Differential susceptibilities of enterococcal species to elfamycin antibiotics

Abstract

The elfamycins are a class of naturally occurring antibiotics not currently used in the therapy of human disease. Enterococcus faecium and closely related species (Enterococcus durans and Enterococcus hirae) are susceptible to these antibiotics, while isolates of Enterococcusfaecalis and other enterococcal species are highly resistant. Among enterococci, susceptibility or resistance to elfamycins appears to be determined by the bacterial protein synthesis elongation factor EF-Tu. Elfamycin susceptibility may be a useful adjunct for rapidly distinguishing E. faecalis and E. faecium in the clinical microbiology laboratory and/or as a supplementary test for use in determining the species of enterococci.

Use of Tests for Acidification of Methyl-α- d -Glucopyranoside and Susceptibility to Efrotomycin for Differentiation of Strains of Enterococcus and Some Related Genera

“…In addition, we have found that E. faecium strains have very diverse phenotypic characteristics (12), which presents a problem for the differentiation of this species from atypical strains of E. casseliflavus and E. gallinarum. In 1994, Miele et al (8) described a test based on susceptibility to elfamycin drugs for the rapid differentiation of Enterococcus faecalis and E. faecium. More recently, Devriese et al (3) demonstrated that a test based on the acidification of methyl-␣-D-glucopyranoside (MGP) could be used to differentiate E. casseliflavus and E. gallinarum from E. faecium and E. faecalis.…”

Elfamycins: inhibitors of elongation factor‐Tu

“…In addition to the complication of multiple gene copies of EF-Tu, compound permeability issues further obfuscate the question of bacterial resistance to the elfamycins. Several groups posit that the narrow spectrum of action of elfamycins is based on permeability barriers to some cells (Zeef et al, 1994), whereas others counter that EF-Tu itself is resistant (Miele et al, 1994;Kraal et al, 1995) and that there are no permeability barriers. Either way, the poor pharmacokinetics of compounds such as GE2270 have been stated to ultimately render these drugs unsuitable for clinical use (Flinspach et al, 2014;Just-Baringo et al, 2014), but have not prevented them from being useful as laboratory tools in crystallography and EF-Tu function studies (see below).…”