Pseudomonas isolates have in vitro antagonistic activity against the dermatophytes Trichophyton rubrum, Trichophyton mentagrophytes var interdigitale and Microsporum canis

Abstract

Purpose: Dermatophytosis are common and persistent fungal infections in Tunisia. An alternative approach to treat dermatophytosis may be the use of microorganisms such as the members of the genus Pseudomonas. These Gram-negative bacteria have been intensively investigated as biocontrol agents and source of antifungal metabolites. Material and methods: A total of 45 bacteria of the genus Pseudomonas were isolated from marine environments and clinical patients. These isolates were tested in vitro against Trichophytron rubrum, Trichophytron interdigitale and Microsporum canis. Results: Results revealed that a marine isolate of Pseudomonas aeruginosa (PsMBA-3) and a clinical isolate of Pseudomonas fluorescens were particularly effective against all three pathogens and six Pseudomonas isolates inhibited the mycelial growth of T. rubrum. The cell-filtrate of the selected stains PsMBA-3 was able to inhibit the growth of T. rubrum. This percentage of inhibition is 20%. However, the antifungal activity, produced by the marine isolate was found better in the aqueous extract of the culture pellet. This percentage of inhibition is 55%. Conclusion: These results showed that suppression of fungal growth by the selected Pseudomonas isolates. To investigate the nature of antifungal substances from P. aeruginosa PsMBA-3, more studies including, characterization tests, purification and structural elucidation of these substances are recommended. © 2009 Elsevier Masson SAS. All rights reserved.