04058nam a22005297a 4500 OSt 20260921095021.0 260918b |||||||| |||| 00| 0 eng d University of Cebu - School of Medicine University of Cebu - School of Medicine Galano, Ralph Dominic C., author. Anti-quorum sensing activity of Psidium guajava L. methanolic leaf extracts against Pseudomonas aeruginosa : an in vitro study / Ralph Galano, Angela Japson, Inah Krizia Lague, Jyrah Mee Makinano, Khylla Gayle Mondarte, Matt Markel Mopon, Lance Morquianos, Ma. Lucia Beatriz Mose, Timothy Bryan Ngo, Jannie Lyka Omictin, Cathelaine Diane Ong, Isabela Louise Perilla, Miguel Luis Quimbo. Subangdaku, Mandaue City : University of Cebu - College of Medicine Foundation, Inc., 2026. iv, 106 pages : color illustrations ; rdacontent text rdamedia unmediated rdacarrier volume 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 Text in English Bacterial infection. Antimicrobial resistance. Pseudomonas aeruginosa. Multidrug-resistant (MDR). Hospital acquired infection. Anti-quorum sensing. Psidium guajava L. Drug resistant bacteria. Japson, Angela B., author. Lague, Inah Krizia O., author. Makinano, Jyrah Mee T., author. Mondarte, Khylla Gayle, author. Mopon, Matt Markel, author. Marquianos, Lance, author. Mose, Ma. Lucia Beatriz, author. Ngo, Timothy Bryan, author. Omictin, Jannie Lyka, author. Ong, Cathelaine Diane, author. Perilla, Isabela Louise, author. Quimbo, Miguel Luis, author. ddc BK Vanessa [new] 09/18/2026 Vanessa [added] 09/21/2026 15680 15680 0 0 ddc 0 0 UCBL_MED UCBL_MED THESIS 2026-09-18 T G13an 2026 3UCSM000001636 2026-09-18 c.1 2026-09-18 THE 0 0 ddc 0 0 UCBL_MED UCBL_MED THESIS 2026-09-18 0 T G13an 2026 3UCSM000001637 2026-09-21 c.2 2026-09-18 THE