Volume 21, Issue 12, 15 October 2014, Pages 1666–1674
Synergistic effect of Myrtus communis L. essential oils and conventional antibiotics against multi-drug resistant Acinetobacter baumannii wound isolates
Abstract
Acinetobacter
baumannii is a rapidly emerging, highly resistant clinical pathogen
with increasing prevalence. In recent years, the limited number of
antimicrobial agents available for treatment of infections with
multi-drug resistant (MDR) strains reinforced tendency for discovery of
novel antimicrobial agents or treatment strategies. The aim of the study
was to determine antimicrobial effectiveness of three Myrtus communis
L. essential oils, both alone and in combination with conventional
antibiotics, against MDR A. baumannii wound isolates. The results
obtained highlighted the occurrence of good antibacterial effect of
myrtle oils when administered alone. Using checkerboard method, the
combinations of subinhibitory concentrations of myrtle essential oils
and conventional antibiotics, i.e. polymixin B and
ciprofloxacine were examined. The results proved synergism among M.
communis L. essential oils and both antibiotics against MDR A. baumannii
wound isolates, with a FIC index under or equal 0.50. Combination of
subinhibitory concentrations of essential oils and ciprofloxacin most
frequently reduced bacterial growth in synergistic manner. The similar
has been shown for combination with polymyxin B; furthermore, the myrtle
essential oil resulted in re-sensitization of the MDR wound isolates, i.e.
MICs used in combination were below the cut off for the sensitivity to
the antibiotic. Time-kill curve method confirmed efficacy of myrtle
essential oil and polymyxin B combination, with complete reduction of
bacterial count after 6 h. The detected synergy offers an opportunity
for future development of treatment strategies for potentially lethal
wound infections caused by MDR A. baumannii.
Keywords
- Essential oils/Myrtus communis;
- Antimicrobial agents;
- Synergism;
- Acinetobacter baumannii;
- Multi-drug resistant
- Corresponding author. Tel.:
+381 214852681; fax: +381 21450620.
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