Antibacterial activity of Zataria multiflora Boiss essential oil against extended spectrum ? lactamase produced by urinary isolates of Klebsiella pneumonia

Introduction and objective: Klebsiella pneumoniae is an opportunistic pathogen most frequently associated with extended spectrum β-lactamase (ESBL) production. These organisms are usually resistant to most antibiotics and pose a serious threat for health care associated infections. Plant essential oils rich in carvacrol and thymol have gained importance for their antimicrobial activity. We determined the composition of Zataria multiflora essential oil of the Jandagh area in Iran and measured its activity against ESBL producing urinary isolates of K. pneumoniae.

Materials and methods: Essential oil was prepared from Z. multiflora at full flowering stage by hydrodistillation and its constituents were analyzed by a combination of capillary GC and GC-MS. Antibacterial activity was measured against 10 ESBL producing urinary isolates of K. pneumoniae as well as six ATCC bacterial standards by disc diffusion, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) using broth microdilution.

Results: Zataria multiflora essential oil contained 25 constituents of which the major components were carvacrol (50.57%), thymol (13.38%) and p-cymene (8.27%). All tested bacteria were susceptible to the essential oil with the exception of Pseudomonas aeruginosa. Disc diffusion results showed inhibition zones of 18.3-30.3mm for the ATCC standards and 20.7- 29.7mm for the 10 clinical isolates. MIC and MBC values were 0.015- 2.0mg/ml for ATCC strains and 0.03 to 0.5mg/ml for the clinical isolates.

Conclusion: Zataria multiflora may have the potential to be used against multidrug resistant organisms such as clinical isolates of ESBL producing K. pneumoniae.