The antimicrobial activity of propolis extract on Klebsiella pneumoniae and Escherichia coli strains isolated from Qazvin hospital personnel

<b>Introduction.</b> Nosocomial infections, particularly those caused by Gram-negative bacilli, indeed pose significant challenges in healthcare settings. Hospital staff can act as carriers of these infections, potentially transmitting them to patients and colleagues. Propolis, a natural resinous substance collected by honeybees, has shown promising antibacterial properties against various microorganisms, including Gram-negative bacteria like <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i>.<b>Hypothesis/Gap Statement.</b> Despite the documented antibacterial properties of propolis, limited research has evaluated its efficacy against clinical isolates from healthcare workers, particularly in Iran.<b>Aim.</b> To evaluate the <i>in vitro</i> effect of propolis on <i>K. pneumoniae</i> and <i>E. coli</i> isolated from the nose and nails of hospital personnel in Qazvin.<b>Methodology.</b> Fifty Gram-negative bacilli were isolated from the nose and nails of hospital personnel in Qazvin. An antibiotic sensitivity test was conducted using the disk diffusion method based on CLSI 2024 guidelines for various antibiotics. The most common isolated strain was analysed using enterobacterial repetitive consensus PCR (ERIC-PCR). Finally, the microbroth dilution method was used to assess the antibacterial effect of propolis on the isolated strains.<b>Results.</b> The most frequent pathogens were <i>K. pneumoniae</i> (66%) followed by <i>E. coli</i> (34%). Most of the isolates were sensitive to the majority of antibiotics tested, and the highest antibiotic resistance was observed in trimethoprim/sulfamethoxazole (55%), ceftazidime (32%) and tetracycline (26%). Extended-spectrum beta-lactamase production was found in 10% of isolates of all Gram-negative bacteria. Additionally, 24% of the strains were multidrug-resistant. ERIC-PCR analysis revealed high genetic diversity among <i>K. pneumoniae</i> strains, which were the most common strains isolated from personnel. The MIC of propolis for both <i>K. pneumoniae</i> and <i>E. coli</i> was 5%, and the minimum bactericidal concentration was 10% after culturing 100 µl on Mueller-Hinton agar.<b>Conclusion.</b> The present study showed that the isolates from the nose and nails of hospital personnel may pose a serious issue in the field of public health. These findings suggest that Iranian bee propolis has medicinal value as a natural product and was identified as an antimicrobial substance with positive effects on bacterial strains isolated from hospital personnel.