title: Evaluation of antibacterial effects of Zataria multiﬂora Boiss extracts against ESBL-producing Klebsiella pneumoniae strains.
abstract: OBJECTIVE
  There are few therapeutic options for treatment of multidrug resistant Klebsiella pneumoniae isolates as a hospital infectious agent (nosocomial infection). The aim of this study was to evaluate the antibacterial activity of Zataria multiﬂora Boiss extracts against ESBL-producing Klebsiella pneumoniae strains.
  
  
  METHODS
  This study was conducted on 100 K. pneumoniae isolates from two hospitals in Tehran, Iran. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion and microdilution broth methods and detection of ESBL was carried out according to CLSI guidelines. The blaCTX-M-15 plasmid gene was detected by PCR and sequencing methods. Extracts susceptibility test was performed by broth microdilution method.
  
  
  RESULTS
  Among 100 K. pneumoniae strains, 48 (48%) were ESBL positive. In this study, fosfomycin, colistin and tigecycline were more active than other antibiotics. The existence of blaCTX-M-15 was detected in 30 (62.5%) of 48 ESBL-producing isolates. The chloroformic extract showed potent activity against ESBL-producing K. pneumoniae strains (MIC50 = 1.56 mg/ml and MIC90=3.12mg/ml). The MIC50 and MIC90 (The MIC50 represents the MIC value at which ≥50% of the isolates in a test population are inhibited and the MIC90 represents the MIC value at which ≥90% of the strains within a test population are inhibited) were 3.12 and 6.25 mg/ml and 6.25 and 12.5 mg/ml for methanolic and acetonic extracts, respectively.
  
  
  CONCLUSIONS
  The incidence of ESBL-producing K. pneumoniae is very high. Therefore, detection of ESBL-producing K. pneumoniae isolates is of great importance in identifying drug resistance patterns in K. pneumoniae isolates and in control of infections. Zataria multiflora may have the potential to be used against multidrug resistant organisms such as clinical isolates of ESBL-producing K. pneumoniae.
authors.affiliation: Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Dadashi
authors.affiliation: Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Hashemi
authors.affiliation: Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Gita
authors.initials: G
authors.lastname: Eslami
authors.affiliation: Pediatric Infectious Research Center, Mofid Children Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Fallah
authors.affiliation: Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Goudarzi
authors.affiliation: Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Soroor
authors.initials: S
authors.lastname: Erfanimanesh
authors.affiliation: Department of Microbiology, Kurdistan University of Medical Sciences, Sanandaj, Iran.
authors.forename: Arezou
authors.initials: A
authors.lastname: Taherpour
keywords: Antibiotic Resistance; Extended-Spectrum-β-Lactamases (ESBLs); Klebsiella pneumoniae; Zataria multiﬂora