title: Assessment ofIn vitroAntibacterial Activity and Cytotoxicity Effect ofNigella sativaOil.
abstract: BACKGROUND
  Methicillin resistance is a serious health concern since it has spread amongStaphylococcus aureusand coagulase-negativeStaphylococci(CoNS) that are frequent community and nosocomial pathogens worldwide. Methicillin-resistant strains are often resistant to other classes of antibiotics, making their treatment difficult.Nigella sativaoil is known to be active against Gram-positive cocci, yet itsin vitrocytotoxicity is rarely investigated, is a proper and powerful candidate for treatment of methicillin-resistant isolates.
  
  
  OBJECTIVE
  The aim of this study is to evaluate thein vitroantibacterial activity and cytotoxicity effect ofN. sativaoil.
  
  
  METHODS
  The minimal inhibitory concentrations (MICs) ofN. sativaoil were determined by broth microdilution method against four different American Type Culture Collection strains, 45 clinical isolates of methicillin-resistantS. aureus(MRSA), and 77 methicillin-resistant CoNS (MRCoNS). The effects of different dilutions (0.25 μg/mL, 0.5 μg/mL, and 1 μg/mL) ofN. sativaoil on the proliferation of gingival fibroblasts were evaluated.
  
  
  RESULTS
  The MIC values ofN. sativaoil against clinical isolates ofStaphylococciwere between <0.25 μg/mL and 1.0 μg/mL. Compared to the control group, there was no cytotoxic effect on the proliferation of the gingival fibroblasts.
  
  
  CONCLUSIONS
  In the present study, the oil ofN. sativawas very active against MRSA and MRCoNS and had noin vitrocytotoxicity at relevant concentrations. These findings emphasize that there is a requirement for further clinical trials onN. sativaoil for "safe" medical management of infections caused by methicillin-resistantStaphylococci.
  
  
  CONCLUSIONS
  The minimal inhibitory concentration (MIC) values ofNigella sativaoil againstStaphylococcus aureusAmerican Type Culture Collection (ATCC) 29213,Enterococcus faecalisATCC 29212,Escherichia coliATCC 25922, andPseudomonas aeruginosaATCC 27853 standard strains were 0.5 μg/mL, 2 μg/mL, 64 μg/mL, and 64 μg/mL, respectivelyTheN. sativaoil showed an excellent antibacterial activity against clinical isolates of methicillin-resistantS. aureusand methicillin-resistant coagulase-negativeStaphylococciwith very low MIC range of <0.25-1.0 µg/mLTheN. sativaoil exhibited no cytotoxic effect on the proliferation of the gingival fibroblasts.Abbreviation used:ATCC: American Type Culture Collection; CLSI: Clinical and Laboratory Standards Institute; CoNS: Coagulase-negative Staphylococci; DMEM: Dulbecco's modified Eagle's medium; DMSO: Dimethyl sulfoxide; FBS: Fetal bovine serum; HGF: Human gingival fibroblast; MIC: Minimal inhibitory concentration; MRCoNS: Methicillin-resistant CoNS; MRSA: Methicillin-resistant S. aureus.
authors.affiliation: Department of Medical Microbiology, Konya Education and Research Hospital, Konya, Turkey.
authors.forename: Ayse Ruveyda
authors.initials: AR
authors.lastname: Ugur
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, Selcuk University, Konya, Turkey.
authors.forename: Hatice Turk
authors.initials: HT
authors.lastname: Dagi
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Selcuk University, Konya, Turkey.
authors.forename: Bahadir
authors.initials: B
authors.lastname: Ozturk
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Selcuk University, Konya, Turkey.
authors.forename: Gulsum
authors.initials: G
authors.lastname: Tekin
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, Selcuk University, Konya, Turkey.
authors.forename: Duygu
authors.initials: D
authors.lastname: Findik
keywords: Cytotoxic effect; Nigella sativa; methicillin-resistant Staphylococci; microdilution