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PubMed2005

Intralaboratory reproducibility of the German test method of prEN ISO 15883-1 for determination of the cleaning efficacy of washer-disinfectors for flexible endoscopes.

In Europe, the evaluation of processing flexible endoscopes in washer-disinfectors (WDs) is performed in accordance with prEN ISO 15883-1, which includes determination of cleaning efficacy. Recent data suggest that large differences are found between cleaning processes when the prEN ISO 15883-1 German test model is applied. Therefore, we analysed 12 separate cleaning processes, and each was assessed by determining the means of three experiments. Transparent test tubes used as test pieces (length 2m, lumen 2mm) were contaminated with a mixture of blood and Enterococcus faecium. The WD used was set to perform the cleaning process alone, which consists of three stages (pre-rinse, cleaning, intermediate rinse). Instead of a cleaning agent, demineralized water was used in all three stages of the cleaning process. The mean bacterial load was 10(11.3)cfu/mL (N=12) in the suspensions of test organism, 10(9.1)cfu/mL (N=12) in the test soils and 10(5.8)cfu/mL (N=12) in the controls (recovery). Mean log(10) reduction factors (RF) for each process, i.e. the difference in microbial loads between the control and the processed tubes, were calculated. The 12 cleaning processes with demineralized water led to a mean RF of 2.2 (range: 1.6-3.2) and excellent visible cleanliness of the test pieces. We found that the prEN ISO 15883-1 German test method leads to reproducible and valid results, and is suitable for determining the cleaning efficacy in WDs.

Colony Count, Microbial↗

PubMed1996

Effective treatment of multidrug-resistant enterococcal experimental endocarditis with combinations of cell wall-active agents.

The efficacy of treatment with a combination of ampicillin, imipenem, and vancomycin was compared with that of two-drug combinations or monotherapy in a model of experimental endocarditis using a strain of Enterococcus faecium with high-level resistance to vancomycin and moderate intrinsic resistance to ampicillin and imipenem. In vitro time-kill synergy studies demonstrated bactericidal synergistic activity only for the triple combination. In vivo, monotherapy with vancomycin was not effective. Treatment with either ampicillin or imipenem alone or in combination with vancomycin resulted in <4 log10 reduction in colony-forming units (cfu) per gram of vegetation. The combination of ampicillin with imipenem was highly active (an additional 5 log10 reduction in cfu per gram of vegetation compared with the most active single agent), but efficacy was not increased by the addition of vancomycin to ampicillin and imipenem. Therapy with the combination of ampicillin and imipenem may be effective for some strains of multidrug-resistant enterococcal infections.

Ampicillin↗

PubMed1994

Enterococcal bacteraemia: a prospective study of 125 episodes.

One hundred and twenty-five episodes of enterococcal bacteraemia occurring over a 50-month period were studied prospectively. Enterococcus faecium was the commonest species, accounting for 76 (59.8%) of the 127 isolates. Overall, 33.1% of isolates were resistant to ampicillin and one isolate (0.8%) to vancomycin; high-level gentamicin resistance was detected in 4.3% of 93 isolates tested. The percentage of nosocomial episodes was 70.4, and 95.2% of the patients had significant underlying illness. Central venous catheters (CVCs) were the commonest source of infection. Eighty-four per cent of episodes were ultimately treated with appropriate antibiotics. The overall mortality rate was 17.6%, and that directly attributable to infection was 8.0%. An increased mortality rate was observed in intensive care and neonatal unit patients, and in patients who had received antimicrobial therapy in the 2 weeks prior to enterococcemia. CVC-related infections were associated with a reduced mortality. No other clinical or microbiological factors were found to influence outcome.

Ampicillin Resistance↗

PubMed2005

Enhanced resistance to erythromycin is conferred by the enterococcal msrC determinant in Staphylococcus aureus.

OBJECTIVES: The msrC gene, found on the chromosome of Enterococcus faecium, shares a high degree of similarity with the staphylococcal erythromycin resistance determinant msr(A). The enterococcal determinant was cloned into Staphylococcus aureus to determine whether msrC could confer antibiotic resistance in staphylococci. METHODS: A shuttle vector comprising pBluescript and pSK265 was used to introduce multiple copies of msrC into S. aureus RN4220. The integration vector pCL84 was employed to insert a single copy of msrC into the S. aureus chromosome. MICs were determined by the broth microdilution method. RESULTS: Expression of msrC from both chromosomal and plasmid loci in erythromycin-susceptible S. aureus RN4220 (MIC 0.25 mg/L) gave rise to enhanced protection against erythromycin, with an MIC of 32-64 mg/L for S. aureus RN4220 containing msrC in multiple copies and an MIC of 16-64 mg/L with msrC inserted as a single copy in the S. aureus chromosome. CONCLUSIONS: MsrC mediates high-level resistance to erythromycin in S. aureus.

Bacterial Proteins↗

PubMed2000

Ability of laboratories to detect emerging antimicrobial resistance in nosocomial pathogens: a survey of project ICARE laboratories.

A proficiency testing project was conducted among 48 microbiology laboratories participating in Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology). All laboratories correctly identified the Staphylococcus aureus challenge strain as oxacillin- resistant and an Enterococcus faecium strain as vancomycin-resistant. Thirty-one (97%) of 32 laboratories correctly reported the Streptococcus pneumoniae strain as erythromycin-resistant. All laboratories testing the Pseudomonas aeruginosa strain against ciprofloxacin or ofloxacin correctly reported the organism as resistant. Of 40 laboratories, 30 (75%) correctly reported resistant MICs or zone sizes for the imipenem- and meropenem-resistant Serratia marcescens. For the extended-spectrum beta-lactamase (ESBL)-producing strain of Klebsiella pneumoniae, 18 (42%) of 43 laboratories testing ceftazidime correctly reported ceftazidime MICs in the resistant range. These results suggest that current testing generally produces accurate results, although some laboratories have difficulty detecting resistance to carbapenems and extended-spectrum cephalosporins. This highlights the need for monitoring how well susceptibility test systems in clinical laboratories detect emerging resistance.

Aminoglycosides↗

PubMed2004

Beta-lactam antibiotics and gastrointestinal colonization with vancomycin-resistant enterococci.

We studied the effect of different subcutaneously administered beta-lactam antibiotics on the establishment of gastrointestinal colonization by vancomycin-resistant Enterococcus faecium C68 in a mouse model. Aztreonam, cefazolin, cefepime, and, to a lesser extent, ceftazidime, which neither have significant antienterococcal activity nor are secreted into human bile at high concentrations, did not promote significant vancomycin-resistant enterococci (VRE) colonization. Piperacillin-tazobactam, which has antienterococcal activity and is secreted in human bile at high concentrations, inhibited colonization after limited exposure to the inoculum but was associated with progressively increased VRE colony counts in stool samples after repeated exposure to the VRE inoculum. Ceftriaxone and cefotetan, which lack antienterococcal activity but are secreted into human bile at high concentrations, were associated with rapid and high-level colonization. These data suggest that the risk of VRE colonization varies during exposure to different beta-lactam antimicrobial agents and that the risk is related to biliary concentration and antienterococcal activity of the specific beta-lactam.

Animals↗

PubMed1999

Dissecting the VanRS signal transduction pathway with specific inhibitors.

The VanRS two-component signal transduction pathway from Enterococcus faecium was reconstituted in vitro from partially purified components and shown to be inhibited by the halophenyl isothiazolone LY-266,400, inhibitor A, a compound shown previously to reduce expression of the AlgR1-AlgR2 two-component signal transduction pathway in Pseudomonas aeruginosa (S. Roychoudhury, N. A. Zielinski, A. J. Ninfa, N. E. Allen, L. N. Jungheim, T. I. Nicas, and A. M. Chakrabarty, Proc. Natl. Acad. Sci. USA 90:965-969, 1993). Inhibitor A attenuates phosphoryl transfer from VanS approximately P to VanR by its action on the ability of VanR to accept. We observed an apparent stimulatory effect of inhibitor A on VanS autophosphorylation which is attributable to the accumulation of VanS approximately P as an intermediate unable to transfer Pi to the inhibited VanR. Thus, inhibitor A acts on the second of two sequential steps which lead to transcriptional activation of the VanHAXYZ gene cluster and the resultant expression of vancomycin resistance.

Bacterial Proteins↗

PubMed1998

Effect of leavening microflora on pizza dough properties.

Fourteen different starter cultures containing one strain of Saccharomyces cerevisiae with and without individual or combinations of lactic acid bacteria (Lactobacillus plantarum, Lact. sanfrancisco, Enterococcus faecium, Leuconostoc mesenteroides) were employed to investigate the role of leavening microflora on the properties of pizza doughs. Microbiological, chemical and physical characteristics of doughs prepared with the same flour and under the same processing conditions were determined. Leavening times and acidification properties depended on the microbial association used. The proportions of lactic and acetic acid produced by lactic acid bacteria were consistent with the metabolic properties of the strains employed. The bacteria/yeast ratios arising from microbial counts at the end of the leavening process were always lower in comparison to sour- or bread-doughs. The size of the yeast population did not change much, while bacteria showed from one to four duplications. Rheologically, the fermented doughs could only be significantly distinguished from the control dough with regard to the elastic modulus. Principal Component Analysis was applied to the acidimetric data. The scattergram of the two principal components effectively discriminated 13 of the 14 pizza dough types.

Acetic Acid↗

PubMed2006

High-level vancomycin-resistant Staphylococcus aureus isolates associated with a polymicrobial biofilm.

Glycopeptides such as vancomycin are the treatment of choice for infections due to methicillin-resistant Staphylococcus aureus. This study describes the identification of high-level vancomycin-resistant S. aureus (VRSA) isolates in a polymicrobial biofilm within an indwelling nephrostomy tube in a patient in New York. S. aureus, Enterococcus faecalis, Enterococcus faecium, Micrococcus species, Morganella morganii, and Pseudomonas aeruginosa were isolated from the biofilm. For VRSA isolates, vancomycin MICs ranged from 32 to >128 microg/ml. VRSA isolates were also resistant to aminoglycosides, fluoroquinolones, macrolides, penicillin, and tetracycline but remained susceptible to chloramphenicol, linezolid, rifampin, and trimethoprim-sulfamethoxazole. The vanA gene was localized to a plasmid of approximately 100 kb in VRSA and E. faecium isolates from the biofilm. Plasmid analysis revealed that the VRSA isolate acquired the 100-kb E. faecium plasmid, which was then maintained without integration into the MRSA plasmid. The tetracycline resistance genes tet(U) and tet(S), not previously detected in S. aureus isolates, were identified in the VRSA isolates. Additional resistance elements in the VRSA isolate included a multiresistance gene cluster, ermB-aadE-sat4-aphA-3, msrA (macrolide efflux), and the bifunctional aminoglycoside resistance gene aac(6')-aph(2")-Ia. Multiple combinations of resistance genes among the various isolates of staphylococci and enterococci, including vanA, tet(S), and tet(U), illustrate the dynamic nature of gene acquisition and loss within and between bacterial species throughout the course of infection. The potential for interspecies transfer of antimicrobial resistance genes, including resistance to vancomycin, may be enhanced by the microenvironment of a biofilm.

Acetamides↗

PubMed1994

Farm animals as a putative reservoir for vancomycin-resistant enterococcal infection in man.

Using a highly selective enrichment broth, 62 isolates of vancomycin-resistant Enterococcus faecium were obtained from non-human sources; 35 isolates from raw sewage, 22 from farm animals and 5 from uncooked chickens. All strains possessed the Van A gene, conferring high-level resistance to vancomycin (MIC > or = 256 mg/L). Ribotyping of 42 of these isolates resulted in 14 distinguishable patterns. Two ribotyping patterns were found among isolates from animals and sewage and those from clinical sources. A blood and a urine isolate from separate hospital patients and porcine isolates shared the same ribotyping pattern number 6 and a stool isolate from a patient in the community and sewage isolates shared another pattern, number 10. This finding suggests that animals may serve as a reservoir of vancomycin-resistant enterococci (VRE), which may enter the human food chain. The emergence of VRE in hospital patients may reflect selection of these organisms in the hospital environment by antibiotic usage from which nosocomial spread might occur.

Animals↗

PubMedDate not supplied

[The role of the carbohydrate composition of the glycocalyx in some species of lactobacilli in the manifestation of their adhesive properties].

Availability of certain monosaccharides in the composition of glycocalyx of lactic acid bacteria (Lactobacillus plantarum--strains 337D and 11/16; Streptococcus thermophilus--strains S1 (nonmucous race) and S5 (mucous race), Enterococcus faecium (K-50) has been investigated with the help of plant lectins with certain carbohydrate specificity labelled by colloid gold. All the microorganisms under investigation were characterized by the presence of N-acetyl-D-galactosamine and N-acetyl-D-glucosamine in rather insignificant amounts. Glycocalyx of lactic acid bacteria was also characterized by availability of essential amount of L-fructose and low amount of sialic acid (except for S. thermophilus S5 (mucous race). Presence of alpha-N-acetyl-D-galactosamine, alpha-D, beta-D-galactose, alpha-D-glucose, alpha-D-mannose in the composition of the lactic acid bacteria glycocalyx composition evidences for the additional role of these monosaccharides in the process of the microorganism adhesion on the human and animal intestine mucosa. It has been confirmed that availability of certain monosaccharides in the composition of surface glycopolymers of lactic acid bacteria was connected with adhesive properties of cells and their existence conditions.

Bacterial Adhesion↗

PubMed2006

[Antimicrobial resistance surveillance: VIRA STUDY 2006].

INTRODUCTION: The objective of this study was to determine the current antimicrobial susceptibility patterns of the most frequent multi-resistant bacteria and to analyze any possible changes with respect to the two VIRA studies carried out in 2001 and 2004. METHODS: In February 2006, the 40 participating hospitals sent the following microorganisms: non-penicillin-susceptible Streptococcus pneumoniae (92), methicillin-resistant Staphylococcus aureus (MRSA) (290), clinically significant coagulase-negative staphylococci (136), ampicillin-resistant Enterococcus faecium (89), ampicillin-resistant Haemophilus influenzae (67), ciprofloxacin-resistant Escherichia coli (365), Pseudomonas aeruginosa (181), and Acinetobacter baumannii (92). The hospitals provided epidemiological data on these microorganisms. Susceptibility was determined with a broth microdilution method. RESULTS: Among the non-penicillin-susceptible S. pneumoniae isolates, the proportion of those ones resistant to this antibiotic showed a significant (p < 0.001) decrease (59.8% in 2001, 30.2% in 2004 and 14.3% in 2006). Among MRSA, we detected one isolate nonsusceptible to linezolid, four resistant to quinupristin-dalfopristin and one strain with a vancomycin MIC of 4 microg/mL. The prevalence of extended-spectrum beta-lactamase-producing E. coli was 12.1%. Resistance of A. baumannii to imipenem varied from 27% in the 2001-2004 period to 47.8% in 2006 (p < 0.005). CONCLUSION: These results again emphasize that resistance surveillance systems are an important tool for preventing the emergence and spread of multi-resistant pathogens.

Acinetobacter baumannii↗

PubMed2006

In vitro activity of daptomycin alone and in combination with various antimicrobials against Gram-positive cocci.

The increasing prevalence of resistant Gram-positive cocci requires the need to search for more effective agents and synergistic combinations. Forty-two vancomycin-resistant Enterococcus faecium (VREF), 30 methicillin-resistant Staphylococcus aureus (MRSA) and 36 Staphylococcus epidermidis (MRSE) strains were studied. Minimum inhibitory concentrations (MICs) were determined and synergy testing was performed by using E test for daptomycin, ampicillin-sulbactam, piperacillin-tazobactam and ticarcillin-clavulanate against staphylococci; for daptomycin, ampicillin, rifampin, and gentamicin against enterococci. Daptomycin in combination with ampicillin, rifampin, and gentamicin was tested against enterococci; daptomycin in combination with ampicillin-sulbactam, piperacillin-tazobactam, and ticarcillin-clavulanate was tested against staphylococci. Interaction categories were defined by the fractional inhibitory concentration (FIC) index. All strains of staphylococci and enterococci were susceptible to daptomycin. All three combinations showed synergy against more than 70% of the MRSA strains. Daptomycin in combination with ampicillin, rifampin, and gentamicin against enterococci showed synergies of 64.2%, 57.1% and 21.4%, respectively. This study indicates that daptomycin alone and combined with beta-lactams seems to be effective against MRSA, but further in vitro and in vivo studies on the subject are required before clinical use can be recommended.

Anti-Bacterial Agents↗

PubMed2005

Antibacterial activity of linezolid and vancomycin in an in vitro pharmacodynamic model of gram-positive catheter-related bacteraemia.

OBJECTIVES: The aim of this study was to compare the activity of linezolid and vancomycin in an in vitro pharmacodynamic model to assess potential differences in activity against biofilm-embedded organisms. METHODS: Single-lumen central venous catheters colonized with biofilm-embedded Staphylococcus aureus, Staphylococcus epidermidis or vancomycin-resistant Enterococcus faecium (VRE) were treated with simulated clinical dosing regimens of linezolid 600 mg every 12 h or vancomycin 1 g every 12 h in a one-compartment in vitro pharmacodynamic model. Quantitative cultures were sampled through the catheter and peripheral ports over 48 h to dynamically assess changes in the burden of catheter colonization and organism seeding, respectively. At 24 and 48 h catheters were removed, sonicated and cultured for adherent organisms. RESULTS: Both linezolid and vancomycin suppressed bacterial growth on the catheter and release of S. aureus and S. epidermidis into the model compared with controls (P < 0.05), while linezolid also suppressed counts compared with control and vancomycin versus VRE. Neither agent completely eradicated bacterial colonization of the catheters. MICs for the isolates recovered from the model did not increase over time with linezolid or vancomycin exposure. CONCLUSIONS: Lack of activity against biofilm-embedded organisms appeared to be the primary reason for microbiological failure of both drugs in the model.

Acetamides↗

PubMed1994

A novel strictly anaerobic recovery and enrichment system incorporating lithium for detection of heat-injured Listeria monocytogenes in pasteurized milk containing background microflora.

Heat-injured cells of Listeria monocytogenes were recovered from heated raw milk containing noninjured Enterococcus faecium by combining a simple method for obtaining strict anaerobiosis with a novel enrichment broth, Penn State University broth (PSU broth). Strictly anaerobic conditions were rapidly achieved by adding 0.5 g of filter-sterilized cysteine per liter to PSU broth and then purging the preparation with N2 gas. Little resuscitation or growth occurred in strictly anaerobic PSU broth without lithium chloride because of overgrowth by E. faecium. The growth of E. faecium decreased dramatically with increasing LiCl concentration; LiCl concentrations of 8 and 10 g/liter were completely bacteriostatic. The mechanism of inhibition by LiCl appeared to involve competition with the divalent cations Ca2+ and Mg2+. Heat-injured L. monocytogenes consistently recovered and grew rapidly in strictly anaerobic PSU broth containing 4, 6, or 7 g of LiCl per liter. The use of strictly anaerobic PSU broth containing 7 g of LiCl per liter permitted detection of severely heat-injured L. monocytogenes in one simple recovery-enrichment step by eliminating oxygen toxicity and inhibiting the growth of background microflora, without preventing the resuscitation and subsequent growth of heat-injured L. monocytogenes. L. monocytogenes heated in raw milk at 62.8 degrees C for 10, 15, and 20 min could be consistently recovered from strictly anaerobic PSU broth enrichment cultures at 30 degrees C after 48, 96, and 144 h, respectively, and hence, use of PSU broth may result in better recovery of both injured and noninjured cells from foods than currently used U.S. Department of Agriculture and Food and Drug Administration preenrichment procedures.

Anaerobiosis↗

PubMed1997

Fecal carriage of vancomycin-resistant enterococci in hospitalized patients and those living in the community in The Netherlands.

In order to determine the prevalence of vancomycin-resistant enterococci (VRE) in The Netherlands, 624 hospitalized patients from intensive care units or hemato-oncology wards in nine hospitals and 200 patients living in the community were screened for VRE colonization. Enterococci were found in 49% of the hospitalized patients and in 80% of the patients living in the community. Of these strains, 43 and 32%, respectively, were Enterococcus faecium. VRE were isolated from 12 of 624 (2%) and 4 of 200 (2%) hospitalized patients and patients living in the community, respectively. PCR analysis of these 16 strains and 11 additional clinical VRE isolates from one of the participating hospitals revealed 24 vanA gene-containing, 1 vanB gene-containing, and 2 vanC1 gene-containing strains. All strains were cross-resistant to avoparcin but were sensitive to the novel glycopeptide antibiotic LY333328. Genotyping of the strains by arbitrarily primed PCR and pulsed-field gel electrophoresis revealed a high degree of genetic heterogeneity. This underscores a lack of hospital-driven endemicity of VRE clones. It is suggested that the VRE in hospitalized patients have originated from unknown sources in the community.

Anti-Bacterial Agents↗

PubMed2006

Dietary probiotic supplementation and resulting effects on performance, health status, and microbial characteristics of primiparous sows.

In an experiment with 33 first-litter sows from day 90 of pregnancy to day 28 of lactation, the influence of a probiotic supplementation on weight performance, feed intake, litter sizes, litter weights, health status and microbiological profile was tested. Enterococcus faecium DSM 7134 was supplemented in a concentration of 5 x 10(8) CFU/kg feed to the gestation and lactation diets of gilts. The supplemented sows showed a significant higher improvement of feed intake (4.16 vs. 3.71 kg/day), litter size (9.2 vs. 7.7 piglets) and weight performance. The average live weight of the probiotic sows at day 28 of lactation was 11 kg higher than of the controls. The bacterial counts/g faeces (lactobacilli, Gram-positive anaerobes, Gram-negative anaerobes, Escherichia coli and enterococci) and the incidence of adhesive and haemolytic E. coli organisms revealed no significant differences between the sows of the two groups or their piglets. While the litter size cannot necessarily be assumed as a primary effect of the probiotic supplementation, the significantly better feed intake and weight performance might be partly due to the probiotic use and can prevent "starvation sterility" of young sows after their first litter caused by reduced feed intake during lactation with high mobilization of body tissue accompanied with lack of energy.

Animal Feed↗

PubMed2006

[Effect of a novel soy fermented product enriched with isoflavones and calcium on bone tissue of rats].

The objective was to evaluate the effect of soy fermented product intake on the corporal weight and bone tissue of ovariectomized mature rats. This product was fermented with Enterococcus faecium and Lactobacillus jugurti and enriched with isoflavones and calcium. The animals were divided in 5 groups: sham-ovariectomized; ovariectomized; ovariectomized treated with soy fermented product enriched with isoflavones and calcium; ovariectomized treated with soy fermented product enriched with calcium and ovariectomized treated with non-fermented product enriched only with calcium. In order to evaluate the effect of the tested product on bone tissue (femur and tibia), the following parameters were analyzed: length; mechanical assay of three points; density (Archimedes principle); mineral content; calcium content; measure of the trabecular widths. The corporal weight of group treated with soy fermented product containing isoflavones and calcium showed no statistical difference from sham-ovariectomized group and trabecular widths tended to have larger than ovariectomized group. However, there was no significant difference to the other evaluated parameters in result of the diverse treatments. Thus, soy fermented product enriched with isoflavones and calcium inhibited the increasing of corporal weight caused by ovariectomy and revealed a tendency to trabecular protection after castration.

Animals↗