VanE, a New Type of Acquired Glycopeptide Resistance in Enterococcus faecalis BM4405

Abstract

ABSTRACT Enterococcus faecalis BM4405 was resistant to low levels of vancomycin (MIC, 16 μg/ml) and was susceptible to teicoplanin (MIC, 0.5 μg/ml). No PCR product was obtained when the total DNA of this clinical isolate was used as a template with primers specific for glycopeptide resistance genes vanA , vanB , vanC , and vanD . However, a 604-bp PCR fragment was obtained when V1 and V2 degenerate primers were used and total DNA was digested with Hin dIII as a template. The product was cloned and sequenced. The deduced amino acid sequence had greater identity (55%) with VanC than with VanA (45%), VanB (43%), or VanD (44%). This was consistent with the fact that BM4405 synthesized peptidoglycan precursors that terminated in d -serine residues. After induction with vancomycin, weak d , d -dipeptidase and penicillin-insensitive d , d -carboxypeptidase activities were detected in cytoplasmic extracts of BM4405, whereas a serine racemase activity was found in the membrane preparation. This new type of acquired glycopeptide resistance was named VanE.