Effects of dispersed recreational activities on the microbiological quality of forest surface water.
(1/2300)
The microbiological quality of forest surface waters in the Greenwater River watershed was examined to investigate the influence of heavy motorized camping in an area with no sanitary facilities. Indicator densities increased during weekend human-use periods when compared to weekdays. Increases in indicator densities were also noted downstream from heavily used camping areas when compared to upstream sites. Seasonal, weekly, and diurnal fluctuations in indicator densities were observed. This study suggests that potential health hazards exist in this watershed during periods of human use. (+info)
Isolation and chemical characterization of a capsular polysaccharide antigen shared by clinical isolates of Enterococcus faecalis and vancomycin-resistant Enterococcus faecium.
(2/2300)
Enterococci are a common cause of serious infections, especially in newborns, severely immunocompromised patients, and patients requiring intensive care. To characterize enterococcal surface antigens that are targets of opsonic antibodies, rabbits were immunized with various gentamicin-killed Enterococcus faecalis strains, and immune sera were tested in an opsonophagocytic assay against a selection of clinical isolates. Serum raised against one strain killed the homologous strain (12030) at a dilution of 1:5,120 and mediated opsonic killing of 33% of all strains tested. In addition, this serum killed two (28%) of seven vancomycin-resistant Enterococcus faecium strains. Adsorption of sera with the homologous strain eliminated killing activity. The adsorbing antigens were resistant to treatment with proteinase K and to boiling for 1 h, but were susceptible to treatment with sodium periodate, indicating that the antigen inducing opsonic activity is a polysaccharide. Antibodies in immune rabbit sera reacted with a capsule-like structure visualized by electron microscopy both on the homologous E. faecalis strain and on a vancomycin-resistant E. faecium strain. The capsular polysaccharides from E. faecalis 12030 and E. faecium 838970 were purified, and chemical and structural analyses indicated they were identical glycerol teichoic acid-like molecules with a carbohydrate backbone structure of 6-alpha-D-glucose-1-2 glycerol-3-PO4 with substitution on carbon 2 of the glucose with an alpha-2-1-D-glucose residue. The purified antigen adsorbed opsonic killing activity from immune rabbit sera and elicited high titers of antibodies (when used to immunize rabbits) that both mediated opsonic killing of bacteria and bound to a capsule-like structure visualized by electron microscopy. These results indicate that approximately one-third of a sample of 15 E. faecalis strains and 7 vancomycin-resistant E. faecium strains possess shared capsular polysaccharides that are targets of opsonophagocytic antibodies and therefore are potential vaccine candidates. (+info)
A new hydrolase specific for taurine-conjugates of bile acids.
(3/2300)
Through the investigation of the bile acid-deconjugation activities of human intestinal anaerobes, a new enzyme was discovered in Peptostreptococcus intermedius which hydrolyzed specifically the taurine-conjugates, but not the glycine-conjugates of bile acids. However, the enzymes in Streptococcus faecalis and Lactobacillus brevis hydrolyzed chiefly the glycine-conjugates. (+info)
Two-step acquisition of resistance to the teicoplanin-gentamicin combination by VanB-type Enterococcus faecalis in vitro and in experimental endocarditis.
(4/2300)
The activity of vancomycin and teicoplanin combined with gentamicin was investigated in vitro against strains of Enterococcus faecalis resistant to vancomycin and susceptible to teicoplanin (VanB type) and against mutants that had acquired resistance to teicoplanin by three different mechanisms. In vitro, gentamicin selected mutants with two- to sixfold increases in the level of resistance to this antibiotic at frequencies of 10(-6) to 10(-7). Teicoplanin selected teicoplanin-resistant mutants at similar frequencies. Both mutations were required to abolish the activity of the gentamicin-teicoplanin combination. As expected, simultaneous acquisition of the two types of mutations was not observed. In therapy with gentamicin or teicoplanin alone, each selected mutants in three of seven rabbits with aortic endocarditis due to VanB-type E. faecalis BM4275. The vancomycin-gentamicin combination selected mutants that were resistant to gentamicin and to the combination. In contrast, the teicoplanin-gentamicin regimen prevented the emergence of mutants resistant to one or both components of the combination. These results suggest that two mutations are also required to suppress the in vivo activity of the teicoplanin-gentamicin combination. (+info)
Efficacy of ampicillin plus ceftriaxone in treatment of experimental endocarditis due to Enterococcus faecalis strains highly resistant to aminoglycosides.
(5/2300)
The purpose of this work was to evaluate the in vitro possibilities of ampicillin-ceftriaxone combinations for 10 Enterococcus faecalis strains with high-level resistance to aminoglycosides (HLRAg) and to assess the efficacy of ampicillin plus ceftriaxone, both administered with humanlike pharmacokinetics, for the treatment of experimental endocarditis due to HLRAg E. faecalis. A reduction of 1 to 4 dilutions in MICs of ampicillin was obtained when ampicillin was combined with a fixed subinhibitory ceftriaxone concentration of 4 micrograms/ml. This potentiating effect was also observed by the double disk method with all 10 strains. Time-kill studies performed with 1 and 2 micrograms of ampicillin alone per ml or in combination with 5, 10, 20, 40, and 60 micrograms of ceftriaxone per ml showed a > or = 2 log10 reduction in CFU per milliliter with respect to ampicillin alone and to the initial inoculum for all 10 E. faecalis strains studied. This effect was obtained for seven strains with the combination of 2 micrograms of ampicillin per ml plus 10 micrograms of ceftriaxone per ml and for six strains with 5 micrograms of ceftriaxone per ml. Animals with catheter-induced endocarditis were infected intravenously with 10(8) CFU of E. faecalis V48 or 10(5) CFU of E. faecalis V45 and were treated for 3 days with humanlike pharmacokinetics of 2 g of ampicillin every 4 h, alone or combined with 2 g of ceftriaxone every 12 h. The levels in serum and the pharmacokinetic parameters of the humanlike pharmacokinetics of ampicillin or ceftriaxone in rabbits were similar to those found in humans treated with 2 g of ampicillin or ceftriaxone intravenously. Results of the therapy for experimental endocarditis caused by E. faecalis V48 or V45 showed that the residual bacterial titers in aortic valve vegetations were significantly lower in the animals treated with the combinations of ampicillin plus ceftriaxone than in those treated with ampicillin alone (P < 0.001). The combination of ampicillin and ceftriaxone showed in vitro and in vivo synergism against HLRAg E. faecalis. (+info)
The osmoprotectant glycine betaine inhibits salt-induced cross-tolerance towards lethal treatment in Enterococcus faecalis.
(6/2300)
The response of Enterococcus faecalis ATCC 19433 to salt stress has been characterized previously in complex media. In this report, it has been demonstrated that this bacterium actively accumulates the osmoprotectant glycine betaine (GB) from salt-enriched complex medium BHI. To further understand the specific effects of GB and other osmoprotective compounds in salt adaptation and salt-induced cross-tolerance to lethal challenges, a chemically defined medium lacking putative osmoprotectants was used. In this medium, bacterial growth was significantly reduced by increasing concentrations of NaCl. At 0.75 M NaCl, 90% inhibition of the growth rate was observed; GB and its structural analogues restored growth to the non-salt-stressed level. In contrast, proline, pipecolate and ectoine did not allow growth recovery of stressed cells. Kinetic studies showed that the uptake of betaines shows strong structural specificity and occurs through a salt-stress-inducible high-affinity porter [Km = 3.3 microM; Vmax = 130 nmol min(-1) (mg protein)(-1); the uptake activity increased 400-fold in the presence of 0.5 M NaCl]. Moreover, GB and its analogues were accumulated as non-metabolizable cytosolic osmolytes and reached intracellular levels ranging from 1-3 to 1.5 micromol (mg protein)(-1). In contrast to the beneficial effect of GB on the growth of salt-stressed cultures of E. faecalis, its accumulation inhibits the salt-induced cross-tolerance to a heterologous lethal challenge. Indeed, pretreatment of bacterial cells with 0.5 M NaCl induced resistance to 0.3% bile salts (survival of adapted cells increased by a factor of 6800). The presence of GB in the adaptation medium reduced the acquisition of bile salts resistance 680-fold. The synthesis of 11 of the 13 proteins induced during salt adaptation was significantly reduced in the presence of GB. These results raise questions about the actual beneficial effect of GB in natural environments where bacteria are often subjected to various stresses. (+info)
Microbiological and inflammatory effects of murine recombinant interleukin-10 in two models of polymicrobial peritonitis in rats.
(7/2300)
A protective effect of interleukin-10 (IL-10) against the development of lethal shock has been demonstrated in various animal models. In contrast, the immunosuppressant properties of this mediator have been minimally evaluated in low-mortality models of infections. The clinical, microbiological, and inflammatory effects of murine recombinant IL-10 (mrIL-10) therapy were evaluated in two models of peritonitis in rats, which differed in the degree of severity of peritoneal inflammation 3 days after inoculation of Escherichia coli and Bacteroides fragilis with or without Enterococcus faecalis. The severity of the disease remained unchanged compared to that in control animals. A dose-related decrease in the peritoneal phagocyte count was observed in the treated groups compared to the counts in control animals. The subsequent experiments were performed exclusively in the mixed gram-positive-gram negative model, which exhibits an intense and prolonged inflammatory response with similar criteria. The early effects of mrIL-10 (evaluated 6 h after inoculation), repeated injections of mrIL-10 (four doses injected from 0 to 9 h after bacterial challenge), and pretreatment (two doses injected 6 and 3 h before inoculation) were evaluated. The clinical and microbiological parameters remained unchanged in the treated animals. Decreases in the peritoneal phagocyte count and the peritoneal concentration of tumor necrosis factor were observed following repeated injections of mrIL-10. In summary, our data suggest that mrIL-10 does not worsen the manifestations of sepsis. However, these results need to be confirmed in clinical practice. (+info)
Isolation of Enterococcus faecalis clinical isolates that efficiently adhere to human bladder carcinoma T24 cells and inhibition of adhesion by fibronectin and trypsin treatment.
(8/2300)
The adherence of Enterococcus faecalis strains to human T24 cells was examined by scanning electron microscopy. Five highly adhesive strains were identified from 30 strains isolated from the urine of patients with urinary tract infections. No efficiently adhesive strains were found among the 30 strains isolated from the feces of healthy students. The five isolated strains also adhered efficiently to human bladder epithelial cells. Analysis of restriction endonuclease-digested plasmid DNAs and chromosome DNAs showed that the five strains were different strains isolated from different patients. The adhesiveness of these strains was inhibited by treatment with fibronectin or trypsin, implying that a specific protein (adhesin) on the bacterial cell surface mediates adherence to fibronectin on the host cell surfaces, and the adhesin differs from the reported adhesins. (+info)