The Medical Journal of Basrah University

Abstract

ABSTRACT
A prospective study was done during the period from October 2005 to July 2006 at the Departments of Microbiology
and dermatology, Basrah University Medical College, and aimed on the evaluation of the effectiveness of topical
antimicrobial agents on the plaque type psoriasis clinically and bacteriologically, before and after drug therapy and to
compare it with that of the non-involved skin of psoriatic patients and healthy controls. Bacteriological examination
was carried out on 500 skin swabs taken from psoriatic plaques before and after treatment for 3 weeks with topical
fusidic acid (2% concentration, IHP, Denmark) or tetracycline (3%, SDI) pre-and post-application and from
uninvolved skin of psoriatic patients and from matched healthy controls. In addition to the responses to either fusidic
acid or tetracycline, topical applications were assessed clinically by psoriasis severity index (PSI). Plaque psoriasis
showed a significant clinical responses (P<0.001) to topical antimicrobial agents (changes in PSI score). Guttate
psoriasis had no such responses. On the other hand, psoriasis plaques harboured a higher density (104-105 CFU/ ml)
of microbial population compared to the non-involved skin of psoriatic patients (Not exceeds 102 CFU/ml). Microbial
density was reduced significantly (P<0.01) by 3 weeks after topical fusidic acid and tetracycline application (from >
105 to <102 CFU/ml). Staphylococcus epidermidis (a species of coagulase-negative staphylococci) was
significantly the most prevalent bacteria (P<0.001) on the psoriatic plaques.
In conclusion, topical fusidic acid (2%) and tetracycline (3%) are effective in the treatment of mild to moderate
plaque psoriasis but not in the treatment of guttate psoriasis. Staphylococcus epdermidis may play a role in the
pathogenesis of plaque psoriasis. Further detailed study is suggested to clarify this role.