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Interactions of organic acids with vancomycin‐resistant Enterococcus faecium isolated from community wastewater in Texas
Author(s) -
Beier R.C.,
Harvey R.B.,
Poole T.L.,
Hume M.E.,
Crippen T.L.,
Highfield L.D.,
Alali W.Q.,
Andrews K.,
Anderson R.C.,
Nisbet D.J.
Publication year - 2019
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.14145
Subject(s) - enterococcus faecium , chemistry , formic acid , enterococcus , butyric acid , microbiology and biotechnology , citric acid , acetic acid , bacteria , lactic acid , vancomycin , food science , chromatography , biochemistry , staphylococcus aureus , biology , antibiotics , genetics
Aims Investigate the interactions of organic acids ( OA s), acetic, butyric, citric, formic, lactic and propionic acid against 50 Gram‐positive vancomycin‐resistant Enterococcus faecium ( VRE ) strains to determine whether pH , undissociated or dissociated acid forms correlate with bacterial inhibition. Methods and Results Concentrations of undissociated and dissociated OA s at the molar minimum inhibitory concentrations ( MIC M s) of the VRE were calculated using the Henderson–Hasselbalch equation. The pH at the MIC M s of all VRE strains against acetic, butyric, formic and propionic acids was similar, 4·66 ± 0·07, but there was a 1·1 pH unit difference for all six OA s. Inhibition of VRE by all six OA s did not appear to be solely dependent on pH or on the undissociated OA species. The inhibition of VRE by all six dissociated acids was within Δ = 3·1 mmol l −1 . Conclusions Vancomycin‐resistant Enterococcus faecium inhibition correlated with the dissociated OA species. A small decrease in the concentration of the dissociated OA s from optimum may result in allowing VRE strains to escape disinfection. Significance and Impact of the Study When an OA is used to disinfect VRE strains, the concentration of the dissociated OA should be carefully controlled. A concentration of at least 20 mmol l −1 dissociated OA should be maintained when disinfecting VRE .