Killing of Gram‐positive cocci by fatty acids and monoglycerides^Note

Abstract

The susceptibilities of three Gram-positive cocci to medium-chain saturated and long-chain unsaturated fatty acids and their one-monoglycerides were studied. The bacteria were incubated with equal volumes of lipid solutions for 10 min. Lauric acid, palmitoleic acid and monocaprin reduced the number of CFU by 6.0 log10 or greater at 5 mM concentration for streptococci of group A (GAS) and group B (GBS). When further compared at lower concentrations and after longer incubation time monocaprin proved to be the most active. Capric acid showed the highest activity against Staphylococcus aureus at 10 mM. However, at lower concentrations monocaprin was the only lipid that showed significant activity against S. aureus. The mode of action of monocaprin against GBS was studied by a novel two-color fluorescent assay of bacterial viability and by electron microscopy. The results indicate that the bacteria are killed by disintegration of the cell membrane by the lipid, leaving the bacterial cell wall intact. The highly lethal effect of monocaprin indicates that this lipid might be useful as a microbicidal agent for prevention and treatment of infections caused by these bacteria.

Effects of dietary caprylic and capric acids on piglet performance and mucosal epithelium structure of the ileum

“…They have strong antibacterial activity against Gram-positive cocci (Bergsson et al, 2001) and Escherichia coli (Skřivanová et al, 2009). Moreover, they can improve post-weaning gut development (Tang et al, 1999).…”

Stable Concentrated Emulsions of the 1-Monoglyceride of Capric Acid (Monocaprin) with Microbicidal Activities against the Food-Borne Bacteria Campylobacter jejuni , Salmonella spp., and Escherichia coli

“…More recently, bacteria such as Chlamydia trachomatis, Neisseria gonorrhoeae, Helicobacter pylori, Staphylococcus aureus, and streptococci of groups A and B were found to be rapidly killed by fatty acids and monoglycerides, although with a considerable difference in activity profiles (3,4,5,6). However, most of the bacterial species tested, either gram negative or gram positive, were found to be particularly susceptible to the 1-monoglyceride of capric acid (monocaprin [MC]).…”

Use of silica supports for enhancing the stability of folates and developing antimicrobial agents

“…The MBC of CA was lower than for E. coli and S. enterica, and fell within the 15-18.5 mM range. These results are similar to those obtained in the study of Bergsson et al (2001), who used culture broth. In this study, the CA 10 mM concentration gave rise to a slightly inhibitory effect on S. aureus after a 10-min incubation at 37 °C.…”

“…According to several authors the mechanism of action of CA on bacteria cells is based on the alteration of the different essential processes occurring at the cell envelope (Bergsson et al, 2001, Chang et al, 2010and Desbois and Smith, 2010, which results in microorganism inhibition. CA in particular, and FFAs in general, are known to create pores that may penetrate the cell membrane, this induces portions of the lipid bilayer to be released and disruption of membrane permeability takes place (Choi et al, 2013).…”

“…A wide range of concentrations of between 5 and 100 mM of CA, dispersed in nutrient broth, was tested according to previous references of FFA inhibitory activity (Bergsson et al, 2001;Chang et al, 2010;Nair et al, 2004;Nobmann et al, 2009;Vasudevan et al, 2005). To achieve final concentrations in test tubes, different volumes of CA (between 8 and 158 μL) were added to 10 mL of TSB.…”