title: In vitro synergistic effect of doxycycline & ofloxacin in combination with ethanolic leaf extract of Vangueria spinosa against four pathogenic bacteria.
abstract: OBJECTIVE
  The in vitro antibacterial activity of ethanolic leaf extract of Vangueria spinosa Roxb. (Rubiaceae) alone and in combination with antibiotics (doxycycline and ofloxacin) by means of fractional inhibitory concentration indices (FICI) as well as by the use of time-kill assays against one Gram-positive bacterium (Staphylococcus aureus) and three Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) was studied.
  
  
  METHODS
  Antibacterial activity was assayed by using the microdilution method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for the ethanolic leaf extract of V. spinosa alone and also in combination with antibiotics using the fractional inhibitory concentration (FIC) and time-kill assay method. Synergism was also tested using checker board dilution method.
  
  
  RESULTS
  MIC/MBC values for ethanolic leaf extract of V. spinosa against all the tested bacteria ranged between 25.5-52.6/22.4-60.5 microg/ml, for doxycycline 4.0/4.0-4.5 microg/ml and for ofloxacin 0.625-2.5/1. 25-5.0 microg/ml respectively. The average log reduction in viable cell count in time-kill assay ranged between 2.4 log(10)-4.5 log(10) cfu/ml after 1 h of interaction and between 3.9 log(10)-5.0 log(10) cfu/ml after 3 h interaction in 1 x MIC to 4 x MIC. When leaf extract and antibiotics were combined, the average log reduction in viable cell count for doxycycline from 1.5 log(10)-5.18 log(10) cfu/ml and for ofloxacin 3.06 log(10)-5.39 log(10) cfu/ml. Synergistic actions were observed in all the cases except against P. aeruginosa which showed an additive effect for ofloxacin and plant extract combination.
  
  
  CONCLUSIONS
  This study provides a preliminary report of synergistic activity of V. spinosa Roxb, ethanolic leaf extract with antibiotics.
authors: Parasitology Laboratory, Department of Zoology, The University of Burdwan, Burdwan, India.
authors: Soroj Kumar
authors: SK
authors: Chatterjee
authors: Indranil
authors: I
authors: Bhattacharjee
authors: Goutam
authors: G
authors: Chandra
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000472:pathogenicity; D004318:Doxycycline / Q000494:pharmacology*; D004357:Drug Synergism; D000431:Ethanol / Q000737:chemistry; D008826:Microbial Sensitivity Tests / Q000379:methods; D015242:Ofloxacin / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D019666:Rubiaceae / Q000033:anatomy & histology / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D000431:Ethanol; D015242:Ofloxacin; D004318:Doxycycline