Exploring the Potential Effects of Nisin and Colistin Combinations Against Drug-Resistant <i>Klebsiella pneumoniae </i>Isolates

Abstract

Background: Klebsiella pneumoniae is a formidable nosocomial pathogen increasingly known for its antibiotic resistance, posing a significant global health challenge. The emergence of carbapenem-resistant strains has necessitated the exploration of alternative therapeutic strategies. Objectives: This study aimed to evaluate the synergistic effects of combining nisin with colistin against K. pneumoniae isolates and to determine whether this combination enhances antibacterial efficacy compared to colistin alone. Methods: Ten K. pneumoniae isolates were collected from hospitalized patients in Iran. Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method. Minimum inhibitory concentration (MIC) assays were performed to determine the MICs of Nisin and Colistin. Synergistic activity testing, biofilm formation assays, and time-kill assays were also carried out to assess the effectiveness of the nisin-colistin combination. Results: The study demonstrated that the nisin-colistin combination exhibited a synergistic effect, significantly reducing colony counts over 24 hours for select isolates. However, the combination did not show statistically significant superiority in antibiofilm activity compared to colistin alone. The time-kill assay confirmed the synergistic effect, showing a notable reduction in colony counts within 24 hours. These findings underscored the complexities of biofilm structures and their resistance mechanisms, highlighting the necessity for further research to optimize treatment outcomes. Conclusions: This study provides a novel perspective on addressing antibiotic resistance in K. pneumoniae by evaluating the synergistic potential of the nisin-colistin combination. The findings contribute to the development of innovative therapeutic approaches to manage infections caused by this challenging pathogen.