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Diaper Rash |
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 Diaper rash (US) or nappy rash (UK), is a generic
term applied to skin rashes in the diaper area that are caused by a various skin
disorders.
Generic rash or irritant diaper dermatitis (IDD) is characterized by joined
patches of erythema and scaling mainly seen on the convex surfaces, with the
skin folds spared.
Diaper dermatitis with secondary bacterial or fungal involvement tends to spread
to concave surfaces (i.e. skin folds), as well as convex surfaces, and often
exhibits a central red, beefy erythema with satellite pustules around the border
(Hockenberry, 2003).
Differential Diagnosis
Other rashes that often occur in the diaper area include Seborrheic dermatitis
and Atopic dermatitis. Both Seborrheic and Atopic dermatitis require
individualized treatment and are not the subject of this article.
Seborrheic dermatitis, typified by oily, thick yellowish scales, is most
commonly seen on the scalp (cradle cap) but can also appear in the inguinal
folds.
Atopic dermatitis, or eczema, is associated with allergic reaction, often
hereditary. This class of rashes may appear anywhere on the body and is
characterized by intense itchiness.
Causes
Irritant diaper dermatitis develops when skin is exposed to prolonged wetness,
increased skin pH caused by urine and feces, and resulting breakdown of the
stratum corneum, or outermost layer of the skin. In adults, the stratum corneum
is composed of 25 to 30 layers of flattened dead keratinocytes, which are
continuously shed and replaced from below. These dead cells are interlay with
lipids secreted by the stratum granulosum just underneath, which help to make
this layer of the skin a waterproof barrier. The stratum corneum's function is
to reduce water loss, repel water, protect deeper layers of the skin from injury
and to repel microbial invasion of the skin (Tortora and Grabowski, 2003). In
infants, this layer of the skin is much thinner and more easily disrupted.
Urine's Effects
Although wetness alone macerates the skin, softening the stratum corneum and
greatly increasing susceptibility to friction injury, urine has an additional
impact on skin integrity because of its effect on skin pH. While studies show
that ammonia alone is only a mild skin irritant, when urea breaks down in the
presence of fecal urease it increases skin pH, which in turn promotes the
activity of fecal enzymes such as protease and lipase (Atherton, 2004; Wolf,
Wolf, Tuzun and Tuzun, 2001). These fecal enzymes increase the skin's
permeability to bile salts and act as irritants in and of themselves.
Diet's Effects
The interaction between fecal enzyme activity and IDD explains the observation
that infant diet and diaper rash are linked, since fecal enzymes are in turn
affected by diet. Breast-fed babies, for example, have a lower incidence of
diaper rash, possibly because their stools have lower pH and lower enzymatic
activity (Hockenberry, 2003). Diaper rash is also most likely to be diagnosed in
infants 8–12 months old, perhaps in response to an increase in eating solid
foods and dietary changes around that age that affect fecal composition. Any
time an infant’s diet undergoes a significant change (i.e. from breast milk to
formula or from milk to solids) there appears to be an increased likelihood of
diaper rash (Atherton and Mills, 2004).
The link between feces and IDD is also apparent in the observation that infants
are more susceptible to developing diaper rash after treatment with antibiotics,
which affect the intestinal microflora (Borkowski, 2004; Gupta & Skinner, 2004).
Also, there is an increased incidence of diaper rash in infants who have
suffered from diarrhea in the previous 48 hours, which may be due to the fact
that fecal enzymes such as lipase and protease are more active in feces which
have passed rapidly through the gastrointestinal tract (Atherton, 2004).
Secondary Infections
The significance of secondary infection in IDD remains controversial. Atherton
contends that, “Candida albicans can only be isolated from a minority of IDD
cases; in many cases this is a reflection of antibiotic therapy. It has also
been established that bacterial infection does not play a substantial part in
the development of IDD.” (Atherton, 2004, p. 646).
However, there is little argument that once the stratum corneum has been damaged
by a combination of physical and chemical factors, the skin is necessarily more
vulnerable to secondary infections by bacteria and fungi. In analyzing swab
samples at the perianal, inguinal and oral areas of 76 infants, Ferrazzini et
al. (2003) found that colonization with Candida albicans was significantly more
likely in children with symptomatic diaper rash than without. Staphylococcus
aureus was also present more frequently in symptomatic than in healthy infants,
but the difference was not statistically significant. A wide variety of other
infections has been reported on occasion, including Proteus mirabilis,
enterococci and Pseudomonas aeruginosa, but it appears that Candida is the most
common opportunistic invader in diaper areas (Ferrazzini et al., 2003; Ward et
al., 2000).
Although apparently healthy infants sometimes culture positive for Candida and
other organisms without exhibiting any symptoms, there does seem to be a
positive correlation between the severity of the diaper rash noted and the
likelihood of secondary involvement (Ferrazzini et al., 2003; Gupta & Skinner,
2004; Wolf et al., 2001).
Treatments
The most effective treatment, although not always the most practical one, is to
discontinue use of diapers, allowing the affected skin to air out. Other
commonly recommended remedies include oil-based protectants, often using various
over-the-counter "diaper creams", but sometimes people use petroleum jelly and
shark liver oil or cod liver oil; zinc oxide based ointments, and, in extreme
cases, anti-fungal cremes. Low concentration hydrocortisone creams are also
sometimes used to treat the symptoms of diaper rash, although they do little to
clear up the rash itself.
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