Enterococcus faecalis strain WCH9 displays a moderate level of resistance to vancomycin (MIC ‫؍‬ 16 g/ml) and full susceptibility to teicoplanin but is negative by PCR analysis using primers specific for all known enterococcal vancomycin resistance genotypes (vanA, vanB, vanC, vanD, and vanE). We have isolated and sequenced a novel putative vancomycin resistance locus (designated vanG), which contains seven open reading frames, from this strain. These are organized differently from those of all the other enterococcal van loci, and, furthermore, the individual vanG gene products exhibit less than 50% amino acid sequence identity to other van gene products.Glycopeptides inhibit cell wall synthesis through the interaction of their N termini with the D-alanyl-D-alanine termini of peptidoglycan precursors (25). The resulting complexes prevent the transglycosylases from incorporating disaccharide pentapeptide subunits into the growing peptidoglycan chain, thereby inhibiting cell wall synthesis (4). In enterococci, both intrinsic and acquired resistance to glycopeptides occurs via a common mechanism involving modification of the peptidoglycan biosynthetic pathway (7). Six enterococcal vancomycin resistance genotypes have been described and characterized. Four of these (vanA, vanB, vanD, and vanE) are acquired mechanisms and the other two (vanC1 and vanC2/C3 specific to Enterococcus gallinarum and Enterococcus casseliflavus/Enterococcus flavescens, respectively [the vanC2 and vanC3 genotypes are closely related, with the loci containing minor sequence differences, and are therefore jointly referred to herein as vanC2/C3; likewise, there is debate over whether E. casseliflavus and E. flavescens are actually separate species, and they are jointly referred to herein as E. casseliflavus/E. flavescens]) are intrinsic properties (15,18,21).The genes for the VanA vancomycin resistance phenotype are located on the 10.8-kb transposable element Tn1546, which encodes 7 polypeptides involved in resistance. These polypeptides function together to confer high-level resistance to vancomycin and teicoplanin (6, 7), as well as variable levels of resistance to all other glycopeptides (18). The VanB resistance phenotype confers variable levels of resistance to vancomycin but leaves the organism susceptible to teicoplanin (8, 13). VanD is characterized by resistance to moderate levels of vancomycin and to low levels of teicoplanin (21), while the VanE resistance phenotype exhibits low-level resistance to vancomycin but full susceptibility to teicoplanin (15).Enterococci Recently, we have investigated the genotype of Australian isolates of vancomycin-resistant enterococci (VRE) (9). Among the strains examined were four Enterococcus faecalis isolates which exhibited moderate resistance to vancomycin (MIC range, 12 to 16 g/ml), but full susceptibility to teicoplanin (MIC ϭ 0.5 g/ml), a phenotype similar to that of VanB and VanE strains. The four isolates were indistinguishable by pulsedfield gel electrophoresis and were isolated from inpatie...

The two-component system TCS08 is one of the regulatory systems that is important for virulence of Streptococcus pneumoniae. In order to investigate the TCS08 regulon, we have analyzed transcription profiles of mutants derived from S. pneumoniae R6 by microarray analysis. Since deletion mutants are often without a significant phenotype, we constructed a mutation in the histidine kinase HK08, T133P, in analogy to the phosphatase mutation T230P in the H box of the S. pneumoniae CiaH kinase described recently (D. Zähner, K. Kaminski, M. van der Linden, T. Mascher, M. Merai, and R. Hakenbeck, J. Mol. Microbiol. Biotechnol. 4:211-216, 2002). In addition, a deletion mutation was constructed in rr08, encoding the cognate response regulator. The most heavily suppressed genes in the hk08 mutant were spr0276 to spr0282, encoding a putative cellobiose phosphoenolpyruvate sugar phosphotransferase system (PTS). Whereas the R6 Sm r parent strain and the ⌬rr08 mutant readily grew on cellobiose, the hk08 mutant and selected mutants with deletions in the PTS cluster did not, strongly suggesting that TCS08 is involved in the catabolism of cellobiose. Homologues of the TCS08 system were found in closely related streptococci and other gram-positive cocci. However, the genes spr0276 to spr0282, encoding the putative cellobiose PTS, represent a genomic island in S. pneumoniae and homologues were found in Streptococcus gordonii only, suggesting that this system might contribute to the pathogenicity potential of the pneumococcus.