by Dr. Madalene Heng MD, FRACP, FACD, FAAD

Bacterial Superinfection

Staphylococcus aureus is present in plaque psoriasis, especially if the lesions are red and itchy. This is due to superantigens (Protein A, enterotoxin A, B and C) released from the cell wall of Staphylococcus aureus by the presence of proteases in serum, causing erythroderma and dissemination of the psoriatic lesions just like poison oak (Heng MCY et al. Erythroderma associated with mixed lymphocyte-endothelial interaction and Staphylococcus aureus infection. British Journal of Dermatology 1986;115:693-705; Heng MCY et al. Predominance of CD8+ subset in id eruption of poison oak dermatitis. Australas J Dermatol1991;32:93-100). See Abstract.

The Staphylococcus aureus bacteria lives inside the holes in the porous psoriatic scales just like bacteria inside the "pumice" stone. This is the reason why we give some form of oral antibiotics to every psoriatic patient. However, the bacteria within the porous psoriatic scales are not killed by the oral Keflex® alone. They also need a topical treatment e.g. chlorox baths. The chlorine water soaks into the scales, and kills the bacteria within.

Chlorox Baths

The chlorine concentration in the chlorox baths resemble that within the swimming pool, and should not be harmful, even for babies. 

  • Add one eighth of a cup of chlorox bleach to a half-filled full bath tub of tepid water. The water must not be too warm or the chlorine with irritate. Mix in the chorox with the fingers. Then the patient gets into the bath tub and soaks for 5 mins, pouring the chlorine water over the head and trunk that is not under water. This is because Staphylococcus aureus can be cultured from normal skin (in 14% of patients based on studies). The patient should keep his head down (i.e. chin to chest), so as not to get the water into his ears. While in the bath tub, there should be no soap as this interferes with the action of the chlorine, which soaks into the pores of the psoriatic scales and kills off the bacteria. Since Staphylococcus aureus has been cultured from the nares in 50% of patients, the nose should be rinsed with chlorine water as well. 
  • After the bath, the patient showers off the chlorine with soap and water, and shampoos his hair. He then uses a fresh towel daily, changes into fresh clothes and socks daily, and changes his bed sheets and pillow cases daily as these are full of bacteria.