Synergistic Antibacterial Activity of Azithromycin-Loaded Chitosan Nanoparticles Alone and in Combination with Cetirizine Dihydrochloride Against Resistant Isolates of Respiratory Tract Infections

Abstract

Background/Objectives: Antibiotic resistance is a major public health concern, with considerable socio-economic consequences. Researchers are exploring alternative strategies, including nanotechnology, which has shown significance in targeted drug delivery. This study evaluates the synergistic antibacterial activity of azithromycin-loaded chitosan nanoparticles (AZM-CSNPs) against azithromycin-resistant clinical respiratory isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella pneumoniae (K. pneumoniae). Methods: A total of 87 sputum samples (n = 87) were collected and analyzed. The ermB gene for K. pneumoniae and the ermA gene for MRSA were used to confirm resistant isolates. Among 87 samples, 29 manifested K. pneumoniae, and 32 exhibited MRSA-positive cultures, confirmed through phenotypic and genotypic methods. The RT-PCR is performed by using a cDNA Kit to determine the gene expression. Results: The results elucidate resistance of K. pneumoniae against several antibiotics, including azithromycin (15 µg), chloramphenicol (30 µg), and amoxicillin (30 µg), while MRSA also showed resistance to cefoxitin (30 µg), azithromycin (15 µg), and gentamycin (10 µg). Reduction in the MIC value of the nanoparticle formulation showed their effectiveness. The AZM-CSNPs combined with cetirizine dihydrochloride helped to down-regulate the resistant genes. Conclusions: Notably, a strong synergistic effect was observed with AZM-CSNPs in combination with cetirizine, significantly enhancing antibacterial efficacy against resistant isolates.