Antibiotic resistance Aminoglycosides Table 1. Mechanisms of resistance to E. faecium and E. faecalis Mechanism of resistance Associated enzyme Low cell wall permeability Ribosome mutation Aminoglycoside- modifying enzyme (AME) AME AME AME AME AME AME AME AME b-lactams and cephalosporins Ribosome-modifying methyltransferase PBP4/5 production PBP4/5 point mutation Glycopeptides Lincosamides ABC-efflux pump Altered cell wall L,D-transpeptidase Destruction of b-lactam ring b-lactamase on bla genes Synthesis of alternative cell wall VanA, VanH, VanY, VanX, VanR, VanS ABC-efflux pump ABC-efflux pump Acetyltransferase Acetyltransferase Acetyltransferase Altered ribosome Altered ribosome Aac(6’)-Ii Aph(3’)-IIIa Ant(4’’)-Ia Aph(2’’)-Ib Aph(2’’)-Ic Aph(2’’)-Id Ant(6’)-Ia Ant(3’’)-Ia EfmM - - - - Lsa MsrC VgaD VatH VgbA ErmA ErmB VatE (SatG) Low-level aminoglycoside resistance, synergy preserved High-level aminoglycoside resistance with MIC . 128,000 mg/ml Low-level tobramycin and kanamycin resistance Low-level kanamycin resistance Low-level resistance to kanamycin, tobramycin, amikacin and neomycin High-level gentamicin resistance High-level gentamicin resistance High-level gentamicin resistance High-level streptomycin resistance High-level streptomycin resistance Tobramycin and kanamycin resistance Low-level penicillin resistance; moderate to high-level cephalosporin resistance High-level ampicillin and imipenem resistance b-lactam resistance b-lactam resistance Resistance to vancomycin +/2 teicoplanin depending on the phenotype Resistance to clindamycin, streptogrammin A and B Low-level resistance to streptogramin B compounds Streptogramin A resistance Streptogramin A resistance Streptogramin B resistance Streptogramin A resistance MLSA phenotype Intrinsic, sporadic or associated MGE Intrinsic Sporadic Intrinsic pJH1 plP810 Tn5281 Unknown pYN134 Unknown Tn1546, Inc.18, Tn5382 pR538–1 Intrinsic Intrinsic Sporadic Intrinsic Intrinsic Intrinsic Putative transposon Putative transposon Putative transposon Unknown Unknown Tn554 Tn552 and others E. faecalis E. faecium Tn1546, Inc.18 E. faecalis E. faecalis E. faecium E. faecium E. faecium E. faecium E. faecalis E. faecium E. faecium E. faecalis E. faecium E. faecium E. faecalis E. faecium E. faecium E. faecium E. faecalis E. faecium E. faecalis E. faecium E .faecium E. faecalis E. faecium E. faecalis E. faecium E. faecium E. faecium E. faecium E. faecium E. faecium E. faecalis E. faecium E. faecalis E. faecium 8–10 42 11 43 44 34 136 38 40 37, 137, 138 37, 41 12 3 25–27 139, 140 4 47 14 16 83 77 83 79 78, 141 142 16, 20 Phenotype Host range References Aph(2’’)-Ia-Aac(6’)Ie High-level gentamicin resistance Acetyltransferase VatD (SatA) Streptogramin A resistance MLSB phenotype Tn917, Tn1545 422 Virulence Volume 3 Issue 5