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PubMed1997

[Isolation rate of Enterococcus spp. from surgical infections and their susceptibilities].

Enterococcus spp. isolated from surgical infections during the period from July 1982 to June 1995 were investigated in a multicenter study involving 19 hospitals in Japan, and the following results were obtained. 1. Though the isolation rate of Enterococcus faecalis and other Enterococcus spp. were not high from primary infections, and from postoperative infections the isolation rate of other Enterococcus spp. was also low, the isolation rate of E. faecalis was highest from postoperative infections after 1993. 2. Vancomycin (VCM) showed strongest activity against E. faecalis, and followed by those of ampicillin (ABPC), imipenem. levofloxacin (LVFX) and meropenem in this order. Against other Enterococcus spp., VCM showed strongest activity, and followed by those of ABPC and LVFX. There were no resistant strains against VCM.

Ampicillin↗

PubMed1998

Effect of quinupristin/dalfopristin alone or in combination with vancomycin on the structure of Enterococcus faecium.

Twenty strains of Enterococcus faecium susceptible to quinupristin/dalfopristin (< 2 mg/l) were DNA fingerprinted to exclude strain duplication. Ten strains were susceptible to vancomycin (minimal inhibitory concentration [MIC] < 2 mg/l) and 10 were resistant to vancomycin (MIC > 400 mg/l). Vancomycin at 1/2 MIC, quinupristin/dalfopristin at 1/4 MIC and their combination, except for a tube control, was added to 10 ml trypticase soy broth tubes which were planted with the respective 24-h trypticase soy broth cultures. The products of incubation were sampled periodically throughout 24 h for gram stain and electron microscopy. Cell size was measured on photographs at 20,000x final magnification and results were statistically analyzed. The cells of all strains of Enterococcus faecium exposed for 12 h to quinupristin/dalfopristin were comparable in size to the control, Most cells, however, showed areas of low density of ribosome in the center of the cells. The cells of Enterococcus faecium resistant to vancomycin exposed to vancomycin were larger than the controls with means of 1.96 micron -2.07 micron versus 1.16 micron (p < 0.001); these cells consisted of individual organisms connected by wide cross walls of abnormal fibrous structure. Enterococcus faecium sensitive to vancomycin exposed to vancomycin remained comparable to the control. The combination of quinupristin/dalfopristin plus vancomycin produced large cells with multiple abnormal cross walls in both vancomycin-resistant and vancomycin-sensitive Enterococcus faecium. The addition of quinupristin/dalfopristin to vancomycin appears to modify the vancomycin-susceptible strains to respond to vancomycin in the same manner as do the vancomycin-resistant organisms.

Anti-Bacterial Agents↗

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↗

PubMed1997

Enterococcus faecium in hospitals.

Most of the characteristics that have ensured the success of enterococci as nosocomial pathogens were described early in this century. Enterococcus faecium and Enterococcus faecalis, the enterococci most frequently isolated from clinical material, differ fundamentally. The intrinsic antimicrobial resistance of Enterococcus faecium, supplemented by acquired resistance mechanisms, can generate a glycopeptide-multiply-resistant nosocomial pathogen that survives on hands and in the environment, and has the potential for intra-hospital and inter-hospital spread. The use of terms such as 'an enterococcus', 'faecal streptococci' and 'group D streptococci' have hindered, and still hinder, our understanding of a species rapidly emerging as the most problematic of nosocomial pathogens.

Anti-Bacterial Agents↗

PubMed2001

Determination of Enterococcus faecalis groESL full-length sequence and application for species identification.

Amplification of the partial Cpn60 (or GroEL) gene segment has been used for identification of many bacteria, including Enterococcus species. To obtain more sequence data from groESL genes of Enterococcus faecalis, the full-length sequence of the E. faecalis groESL genes containing groES (285 bp), spacer (57 bp), and groEL (1,626 bp) was determined. A database search of GenBank revealed that the deduced E. faecalis GroES and GroEL proteins show significant homology to the GroES and GroEL proteins of other bacteria. The GroEL (groEL) of E. faecalis had the highest identity with Streptococcus pneumoniae (81.8% amino acid sequence identity and 73.0% nucleotide sequence identity), followed by Lactococcus zeae, while GroES (groES) had 60.2% (64.6%) identity with Lactobacillus zeae and 58.5% (66.2%) identity with Lactococcus lactis, followed by 57.0% (65.5%) identity with Bacillus subtilis. Based on the groES sequence, an E. faecalis-specific PCR assay was developed, and this PCR assay was positive for all the E. faecalis strains tested. Dot blot hybridization using either groES or groEL as the probe distinguished E. faecalis clearly from other species, indicating that both genes can be used as suitable targets for E. faecalis identification. Moreover, broad-range PCR-restriction fragment length polymorphism of groESL was designed to differentiate eight commonly encountered Enterococcus species. The Enterococcus species of reference strains could be easily differentiated on the basis of restriction patterns produced by HaeIII and RsaI. The DNA-based assays developed in this study provide an alternative to currently used methods of identification for clinically important enterococcal species.

Bacterial Proteins↗

PubMed1998

Time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy.

BACKGROUND AND OBJECTIVE: To determine and then compare the time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy. PATIENTS AND METHODS: The time-kill profiles of four endophthalmitis isolates of Enterococcus faecalis, one vancomycin-resistant E. faecalis isolate, and three vancomycin-resistant isolates of E. faecium were determined against vancomycin, amikacin, cefazolin, gentamicin, ampicillin, ciprofloxacin, ceftazidime, clindamycin, and the combinations of vancomycin and amikacin, vancomycin and ceftazidime, vancomycin and gentamicin, vancomycin and ampicillin, cefazolin and gentamicin, and ampicillin and gentamicin. RESULTS: No single antibiotic or combination was bactericidal (defined as 99.9% kill) to all isolates of Enterococcus. Gentamicin was bactericidal to all E. faecalis isolates. None of the tested antibiotics were bactericidal to vancomycin-resistant E. faecium. CONCLUSIONS: The time-kill profiles demonstrated that vancomycin and ceftazidime did not produce a 99.9% kill for E. faecalis in this small study. Gentamicin combined with either cefazolin or ampicillin had somewhat better bactericidal activity and should be considered as an alternative therapy. Novel therapy may be necessary to treat endophthalmitis because of vancomycin-resistant Enterococcus, depending on the susceptibility patterns of the individual isolate and the response to initial therapy.

Anti-Bacterial Agents↗

PubMed2002

The virulence of Enterococcus to freshwater prawn Macrobrachium rosenbergii and its immune resistance under ammonia stress.

Growth of pathogen bacterium. Enterococcus was not affected in tryptic soy broth (TSB) medium containing ammonia-N concentration in the range of 0-5.14 mg l(-1). Giant freshwater prawn Macrobrachium rosenbergii (8-12 g) were challenged with Enterococcus which had been incubated for 24 h in TSB medium containing different concentrations of ammonia-N at 0-5.14 mg l(-1) Cumulative mortality of M. rosenbergii was higher for the bacteria incubated in TSB medium having ammonia-N at 0 and 0.26 mg l(-1), than those incubated in TSB medium having 1.28, 2.57 and 5.14 mg l(-1) ammonia-N after 24 h of challenge. However, cumulative mortality of prawn was significantly higher for the bacteria incubated in TSB medium with no ammonia added after 120 h of challenge. The prawns (8-12 g) were challenged with Enterococcus previously incubated in TSB medium for 24 h, then placed in water having concentrations of ammonia-N at control (0.06 mg l(-1)), 0.55, 1.01, 1.68 and 3.18 mg l(-1). Mortality of prawns increased directly with ammonia-N concentrations after 72 h challenge. The pranws (20-30 g) which had been exposed to control, 0.55, 1.68 and 3.18 mg (-1) ammonia-N for 7 days were examined for the total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase activity and respiratory burst of haemocytes. Phenoloxidase activity decreased when the prawns were exposed to ammonia-N greater than 0.55 mg l(-1). The respiratory burst increased significantly at 0.55 mg l(-1) but decreased significantly at 1.68 and 3.18mg (-1) ammonia-N. No significant difference in haemocyte count was observed among the prawns at different ammonia-N concentrations. It is suggested that ammonia in water decreases the virulence of Enterococcus, and reduces the immune resistance of M. rosenbergii.

Ammonia↗

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↗

PubMed1997

Identification and characterization of proteolytic activity of Enterococcus spp. isolated from milk and Roncal and Idiazábal cheese.

Roncal and Idiazábal cheeses are manufactured from ewe's milk in the Autonomous Region of Navarre in Spain. Levels of enterococci are high in these cheeses and in other types of ewe's-milk cheeses. The present study has identified enterococci present in the milk used and in the Roncal and Idiazábal cheeses after 120 days of ripening. A total of 282 strains were isolated and identified, and the cytoplasmic and extracellular enzymatic activities of some of the strains were assessed. The dominating species were Enterococcus faecalis, which accounted for 85% of the total both in the milk as well as in the two types of cheese, and Enterococcus faecium, Enterococcus durans, and Enterococcus avium which were present in lower proportions. Aminopeptidase and proteinase activity levels in enterococci were low, and considerable variation between strains of the same species was recorded, highlighting the need to study individual strains when selecting the most suitable bacteria as a starter culture. Aminopeptidase activity levels for the enterococci were appreciably higher at pH 7 than at pH 5.5, hence aminopeptidase activity by enterococci would appear to be less significant in the normal manufacturing conditions of the two cheeses.

Aminopeptidases↗

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↗

PubMed2001

Enterococcus villorum sp. nov., an enteroadherent bacterium associated with diarrhoea in piglets.

The taxonomic positions of five enteroadherent bacterial pig isolates, showing phenotypic characteristics most similar to those of Enterococcus durans and Enterococcus hirae, were investigated in a polyphasic study that included 16S rDNA sequence analysis, DNA-DNA hybridizations, DNA base-ratio determinations, whole-cell protein fingerprinting, D11344-primed PCR typing and an extensive examination of phenotypic properties. The results demonstrated that the organisms represent a new species in the Enterococcus faecium species group, for which the name Enterococcus villorum sp. nov. is proposed. The type strain is LMG 12287T (= CCM 4887T).

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↗