University of Cebu-Banilad Library

Includes bibliographical references.

"The emergence of multidrug-resistant Pseudomonas aeruginosa necessitates alternative antimicrobial strategies, such as quorum sensing (QS) inhibition, which targets virulence without exerting selective survival pressure. This study evaluated the anti-quorum sensing and antibiofilm activity of Psidium quajava L. methanolic leaf extracts against P. aeruginosa in vitro. Leaves collected from Medellin, Cebu, were extracted via methanolic maceration, yielding a 5.493% crude extract. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined using a resazurin-based microplate broth dilution assay. Anti-QS activity was quantitatively assessed by measuring biofilm inhibition at sub-inhibitory concentrations using a crystal violet assay, with cinnamaldehyde as the positive control. The extract exhibited poor direct antimicrobial activity, recording an MIC of 12.5 mg/mL and an MBC of >12.5 mg/mL. However, it demonstrated potent, dose-dependent antibiofilm efficacy. At the baseline MIC (12.5 mg/mL), the extract achieved a 96.93% biofilm inhibition rate, remaining significantly effective at 87.68% (6.25 mg/mL) and 73.20% (3.125 mg/mL). Welch's t-test revealed the extract performs comparably to the commercial standard, cinnamaldehyde ($p = 0.408$). Furthermore, Welch's ANOVA indicated maximum statistical efficacy was achieved at 6.25 mg/mL, with no significant difference in inhibition compared to the maximum dose. These findings establish that while P. guajava methanolic leaf extract possesses weak bactericidal effects, it is a highly capable anti-quorum sensing agent that effectively disrupts biofilm formation, offering a promising alternative therapeutic strategy against antibiotic-resistant infections." --Abstact

Adult

Montoya, Ma. Melfer School of Medicine Microbiology

Montoya, Ma. Melfer School of Medicine Microbiology

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