BIOFILM FORMATION FROM CO-EXISTENCE BETWEEN MALASSEZIA PACHYDERMATIS AND CANDIDA PARAPSILOSIS AND THEIR ANTIFUNGAL SUSCEPTIBILITIES

Abstract

The co-existence and increasing of yeast populations; Malassezia pachydermatis and Candida parapsilosis on dog skin was associated with acute and chronic seborrhea dermatitis (SD). However, consequences of co-existence on dog skin are still unclear in term of symbiosis role and antifungal response. This study aimed to demonstrate biofilm formation of M. pachydermatis together with that of C. parapsilosis and to compare between single and co-colonization. A total of 40 isolates comprised of 20 isolates of M. pachydermatis and 20 isolates of C. parapsilosis were selected from 10 healthy and 10 SD dogs. All was confirm their genotype and phospholipase activity were confirmed by partial DNA sequencing at IGS1 region and a semi-quantitative egg-yolk plate, respectively. Yeast morphology and characterizations were examined by crystal violet assay and scanning electron microscope. The antifungal susceptibilities among sessile and planktonic cells were determined by a broth microdilution method. Nineteen of 20 M. pachydermatis were grouped in genotype 1A and another was in genotype 3D. All tested yeasts had a high level of phospholipase activity. Overall, biofilm formation could be observed within 24 hour incubation and gave the highest reacted value within 72 hr. Biofilm belonging to co-colonization was higher than that of single colonization (Pair t-test, P<0.05). There was no significant difference of susceptibility values between single or co-colonized growth with biofilm. Nevertheless, the susceptibility value derived from the cells with biofilm was higher than that without biofilm at least 530 times. This finding confirmed a diametrical resistance of yeasts beneath biofilm production and demonstrated mutualizing on biofilm formation in the in vitro co-colonization.