Antibacterial Effects of Zataria multiflora, Ziziphus, Chamomile and Myrtus communis Methanolic Extracts on IMP-Type Metallo-Beta-Lactamase-Producing Pseudomonas aeruginosa

Abstract

Background: Carbapenem resistance due to acquired metallo-beta-lactamases (MBLs) is considered to be more serious than other resistance mechanisms. Objectives: The aim of this study was to examine the effects of the methanolic extracts of Zataria multiflora, Ziziphus, Chamomile and Myrtus communis leaves on IMP-type MBL- producing Pseudomonas aeruginosa strains. Materials and Methods: This cross-sectional descriptive study was conducted on burn patients hospitalized in Shahid Motahari Hospital, Tehran, Iran, during 2012 - 2013. Antibiotics and extracts susceptibility tests were performed using the disc diffusion and broth micro dilution methods. The metallo-beta-lactamase detection was performed by combination disk diffusion test. The bla (VIM) and bla (IMP) genes were detected by polymerase chain reaction (PCR) and sequencing methods. Results: Eighty-three out of 96 samples were imipenem-resistant P. aeruginosa strains. Among 83 imipenem-resistant P. aeruginosa strains, 48 (57.9%) were MBL producers. Polymerase chain reaction and sequencing methods proved that these isolates were positive for blaIMP-1 genes, whereas none were positive for bla (VIM) genes. The minimum inhibitory concentration (MIC) for imipenem was 128 (ig/mL) for all strains. The MIC and minimum bactericidal concentration (MBC) of M. communis were 6.25 and 12.5 (mg/mL) for all isolates, respectively; the MIC and MBC of Z. multiflora were somehow the same. Methanolic extract of Chamomile showed to have a beneficial effect on this strain, while the Ziziphus leaves methanolic extract showed no significant effect on these isolates. Conclusions: The results of this study reveal that the M. communis extract and methanolic extract of Chamomile have a high antibacterial effect on regular and IMP-producing P. aeruginosa strains; so, these extracts can be suitable alternatives for less-effective antibiotics, which are commonly used.