SCREENING OF FUNGAL ISOLATE AGAINST CLINICAL ISOLATES OF STAPHYLOCOCCUS AUREUS BY CO-CULTURE ASSAY FOR NOVEL ANTIMICROBIAL COMPOUNDS

Abstract

Asia is among the regions with the highest prevalence rates of healthcare-associated methicillin-resistant Staphylococcus
aureus (HA-MRSA) and community-associated methicillin-resistant S. aureus (CA-MRSA) in the world. To overcome
some of these severe multi-drug resistant pathogens, eukaryotes are better source of diverse compounds, in which fungi
serves as second largest group after plants, producing bioactive secondary metabolites. In the present study using coculture
assay method, the fungal isolates were screened against clinical isolates of Staphylococcus aureus (Gram positive
coccoid bacteria) that is known to cause simple skin infections to life threatening septiceamia. Clinically they are known
to show an alarming rate of resistance against multiple antibiotics (multi-drug resistance). Twelve, S. aureus isolates,
screened for multi-drug resistance were procured from KIMS Medical College and Hospital, Hubballi Karnataka, India.
To assess the resistance pattern of these clinical isolates, antibiogram assay was performed by Kirby Bauer’s method. The
antibiotics used for this assay were penicillin, clindamycin, methicillin, vancomycin and lincomycin. The zone of
inhibition was measured by the reference standards of CLSI (Clinical Laboratory Standards Institute) chart. Our results
infer varying resistance pattern for penicillin 83%, clindamycin 2%, methicillin 100%, vancomycin 8.3% and lincomycin
8.3%. To verify its antagonistic property, these S. aureus isolates were co-cultured with fungi. Co-culture assay has been
observed as one of the efficient tools to evaluate the metabolite production ability and antibacterial efficacy of the fungal
isolates. Results were evaluated on the basis of zone-of contact inhibition, distance inhibition, zone-line inhibition and
overgrowth inhibition. Our results out of 12 interactions revealed, 05-contact inhibition, 03-overgrowth inhibition, 02-
distance and 02-zone line inhibition.