We studied vancomycin and daptomycin susceptibility in methicillin-resistant Staphylococcus aureus from patients exposed to vancomycin, glycopeptide-intermediate S. aureus, and S. aureus passaged in vancomycin-containing medium. A correlation between vancomycin and daptomycin heteroresistance was noted in some strains, suggesting that exposure of S. aureus to vancomycin may affect susceptibility to daptomycin.

In vitro, the antimicrobial agent taurolidine inhibited virtually all of the bacteria tested, including vancomycin-resistant enterococci, oxacillin-resistant staphylococci, and Stenotrophomonas maltophilia, at concentrations between 250 and 2,000 g/ml. Taurolidine was not effective in experimental endocarditis. While it appears unlikely that this antimicrobial would be useful for systemic therapy, its bactericidal activity and the resistance rates found (<10 ؊9 ) are favorable indicators for its possible development for topical use.With the continuing emergence of multiply antibiotic-resistant organisms, the need to develop new therapeutic agents remains evident. Taurolidine [bis-(1,1-dioxoperhydro-1,2,4-thiadiazinyl-4)methane], a derivative of the amino acid taurine, is an antimicrobial agent which inhibits and kills a broad range of microorganisms in vitro, albeit at high concentrations (3,4,9,11,13). This compound acts through mechanisms unlike those described for other currently available antimicrobials. Specifically, it is believed that methylol derivatives interact with components of bacterial cell walls resulting in irreparable injury (4). Taurolidine also appears to have immunoregulatory properties, blunting lipopolysaccharide-induced tumor necrosis factor and interleukin-1 release from human peripheral blood mononuclear cells (2) and also reducing adherence of bacteria to human epithelial cells in vitro (5). The compound has been given to humans both intravenously (i.v.) and by peritoneal lavage (1, 12).The purpose of the present study was to examine the in vitro activity of taurolidine against a broad variety of bacterial species, including antibiotic-resistant strains. We also evaluated the activity of taurolidine in vivo in experimental endocarditis using two strains of enterococci, one of which was a vancomycin-resistant strain of Enterococcus faecium.Most of the bacterial strains used in this study were routine isolates collected by our clinical microbiology laboratory during 1997. Additional strains from our collection were included based upon specific resistance traits. Taurolidine was provided by Wallace Laboratories, Cranbury, N.J. Antimicrobial reference standards of ciprofloxacin, imipenem, and cefotaxime were provided by Bayer Corporation, West Haven, Conn.; Merck & Co., Inc., West Point, Pa.; and Hoechst Marion Roussel, Inc., Kansas City, Mo., respectively. Vancomycin was obtained from Eli Lilly & Co., Indianapolis, Ind. MICs were determined by agar dilution (7, 8) on Mueller-Hinton II agar (BBL Microbiology Systems, Cockeysville, Md.) except as noted otherwise. Agar was supplemented with 5% sheep blood for streptococci and diphtheroids. Inocula were ca. 10 4 (10 5 for anaerobes) CFU/spot. Plates were incubated in room air and read at 18 to 20 h, except for lactobacilli, Leuconostoc spp., Pediococcus spp., and pneumococci, which were incubated in 5% CO 2 and examined for growth at 24 h. Anaerobes were incubated for 48 h on brucella agar in an atmosphere produced by Gas-Pak Plus (BBL). Time-...

We report the sequence of a 630-bp fragment of a gene associated with resistance to high levels of vancomycin in a clinical isolate of Enterococcusfaecalis which retained susceptibility to teicoplanin. This gene was similar to the recently sequenced vanB and partially homologous with vanA, but it showed less-marked similarity to vanC. A DNA probe, derived from this polymerase chain reaction-amplified gene fragment, hybridized specifically with genomic DNA from Enterococcus faecium and E. faecalis isolates which were vancomycin resistant (MICs ranged from 8 to 512 ,ug/ml) but susceptible to teicoplanin. Curing of vancomycin resistance was associated with loss of DNA hybridization with the gene probe. Transfer of DNA which hybridized with the probe accompanied transfer of vancomycin resistance to a susceptible recipient strain. Neither curing nor transfer of vancomycin resistance was consistently related to loss or acquisition, respectively, of plasmid DNA.