MALDI-TOF lipidomics rapidly detects modification of 2-hydroxymyristate lipid A, a potential virulence trait in <i>Enterobacter bugandensis</i>

<i>Enterobacter bugandensis</i> is now recognized as a potential threat in neonatal wards due to its ability to survive in incubators and its virulence properties. Its increased virulence is linked to the addition of 2-hydroxymyristate on lipid A, resulting from the action of the LpxO enzyme. Here, we proposed a rapid and simple assay to decipher the presence of 2-hydroxymyristate on lipid A directly from the bacterial colony. This assay can be performed easily on MALDI-TOF routine machine using a commercial kit (MBT Lipid Xtract Kit, Bruker Daltonic). This test can accurately detect the 2-hydroxymyristate on lipid A of lpxO-positive ECC isolates, including <i>E. bugandensis</i>. In neonate wards, newborns are now screened for ECC carriage. Accordingly, the MALDIxin test might help clinicians detect the presence of lpxO-positive <i>E. bugandensis,</i> which can be considered a risk factor for the newborn, and implement measures to avoid potentially fatal septicemia.