In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>

<b>Background/Objectives</b>: Biofilm-embedded bacteria, such as <i>Pseudomonas aeruginosa (P. aeruginosa)</i>, are highly resistant to antibiotics, making their treatment challenging. Plant-based natural compounds (PBCs) and metal(loid)-based antimicrobials (MBAs) are promis...

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Main Authors: Melika Moradi, Effat Abbasi Montazeri, Sirous Rafiei Asl, Ali Pormohammad, Zahra Farshadzadeh, Dian Dayer, Raymond J. Turner
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Antibiotics
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Online Access:https://www.mdpi.com/2079-6382/14/4/367
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author Melika Moradi
Effat Abbasi Montazeri
Sirous Rafiei Asl
Ali Pormohammad
Zahra Farshadzadeh
Dian Dayer
Raymond J. Turner
author_facet Melika Moradi
Effat Abbasi Montazeri
Sirous Rafiei Asl
Ali Pormohammad
Zahra Farshadzadeh
Dian Dayer
Raymond J. Turner
author_sort Melika Moradi
collection DOAJ
description <b>Background/Objectives</b>: Biofilm-embedded bacteria, such as <i>Pseudomonas aeruginosa (P. aeruginosa)</i>, are highly resistant to antibiotics, making their treatment challenging. Plant-based natural compounds (PBCs) and metal(loid)-based antimicrobials (MBAs) are promising alternatives. This study evaluated the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and synergistic effects of zinc sulfate (ZnSO<sub>4</sub>), carvacrol (CV), and antibiotics (ciprofloxacin [CIP], tobramycin [TOB], and azithromycin [AZM]) against <i>P. aeruginosa</i> PAO1. <b>Methods</b>: The MIC and MBC of ZnSO<sub>4</sub>, CV, and antibiotics were determined using a 96-well plate method. Cytotoxicity was assessed via MTT assay. Fractional inhibitory concentration (FIC), fractional bactericidal concentration (FBC), minimal biofilm inhibition concentration (MBIC), and minimum biofilm eradication concentration (MBEC) indices were calculated for each combination of agents. Checkerboard assays identified interactions, and the effectiveness of combinations was further evaluated in a mouse chronic lung infection model with treatments delivered intratracheally, intraperitoneally, and orally. <b>Results</b>: TOB had the lowest MIC and MBC values, proving most effective against <i>P. aeruginosa</i> PAO1. Strong synergy was observed with CV + ZnSO<sub>4</sub> (CV + Zn) combined with CIP, CV with CIP, and CV + Zn with TOB, as indicated by low FIC indices. CV + Zn with TOB and CV with TOB had low FBC indices, while CV + Zn with AZM showed antagonism. In vivo, intratracheal TOB + CV + Zn reduced lung inflammation and tissue involvement, yielding the best histopathological outcomes. The MIC of CIP and TOB was reduced 5-fold and 4-fold, respectively, when combined with CV + Zn. <b>Conclusions</b>: CV + Zn demonstrated strong synergistic effects with antibiotics and effectively managed <i>P. aeruginosa</i> lung infections in mice. These findings highlight its potential as an innovative therapy for biofilm-associated infections.
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spelling doaj-art-9a074fc4e46745e79abf35e5aa68ad502025-08-20T02:17:25ZengMDPI AGAntibiotics2079-63822025-04-0114436710.3390/antibiotics14040367In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>Melika Moradi0Effat Abbasi Montazeri1Sirous Rafiei Asl2Ali Pormohammad3Zahra Farshadzadeh4Dian Dayer5Raymond J. Turner6Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715794, IranInfectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715794, IranCancer, Environmental and Petroleum Pollutants Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715794, IranDepartment of Biological Sciences, Faculty of Science, University of Calgary, Calgary, AB T2N 1N4, CanadaInfectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715794, IranCellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135715794, IranDepartment of Biological Sciences, Faculty of Science, University of Calgary, Calgary, AB T2N 1N4, Canada<b>Background/Objectives</b>: Biofilm-embedded bacteria, such as <i>Pseudomonas aeruginosa (P. aeruginosa)</i>, are highly resistant to antibiotics, making their treatment challenging. Plant-based natural compounds (PBCs) and metal(loid)-based antimicrobials (MBAs) are promising alternatives. This study evaluated the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and synergistic effects of zinc sulfate (ZnSO<sub>4</sub>), carvacrol (CV), and antibiotics (ciprofloxacin [CIP], tobramycin [TOB], and azithromycin [AZM]) against <i>P. aeruginosa</i> PAO1. <b>Methods</b>: The MIC and MBC of ZnSO<sub>4</sub>, CV, and antibiotics were determined using a 96-well plate method. Cytotoxicity was assessed via MTT assay. Fractional inhibitory concentration (FIC), fractional bactericidal concentration (FBC), minimal biofilm inhibition concentration (MBIC), and minimum biofilm eradication concentration (MBEC) indices were calculated for each combination of agents. Checkerboard assays identified interactions, and the effectiveness of combinations was further evaluated in a mouse chronic lung infection model with treatments delivered intratracheally, intraperitoneally, and orally. <b>Results</b>: TOB had the lowest MIC and MBC values, proving most effective against <i>P. aeruginosa</i> PAO1. Strong synergy was observed with CV + ZnSO<sub>4</sub> (CV + Zn) combined with CIP, CV with CIP, and CV + Zn with TOB, as indicated by low FIC indices. CV + Zn with TOB and CV with TOB had low FBC indices, while CV + Zn with AZM showed antagonism. In vivo, intratracheal TOB + CV + Zn reduced lung inflammation and tissue involvement, yielding the best histopathological outcomes. The MIC of CIP and TOB was reduced 5-fold and 4-fold, respectively, when combined with CV + Zn. <b>Conclusions</b>: CV + Zn demonstrated strong synergistic effects with antibiotics and effectively managed <i>P. aeruginosa</i> lung infections in mice. These findings highlight its potential as an innovative therapy for biofilm-associated infections.https://www.mdpi.com/2079-6382/14/4/367<i>Pseudomonas aeruginosa</i>biofilm-associated infectionsplant-based natural compoundszinccarvacrolcombination effects
spellingShingle Melika Moradi
Effat Abbasi Montazeri
Sirous Rafiei Asl
Ali Pormohammad
Zahra Farshadzadeh
Dian Dayer
Raymond J. Turner
In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>
Antibiotics
<i>Pseudomonas aeruginosa</i>
biofilm-associated infections
plant-based natural compounds
zinc
carvacrol
combination effects
title In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>
title_full In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>
title_fullStr In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>
title_full_unstemmed In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>
title_short In Vitro and In Vivo Antibacterial and Antibiofilm Activity of Zinc Sulfate (ZnSO<sub>4</sub>) and Carvacrol (CV) Alone and in Combination with Antibiotics Against <i>Pseudomonas aeruginosa</i>
title_sort in vitro and in vivo antibacterial and antibiofilm activity of zinc sulfate znso sub 4 sub and carvacrol cv alone and in combination with antibiotics against i pseudomonas aeruginosa i
topic <i>Pseudomonas aeruginosa</i>
biofilm-associated infections
plant-based natural compounds
zinc
carvacrol
combination effects
url https://www.mdpi.com/2079-6382/14/4/367
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