Abstract
Resistance mechanisms occur in almost all clinical bacterial isolates and represent one of the most worrisome health problems worldwide. Bacteria can form biofilms and communicate through quorum sensing (QS), which allow them to develop resistance against conventional antibiotics. Thus, new therapeutic candidates are sought. We focus on alkylglycerols (AKGs) because of their recently discovered quorum sensing inhibition (QSI) ability and antibiofilm potential. Fifteen natural enantiopure AKGs were tested to determine their effect on the biofilm formation of other clinical bacterial isolates, two reference strains and their QSI was determined using Chromobacterium violaceum ATCC 12472. The highest biofilm inhibition rates (%) and minimum QS inhibitory concentration were determined by a microtiter plate assay and ciprofloxacin was used as the standard antibiotic. At subinhibitory concentrations, each AKG reduced biofilm formation in a concentration-dependent manner against seven bacterial isolates, with values up to 97.2%. Each AKG displayed QSI at different levels of ability without affecting the growth of C. violaceum. AKG (2S)-3-O-(cis-13’-docosenyl)-1,2-propanediol was the best QS inhibitor (20 μM), while (2S)-3-O-(cis-9’-hexadecenyl)-1,2-propanediol was the least effective (795 μM). The results showed for the first time the QSI activity of this natural AKG series and suggest that AKGs could be promising candidates for further studies on preventing antimicrobial resistance.
Highlights
Antibiotics were discovered in the early 20th century and have been widely used in the treatment of bacterial infections
The indiscriminate and excessive usage of antibiotics has led to the development of antimicrobial resistance, which has steadily decreased the effectiveness of current antibacterial therapies [1,2]
Biofilms are another critical reason for microbial resistance and they consist of bacteria embedded in a self-produced extracellular matrix of polysaccharides, fibrins, lipids, proteins and DNA that can reduce the effect of antibiotics [7,10,43]
Summary
Antibiotics were discovered in the early 20th century and have been widely used in the treatment of bacterial infections. Resistance mechanisms occur in almost all clinical isolates of bacteria and recurrent infections caused by persistent bacteria hamper the successful treatment of infections [3]. This situation highlights the urgency of identifying new therapeutic candidates and less toxic treatment targets. Considerable research has focused on developing novel strategies to control bacterial diseases [4]. Infectious diseases cause the death of more than 16 million people annually and at least 65% of these cases are linked to bacterial communities that proliferate by forming biofilms [5,6]. Biofilms consist of microorganisms that are attached to a substratum and embedded in a matrix of extracellular polymers that protects the cells from harsh environmental conditions, including disinfectant treatments and antibiotics [7]
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