Antimicrobial and Anti-Biofilm Effects of Essential Oils on Hypermucoviscous Klebsiella pneumoniae

The multidrug-resistant bacterium Klebsiella pneumoniae is known to cause critical infections.Its hypermucoviscous phenotype enhances virulence.This study investigates the antimicrobial and anti-biofilm potential of essential oils against these strains.A total of 57 Klebsiella pneumoniae strains were collected from diverse clinical specimens obtained from hospitals in Baghdad.These isolates underwent identification and assessment for hypermucoviscosity characteristics through the string test.The antimicrobial properties of essential oils extracted from thyme (Thymus vulgaris), peppermint (Mentha piperita), and rosemary (Rosmarinus officinalis) were analyzed utilizing both agar diffusion and broth dilution techniques.Biofilm formation and hypermucoviscosity were assessed using the microtiter plate and silicon catheter methods.Among the 57 K. pneumoniae isolates, 9% exhibited the hypermucoviscous phenotype.Resistance was highest to ceftazidime and cefotaxime (94.42%), followed by ampicillin and cefepime (91.42%).Biofilm was formed in 65.46% of the isolates.Essential oils of thyme, peppermint, and rosemary exhibited antimicrobial activity.Notably, thyme and peppermint oils were effective in inhibiting both hypermucoviscosity and biofilm formation.Thyme oil exhibited the highest biofilm inhibition (46.64%), followed by peppermint oil (39.68%).Both oils reduced bacterial adhesion on catheters.The findings of the present study suggest essential oils (Eos), especially those obtained from thyme, peppermint, and rosemary, as potential alternatives for combating hypermucoviscous K. pneumoniae infections, antibiotic resistance, and biofilm-related issues.