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PubMed1989

Identification of Enterococcus species isolated from human infections by a conventional test scheme.

Streptococci (206 cultures) previously identified as enterococci were retrieved from storage and reidentified by using tests designed to identify species of the genus Enterococcus. Of these 188, 91% were correctly identified as Enterococcus species. Of the remaining strains, nine (4%) were unidentified and six (3%) and 3 (1.5%) were identified as Leuconostoc sp. and Lactococcus sp., respectively. Two new Enterococcus species were discovered: E. raffinosus and E. solitarius. DNA-DNA hybridizations were performed on selected strains to assure correct identification. Cultures representing 10 of the 12 Enterococcus species were among the 188 strains identified. An identification system based on the grouping of key reactions of 20 phenotypic characteristics of Enterococcus species is described.

Bacteriological Techniques↗
PubMed1995

Epidemiologic analysis of glycopeptide-resistant Enterococcus strains in neutropenic patients receiving prolonged vancomycin administration.

Vancomycin-resistant enterococci have been isolated with increasing frequency since 1988. Thus far, most of these resistant enterococci have belonged to the Enterococcus faecium species, and epidemiological studies have shown a wide diversity among interhospital and intrahospital isolates. This report presents an epidemiologic investigation of 25 vancomycin-resistant Enterococcus strains--24 Enterococcus faecium and one Enterococcus gallinarum--isolated from the stools or blood of adult patients receiving intravenous vancomycin prophylaxis during neutropenia and hospitalized in a single hematologic unit. Macrorestriction patterns of total DNA and of ribosomal DNA regions were used to analyze the strains. Strains produced different total DNA restriction fragment length polymorphism patterns after SmaI digestion. Ribotyping was less discriminative than pulsed-field gel electrophoresis. The results confirmed the genetic unrelatedness of the strains. Prolonged vancomycin administration, commonly used in hematologic units, could be involved in the selection of endogenous resistant enterococcal strains.

Anti-Bacterial Agents↗
PubMed1984

Role of enterococcus in intraabdominal sepsis.

Although enterococcus is well recognized as a pathogen in endocarditis, urinary tract infections, and biliary sepsis, its role in other forms of intraabdominal sepsis remains controversial. Antibiotics that lack activity against enterococcus can often be employed successfully in intraabdominal infections, even when enterococci are present as part of the polymicrobial flora. Furthermore, the enterococcus rarely emerges as a blood borne pathogen in such a setting. Breakthrough enterococcal septicemia may occur, however, in the immunodepressed host, particularly in the face of broad-spectrum antibiotic therapy not specific for enterococcus. Like infections with other opportunistic pathogens, enterococcal sepsis under these circumstances carries a high mortality. Specific antienterococcal drug therapy may be indicated as an adjunct to surgical management in selected patients with intraabdominal sepsis.

Abdomen↗
PubMed1994

Investigation of the potential role of Enterococcus faecalis in the pathophysiology of experimental peritonitis.

Two nonfatal models of peritonitis differing by the duration and the severity of the disease were studied in rats by implantation of Escherichia coli and Bacteroides fragilis with or without increasing concentrations of Enterococcus faecalis. Results were evaluated at 3 or 6 days after inoculation. The highest enterococcal concentrations (10(9) cfu/mL) enhanced the severity of the infection, evident by increased emaciation, increased peritoneal counts of E. coli and B. fragilis, and increased frequency of E. coli and B. fragilis bacteremia compared with enterococcus-free animals. Six therapeutic regimens (low-dose amoxicillin + low-dose gentamicin, high-dose amoxicillin + high-dose gentamicin, pefloxacin, ornidazole, pefloxacin + ornidazole, imipenem + gentamicin) were tested. All treatments failed to eradicate E. faecalis except the combination pefloxacin + ornidazole, which achieved a significant reduction of local bacterial counts and suppressed bacteremia. Enterococcus played an important role in the mechanisms of bacterial synergy in experimental peritonitis. However, eradication of enterococcus did not seem possible by conventional antienterococcal therapy.

Abscess↗
PubMed1996

Augmented production of extracellular superoxide by blood isolates of Enterococcus faecalis.

To assess the frequency of extracellular superoxide (O-2) production by enterococci, multiple species were surveyed in a whole organism assay for their ability to reduce ferricytochrome c in a superoxide dismutase-inhibitable fashion. For stool and clinical enterococcal isolates and 12 type strains, only Enterococcus faecalis (87/91 isolates and ATCC 19433), Enterococcus faecium (5/13 isolates), Enterococcus casseliflavus (ATCC 25778), and Enterococcus gallinarum (ATCC 35038) produced extracellular O-2. Among 106 strains comprising 13 species of enteric gram-negative bacilli and gram-positive cocci, only Lactococcus lactis subspecies lactis produced extracellular O-2. Mean (+/-SE) rates of extracellular O-2 production in vitro by E . faecalis for isolates associated with bacteremia and endocarditis and for isolates from stool were 2.4+/-0.2, 1.9+/-0.2, 1.5+/-0.3 nmol of O-2 min(-1) 10(9) cfu(-1), respectively (P=.025, analysis of variance), suggesting an association between invasiveness and extracellular O-2 production.

Bacteremia↗
PubMed1996

Phenotypic and genotypic characterization of atypical Lactococcus garvieae strains isolated from water buffalos with subclinical mastitis and confirmation of L. garvieae as a senior subjective synonym of Enterococcus seriolicida.

During a survey of bacterial agents that cause subclinical mastitis in water buffalos, we isolated several strains of gram-positive cocci that appeared to be enterococci except that they grew very slowly at 45 degrees C and grew slowly in broth containing 6.5% NaCl. On the basis of the results of conventional physiologic tests, these strains were identified as Enterococcus durans. However, none of the strains reacted with the AccuProbe Enterococcus genetic probe. The whole-cell protein profiles of these organisms were compared with the profiles of Enterococcus and Lactococcus reference strains. apart from minor quantitative differences, the mastitis isolates had indistinguishable protein profiles that were similar to the profiles of the Lactococcus garvieae and Enterococcus seriolicida type strains. The results of DNA relatedness studies performed by using the hydroxyapatite method at 55 and 70 degrees C indicated that all of the mastitis isolates were related to the type strain of L. garvieae at the species level, despite the fact that they exhibited several uncommon phenotypic characteristics (growth at 45 degrees C, growth in broth containing 6.5% NaCl, and failure to produce acid from mannitol and sucrose). The high levels of DNA relatedness between strains of L. garvieae is a senior synonym of E. seriolicida, L. garvieae should be retained as the species name and strain ATCC 43921 should remain the type strain of this species.

Animals↗
PubMed2026

Antimicrobial Resistance in Nontyphoidal Salmonella and Clinically Relevant Enterococcus From Faecal Samples of Conservation-Priority Captive Ungulates in a United Arab Emirates Urban Zoo: A Cross-Sectional Baseline Study.

Antimicrobial resistance (AMR) is a One Health challenge driven by microbial exchange among humans, animals and the environment. Zoological institutions offer useful settings for environmental AMR surveillance. This single-zoo cross-sectional study examined the occurrence, antimicrobial susceptibility and genomic characteristics of nontyphoidal Salmonella enterica (NTS) and clinically relevant Enterococcus spp. in faecal samples from 101 clinically healthy captive ungulates representing seven conservation-priority species at a major urban zoo in the United Arab Emirates. NTS was detected in 4/101 samples (3.9%), including serovars Schwarzengrund (n = 2), Kentucky (n = 1) and Chester (n = 1). Among the four recovered NTS isolates, all met the study MDR definition within the tested panel, including a Salmonella Kentucky ST198 isolate carrying multiple resistance genes and quinolone-associated mutations. Enterococcus spp. were detected in 77/101 samples (76.2%), dominated by Enterococcus faecium and Enterococcus casseliflavus (each 41.5%). Among 33 E. faecium/Enterococcus faecalis isolates tested phenotypically, resistance was generally low, with erythromycin and ciprofloxacin resistance each observed in 9.1%. One clinically important E. faecium isolate showed glycopeptide resistance and genetic markers associated with reduced daptomycin susceptibility. These single-institution cross-sectional data provide an initial regional baseline for AMR-relevant enteric bacteria in conservation-managed ungulates and identify priorities for broader longitudinal and interface-based surveillance.

Animals↗
PubMed1994

Presence of the Listeria tetracycline resistance gene tet(S) in Enterococcus faecalis.

Two hundred thirty-eight tetracycline- and minocycline-resistant clinical isolates of Enterococcus and Streptococcus spp. were investigated by dot blot hybridization for the presence of nucleotide sequences related to tet(S) (first detected in Listeria monocytogenes BM4210), tet(K), tet(L), tet(M), tet(O), tet(P), and tet(Q) genes. The tet(S) determinant was found in 22 strains of Enterococcus faecalis, associated with tet(M) in 9 of these isolates and further associated with tet(L) in 3 of these strains. tet(M) was detected in all strains of Streptococcus spp. and in all but 10 isolates of Enterococcus spp.; tet(L) was found in 93 enterococci and tet(O) was found in single isolates of E. faecalis and Streptococcus milleri. No hybridization with the tet(K), tet(P), and tet(Q) probes was observed. Transfer of tet(S) by conjugation to E. faecalis or to E. faecalis and L. monocytogenes was obtained from 8 of the 10 E. faecalis strains harboring only this tet gene. Hybridization experiments with DNAs of four donors and of the corresponding transconjugants suggested that tet(S) was located in the chromosome. These results indicate that the genetic support of tet(S) in E. faecalis is different from that in L. monocytogenes, where it is carried by self-transferable plasmids, and confirm the notion of exchange of genetic information between Enterococcus and Listeria spp. in nature.

Conjugation, Genetic↗
PubMed1994

Overproduction of a low-affinity penicillin-binding protein and high-level ampicillin resistance in Enterococcus faecium.

Five ampicillin-resistant clinical isolates of Enterococcus faecium were analyzed for a correlation between overproduction of the low-affinity penicillin-binding protein (PBP 5) and the level of ampicillin resistance. Comparison was made with one susceptible clinical isolate and its ampicillin-resistant derivative obtained in the laboratory by selection with increasing concentrations of penicillin. Overproduction of the low-affinity PBP relative to the susceptible isolate was noted in moderately resistant strains (MIC, 32 micrograms/ml) but not in highly resistant strains (MIC, 128 micrograms/ml). Polyclonal antibodies specifically reacting with the low-affinity PBP of Enterococcus hirae, Enterococcus faecalis, and Enterococcus faecium (M. Ligozzi, M. Aldegheri, S. C. Predari, and R. Fontana, FEMS Microbiol. Lett. 83:335-340, 1991) were used to determine the amount of this PBP in the E. faecium isolates. In all strains, the antibody preparation reacted with a membrane protein of the same molecular mass as PBP 5. The amount of this protein was very small in the susceptible strain but large in all of the resistant strains. These results suggest that the highly resistant strains also overproduced the low-affinity PBP, which, compared with PBP 5 of moderately resistant strains, appeared to be modified in its penicillin-binding capability.

Ampicillin Resistance↗
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↗
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↗
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↗
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↗
PubMed1994

Sequence of the vanB and ddl genes encoding D-alanine:D-lactate and D-alanine:D-alanine ligases in vancomycin-resistant Enterococcus faecalis V583.

A pair of degenerate oligodeoxyribonucleotides was used to amplify, by the polymerase chain reaction (PCR), DNA fragments internal to genes encoding D-Ala:D-Ala ligase-related proteins of vancomycin-resistant (VmR) Enterococcus faecalis V583. Cloning and nucleotide sequencing of the PCR products indicated that fragments of two genes, designated vanB and ddl, were co-amplified. The vanB gene was previously shown to be present in Enterococcus strains expressing VanB-type VmR [Quintiliani Jr. et al., J. Infect. Dis. 8 (1993) 943-950]. The ddl gene was detected by Southern hybridization in all VmR and VmS strains of En. faecalis, but not in representatives of 17 other species of Enterococcus. The vanB and ddl genes were cloned in bacteriophage lambda and sequenced. There was extensive similarity (76% amino-acid identity) between the product of vanB and the VmR protein, VanA. The product of ddl, the D-Ala:D-Ala ligases, DdlA and DdlB, of Escherichia coli and the resistance proteins, VanA and VanB, were more distantly related (32-40% aa identity). After induction of VmR, En. faecalis V583 synthesized the cell wall precursor, UDP-N-acetylmuramyl-tetrapeptide-D-lactate, indicating that the mechanism of glycopeptide resistance in strains with the VanA and VanB phenotype is similar.

Amino Acid Sequence↗