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Updated: Jun 23, 2025
Evaluation of Antimicrobial Activities of Nanoparticles and Nanostructured Surfaces In Vitro
Published on: April 21, 2023
Evaluating the antibacterial effect of meropenem-loaded chitosan/sodium tripolyphosphate (TPP) nanoparticles on
Marziyeh Sadat Amini1, Majid Baseri Salehi2, Nima Bahador3
1Department of Microbiology, Kazeroun Branch, Islamic Azad University, Kazeroun, Iran.
Background:
Acinetobacter baumannii is a health threat due to its antibiotic resistance. Herein, antibiotic susceptibility and its association with the Toxin-antitoxin (TA) system genes in A. baumannii clinical isolates from Iran were investigated. Next, we prepared meropenem-loaded chitosan nanoparticles (MP-CS) and investigated their antibacterial effects against meropenem-susceptible bacterial isolates.
Methods:
Out of 240 clinical specimens, 60 A. baumannii isolates were assessed. Antibiotic resistance of the isolates against conventional antibiotics was determined alongside investigating the presence of three TA system genes (mazEF, relBE, and higBA). Chitosan nanoparticles were characterized in terms of size, zeta potential, encapsulation efficiency, and meropenem release activity. Their antibacterial effects were assessed using the well diffusion method, minimum inhibitory concentration (MIC), and colony-forming unit (CFU) counting. Their cytotoxic effects and biocompatibility index were determined via the MTT, LDH, and ROS formation assays.
Results:
Ampicillin, ceftazidime, and colistin were the least effective, and amikacin and tobramycin were the most effective antibiotics. Out of the 60 isolates, 10 (16.7%), 5 (8.3%), and 45 (75%) were multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. TA system genes had no significant effect on antibiotic resistance. MP-CS nanoparticles demonstrated an average size of 191.5 and zeta potential of 27.3 mV alongside a maximum encapsulation efficiency of 88.32% and release rate of 69.57%. MP-CS nanoparticles mediated similar antibacterial effects, as compared with free meropenem, against the A. baumannii isolates with significantly lower levels of meropenem. MP-CS nanoparticles remarkably prevented A549 and NCI-H292 cell infection by the A. baumannii isolates alongside demonstrating a favorable biocompatibility index.
Conclusion:
Antibiotic-loaded nanoparticles should be further designed and investigated to increase their antibacterial effect against A. baumannii and assess their safety and applicability in vivo settings.
Insights
Meropenem-loaded chitosan nanoparticles show promise against antibiotic-resistant Acinetobacter baumannii. These nanoparticles offer effective antibacterial action with reduced drug levels and good biocompatibility.
Area of Science:
- Microbiology
- Nanotechnology
- Infectious Diseases
Background:
- Acinetobacter baumannii poses a significant health threat due to widespread antibiotic resistance.
- Investigating antibiotic susceptibility and Toxin-antitoxin (TA) system genes in clinical A. baumannii isolates from Iran.
- Development of meropenem-loaded chitosan nanoparticles (MP-CS) to combat meropenem-susceptible isolates.
Purpose of the Study:
- To evaluate the antibiotic resistance patterns of A. baumannii clinical isolates.
- To determine the association between TA system genes and antibiotic resistance.
- To assess the antibacterial efficacy and safety of meropenem-loaded chitosan nanoparticles.
Main Methods:
- Characterization of A. baumannii isolates for antibiotic susceptibility and TA genes (mazEF, relBE, higBA).
- Physicochemical characterization of MP-CS nanoparticles (size, zeta potential, encapsulation, release).
- Evaluation of antibacterial activity (well diffusion, MIC, CFU), cytotoxicity (MTT, LDH), and biocompatibility (ROS assays).
Main Results:
- High rates of multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) A. baumannii were observed.
- TA system genes showed no significant correlation with antibiotic resistance.
- MP-CS nanoparticles exhibited efficient meropenem loading and release, with comparable antibacterial effects to free meropenem at lower concentrations.
- MP-CS nanoparticles demonstrated significant potential in preventing A. baumannii infection in cell lines with favorable biocompatibility.
Conclusions:
- Meropenem-loaded chitosan nanoparticles are effective against A. baumannii.
- Nanoparticle formulation enhances antibacterial efficacy and potentially reduces drug dosage.
- Further research is needed to explore in vivo applications and safety of these nanoparticles.
