reduce the chances of it spreading to other people. Certain antibiotics, like flucloxacillin, dicloxacillin, and cloxacillin, are particularly effective because they can fight bacteria that are resistant to penicillin.
If your blister tests positive for MRSA, a specific type of drug-resistant bacteria, and you start showing signs of a system-wide infection, your doctor may need to give you vancomycin through an IV line. After starting antibiotics, you should see an improvement in your symptoms within 24 to 48 hours. However, treatment needs to continue for 7 to 14 days, based on your response to the medication.
If you’re not feeling better after two days of taking antibiotics, if your symptoms are getting worse, or if you’re starting to show signs of a more widespread infection, you may need to go back to the doctor. They will likely retest you and adjust your treatment plan based on the results.
What else can Blistering Distal Dactylitis be?
When trying to diagnose BDD (bacterial diseases of the dermis), doctors need to consider other conditions that might present with similar symptoms. These could include:
- Herpetic whitlow: This is a herpes infection that can look like BDD, with grouped fluid-filled blisters. The blisters from BDD are usually larger and certain tests can confirm if it’s herpetic whitlow.
- Friction blisters: These blisters could be caused by things like thumb sucking or new shoes. They can sometimes look like BDD.
- Paronychia: This condition causes swelling around the nails and deformities with the nails themselves. It can also present with blisters that are located further away from the tip of the finger than BDD.
- Burns: Burns can be distinguished from BDD by examining the fluid in the blisters and the type of bacteria present.
- Insect bites: These tend to cause more itching than pain, helping to differentiate them from BDD.
- Contact dermatitis: This is a skin irritation caused by contact with certain substances. It can be confirmed with additional tests.
- Pompholyx: This condition causes recurring, deep blisters with intense itching or burning. These can also look like BDD, especially if the patient has other skin infections, sweats excessively, or has been in contact with irritants.
- Bullous impetigo: Impetigo can also present with blisters, but they tend to be more on the surface of the skin.
- Blistering disorders: Certain disorders like epidermolysis bullosa simplex (EBS) and localized bullous pemphigoid (BP) can cause blisters at sites of physical trauma. These conditions can be confirmed through additional tests.
Each of these conditions may look similar to BDD, but there are specific signs, symptoms, and tests that can help doctors make the correct diagnosis.
What to expect with Blistering Distal Dactylitis
Most of the time, BDD, which stands for bacterial digital dermatitis, can be quickly cleared up using the right antibiotics and wound care, without any lingering issues. However, there have been cases where BDD has led to the removal of a finger, making it extremely important to treat these infections with a serious approach. This is especially true for individuals who have HIV. In general though, it’s rare for BDD to come back after it has been treated.
Possible Complications When Diagnosed with Blistering Distal Dactylitis
Body-focused repetitive behavior disorder (BDD) is usually straightforward and most often gets better with appropriate treatment. There are reports of it coming back in cases like ingrown toenails. More serious cases of BDD have also been reported, such as inflammation of the bone and self-amputation, in an HIV-positive infant who did not get the proper treatment until two months after the symptoms began. However, no cases of kidney problems caused by streptococcal bacteria, known as post-streptococcal glomerulonephritis, have been reported in medical research.
Common scenarios with BDD:
- Can improve with appropriate treatment
- Possible recurrence, as in cases of ingrown toenails
- Serious cases like bone inflammation and self-amputation possible, especially without timely treatment
- No reported cases of kidney trouble triggered by bacterial infections
Preventing Blistering Distal Dactylitis
Patients need to quickly recognize the tight, swollen blisters that specifically occur on the fleshy part under the tip of the fingers or toes. These blisters are a sign of an infection that needs medical attention. If this infection is not identified and treated quickly, it can possibly lead to serious problems.
