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PubMed2006

Short course of linezolid treatment for vancomycin-resistant Enterococcus faecium meningitis.

Enterococci might be one of the meningitis pathogens, but meningitis is rarely caused by vancomycin-resistant enterococci. In this report, we present a 69-year-old man who had the underlying chronic obstructive pulmonary disease with long-term steroid treatment suffered from a meningitis episode after hospitalisation for the urinary tract infection. The cerebrospinal fluid culture of the patient grew Enterococcus faecium which was resistant to vancomycin. A vancomycin-resistant E. faecium was also isolated from the rectal swab of the patient. These two E. faecium isolates were found to harbour the vanA gene and to be identical by pulsed field gel electrophoresis typing. The patient was treated successfully with intravenous linezolid, 600 mg every 12 h for 2 weeks. This was the first case of meningitis caused by vancomycin-resistant E. faecium in Taiwan.

Acetamides↗
PubMed2005

Consequences of vancomycin-resistant Enterococcus in liver transplant recipients: a matched control study.

BACKGROUND: Liver transplant recipients are at high risk for multi-drug resistant infections because of broad-spectrum antibiotic and immunosuppression. This study evaluates the clinical and financial impact of vancomycin resistant Enterococcus (VRE) in liver transplant recipients. METHODS: Liver transplant recipients with VRE from 1995 to 2002 were identified and matched (age, gender, UNOS status, liver disease and transplant date) to controls. Demographics, clinical factors, co-infections, antibiotic use, length of stay, abdominal surgeries, biliary complications, survival and resource utilization were compared with matched controls. RESULTS: Nineteen patients were found to have 28 VRE infections via evaluation of microbiologic culture results of all liver transplant patients in the transplant registry. Thirty-eight non-VRE patients served as matched controls. The four most common sites VRE was cultured from included blood (35%), peritoneal fluid (35%), bile (20%), and urine (12%). Median time from transplant to infection was 48 d (range of 4-348). No significant differences in demographics were observed. The VRE group had a higher incidence of prior antibiotic use than the non-VRE group (95% vs. 34%; p < 0.05). The VRE group also experienced more abdominal surgery (20/19 vs. 3/38; p = 0.029), biliary complications (9/19 vs. 9/38; p = 0.018) and a longer length of stay (42.5 vs. 21.7 d; p = .005). Survival in the VRE group was lower (52% vs. 82%; p = 0.048). Six of the 19 VRE patients were treated with linezolid for eight infection episodes, and four of six patients survived. Eight patients were treated with quinupristin/dalfopristin for nine infections, and two of eight survived. Increased cost of care was observed in the VRE group. Laboratory costs were higher in the VRE group (6500 dollars vs. 1750; p = 0.02) as well. CONCLUSION: VRE was associated with prior antibiotic use, multiple abdominal surgeries, biliary complications and resulted in decreased survival compared to non-VRE control patients. VRE patients also utilized more hospital resources. Linezolid showed a trend toward improved survival.

Enterococcus↗
PubMed2004

In vitro antimicrobial effect of bacteriophages on human dentin infected with Enterococcus faecalis ATCC 29212.

This study assessed the effect of bacteriophages on the viability of Enterococcus faecalis. Human dental roots were inoculated with a suspension of E. faecalis at three different multiplicities of infection - 0.1, 1.0 and 10.0. The phage lysate was able to significantly inhibit bacteria growth when incubated at the multiplicities of infection of 1.0, 10.0 and 0.1. The dental roots were also inoculated with bacteria for 6 days to allow bacterial penetration into the teeth tubules. Addition of the phage lysate to the roots following the 6-day incubation period led to a substantial reduction in bacteria viability. Phage therapy may be an important alternative for the treatment of root canal infections refractory to conventional endodontic therapy.

Bacteriophages↗
PubMed2006

Antimicrobial susceptibility and molecular analysis of Enterococcus faecalis originating from endodontic infections in Finland and Lithuania.

BACKGROUND/AIMS: Enterococcus faecalis strains with multiple antibiotic resistances can cause infections that are difficult to treat. The microbial flora in treatment-resistant apical periodontitis is dominated by E. faecalis, and is a potential source of infections at other sites. MATERIAL AND METHODS: Sensitivities to a range of antibiotics were determined for 59 endodontic E. faecalis isolates from Finland and Lithuania. The DNA sequence of the gene responsible for the species' intrinsic quinupristin-dalfopristin resistance, lsa, was determined from two isolates with diminished resistance. Four pairs of isolates from the same root canal were typed by pulsed-field gel electrophoresis. RESULTS: A high prevalence of resistance to rifampicin was found, whereas all isolates were susceptible or showed intermediate susceptibility to penicillin and ampicillin and four isolates were unusually susceptible to cefotaxime. No vancomycin or high-level gentamicin resistance was detected. Nine of 59 isolates were susceptible to quinupristin-dalfopristin. A fully quinupristin-dalfopristin-susceptible isolate also susceptible to clindamycin produced a truncated Lsa polypeptide, and an isolate with borderline quinupristin-dalfopristin-susceptibility had mutations proximal to the predicted ribosomal binding site. Pulsed-field gel electrophoresis showed that the same root canal could harbor two different strains of E. faecalis during the course of the same infection. CONCLUSION: Despite the differing antibiotic usage in Finland and Lithuania, E. faecalis from endodontic infections in these countries showed similar susceptibility patterns with levels of resistance considered typical for the species, and decreased resistance to clindamycin and quinupristin-dalfopristin as well as lesions in the lsa gene which were similar to those described in other clinical isolates.

ATP-Binding Cassette Transporters↗
PubMed2006

Resistance to acidic and alkaline environments in the endodontic pathogen Enterococcus faecalis.

BACKGROUND/AIMS: This study aimed to investigate the biochemical mechanisms employed by the endodontic pathogen Enterococcus faecalis to confer acid- and alkali-resistance and to compare these with the mechanisms of representative oral streptococci. METHODS: E. faecalis JCM8728, Streptococcus mutans NCTC10449 and Streptococcus sanguinis ATCC10556 were used to assess both acid- and alkali-resistance by examining: (i) growth in complex media; (ii) stability of intracellular pH (pH(in)); (iii) cell durability to leakage of preloaded BCECF (2',7'-bis-(2-carboxyethyl)-5,6-carboxy-fluorescein); and (iv) cell permeability to SYTOX-Green. RESULTS: Growth was initiated by E. faecalis at pH 4.0-11.0, by S. mutans at pH 4.0-9.0 and by S. sanguinis at pH 5.0-9.0. The pH(in) was similar to the extracellular pH in S. mutans and S. sanguinis at pH 5-10, while the pH(in) of E. faecalis was maintained at approximately 7.5-8.5 when extracellular pH was 7.5-10 and was maintained at levels equivalent to the extracellular pH when pH < 7.5. Cell membranes of E. faecalis were resistant to BCECF leakage when extracellular pH was 2.5-12 and to SYTOX-Green permeability at pH 4-10. The cell membrane durability to extracellular pH in E. faecalis was higher than that observed in the Streptococcus strains. CONCLUSION: Compared to S. mutans, E. faecalis was found to be equally resistant to acid and more resistant to alkalis. The results suggest that pH-resistance in E. faecalis is attributed to membrane durability against acid and alkali, in addition to cell membrane-bound proton-transport systems. These characteristics may account for why E. faecalis is frequently isolated from acidic caries lesions and from persistently infected root canals where calcium hydroxide medication is ineffective.

Acids↗
PubMed2004

Successful treatment of vancomycin-resistant Enterococcus faecium endocarditis with linezolid in a renal transplant recipient with human immunodeficiency virus infection.

Infections with vancomycin-resistant Enterococci cause significant morbidity and mortality in hospitalized patients, including transplant recipients. We report the successful use of oral linezolid to treat a case of vancomycin-resistant Enterococcus faecium endocarditis in a renal transplant recipient with human immunodeficiency virus infection.

Acetamides↗
PubMed1992

Isolation and characterisation of the pyruvate dehydrogenase complex of anaerobically grown Enterococcus faecalis NCTC 775.

In this contribution the isolation and some of the structural and kinetic properties of the pyruvate dehydrogenase complex (PDC) of anaerobically grown Enterococcus faecalis are described. The complex closely resembles the PDC of other Gram-positive bacteria and eukaryotes. It consists of four polypeptide chains with apparent molecular masses on SDS/PAGE of 97, 55, 42 and 36 kDa, and these polypeptides could be assigned to dihydrolipoyl transacetylase (E2), lipoamide dehydrogenase (E3) and the two subunits of pyruvate dehydrogenase (E1 alpha and E1 beta), respectively. The E2 core has an icosahedral symmetry. The apparent molecular mass on SDS/PAGE of 97 kDa of the E2 chain is extremely high in comparison with other Gram-positive organisms (and eukaryotes) and probably due to several lipoyl domains associated with the E2 chain. NADH inhibition is mediated via E3. The mechanism of inhibition is discussed in view of the high PDC activities in vivo that are found in E. faecalis, grown under anaerobic conditions.

Acetyltransferases↗
PubMed1993

Biochemical, immunological and ultrastructural characterization of aggregation substances encoded by Enterococcus faecalis sex-pheromone plasmids.

The sex-pheromone system of Enterococcus faecalis can be viewed as a unique and highly efficient plasmid-collection mechanism. The contact needed for transfer of the conjugative sex-pheromone plasmids is mediated by an adhesin, called aggregation substance, which is encoded by these plasmids. We show here that for 17 of the 18 sex-pheromone plasmids (pAM373 being the exception) described to date, their adhesins are immunologically related to each other. In each case, we observed the presence of an N-terminal fragment of about 78 kDa in addition to the 137-kDa form of mature aggregation substance. The cross-reactions were different for the various plasmids. In the case of pPD1 the 78-kDa fragment reacted only weakly. The aggregation substance encoded by sex-pheromone plasmid pAD1 (Asa1) was characterized in detail. The conditions used for SDS/PAGE had a drastic influence on the migration behavior of mature aggregation substance and differently migrating, interconvertible forms were identified. Preliminary data indicate that Asa1 might be a glycoprotein. Antibodies were isolated which are directed against the N- and C-terminal parts of aggregation substance. They showed about the same reactivity on Western blots; however, only antibodies directed against the N-terminal part of the aggregation substance could inhibit the bacterial cell/cell contact. The reactions of the two antibody preparations with induced cells of E. faecalis was analyzed by transmission electron microscopy. The results indicated that especially the N-terminal part of aggregation substance is exposed on the cell surface of E. faecalis; the C-terminal part seems to be much less exposed.

Antibodies↗
PubMed1993

Sex pheromone plasmid pAD1-encoded aggregation substance of Enterococcus faecalis is positively regulated in trans by traE1.

Sex-pheromone-plasmid-bearing strains of Enterococcus faecalis react with sex pheromone to induce the expression of an adhesin, the so-called aggregation substance, on their cell surface. Here we show that, by complementation studies, for sex-pheromone plasmid pAD1, expression of the structural gene asa1, coding for an aggregation substance, is mediated by a diffusible factor encoded on pAD1. We were able to demonstrate that a small open reading frame, traE1, is sufficient for transcription of the operon containing asa1. A model for expression of asa1 under the influence of the positive regulator is presented, which is supported by our observation that regulation involves an all-or-nothing induction phenomenon, leading to cells either fully expressing asa1 or not at all.

Bacterial Proteins↗
PubMed1994

The sex pheromone system of Enterococcus faecalis. More than just a plasmid-collection mechanism?

The sex pheromone system of Enterococcus faecalis was discovered by observing a clumping reaction of E. faecalis strains during conjugative transfer of plasmids. It was found that only a special type of E. faecalis plasmids, the so-called sex pheromone plasmids, are transferred via this mechanism. Various experiments, especially by the group of D. B. Clewell, led to the formulation of a model describing how the sex pheromone system works. Small linear peptides, the so-called sex pheromones, are excreted by strains not possessing the corresponding sex pheromone plasmid. Donor strains harboring the plasmid do not produce the corresponding sex pheromone; they react to the presence of the peptide by production of a plasmid-encoded adhesin, the so-called aggregation substance. This adhesin allows contact between the non-motile mating partners; after conjugative transfer of the plasmid, the former recipient possesses and replicates the new plasmid. Thereby the population of E. faecalis strains is shifted to a high percentage of donor strains. This is especially true because a donor strain will still excrete sex pheromones corresponding to plasmids it does not harbor; therefore, such a strain can also function as recipient for other sex pheromone plasmids it does not possess. Various aspects of this unique plasmid collection mechanism have been studied during the last few years. The data indicate that, with the exception of pAM373, all sex pheromone plasmids possess one DNA region which is highly similar to and codes for the adhesin. It is also becoming more and more clear that regulatory functions/proteins are not conserved between different sex pheromone plasmids. Induction of adhesin synthesis needs the action of a regulatory cascade composed of unique features; at the moment we are just beginning to understand this cascade. By sequencing the first structural gene for one of those adhesins, we realized that the aggregation substance might act also as an adhesin for eucaryotic cells, probably by interaction with integrins. At least in the case of the in vitro cultured pig kidney tubulus cell line LLC-PK1 this idea could be verified. An interesting aspect of the sex pheromone system of E. faecalis is its evolution. I will discuss the idea that two different components, both of which well might contribute to virulence of the opportunistic pathogenic bacterium, were combined in the species E. faecalis to result in this unique plasmid collection system.

Adhesins, Bacterial↗
PubMed2006

Effects of a probiotic Enterococcus faecium strain supplemented from birth to weaning on diarrhoea patterns and performance of piglets.

This placebo-controlled double-blind study was conducted to evaluate effects of Enterococcus faecium DSM 10663 NCIMB 10415 (EcF) orally given from birth to weaning on diarrhoea and performance of piglets. At the first 3 days postnatum (p.n.), piglets from 54 [verum group (VG)] and 60 [placebo group (PG)] sows got 1 g of a gel directly per mouth by a dosing device. Gel for the VG contained 2.8 x 10(9) colony forming units (CFU) EcF/g. From day 4 p.n. until weaning (24 +/- 3.2 days p.n.) a liquid additive was given that administered twice a day 1.26 x 10(9) CFU EcF to each VG piglet. In case of diarrhoea, an electrolyte solution was used which provided daily 2.9 and 5.8 (week 1 and >or= 2, respectively) x 10(8) CFU EcF per VG piglet. Diarrhoea scores were defined as follows: (i) no diarrhoea; (ii) piglets developed diarrhoea, but were vital and (iii) piglets suffered from diarrhoea and additionally looked pale, developed rough coat, showed slackening of the flank and lethargy. Counts of viable born, stillborn and weaned piglets were normal and not different between groups (p > 0.05). Placebo group vs. VG piglets suffered more frequently from diarrhoea (40.0 vs. 14.8%, p < 0.05). Duration of diarrhoea was not affected by feeding EcF (2.2 +/- 0.81 days, p > 0.05). Diarrhoea score was lower in VG vs. PG (1.2 vs. 1.5 +/- 0.54, p < 0.05) and the daily weight gain (DWG) was higher by 17 g/day (p < 0.05). Results suggest that the daily oral supplementation of EcF from birth to weaning reduces the portion of piglets suffering from diarrhoea. This may improve performance, as the higher DWG indicates. In contrast, no obvious benefit seems to result from an additional supply of EcF via electrolyte solution when diarrhoea is always present.

Administration, Oral↗
PubMed2004

Microbiological and epidemiological studies of Enterococcus faecium resistant to amoxycillin in a university hospital in eastern France.

Over 3 years, during six 1-month periods of surveillance, 69 cases of Enterococcus faecium colonisation or infection were detected in a university hospital in eastern France. Thirty-two cases involved strains resistant to amoxycillin (crude incidence of 0.21/1000 patient-days). The risk of infection with E. faecium was higher if the patient was hospitalised in a haematology ward and/or treated with cephalosporins. Amoxycillin-resistant isolates (AmRE) were isolated from different wards and time periods, and none of the characteristics studied were associated significantly with amoxycillin resistance. Amoxycillin-sensitive and -resistant isolates were characterised by pulsed-field gel electrophoresis. Three epidemic patterns were identified which contained 87.5% (28/32) of the AmRE isolates, indicating that clonal spread was responsible, at least partially, for the high incidence of AmRE in this hospital.

Amoxicillin↗
PubMed2006

Increased conjugation frequencies in clinical Enterococcus faecium strains harbouring the enterococcal surface protein gene esp.

This study compared the in-vitro ability of Enterococcus faecium isolates of different origin to acquire vanA by conjugation in relation to the occurrence of the esp gene. In total, 29 clinical isolates (15/29 esp+), 30 normal intestinal microflora isolates (2/30 esp+) and one probiotic strain (esp-) were studied with a filter-mating assay. Conjugation events were confirmed by PCR and pulsed-field gel electrophoresis. Among the infection-derived isolates, the esp+ isolates had higher conjugation frequencies compared with esp- isolates (p < 0.001), with a median value of 6.4 x 10(-6) transconjugants/donor. The probiotic strain was shown to acquire vanA vancomycin resistance in in-vitro filter mating experiments.

Bacterial Proteins↗
PubMed2006

Multilocus sequence typing and analysis of putative virulence factors in vancomycin-resistant and vancomycin-sensitive Enterococcus faecium isolates from Brazil.

Enterococci are leading causes of hospital-acquired infections that are often difficult to treat because of high-level aminoglycoside and glycopeptide resistance. Vancomycin-resistant enterococci are a global problem, and have been isolated with increasing frequency in hospitals in Brazil. The objective of this study was to determine the genetic relatedness of vancomycin-resistant Enterococcus faecium (VREFM) and vancomycin-sensitive E. faecium (VSEFM) isolated from human infections and faecal sources in Brazil, and to compare these isolates with those from domesticated animals. Isolates (n = 56) were classified by multilocus sequence typing (MLST) and assessed for putative virulence traits. The acm gene was detected in 98% of all isolates. The 56 isolates studied comprised 26 different MLST types. VSEFM isolates from the faeces of pigs were found to be distinct from all human isolates characterised previously by MLST, and were assigned new sequence type (ST) numbers. VREFM isolates were represented by four different STs (ST-114, ST-17, ST-281, ST-50). Among the 26 STs identified in this study, eBURST detected three groups of STs with related allelic profiles, and 19 unrelated STs. Among E. faecium isolates from Brazil, the esp gene was restricted to vancomycin-resistant isolates. Furthermore, isolates classified as ST-17 by MLST, an epidemic strain type isolated internationally with the purK-1 gene, were found among VREFM isolates from Brazil that also harboured the esp and hyl genes.

Adhesins, Bacterial↗
PubMed2006

Genetic and phenotypic differences among Enterococcus faecalis clones from intestinal colonisation and invasive disease.

This study investigated the differences among Enterococcus faecalis isolates from the intestinal compartment of healthy volunteers (n = 36), intensive care unit (ICU) patients (n = 29) and blood isolates (n = 31) from the same institution, in comparison with seven epidemic clones from other institutions. In general, isolates from colonised ICU patients and from bacteraemic patients showed higher rates of antimicrobial resistance than isolates from colonised healthy volunteers, particularly for erythromycin and aminoglycosides. The proportion of isolates/clone was 1.05 in the community, 2.63 in the ICU, and 1.47 among bacteraemic cases, suggesting low clonal variation in ICUs. Two clones, RENC1 and RENC2, were frequently found as intestinal colonisers of ICU patients, and RENC1 was also found to colonise healthy volunteers. These two clones were a cause of bacteraemia in the institution studied, and RENC2 was also detected in various other Spanish hospitals. Both RENC1 and RENC2 were esp+, bacteriocin producers, and were resistant to all antibiotics tested except vancomycin and ampicillin. RENC1 produced haemolysin whereas RENC2 produced protease. The ace, agg, cylA, esp and gelE genes were more common among colonising strains from ICU patients than among isolates from individuals in the community. In both colonised groups (ICUs and the community), 40-50% of isolates harbouring the gelE and cylA genes did not express the corresponding phenotypes. Thus, the study indicated that particular E. faecalis clones might be well-adapted to hospital environments, and that surveillance should be directed specifically towards rapid detection of these disseminating clones in order to prevent infections and clonal spread.

Antigens, Bacterial↗
PubMed2007

Emergence of VanD-type vancomycin-resistant Enterococcus faecium in Stockholm, Sweden.

A vancomycin-resistant Enterococcus faecium isolate from the urine of a liver transplant patient in Stockholm was found to contain a vanD gene. The sequence of the vanD PCR product shared 100% identity with the vanD5 allele. The isolate was resistant to a relatively high level of vancomycin (128 mg/L) and a low level of teicoplanin (4 mg/L). This is the first VanD-type vancomycin-resistant E. faecium isolate reported in Sweden. The emergence of this strain reinforces the necessity of infection control efforts to interrupt the spread of these organisms.

Alleles↗
PubMed1996

Purification and N-terminal amino acid sequence of Enterocin CRL 35, a 'pediocin-like' bacteriocin produced by Enterococcus faecium CRL 35.

Enterocin CRL 35, a bacteriocin produced by Enterococcus faecium CRL 35 that inhibits food-borne pathogens, was purified by precipitation with (NH4)2SO4, gel filtration, ion exchange and reverse phase chromatography. The partial N-terminal amino acid sequence indicated a strong homology with other 'pediocin-like bacteriocins' previously described.

Amino Acid Sequence↗
PubMed1996

Physiological response of Enterococcus faecalis JH2-2 to cold shock: growth at low temperatures and freezing/thawing challenge.

Growth at low positive temperatures and induced phenotypic resistance to extreme cold temperature (freezing/thawing cycles) of Enterococcus faecalis were investigated. The effect of low temperatures on the specific growth rates was studied; use of Arrhenius profile and Ratkovsky 'square-root' model allowed determination of the 'temperature characteristic' (mu approximately equal to 13,800 cal mol-1), the critical temperature (Tcrit approximately equal to 17.9 degrees C) and the notional minimum growth temperature (T0 approximately equal to 3.6 degrees C). Preincubation of Ent. faecalis cells at low temperatures (8-16 degrees C) during periods corresponding to their generation time resulted in an increased ability of the bacterial cells to withstand short periods of freezing/thawing (-20 degrees C/+37 degrees C) challenge. Moreover, the increase of the incubation period at low positive temperature led to a higher degree of adaptation.

Cold Temperature↗