Antibiofilm activity of Acronychiapedunculata against methicillin-resistant Staphylococcus aureus
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Date
2013-07-04
Authors
Nishya, M. R.
Bandara, B. M. R.
Parahatiyawa, N. B.
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Peradeniya
Abstract
Acronychiapedunculata (L.)Miq. (Rutaceae) is reported to display antimicrobial activity against a range of microbes. However, the effect of the plant extracts against infectious biofilms has not been described. We report the results of preliminary studies on the anti-adhesion activity of A. pedunculata extracts on the formation of biofilms by a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA) and a standard strain of methicillin-sensitive S.aureus NCTC 6571.
Air-dried powdered leaves and stem-bark of A. pedunculata were extracted into methanol using a sonicator (30 °C for 30 min) or a Soxhlet apparatus (65 °C for 24 h). The extracts were tested for antibacterial activity against S. aureus and MRSA using the agar well diffusion assay (well diameter, 9 mm). Minimum inhibitory concentration (MIC) values of the extracts were determined by the broth dilution method. Anti-adhesion activity was measured as colony forming units (CFU) by growing biofilms on a catheter tube in the presence of extracts at MIC values and culturing the viable bacteria present in the dislodged biofilms to form colonies on a Muller-Hinton agar plate.
The plant displayed large zones of inhibition (S. aureus and MRSA) at relatively low concentrations of leaf (1.0 mg/ml) and stem-bark (0.7 mg/ml) extracts: 14-16 mm (sonicator extracts) and 17-18 mm (Soxhlet extracts). The MIC values were consistently lower for the Soxhlet extracts (2-64 ppm) than for the corresponding sonicator extracts (16-128 ppm). The MIC values of the stem-bark extracts (2-64 ppm) were lower than the corresponding values of the leaf extracts (64-128 ppm). The lowest MIC values were observed for the Soxhlet stem-bark extracts (4 ppm, S. aureus; 2 ppm, MRSA), and the highest MIC values were for the sonicator leaf extracts (64 ppm, S. aureus; 128 ppm, MRSA). The results show that the stem-bark extract prepared using the Soxhlet apparatus had the highest antibacterial activity.
In the antibiofilm assay with MRSA, the CFU values were <formula> and <formula> in the presence ofSoxhlet stem-bark extract (at 2 ppm) and sonicator stem-bark extract (at 64ppm), respectively; the CFU values for the negative control (nutrient broth medium) and positive control (vancomycin, 1 ppm) were <formula> and <formula>, respectively. There was a reduction in the adherence of MRSA on the catheter tube at the MIC values of all the extracts. Further, the extracts showed higher anti-adhesion activity towards MRSA than S. aureus. However, increasing the concentration of the extracts did not always improve the antibiofilm activity
Description
Keywords
Chemistry , Staphylococcus aureus , Acronychiapedunculata
Citation
Peradeniya University Research Sessions PURSE - 2012, Book of Abstracts, University of Peradeniya, Sri Lanka, Vol. 17, July. 4. 2012 pp. 192