Untitled - MendelNet 2013 - Mendelova zemědělská a lesnická ...

MENDELNET 2013INTRODUCTIONAntimicrobials are widely used for treatment of various animals. Over the years, the continuous useof antimicrobials in the dairy sector has led to the emergence of resistant strains of severalpathogens that are linked to the cause of mastitis disease in animals (Pitkala et al., 2004). The needfor cheaper and available source of active medicinal plant for mastitis therapy gave a reason for thestudy. The study aimed to evaluate the in-vitro antimicrobial activity of methanolic and ethylacetateextracts of Usnea barbata lichens on some selected Staphylococcus species isolated frommilk of cows.MATERIAL AND METHODSIsolation and identificationStaphylococcus species were done using several biochemical tests including gram staining, catalaseand oxidase test before they were finally identified as Staphylococcus species (to their specieslevel) with API staph kit (Biomerieux Inc., Quebec).Plant sample and extracts preparationGround Usnea barbata lichen air-dried in room temperature was serially extracted with methanoland ethyl acetate solvent, respectively. Extraction was done using a portion of 400 g of the Usneabarbata plant lichen in an extraction bottle with methanol and ethyl-acetate.Testing for antimicrobial sensitivityThe agar well diffusion technique was used to test for the antimicrobial sensitivity of the plant.Determination of minimum inhibitory concentration (MIC) and minimum bacteriaconcentration (MBC) of plant extractsMinimum inhibitory concentration (MIC) of the plant extracts against the bacterial species wasdetermined using the broth micro-dilution method in 96-well micro-titer plates (Banfi et al., 2003).The minimum bacteria concentration (MBC) of the plant extracts was determined from the MICresult.RESULT AND DISCUSSIONThe results obtained from the experiment showed that the zones of inhibition for methanol extractranged from 10 to 34 mm while that of ethyl- acetate ranged from 0 to 23 mm (Table 1).Amoxicillin (0.01 µg/ml) which was used as a positive control gave a zone of inhibition in therange of 17 to 47 mm (Table 1). With reference to the break point (inhibition zone diameter ≥ 11),six out of the thirteen bacterial strains subjected to the plant extract were the most resistantorganisms to both methanol and ethyl-acetate extract with partial zones of inhibition viz,Staphylococcus haemolyticus, Staphylococcus capitis, Staphylococcus cohnii-urealyticus,Staphylococcus cohnii-cohnii, Staphylococcus hominis and Staphylococcus saprophyticus.204 | P age