Abstract

Impetigo is a highly infectious superficial bacterial disease, most common among pre-school children. Applying 11 antimicrobial agents to the Staphylococcus aureus, the most causative organism for impetigo, S. aureus isolates are resistant to all agents except of vancomycin and fusidic acid. Nevertheless, treatment of impetigo usingantimicrobial agents may cause serious medical problems, such as destroying normal gut and skin flora and producing gastrointestinal irritations, dermatitis or serious hypersensitivity problems. Thus, the test of new microbial infection-fighting natural compounds is urgent. The in vitro measuring the antibacterial activity ofSpirulina platensis extracts, following agar-well diffusion method, against methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) clinical isolates showed that the methanolic S. platensis extract is the most active. The in vivo efficacy of applied topical S. platensis creams, both methanolic extract and crude, in treatment of impetigo were compared. In general, clinical application of both active ingredients of S. platensis (Group 1-G1) and crude S. platensis form (Group 2-G2) gave promising and excellent response rates. However, the Group 1 application had the best efficacy, no side effects and no recurrence during the follow-up period. Gas chromatography-mass spectrometry (GC-MS) analysis of both crude alga and its methanolic extract concludes that the potential antimicrobial activity is attributed to synergic effect of some fatty acids. We propose that the higher percentage of linoleic and palmitic acids and the presence of squalane in methanolic extract of Spirulinamost probably are the causes of its higher antimicrobial activity.

Key words: Staphylococcus aureus, impetigo, Spirulina platensis, extracts, topical cream, gas chromatography-mass spectrometry (GC-MS), antimicrobial activity.

Abbreviation

MRSA, Methicillin-resistant S. aureus; MSSA, methicillin-sensitive S. aureus; SIRS, skin infection rating scale; GC-MS, gas chromatography-mass spectrometry.