Evaluation of Psidium guajava (Guava) Leaf Extract Against Gram-Negative Bacteria in Planktonic and Biofilm Lifestyles
C. J. O. Cruzada
College of Medicine, University of the Philippines Manila, Philippines.
K. J. A. Co
College of Medicine, University of the Philippines Manila, Philippines.
T. M. C. Chua
College of Medicine, University of the Philippines Manila, Philippines.
V. A. Chuabio
College of Medicine, University of the Philippines Manila, Philippines.
K. M. D. G. Cruz
College of Medicine, University of the Philippines Manila, Philippines.
D. A. M. De Castro
College of Medicine, University of the Philippines Manila, Philippines.
J. S. Chua
College of Medicine, University of the Philippines Manila, Philippines.
J. E. E. Chua
College of Medicine, University of the Philippines Manila, Philippines.
A. I. T. Contreras
College of Medicine, University of the Philippines Manila, Philippines.
K. A. Cortez
College of Medicine, University of the Philippines Manila, Philippines.
B. M. P. Crisostomo
College of Medicine, University of the Philippines Manila, Philippines.
M. K. A. Crisostomo
College of Medicine, University of the Philippines Manila, Philippines.
F. R. A. Cruz
College of Medicine, University of the Philippines Manila, Philippines.
K. M. E. Cruzado
College of Medicine, University of the Philippines Manila, Philippines.
V. A. C. Cuyegkeng
College of Medicine, University of the Philippines Manila, Philippines.
P. M. B. Medina *
Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila, Philippines.
*Author to whom correspondence should be addressed.
Abstract
Aims: To test and compare relative efficiencies of Guava Leaf Ethanolic Extract (GLEEx) and antibiotic standards against two pathogenic gram-negative bacteria in planktonic and biofilm lifestyles.
Study Design: In vitro antibacterial study.
Place and Duration of Study: Department of Biochemistry & Molecular Biology in the University of the Philippines Manila, between January 2014 and April 2014.
Methodology: The susceptibility of planktonic and biofilm forms of Escherichia coli and Pseudomonas aeruginosa to GLEEx and to appropriate antibiotic standards were evaluated using the Kirby-Bauer disc diffusion assay (KB) and the Bio Timer Assay (BTA), respectively.
Results: In KB, GLEEx exhibited comparable antibacterial strengths against both bacteria (P > .05), but was significantly less than the antibiotic standards (P < .001). However in BTA, there is no significant difference between the antibacterial properties of GLEEx and the antibiotic standards (P> .05).
Conclusion: The relative antibacterial potencies of GLEEx and standard antibiotics vary depending on bacterial lifestyle, thus suggesting the need to use BTA alongside KB when assessing the antibacterial properties of natural products.
Keywords: Guava, biofilm, planktonic, BioTimer assay, Kirby-Bauer assay