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PubMed2002

Heterologous expression of the Lactococcus lactis bacteriocin, nisin, in a dairy Enterococcus strain.

The bacteriocin nisin is produced only by some strains of Lactococcus lactis, and to date production in other lactic acid bacteria has not been achieved. Enterococcus sp. strain N12beta is a nisin-immune transconjugant obtained from a nisin-producing donor (L. lactis ATCC 11454) and a dairy recipient (Enterococcus sp. strain S12beta), but it does not produce nisin. In this study, using PCR amplification, we confirmed that the whole nisin operon is likely present in Enterococcus sp. strain N12beta. Northern hybridization of total RNA from strain N12beta with a nisA probe and the results of reverse transcriptase PCR showed the lack of nisA transcription in this strain. However, nisA transcription was partially restored in strain N12beta upon growth in the presence of exogenous nisin, and the nisA transcription signal was intensified after an increase in the external nisin level. Furthermore, bioassays showed that active nisin was produced in a dose-dependent fashion by strain N12beta following induction by exogenous nisin. These results indicated that expression of the nisin genes in Enterococcus sp. strain N12beta depended on autoinduction via signal transduction. However, the amount of external inducing signal required was significantly greater than the amount needed for autoinduction in L. lactis.

Bacteriocins↗
PubMed1994

Use of cephalexin-aztreonam-arabinose agar for selective isolation of Enterococcus faecium.

Cephalexin-aztreonam-arabinose agar (CAA), a new selective agar, was examined in comparison with nalidixic acid-colistin agar for the differentiation of Enterococcus faecium from other enterococci and the ability to isolate the organism from feces. Two hundred sixteen enterococcus isolates and a variety of gram-positive and gram-negative control strains were inoculated onto both media. All control strains of E. faecium were easily differentiated from Enterococcus faecalis and Enterococcus durans on the basis of arabinose fermentation on CAA. Differentiation of E. faecium from other enterococci or Streptococcus bovis was not possible on nalidixic acid-colistin agar. Increased isolation of E. faecium was demonstrated on CAA when both media were compared for the isolation of the organism from feces. CAA has been shown to possess excellent differential and selective features allowing the simple and effective isolation of E. faecium from heavily contaminated sites.

Agar↗
PubMed2000

Typing of Enterococcus faecium by polymerase chain reaction and pulsed field gel electrophoresis.

Polymerase chain reaction (PCR) with JB1 or REP consensus oligonucleotides and pulsed field gel electrophoresis (PFGE) were used to study genomic DNA extracted from 31 strains of enterococci. Eleven ATCC strains, representative of 11 species of Enterococcus, were initially tested by JB1-PCR, revealing that Enterococcus malodoratus and Enterococcus hirae presented identical banding patterns. Eight Enterococcus faecium isolates from Stanford University and 12 from São Paulo Hospital were studied by JB1-PCR, REP-PCR (1/2)R and PFGE. Among the isolates from Stanford University, 5 genotypes were defined by JB1-PCR, 7 by REP-PCR (1/2)R and 4 by PFGE. Among the isolates from São Paulo Hospital, 9 genotypes were identified by JB1-PCR, 6 by REP-PCR and 5 by PFGE. The three methods identified identical genotypes, but there was not complete agreement among them.

Bacterial Typing Techniques↗
PubMed1996

[Identification of Enterococcus species from clinical samples and their antimicrobial susceptibility].

The genus enterococcus has 12 species of which, E faecalis and E faecium are most important in human infections. A progressive resistance to penicillin and ampicillin has been detected in these species. The aim of this work was to identify Enterococcus species isolated in a hospital and to study their antimicrobial susceptibility. We studied 209 Enterococcus species coming from patients admitted to a public hospital. Their susceptibility to penicillin, ampicillin, imipenem, vancomycin, tetracycline, chloramphenicol, ciprofloxacin, gentamicin and streptomycin was determined with the agar dilution technique. Eighty seven percent of species were E faecalis and 7.1% were E fecium, other isolated species were E hirae, E casseliflaws, E avium, E solitarius and E faecalis variant. Thirty eight percent of these species were isolated from the urinary tract, 22% from the skin and 14% from surgical wounds. All E faecalis species were susceptible to penicillin, ampicillin, imipenem and vancomycin; 27.3% were susceptible to tetracycline, 54.7% to chloramphenicol and 80% to ciprofloxacin. Seventy three percent of E faecium species were susceptible to penicillin, 80% to ampicillin and 60% to imipenem. Sixty two percent of E faecalis and 42.4% of E faecium were resistant to streptomycin. It is concluded that the correct identification of Enterococcus species has therapeutic implications.

Anti-Bacterial Agents↗
PubMed1997

[Evaluation of a rapid method for the identification of the Enterococcus genus].

BACKGROUND: The evaluation of the reliability of a group of three tests: pyrrolidonil-arilamidase, rapid test in NaCl esculin broth and group D antistreptococci agglutination for the rapid identification of the Enterococcus genus were performed. METHODS: One hundred fifty-eight strains of streptococci: 110 strains of Enterococcus faecalis, 8 E. faecium, 3 E. avium, 16 Streptococcus intermedius, 7 S. salivarius, 4 S. bovis, 4 S. constellatus, 2 S. sanguis and 1 strain of S. equinus, S. mitis, S. uberis and S. mutans were studied. The tests used were: rapid test in NaCl- esculin broth, pyrrolidonyl-arilamidase and antigroup D streptococcus agglutination (Patho Dx Strep D/PYR; Diagnostic Product Corporation). All catalase-negative gram-positive cocci or coccibacilli which were positive in the three tests were considered to belong to the Enterococcus genus. The usefulness of Gram staining in culture in thioglycolate broth was also studied comparing it with the results obtained with solid medium. RESULTS: The results of the proposed identification scheme were evaluated calculating different parameters: sensitivity 98%, specificity 100%, positive predictive value, 100%, and negative predictive value 94%. No significant differences were observed between the results obtained with Gram staining with thioglycolate broth and those obtained with solid medium except in the case of the Streptococcus mutans strain. CONCLUSIONS: The application of a combination of tests: pyrroidonyl-arilamidase, antistreptococci group D agglutination and rapid test in NaCl-esculin broth to catalase-negative gram-positive cocci and coccobacilli allows reliable identification in a maximum of three hours of strains belonging to the Enterococcus genus.

Bacteriological Techniques↗
PubMed1998

Susceptibility patterns of Enterococcus spp. isolated in Poland during 1996.

Susceptibility of Enterococcus spp. isolated from various clinical specimens to different antimicrobial agents was evaluated. Of the 346 enterococcal isolates obtained from four regional Polish hospitals during 6 months of 1996, 261 (75.4%) were identified as Enterococcus faecalis, 75 (21.7%) as Enterococcus faecium and ten (2.9%) as other enterococcal species. High-level resistance to gentamicin was expressed by 33.4% of E. faecalis and 86.5% of E. faecium strains and corresponding streptomycin resistance by 43.9 and 82.4%, respectively. Over 80% of E. faecium isolates were resistant to ampicillin. None of the isolates was resistant to teicoplanin, however 7.9% of E. fecalis and 1.4% of E. faecium strains were moderately susceptible to vancomycin.

Anti-Bacterial Agents↗
PubMedDate not supplied

Enterococcus lactic acid bacteria strain SF68 and lactulose in hepatic encephalopathy: a controlled study.

Forty cirrhotic patients with non-advanced hepatic encephalopathy were randomly allocated into groups which were given orally either two capsules three times daily of a preparation of Enterococcus lactic acid bacteria strain SF68 or 30 ml lactulose four times daily. The patients were evaluated over a 10-day course of treatment and for 10 days post-treatment. The Enterococcus SF68 preparation proved to be as effective as lactulose in lowering blood ammonia, and in improving mental state and psychometric performance. Moreover, the effects of Enterococcus SF68, contrary to that of lactulose, persisted longer after treatment withdrawal. Some patients reported diarrhoea and abdominal pain with lactulose. Lactulose is a standard therapy in the treatment of patients with hepatic encephalopathy. In this study, however, the use of the Enterococcus SF68 preparation was shown to offer advantages over lactulose in these patients.

Adult↗
PubMedDate not supplied

Double-blind report on the efficacy of lactic acid-producing Enterococcus SF68 in the prevention of antibiotic-associated diarrhoea and in the treatment of acute diarrhoea.

A multicentre double-blind, placebo-controlled clinical trial, involving 123 patients at 10 centres, was carried out to assess the efficacy of a preparation of lactic acid-producing Enterococcus SF 68 in the prevention of antibiotic-associated diarrhoea and in the treatment of acute diarrhoea. In the prevention study, 45 patients being treated with antibiotics were given, concurrently, one capsule twice daily of either Enterococcus SF68 or placebo. Acute diarrhoea was present in 78 patients who were given the same treatment but three times daily. All treatments were continued for 7 days. Enterococcus SF 68 was shown to be effective in reducing the incidence of antibiotic-associated diarrhoea in comparison with placebo (8.7% compared with 27.2%, respectively). Patients with acute enteritis showed a significantly faster resolution of bowel abnormalities during treatment with Enterococcus SF68 compared with placebo.

Adult↗
PubMed1996

Structure of the low-affinity penicillin-binding protein 5 PBP5fm in wild-type and highly penicillin-resistant strains of Enterococcus faecium.

Among its penicillin-binding proteins (PBPs), Enterococcus faecium possesses a low-affinity PBP5, PBP5fm, which is the main target involved in beta-lactam resistance. A 7.7-kb EcoRI chromosomal fragment of E. faecium D63r containing the pbp5fm gene was cloned and sequenced. Two open reading frames (ORFs) were found. A 2,037-bp ORF encoded the deduced 73.8-kDa PBP5fm, the amino acid sequences of which were, respectively, 99.8, 78.5, and 62% homologous to those of the low-affinity plasmid-encoded PBP3r of Enterococcus hirae S185r and the chromosome-encoded PBP5 of E. hirae R40 and Enterococcus faecalis 56R. A second 597-bp ORF, designated psrfm, was found 2.3 kb upstream of pbp5fm. It appeared to be 285 bp shorter than and 74% homologous with the regulatory gene psr of E. hirae ATCC 9790. Different clinical isolates of E. faecium, for which a wide range of benzylpenicillin MICs were observed, showed that the increases in MICs were related to two mechanisms. For some strains of intermediate resistance (MICs of 16 to 64 micrograms/ml), the increased level of resistance could be explained by the presence of larger quantities of PBP5fm which had an affinity for benzylpenicillin (second-order rate constant of protein acylation [k+2/K] values of 17 to 25 M(-1) s(-1)) that remained unchanged. For the two most highly resistant strains, EFM-1 (MIC, 90 micrograms/ml) and H80721 (MIC, 512 micrograms/ml), the resistance was related to different amino acid substitutions yielding very-low-affinity PBP5fm variants (k+2/K < or = 1.5 M(-1) s(-1)) which were synthesized in small quantities. More specifically, it appeared, with a three-dimensional model of the C-terminal domain of PBP5fm, that the substitutions of Met-485, located in the third position after the conserved SDN triad, by Thr in EFM-1 and by Ala in H80721 were the most likely cause of the decreasing affinity of PBP5fm observed in these strains.

Amino Acid Sequence↗
PubMed1999

Evaluation of the revised MicroScan dried overnight gram-positive identification panel to identify Enterococcus species.

The revised MicroScan Dried Overnight Gram-Positive Identification panel was evaluated for its efficacy at identifying Enterococcus species in comparison with conventional biochemical tests. Supplemental testing of ampicillin-susceptible Enterococcus faecium for motility and the ability to acidify methyl-alpha-D-glucopyranoside helped recognize E. gallinarum and increased the accuracy of the panel for identifying Enterococcus species to 98.5%.

Ampicillin Resistance↗
PubMed1998

Third-generation cephalosporins and vancomycin as risk factors for postoperative vancomycin-resistant enterococcus infection.

OBJECTIVE: To examine use of third-generation cephalosporins (3GCs) alone and in association with vancomycin hydrochloride as a risk factor for vancomycin-resistant enterococcus (VRE) infection in surgical patients. DESIGN: Case-control retrospective study analyzing antibiotic use in the 30 days preceding culture of VRE or vancomycin-sensitive enterococcus from an infected site. SETTING: A large tertiary care teaching hospital. PATIENTS: Surgical inpatients with VRE infections between September 3, 1993, and January 29, 1997, were matched with patients with vancomycin-sensitive enterococcus infections. Matches were based on surgical procedure, initial infection site, and immunosuppression. Matches were found for 32 of 50 surgical patients with VRE. Twenty matched pairs of patients were recipients of solid organ transplants. MAIN OUTCOME MEASURES: Multivariate logistic regression analysis was done to examine 3GCs and vancomycin as risk factors for VRE infection. Univariate analysis of use of other antibiotic agents and demographic data was also performed. RESULTS: Multivariate analysis showed significant differences in the use of 3GCs both alone and concurrently with vancomycin. Univariate analysis also showed higher use of metronidazole, concurrent vancomycin and metronidazole, concurrent vancomycin and ceftazidime, and all antibiotics combined in patients with VRE infections. CONCLUSIONS: This matched control study showed that use of 3GCs, alone (P=.05) or concurrently with vancomycin (P=.05), was a risk factor for VRE infection in surgical patients. Judicious administration of third-generation antibiotics is warranted in surgical patients with other risk factors for VRE.

Adult↗
PubMed1995

Detection of aminoglycoside-penicillin synergy against Enterococcus faecium using high-content aminoglycoside disks.

Thirty-seven Enterococcus faecium strains were screened for high-level aminoglycoside resistance with an agar diffusion test using high-content aminoglycoside disks (300 micrograms of streptomycin and 120 micrograms of gentamicin, tobramycin, kanamycin or amikacin). The inhibition zones obtained were correlated with results of time-kill penicillin-aminoglycoside synergy studies. An 11 mm breakpoint differentiated strains susceptible or resistant to the synergy of streptomycin plus penicillin. Irrespective of the inhibition zones obtained with tobramycin and kanamycin disks, Enterococcus faecium strains never showed synergy with penicillin in combination with these aminoglycosides. Penicillin-amikacin synergy cannot be predicted by the amikacin disks. Nevertheless, even though kanamycin disks do not predict penicillin-kanamycin synergy, they can be used to predict penicillin-amikacin synergy. In summary, high-content streptomycin, gentamicin and kanamycin disks can be used to predict the susceptibility of Enterococcus faecium strains to the synergistic combination of penicillin plus one of the aminoglycosides (streptomycin, gentamicin or amikacin, respectively).

Aminoglycosides↗
PubMed1990

In vitro activity of daptomycin-metronidazole combinations against mixed bacterial cultures: reduced activity of metronidazole against Bacteroides species in the presence of Enterococcus faecalis.

The in vitro activity of daptomycin-metronidazole combinations against mixed cultures of gram-positive facultative cocci and strains of the Bacteroides fragilis group was investigated. Metronidazole did not influence the high activity of daptomycin against strains of Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis in the absence or presence of the co-cultured Bacteroides strains. In contrast, the Enterococcus faecalis isolates protected the co-cultured Bacteroides strains against the killing effect of metronidazole, even at a concentration four- or eightfold the MIC of metronidazole. Killing curve experiments confirmed this protective effect of different isolates of Enterococcus faecalis.

Anti-Bacterial Agents↗
PubMed1990

Isolation of three strains of beta-lactamase-producing Enterococcus faecalis in Argentina.

Of the 90 strains of Enterococcus spp. isolated in an Argentine laboratory in the period from January to July 1989, three were identified as beta-lactamase-producing Enterococcus faecalis. According to the literature reviewed, these appear to be the first beta-lactamase-positive strains of Enterococcus isolated outside the USA. They differed from most beta-lactamase-producing strains already described in that they were susceptible to low concentrations of macrolides. All three strains were resistant to high concentrations of aminoglycosides.

Aminoglycosides↗
PubMed1997

Enterococcus cecorum septicemia in a malnourished adult patient.

Enterococcus cecorum, a species typically isolated from chicken, pigs, calves, horses, ducks, cats, dogs, and canaries, was isolated from the blood of a patient with severe septicemia. The isolate was identified by conventional biochemical tests. Identity as Enterococcus cecorum was confirmed by SDS-PAGE analysis of whole cell protein. This is the first report of the isolation of Enterococcus cecorum in a clinical setting.

Adult↗
PubMed1998

Identification of clinically important species of Enterococcus within 1 day with randomly amplified polymorphic DNA (RAPD).

The use of randomly amplified polymorphic DNA (RAPD) for rapid, reliable, and easily interpreted identification of enterococci was evaluated. Nineteen type strains of Enterococcus, 12 reference strains, and 114 clinical isolates of Enterococcus were analyzed. Discrimination was obtained between most type strains, the exceptions being Ent. casseliflavus and Ent. flavescens, which had relatively similar RAPD-profiles. Ent. faecalis and Ent. faecium were readily separated, and Ent. gallinarum and Ent. durans could also be identified. Extracts to be used in the polymerase chain reaction (PCR) were prepared directly from agar plate colonies, which made it possible to complete the identification procedure in one day. RAPD was proved to be a fast and reliable method for identification of most Enterococcus spp. of clinical significance.

Enterococcus↗
PubMed2001

Photobiological activity of exogenous and endogenous porphyrin derivatives in Escherichia coli and Enterococcus hirae cells.

Photodynamic treatment, the combined application of a photosensitiser and visible light, represents a new and promising approach for the inactivation of microorganisms. The photosensitising potentials of exogenous zinc-phthalocyanine-tetrasulphonate (ZnPsTS), tetraphenylporphyrins (TPPs) and endogenous porphyrin derivatives were tested and compared on Gram-negative and Gram-positive bacteria, Escherichia coli B. and Enterococcus hirae, respectively. The synthesis of endogenous porphyrins was induced by 5-aminolevulinic acid (delta-ALA). The porphyrin- or delta-ALA-treated cells were irradiated with white light. The photosensitising efficiency of endogenous derivatives on both types of bacteria is ZnPcTS < TP(4-OGluOH)3P < TP(4-OGluOH)4P. However, neither exogenous derivatives exhibit appreciable photosensitising activity for disinfection application. ALA-induced photodynamic treatment showed good potential for the inactivation of Escherichia coli cells, but not towards Enterococcus hirae cells. The failure of photosensitisation of the Enterococcus hirae strain selected indicates that apart from the Gram-positive character, other structural elements of the membrane can influence the result of photodynamic treatments.

Dose-Response Relationship, Radiation↗
PubMed2000

Epidemiological, microbiological, clinical, and prognostic factors of bacteremia caused by high-level vancomycin-resistant Enterococcus species.

A case-control study was performed between 1994 and 1996 in order to study the epidemiological, microbiological, clinical, and prognostic features of high-level vancomycin-resistant enterococcal bacteremia. Seventeen consecutive patients who had clinically significant bacteremia due to vancomycin-resistant enterococci (vanA genotype: 16 Enterococcus faecalis, 1 Enterococcus faecium) were compared with 169 who had vancomycin-susceptible enterococcal bacteremia. The following were selected by multivariate analysis as independent risk factors that influenced the development of high-level vancomycin-resistant enterococcal bacteremia: prior glycopeptide therapy (P=0.049); inclusion in a hemodialysis program (P=0.046); prior therapy with corticosteroids or antineoplastic agents (P=0.029); and prior surgical treatment (P=0.022). The following other factors were selected by univariate analysis: tracheostomy (P=0.002); prolonged hospitalization (P=0.01); and any kind of puncture (P=0.02). The crude associated-mortality rate was 13.4%. Gene amplification of vanA was positive for 17 strains of enterococci. Pulsed-field gel electrophoresis of genomic DNA after SmaI digestion of vanA isolates revealed that one strain predominated (10 isolates), though at least four similar banding patterns were identified (6 isolates). The 16 strains closely related to the outbreak were investigated further. The surgical intensive care unit was the first and most involved service. The hospital outbreak of vanA vancomycin-resistant enterococcal bacteremia occurred between 1994 and 1995 and was caused by Enterococcus faecalis. This is believed to be the first and only such outbreak described in a Spanish hospital thus far.

Adolescent↗