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PubMed1998

In vitro activities of six fluoroquinolones against Canadian isolates of vancomycin-sensitive and vancomycin-resistant Enterococcus species.

The in vitro activities of six fluoroquinolones were determined against 1482 Enterococcus species isolates collected as part of a 1996 Canadian surveillance study. Clinafloxacin MIC90s were 4 or 8 microg/mL, trovafloxacin and BAY 12-8039 MIC90s were 8 or 16 microg/mL, sparfloxacin MIC90s were 32 microg/mL, and ciprofloxacin and ofloxacin MIC90s were >32 microg/mL for the vancomycin-sensitive Enterococcus faecalis, vancomycin-sensitive Enterococcus faecium, and vancomycin-resistant E. faecium isolates collected.

Anti-Bacterial Agents↗
PubMed2000

Aminoglycoside-modifying enzymes in high-level streptomycin and gentamicin resistant Enterococcus spp. in Spain.

Aminoglycoside resistance was evaluated in 690 enterococcus strains isolated from different clinical sources originating from patients at the University Clinic Hospital of Zaragoza (Spain). The enterococci obtained from clinically significant samples (blood, urine, or exudates) showed more high-level resistance to gentamicin and streptomycin (65 and 42%, respectively) than those isolated from faecal samples (49 and 23%, respectively). Aminoglycoside-modifying enzymes (AME) from 119 of these high-level gentamicin and streptomycin resistant enterococcus strains were studied. The most frequent AMEs found were APH(3') and AAC(6')-APH(2"). More than one enzyme was detected in 71% of the strains (four different enzymes in 5% of the strains). Three Enterococcus faecalis strains had ANT(4')(4") enzymatic activity. Different enzymatic expressions of the bifunctional enzyme AAC(6')-APH(2") were demonstrated in strains in which the complete aac(6')-aph(2") gene was detected by PCR and hybridization: (i) AAC(6') + APH(2") activity; (ii) AAC(6') only; (iii) APH(2") only; and (iv) no activity of AAC(6') or APH(2").

Anti-Bacterial Agents↗
PubMed2002

Interaction of fibronectin and aggregation substance promotes adherence of Enterococcus faecalis to human colon.

This in vitro study investigates the interaction between aggregation substance (AS), a virulence factor of Enterococcus faecalis, and colonic mucosal fibronectin in normal colon and colon from patients with Crohn's disease. Fibronectin was found to be overexpressed in Crohn's disease compared to normal colon. Compared to E. faecalis OG1X:pAM944 (AS-negative), E. faecalis OG1X:pAM721 (expressing AS) showed a significantly enhanced adhesion to human colonic mucosa in normal colon and in colon from patients with Crohn's disease. Double-staining of fibronectin and AS-positive enterococci showed that colocalization of bacteria and fibronectin was significantly more frequent in Crohn's disease than in normal colon. Preincubation of bacteria with soluble fibronectin caused a significant reduction in the adherence to fibronectin. In conclusion, the interaction between AS and fibronectin plays is an important factor that mediates adhesion of Enterococcus faecalis to colonic mucosa. This might be one of the mechanisms responsible for bacterial translocation of Enterococcus faecalis.

Bacterial Adhesion↗
PubMed2003

Potential of the enterocin regulatory system to control expression of heterologous genes in Enterococcus.

AIMS: To exploit the enterocin regulatory system for regulated expression of genes in Enterococcus. METHODS AND RESULTS: Production of some pediocin-like bacteriocins such as enterocin A in Enterococcus is regulated by a three-component system comprising a histidine kinase (entK ), a response regulator (entR) and an induction factor (entF ). Exposure to the induction factor results in the transcription of gene(s) under the control of the enterocin A promoter, including entA which encodes the bacteriocin. In an effort to exploit this system for expression of genes in Enterococcus, a number of vectors were constructed which contain the entA promoter followed by convenient cloning sites to introduce gene(s) of interest. These vectors were used in an enterococcal background which does not produce induction factor but does produce both the kinase and regulator proteins. The system was tested using the reporter genes ltnI (lacticin 3147 immunity) and gusA (beta-glucuronidase) under the control of the entA promoter. CONCLUSIONS: Upon addition of the induction factor, the beta-glucuronidase activity increased 20-fold when compared with uninduced cells. In addition, concentrations of as little as 0.2 nm synthetic EntF were sufficient to give maximal expression. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential benefit of having an expression system based on EntF is that gene expression can be finely controlled upon addition of low concentrations of a peptide that can easily be artificially synthesized.

Anti-Bacterial Agents↗
PubMed2002

Emergence of vancomycin-resistant Enterococcus faecium at a tertiary care hospital in Karachi, Pakistan.

Vancomycin-resistant enterococcus (VRE) has not been reported previously in Pakistan. This is the first report where in vancomycin-resistant Enterococcus faecium was isolated from the clinical specimens of six patients admitted to the intensive care unit (ICU) and neonatal intensive care unit (NICU) of the Aga Khan University Hospital, Karachi. To identify the extent of the outbreak, rectal swabs were obtained from all the patients admitted to the ICU and NICU at that time. A total of 10 strains of vancomycin-resistant Enterococcus faecium were isolated. All the strains showed high-level resistance to both glycopeptides (vancomycin and teicoplanin) with a vancomycin minimum inhibitory concentration greater than 256 mg/L. All isolates had the vanA gene detected by polymerase chain reaction. The contour-clamped homogeneous electric field (CHEF) pattern demonstrated that all but one of the isolates were of a single clone, suggesting that they were derived from common source. Use of vancomycin and prolonged hospitalization were common features in all cases investigated.

Adult↗
PubMed1995

Quinupristin/dalfopristin (RP 59500) therapy for vancomycin-resistant Enterococcus faecium aortic graft infection: case report.

A 46-year-old woman was admitted to the hospital with severe peripheral vascular disease, requiring multiple vascular surgical procedures. During the sixth hospital week, after prior therapy with multiple antibiotics, Enterococcus faecium was isolated as the only organism from an operating room culture of an infected aortic graft. Histological examination of the graft showed infiltration with polymorphonuclear leukocytes. Subsequently, cultures of an infected inguinal wound yielded Enterococcus faecium with mixed bacterial growth. Both isolates of Enterococcus faecium were resistant to all available antimicrobials, including ampicillin, vancomycin, tetracycline, chloramphenicol, and ciprofloxacin. Compassionate use therapy with quinupristin/dalfopristin (RP59500) was administered for 25 days, the patient's clinical condition improved, and wound healing occurred. Transient elevation of serum alkaline phosphatase was noted. This case demonstrates successful eradication of deep VREF infection by quinupristin/dalfopristin with good tolerance of prolonged therapy.

Anti-Bacterial Agents↗
PubMed1992

Enterococcus species in urinary tract infection.

Significant urinary isolates have been prospectively recorded since 1971. Enterococcus species, a common cause of nosocomial urinary tract infection, have been identified, and susceptibilities to a range of antibiotics have been determined. In addition, isolates in 1988 were tested for breakpoint susceptibility to vancomycin and teicoplanin. Despite changes in the hospitals covered, isolation of Enterococcus species rose steadily from 4% in 1971 to 12.6% in 1990 in hospital patients and from 2% to 5.6% in general-practice patients (P less than .01). All isolates of Enterococcus species were sensitive to ampicillin. Teicoplanin inhibited all 526 strains tested at a concentration of 2 micrograms/mL, but the same concentration of vancomycin inhibited only 370 (70%). The increased prevalence of enterococcal urinary tract infection is probably the result of increasing use of catheterization and broad-spectrum antibiotics. Glycopeptides reach high levels in the urine, and teicoplanin might be an alternative for the treatment of urinary tract infections due to enterococci.

Anti-Bacterial Agents↗
PubMed1996

Differences in outcomes for patients with bacteremia due to vancomycin-resistant Enterococcus faecium or vancomycin-susceptible E. faecium.

To determine the differences in outcome in cases of enterococcal bacteremia due to vancomycin-resistant organisms, we compared consecutive patients on a liver transplant service who had clinically significant bacteremia due to vancomycin-resistant Enterococcus faecium (VREF) (n = 54) with a contemporaneous cohort of patients who had vancomycin-susceptible E. faecium (VSEF) bacteremia (n = 48). VREF bacteremia occurred significantly later in the hospitalization than did VSEF bacteremia (43 days vs. 24 days, respectively; P < .01); in addition, VREF was more frequently the sole blood pathogen isolated (91% of patients) than was VSEF (56% of patients) (P = .0002). Invasive interventions for intraabdominal and intrathoracic infection were required more often in the VREF cohort than in the VSEF cohort (34 of 45 patients vs. 20 of 41 patients, respectively; P = .01). Vancomycin resistance more frequently resulted in recurrent bacteremia (22 of 54 patients infected with VREF vs. 7 of 48 patients infected with VSEF; P = .006), persistent isolation of Enterococcus species at the primary site (27 of 33 patients infected with VREF vs. 7 of 18 patients infected with VSEF; P = .005), and endovascular infection (4 patients infected with VREF vs. none infected with VSEF). The decrement in patient survival, as measured from the last bacteremic episode, was greater in the VREF cohort (P = .02). Vancomycin resistance, shock, and liver failure were independent risk factors for Enterococcus-associated mortality. Higher rates of refractory infection, serious morbidity, and attributable death occurred in the VREF cohort and were partially mediated by the lack of effective antimicrobial therapy.

Adult↗
PubMed1994

vanA-mediated vancomycin-resistant Enterococcus spp. in sewage.

Three high-level vancomycin-resistant Enterococcus strains (two Enterococcus faecium and one Enterococcus durans) were recovered from three of eight sewage samples taken from the general sewage collector at Logroño (Northern Spain). The strains were present in the sewage samples at estimated concentrations of ten resistant bacteria/mL, corresponding to about 0.4% of the enterococcal population. The VanA protein was detected in each strain by immunoblotting of membrane extracts of the vancomycin-induced cells, and the vanA gene was demonstrated in the wild strains and their transconjugants by DNA-DNA hybridization. This is the first, confirmed report of vanA mediated vancomycin resistance in E. durans.

Bacterial Proteins↗
PubMed1995

A survey of antimicrobial susceptibility of clinical isolates of Enterococcus spp. from Irish hospitals.

Nosocomial enterococcal infections are increasing. In order to establish the species distribution and antibiotic resistance patterns of enterococci in clinical specimens from hospitalized patients, we undertook a survey of 23 Irish hospitals. One thousand and five viable enterococcal strains were studied. Nine different species of enterococci were identified, including Enterococcus faecalis (84%); Enterococcus faecium (9%); and Enterococcus hirae (3%). The most common sites of isolation were the urinary tract (66%), wound and soft tissues (23%) and blood stream (3%). Many of the isolates were multiply antibiotic resistant. Ampicillin resistance was detected in 16%. Neither beta-lactamase production, nor high level penicillin resistance was detected. High level gentamicin resistance was evident in 7% of isolates and varied among species, e.g. 4% E. faecalis, 24% E. faecium, and 34% E. hirae. A number of isolates (23%) were also highly resistant to streptomycin. No clinically significant glycopeptide resistance was detected. The species distribution and incidence of multiple resistance was geographically widespread. This emphasizes the need for detailed speciation and in-vitro susceptibility testing along with the evaluation of alternative combination chemotherapeutic regimens for the management of serious enterococcal infection.

Anti-Bacterial Agents↗
PubMed1997

Comparative in-vitro activity of quinupristin/dalfopristin against Enterococcus spp.

The in-vitro activity of quinupristin/dalfopristin against Enterococcus spp. was compared with that of amoxycillin, vancomycin, telcoplanin and erythromycin. The susceptibility of 106 vancomycin-susceptible Enterococcus faecalis, 92 vancomycin-susceptible Enterococcus faecium and 14 vancomycin-resistant enterococci (VRE) was tested. Only one strain of vancomycin-susceptible E. faecium was not susceptible to < or = 0.5 mg/L quinupristin/dalfopristin; this strain required 4 mg/L. All strains of E. faecalis were inhibited by < or = 8 mg/L quinupristin/dalfopristin and all VRE strains were inhibited by < or = 2 mg/L. In contrast, teicoplanin and vancomycin showed inhibitory activity against E. faecalis and E. faecium but not against VRE. Amoxycillin was active against E. faecalis but not usually against E. faecium and showed variable activity against VRE; 38% of E. faecalis, 84% of E. faecium and 80% of VRE strains were resistant to erythromycin. The bactericidal activity of quinupristin/dalfopristin against E. faecium exceeded that of the comparator drugs as judged by MIC:MBC ratios and killing curves. The MBC99 of quinupristin/dalfopristin determined by a microdilution broth technique was < or = 1 mg/L for E. faecium. Four of the five strains of vancomycin-susceptible E. faecium and three of the five VRE strains tested with time-kill curves showed a > or = 2 log reduction in viable count after exposure to quinupristin/dalfopristin for 6 h.

Amoxicillin↗
PubMed2001

Successful treatment of vancomycin-resistant enterococcus meningitis with linezolid: case report and review of the literature.

OBJECTIVE: To describe the successful treatment of a case of vancomycin-resistant enterococcus meningitis with linezolid. DESIGN: Case report and review of the literature. PATIENTS: The patient is a 35-yr-old man who suffered a cerebellar hemorrhage after embolization of a cerebellar arteriovenous malformation. The patient underwent ventriculostomy drainage and craniectomy. The patient was on broad-spectrum antibiotics for pneumonia including vancomycin. The patient remained febrile and grew vancomycin-resistant Enterococcus faecium from the cerebrospinal fluid. INTERVENTIONS: The patient was treated with intravenous chloramphenicol without success. On postoperative day 16, the patient was begun on intravenous linezolid. MAIN RESULTS: The patient received 4 wks of intravenous linezolid with complete eradication of the meningitis. CONCLUSIONS: Intravenous linezolid appears to be a safe and effective therapy for vancomycin-resistant enterococcus meningitis.

Acetamides↗
PubMed2001

Intraabdominal vancomycin-resistant enterococcus infections: the new threat.

GOALS: To determine the clinical course and outcome in patients with intraabdominal vancomycin-resistant enterococcus infections (VRE-A) and to identify probable risk factors for VRE-A. BACKGROUND: Vancomycin-resistant enterococcus is one of the most notable nosocomial emerging pathogens. The incidence is increasing, especially in the abdominal surgery setting. STUDY: A comparative study of patients with VRE-A and VRE infection in other sites (VRE-O) who were hospitalized for over 1 year. Fisher exact test and Student t test were used; a two-tailed p value of less than 0.05 was considered to be significant. RESULTS: Of 89 nine patients with VRE, six had VRE-A, 24 had VRE-O, and 59 had VRE colonization. The VRE-A group was comprised of one patient with an inoperable Klatskin tumor and biliary sepsis, one with acquired immune deficiency syndrome and an infected pancreatic pseudocyst, two with fecal peritonitis, and two with biliary sepsis after surgery for common bile duct stones. All six patients with VRE-A had recent surgery before VRE isolation, as compared with three in the VRE-O group (p = 0.0001). Despite adequate treatment with intravenous chloramphenicol, resulting in eradication of VRE in all six VRE-A cases, the mortality rate remained high at 50%. CONCLUSIONS: Vancomycin-resistant enterococcus should be recognized as an emerging nosocomial pathogen that causes potentially fatal intraabdominal infections in the postsurgical setting. However, the impact of treatment on ultimate outcome needs further evaluation.

Abdomen↗
PubMed1993

A new approach to use of bacteriolytic enzymes as a tool for species identification: selection of species-specific indicator strains with bacteriolytic activity towards Enterococcus strains.

We describe the bacteriolytic activity of 377 group D Enterococcus isolates expressed towards 25 Enterococcus strains belonging to different species and Micrococcus luteus ATCC 4698. Of the 26 indicator strains used to reveal bacteriolytic activity, 5 were lysed by all of the strains of some species and were not lysed by all of the strains of other species. The use of these indicator strains allowed us to devise a new method to differentiate group D Enterococcus strains, based on qualitative analysis (lysis or no lysis of the indicator strains) of bacteriolytic activity. The bacteriolytic patterns obtained fell into six bacteriolytic groups corresponding (98% agreement) to species or groups of enterococci as determined by a comparison with data from a phenetic similarity study.

Bacterial Typing Techniques↗
PubMed1985

The phylogenetic position of Streptococcus and Enterococcus.

Streptococcus pyogenes, S. equinus, S. bovis, S. salivarius, S. sanguis, S. mutans, S. rattus, S. cricetus, S. lactis, S. raffinolactis and Enterococcus faecalis have been characterized by oligonucleotide cataloguing of their 16S ribosomal RNA. All the organisms form a loose but coherent group that is phylogenetically equivalent to those of lactobacilli, bacilli, the Brochothrix and Listeria group, and related taxa that constitute one of several sublines within the 'Clostridium' branch of Gram-positive eubacteria. Within the Steptococcus-Enterococcus group, organisms fall into three moderately related clusters defined by Enterococcus, the lactic acid streptococci and streptococci of the pyogenic and oral groups, respectively.

Animals↗
PubMed1998

Division of the genus Enterococcus into species groups using PCR-based molecular typing methods.

Broad-range 16S rDNA PCR (BR-PCR) applied to DNA from 32 clinical enterococcal isolates and 12 other enterococci from a clinical reference collection followed by species-specific hybridization analysis identified 25 strains of Enterococcus faecalis and 19 Enterococcus species. Randomly amplified polymorphic DNA (RAPD) analysis using UPGMA clustering on the same material revealed four different clusters at a similarity level of 49%. Based on partial 16S rDNA sequence analysis of variable regions V4 and V9, it was possible to divide the 19 type strains specifying the genus Enterococcus into 12 different 16S rDNA species groups. The type strain distribution then served as a template for the analysis of the other 44 strains which were assigned to four different species groups (a-d) based on their 16S rDNA motifs. There was good agreement with the RAPD clusters. Species group a was an individual species line containing 25 strains that were identified as E. faecalis. Group b also represented an individual species line of 12 strains identified as E. faecium. The remaining seven strains that formed species groups c and d could not be fully identified to species by this analysis. It was concluded that BR-PCR of 16S rDNA followed by partial sequence analysis of the PCR products is a reliable technique for the identification and classification of enterococci. Further division of unresolved species groups should be achievable if regions other than V4 and V9 of 16S rDNA are also analysed.

Bacterial Typing Techniques↗
PubMed2001

The penicillin resistance of Enterococcus faecalis JH2-2r results from an overproduction of the low-affinity penicillin-binding protein PBP4 and does not involve a psr-like gene.

A penicillin-resistant mutant, JH2-2r (MIC 75 microg ml(-1)), was isolated from Enterococcus faecalis JH2-2 (MIC 5 microg ml(-1)) by successive passages on plates containing increasing concentrations of benzylpenicillin. A comparison of the penicillin-binding protein (PBP) profiles in the two strains revealed a more intensely labelled PBP4 in JH2-2r. Because the sequences of the JH2-2 and JH2-2r pbp4 genes were strictly identical, even in their promoter regions, this intensive labelling could only be associated with an overproduction of the low-affinity PBP4. No psr gene analogous to that proposed to act as a regulator of PBP5 synthesis in Enterococcus hirae and Enterococcus faecium could be identified in the vicinity of pbp4 in E. faecalis JH2-2 and JH2-2r. However, a psr-like gene distant from pbp4 was identified. The cloning and sequencing of that psr-like gene from both E. faecalis strains indicated that they were identical. It is therefore postulated that the PBP4 overproduction in E. faecalis JH2-2r results from the modification of an as yet unidentified factor.

Bacterial Proteins↗
PubMed2005

Biochemical and genetic evidence for the transfer of Enterococcus solitarius Collins et al. 1989 to the genus Tetragenococcus as Tetragenococcus solitarius comb. nov.

Phylogenetic analysis of 16S rRNA gene sequences revealed that Enterococcus solitarius is not a member of the genus Enterococcus, but is related to species of the genus Tetragenococcus. On a phylogenetic tree, E. solitarius clustered with Tetragenococcus halophilus and Tetragenococcus muriaticus, with which it showed the highest 16S rRNA gene sequence similarity level (about 94 %). Phenotypic studies indicated that E. solitarius was also unable to produce acid from lactose, providing further evidence of its affiliation to the genus Tetragenococcus. DNA hybridization studies indicated that E. solitarius was clearly a separate species, different from T. halophilus and T. muriaticus (reassociation levels of about 23 and 54 %, respectively). As suggested in previous studies, E. solitarius is closely related to but clearly distinct from T. halophilus. Based upon properties that taxonomically distinguish it from species of the genus Enterococcus, it is proposed that E. solitarius be transferred to the genus Tetragenococcus and reclassified as Tetragenococcus solitarius comb. nov. (type strain, 885/78(T)=ATCC 49428(T)=CCUG 29293(T)=CIP 103330(T)=DSM 5634(T)=JCM 8736(T)=LMG 12890(T)=NCTC 12193(T)).

Bacterial Typing Techniques↗