Bullous Impetigo is a cutaneous condition that characteristically occurs in the newborn, and is caused by a bacterial infection, presenting with bullae.

It can be caused by Exfoliative toxin A. The phyogenic superficial infection can be divided into two other subdivisions; Impetigo

Impetigo

Impetigo is a highly contagious bacterial skin infection most common among pre-school children. People who play close contact sports such as rugby, American football and wrestling are also susceptible, regardless of age. Impetigo is not as common in adults. The name derives from the Latin impetere...

, and non-Bullous impetigo. Bullous impetigo is caused by Staphylococcus aureus, which produces exfoliative toxins, where as impetigo is caused by either Staphylococcus aureus

Staphylococcus aureus

Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

, or Streptococcus

Streptococcus

Streptococcus is a genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the lactic acid bacteria group. Cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek στρεπτος streptos, meaning...

. Bullous Impetigo can cause deaths in fewer than 3% of infected children, but up to a 60% death rate in adults. 30% of all Impetigo cases are related to Bullous impetigo.

S. aureus Pathogenesis

A phyogenic non-motile Gram-positive cocci which forms into grape like clusters. Just like other forms of staph, S. aureus has a variety of virulence factors which include surface proteins involved in adherence, secretion of enzymes that degrade proteins, and secrete toxins which damage the host’s cells.
S. aureus expresses surface receptors for fibrinogen

Fibrinogen

Fibrinogen is a soluble plasma glycoprotein, synthesised by the liver, that is converted by thrombin into fibrin during blood coagulation. This is achieved through processes in the coagulation cascade that activate the zymogen prothrombin to the serine protease thrombin, which is responsible for...

, fibronectin

Fibronectin

Fibronectin is a high-molecular weight glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. In addition to integrins, fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans...

, and vitronectin

Vitronectin

Vitronectin also known as VTN is a protein that in humans is encoded by the VTN gene.The protein encoded by this gene is a member of the pexin family...

. These surface receptors allow a bridge to be formed which binds to host endothelial cells. Lipases allow for the degradation of lipids on the skin surface and its expression can be directly correlated with its ability of the bacteria to produce abscesses.

Bullous impetigo Pathogenesis

Exfoliating toxins are serine proteases that specifically bind to and cleave desmoglein 1 (Dsg1). Previous studies suggested that exfoliating toxins bind to gangliosides, causing a release of protease by keratinocytes acting as superantigens in stimulating the skin’s immune system. A more recent proposal states there are three known exfoliating toxins; ETA, ETB, and ETD which act as a glutamic acid-specific serine protease with concentrated specificity. Which results in the cleavage of human Dsg1 at a unique site after glutamic acid residues causing deactivation. Proteolysis of the peptide bond leading up to the dysfunction of Dsg1 and the desmosome allows for an understanding as to why the bullous forms, making the peptide bond crucial for proper function if Dsg1.

symptoms

Bullous impetigo can appear around the diaper region, axilla, or neck. The bacteria causes for a toxin to be produced with reduced cell-to-cell stickiness (adhesion), causing for the top layer of skin (epidermis), and lower layer of skin (dermis) top separate. Vesicles rapidly enlarge and form the bullae which is a blister more than 5mm across. Bullae is also known as Staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome, SSSS, also known as Pemphigus neonatorum or Ritter's disease, or Localized bullous impetigo is a dermatological condition caused by Staphylococcus aureus.-Pathophysiology:...

. Other associated symptoms are itching, swelling of nearby glands, fever and diarrhea. It should also be noted that pain is very rare.

Diagnosis

Observing the skins physical appearance, or swabbing a culture of the lesion for S. aureus. Nasal swabs from the patient’s immediate family members are necessary to identify them as being asymptomatic nasal carriers of S. aureus.

Long term effects:
Once the scabs on the bullous have fallen off scarring is very minimal. Possible long term effects are kidney disease.

Uncommon Bullous with other variants

Erythema multiform, systemic lupus erythematosus

Systemic lupus erythematosus

Systemic lupus erythematosus , often abbreviated to SLE or lupus, is a systemic autoimmune disease that can affect any part of the body. As occurs in other autoimmune diseases, the immune system attacks the body's cells and tissue, resulting in inflammation and tissue damage...

, Stevens-johnson syndrome

Stevens-Johnson syndrome

Stevens–Johnson syndrome and toxic epidermal necrolysis are two forms of a life-threatening skin condition, in which cell death causes the epidermis to separate from the dermis. The syndrome is thought to be a hypersensitivity complex that affects the skin and the mucous membranes...

, pemphigous vulgaris

Where outbreaks can occur

Hospital wards and, nurseries, and can be passed from person to person. There for it is advised that the patient try to limit as much human contact as possible to limit transmission of infection.

Infectious Period

After 48 hours the disease is considered no longer contagious assuming the proper antibiotic treatments have been administered. Antibiotic treatment typically last 7–10 days, and although highly effective some cases were Methicillin resistant S.aureus.

Management

Antibiotic creams are only good enough for the initial disorder because they are only good enough for destroying the bacteria and curing the infection. Such prescribed ointments are Neosporin

Neosporin

Neosporin is the product branding & formulas now owned by Johnson & Johnson of an antibiotic over-the-counter topical created under Warner-Lambert Consumer Healthcare, now a part of Pfizer...

, Fusidic Acid

Fusidic acid

Fusidic acid is a bacteriostatic antibiotic that is often used topically in creams and eyedrops, but may also be given systemically as tablets or injections...

, Chlorampheniol and Mupirocin

Mupirocin

Mupirocin is an antibiotic originally isolated from Pseudomonas fluorescens NCIMB 10586, developed by Beecham....

. If Bullous Impetigo is diagnosed in the later stages oral medication such as Flucloxacillin

Flucloxacillin

Flucloxacillin or floxacillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. Unlike other penicillins, flucloxacillin has activity against beta-lactamase-producing organisms such as Staphylococcus...

, Erythromycin

Erythromycin

Erythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and...

, or Dicloxacillin

Dicloxacillin

Dicloxacillin is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It is used to treat infections caused by susceptible Gram-positive bacteria. It is active against beta-lactamase-producing organisms such as Staphylococcus aureus, which would otherwise be resistant to most...

 may be prescribed.

Home Remedies:
For those who rather try natural remedies the blisters can be washed with an antibacterial soap several times a day, to help remove any crust and prevent itchiness of the skin due to drainage at the site. The other natural remedy which can be tried is mixing a tablespoon of white vinegar with a pint of water several times a day. The vinegar, water solution helps loosen up scabs making removal easy.

Prevention

Keeping the child’s finger nails clipped to avoid scratching of the skin which may introduce S. aureus. An avoid using towels and other object that might have come in to contact with another infected child.

Histology of normal epidermal tissue through H&E

Composed of four layers, Stratum basale, Stratum spinosum

Stratum spinosum

The stratum spinosum is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer is also referred to as the "spinous" or "prickle-cell" layer. This appearance is due to desmosomal connections of adjacent cells. Keratinization begins in the stratum spinosum....

, Stratum granulosum

Stratum granulosum

The stratum granulosum is a thin layer of cells in the epidermis. Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer...

, and Stratum corneum

Stratum corneum

The stratum corneum is the outermost layer of the epidermis, consisting of dead cells that lack nuclei and organelles. The purpose of the stratum corneum is to form a barrier to protect underlying tissue from infection, dehydration, chemicals and mechanical stress...

. Normal pathology of the skin, displaying the dermis which is attached to underlying loose connective tissue which subsequently contains primary adipose tissue.

Histology of Bullous Impetigo through H&E

The cleavage plane can be found either subcorneal or within the upper stratum granulosum. The roof of the pustule is parakeratotic stratum cirneum, and the floor is formed of keratinocytes, which may or may not be acantholytic. Neutrophils begin to fill the pustule. Toxins are produced by S. aureus and target desmoglein, which is a desmosomal cell-cell adhesion molecule that is found in the upper levels of the epidermis. Stratum Lucidum is no longer present and can be seen infiltrated with inflammatory cells.This correlates with the subcorneal localization of the bullae.