Efficacy of water extracts of mushrooms on multidrug-resistant bacteria isolated from raw cow milk

Abstract

The high rate of antibiotic-resistant bacteria observed in food samples has been alarming. The majority of the antibiotics now used in medicine have become ineffective against groups of bacteria. The use of bioactive substances from natural products against antibiotic-resistant bacteria is becoming attractive. Mushrooms are natural reservoirs of potent pharmaceuticals and are now the new interface for drug discovery. Aqueous extracts of five medicinal mushrooms namely Agaricus sp., Pleurotus pulmonarius, Pleurotus oestratus., Lentinus sp. and Ganoderma were prepared. Bacteria were isolated from raw cow milk using standard techniques and antibiotic sensitivity testing was carried out using 6 antibiotics. The efficacy of the mushroom extract was tested on 12 MAR bacteria using the disc diffusion method. It was observed that the aqueous extracts from the two Pleurotus spp were very active in killing the bacteria. Pleurotus oestratus was active against 5 isolates while Pleurotus pulmonarius was active against 3 isolates. Agaricus and Lentinus extracts were active against 4 isolates each while Ganoderma was active against only 3. Bacillus tropicus, Enterobacter hormaechei and Klebsiella pneumoniae isolates were totally resistant to the effects of the extracts. This study shows the effectiveness of mushroom aqueous extracts. This may be used to reduce bacterial load in food especially milk so as to prolong its shelf life in the natural state.