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PubMed2004

Molecular-biological analysis of vancomycin-resistant enterococci isolated from a community in the Czech Republic.

OBJECTIVE: To determine the occurrence of vancomycin-resistant enterococci (VRE) in a community of the Czech Republic and a molecular-biological analysis of the VRE isolated. METHODS: Enterococci were isolated from the rectal swabs of healthy people in the Olomouc region (population 300,000), Czech Republic in the period of January-December 2003. The molecular-biological analysis of VRE was performed by analysis of isolated DNA, which was cleaved by restriction enzyme SmaI and separated by pulse field gel electrophoresis (PFGE). RESULTS: A total number of 5,283 swabs were evaluated and 558 Enterococcus sp. strains were isolated during the follow-up period. 9 strains (1.6%) were identified as VRE. Two strains were E. faecium phenotype VanA, one strain was E. faecalis phenotype VanB, two strains were E. gallinarum phenotype VanC and four strains were E. casseliflavus phenotype VanC. PFGE was used to obtain 9 different restriction profiles of VRE strains. The analysis showed closer a similarity of E. casseliflavus strains (80-95%) than between E. faecium strains (41%). CONCLUSIONS: The presence of VRE in a sample community of the Czech population was confirmed. It is clear that it is necessary to take into account the possibility of VRE spreading from the community into health care facilities.

Czech Republic↗
PubMed2006

Sources and pathways of spread of vancomycin-resistant enterococci in hemato-oncological patients.

The presented study aims at analyzing an increasing prevalence of vancomycin-resistant enterococci (VRE) isolated from various kinds of clinical material obtained from patients in the Department of Hemato-oncology (DHO), University Hospital in Olomouc, Czech Republic. Between January 1 and March 31, 2005, enterococci were isolated by standard microbiological procedures using both clinical material obtained from hospitalized patients and samples from the department environment. Resistance to vancomycin and teicoplanin was determined by a standardized microdilution method. Phenotype determination of resistance to vancomycin was verified by PCR detection of vanA and vanB genes. In VanA Enterococcus faecium, macrorestriction analysis was performed by pulsed-field gel electrophoresis. During the monitored period, a total of 128 Enterococcus sp. strains were isolated, of which 38 (30 %) isolates from 22 different patients were determined as VRE. Dominating were Enterococcus faecium VanA (63 %) and Enterococcus casseliflavus VanC (16 %) strains. At the same time, one Enterococcus faecium VanA strain was acquired from a bed-side table used by a patient in whom a similar strain had been isolated repeatedly from various clinical materials including a rectal swab taken in 2004. Based on the macrorestriction analysis of genome DNA in 24 vancomycin-resistant Enterococcus faecium VanA strains isolated from the patients' clinical material, one strain from the bed-side table surface and one strain isolated from stools in 2004, 8 unique restriction profiles with similarity ranging from 90 % to 100 % were identified, which could be classified into 3 clonal types. Thus, we can assume not only the endogenous origin of the VRE in hemato-oncological patients and their potential selection caused by therapy with broad-spectrum antibiotics but also the ability of the strains to survive in a hospital setting and, subsequently, to be spread clonally by various vectors.

Cross Infection↗
PubMed1994

Amides of de-acetylglucosaminyl-deoxy teicoplanin active against highly glycopeptide-resistant enterococci. Synthesis and antibacterial activity.

Removal, by selective reduction, of the acetylglucosamine from teicoplanin A2-2 (CTA/2) produced the 34-de(acetylglucosaminyl)-34-deoxy pseudoaglycone (II). This compound was more active in vitro than CTA/2 against coagulase-negative staphylococci (CNS). Amide derivatives obtained by condensation of the carboxyl group of II with primary amines were particularly active against Streptococcus pyogenes and had some in vitro activity against VanA enterococci highly resistant to both teicoplanin and vancomycin. Among them, a carboxamide (VII) with a branched tetramine also had better activity than the corresponding amide of teicoplanin against CNS. In contrast, the dimethylamide (VIII) of II had little activity against VanA enterococci. While the overall structure of the heptapeptide backbone of the secondary carboxamides of II is the same as in CTA/2 and its amide derivatives, in deoxy pseudoaglycone II and its tertiary amide VIII the 51,52-peptide bond undergoes a conformational change from the original cisoid to the transoid orientation. This difference between the secondary amides of II and dimethylamide VIII is reflected in their different antibacterial spectrum. The direct synthesis of the amides of deoxy pseudoaglycone II from parent CTA/2-amides by reaction with sodium borohydride is also described.

Amides↗
PubMed1995

New semisynthetic glycopeptides MDL 63,246 and MDL 63,042, and other amide derivatives of antibiotic A-40,926 active against highly glycopeptide-resistant VanA enterococci.

A series of amide derivatives of natural glycopeptide A-40,926 (A), its 6B-methyl ester (MA) and 6B-decarboxy-6B-hydroxymethyl derivative (RA) were prepared with the aim of obtaining activity against glycopeptide-resistant enterococci. These compounds are structurally related to a class of amides of 34-de(acetylglucosaminyl)-34-deoxy teicoplanin which showed interesting activity against strains of Enterococcus faecalis and E. faecium highly resistant to both vancomycin and teicoplanin. Among them, RA-amides MDL 63,246 and MDL 63,042 were the most active derivatives against several Gram-positive bacteria, including VanB and VanC enterococci, and were moderately active (MIC range 0.5 approximately 64 micrograms/ml) against strains of Enterococcus for which vancomycin and teicoplanin MICs were > or = 128 micrograms/ml. The chemical rationale and the synthesis of these new series of glycopeptide derivatives are described. Preliminary in vitro data are reported and structure-activity relationships are discussed.

Anti-Bacterial Agents↗
PubMed1998

Novel glycopeptide antibiotics: N-alkylated derivatives active against vancomycin-resistant enterococci.

LY264826 (A82846B) is a naturally-occurring glycopeptide antibiotic, differing from vancomycin in the stereochemistry of the amino-sugar of the disaccharide function, and the presence of a third sugar attached at the benzylic position of amino acid residue 6. Despite these seemingly subtle differences, LY264826 is approximately 10 times more active than vancomycin against the enterococci. In the pursuit of new antibiotics active against multiresistant Gram-positive organisms, an extensive side chain SAR was developed focusing on the reductive alkylation of LY264826 at the amino function of the disaccharide moiety. A new series of derivatives having varying degrees of structural diversity in the side chain (e.g. varying lengths and degrees of rigidity) was found to have potent activity against vancomycin-resistant enterococci (MIC's < 1.0 microgram/ml) as well as activity against staphylococci and streptococci as good or better than vancomycin.

Alkylation↗
PubMed2001

The effect of vancomycin and third-generation cephalosporins on prevalence of vancomycin-resistant enterococci in 126 U.S. adult intensive care units.

BACKGROUND: Patient-specific risk factors for acquisition of vancomycin-resistant enterococci (VRE) among hospitalized patients are becoming well defined. However, few studies have reported data on the institutional risk factors, including rates of antimicrobial use, that predict rates of VRE. Identifying modifiable institutional factors can advance quality-improvement efforts to minimize hospital-acquired infections with VRE. OBJECTIVE: To determine the independent importance of any association between antimicrobial use and risk factors for nosocomial infection on rates of VRE in intensive care units (ICUs). DESIGN: Prospective ecologic study. SETTING: 126 adult ICUs from 60 U.S. hospitals from January 1996 through July 1999. PATIENTS: All patients admitted to participating ICUs. MEASUREMENTS: Monthly use of antimicrobial agents (defined daily doses per 1000 patient-days), nosocomial infection rates, and susceptibilities of all tested enterococci isolated from clinical cultures. RESULTS: Prevalence of VRE (median, 10%; range, 0% to 59%) varied by type of ICU and by teaching status and size of the hospital. Prevalence of VRE was strongly associated with VRE prevalence among inpatient non-ICU areas and outpatient areas in the hospital, ventilator-days per 1000 patient-days, and rate of parenteral vancomycin use. In a weighted linear regression model controlling for type of ICU and rates of VRE among non-ICU inpatient areas, rates of vancomycin use (P < 0.001) and third-generation cephalosporin use (P = 0.02) were independently associated with VRE prevalence. CONCLUSIONS: Higher rates of vancomycin or third-generation cephalosporin use were associated with increased prevalence of VRE, independent of other ICU characteristics and the endemic VRE prevalence elsewhere in the hospital. Decreasing the use rates of these antimicrobial agents could reduce rates of VRE in ICUs.

Anti-Bacterial Agents↗
PubMed1998

[Selection of phenotype characteristics in differentiation of various species of enterococci using an inductive mathematical program].

In this paper a novel computer example-based learning system (Inductive learning by logic minimization) was used to determine the sufficient set of biochemical reactions and necessary conditions that have to be fulfilled for the correct identification of enterococci isolated from human specimens. Several combinations for accurate identification of Enterococcus faecalis and Enterococcus feacium from other enterococci were found. The simplest combination set for E. faecalis identification consists of 3 reactions: growth in 0.04% K-tellurite, mannitol acidification, failure to acidify raffinose. The simplest set for E. faecium differentiation from other enterococcal species is performed by the following 3 reactions: failure to acidify D-xylose and Na-pyruvate, and acidification of L-arabinose. Only 4 tests are sufficient (acid from D-xylose, mannitol, L-arabinose and Na-pyruvate) for the correct identification of these two, the most frequently isolated species. If it is necessary to analyze all enterococcal species, then even three combinations of 9 tests for the correct differentiation of any of them, are available.

Artificial Intelligence↗
PubMed1999

[Multicenter study of resistance in enterococci. The role of teicoplanin. Spanish Group for Study and Surveillance of Resistance].

Enterococci are a frequent cause of nosocomial and community infections, especially the E. faecalis and E. faecium species. They often show intrinsic resistance to cephalosporins and quinolones, and acquired resistance to other antimicrobials, such as glycopeptides, has also been described. In order to test the impact of antibiotic resistance in enterococci isolated from infections, we carried out a multicenter study in 19 hospitals in Spain. We verified whether resistance to a high concentration of aminopenicillins and aminoglycosides was high (30.86% for ampicillin, 32.32% for gentamicin at a 500 micrograms dose, 55.93% for streptomycin at a 1000 micrograms dose) while the resistance to glycopeptides was low (1.8% for vancomycin and 1% for teicoplanin). It was also shown that teicoplanin had greater intrinsic activity than vancomycin, with teicoplanin 0.5 mg/l inhibiting 86.1% of the strains studied, whereas only 12.8% were inhibited with the same concentration of vancomycin.

Anti-Bacterial Agents↗
PubMed2000

Problems and perils of vancomycin resistant enterococci.

Enterococci have been a therapeutic challenge for haIfa century; first in the management of endocarditis, then associated with the emergence of resistance to streptomycin and later to all aminoglycosides, and now with the increasing levels of resistance to penicillins. A major leap in the problem of antimicrobial resistance occurred more than a decade ago when vancomycin resistant enterococci (VRE) were first identified. This resulted from the acquisition by Enterococcus faecium of vancomycin resistant genes. Five types of vancomycin resistance have since been described (VanA-VanE) and others also appear to exist. VanA and VanB are caused by complex gene clusters that may be plasmid and/or transposon encoded. As a result of the gene cluster, cell wall precursors in the bacteria are formed that do not allow effective vancomycin binding, thus the action of vancomycin to inhibit cell wall synthesis is prevented. Therapy of infections caused by VRE is difficult, but a number of potentially effective antibiotics are now being tested in humans, including quinupristin/dalfopristin, linezolid, evernimomycin, daptomycin and LY333328. Combinations of antibiotics such as ampicillin with quinupristin/dalfopristin or with imipenem, and newer fluoroquinolones are also being evaluated. Until the time when these drugs become available, we must rely on careful monitoring of microbial transmission in hospitals, and we must utilize multi-faceted approaches to prevent the increase in the number and spread of VRE.

Enterococcus↗
PubMed2001

Methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci: emerging problems and new prospects for management.

INTRODUCTION: Infections due to multidrug-resistant Gram-positive bacteria are a growing worldwide problem, particularly among seriously ill patients. A number of studies have demonstrated that patients infected with either methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) are at higher risk for mortality and medical resource expenditures. METHODS: A non-systematic evidence-based review of linezolid, the first commercially available oxazolidinone, and quinupristin/dalfopristin, the first injectable streptogramin, for management of these multidrug-resistant infections was conducted. RESULTS: As infections due to VRE increase and vancomycin-insensitive MRSA emerge, vancomycin is becoming less effective for managing Gram-positive infections. Preclinical comparative studies demonstrated that linezolid and quinupristin/dalfopristin are highly effective in eradicating both susceptible and resistant staphylococci, streptococci, and enterococci. Clinical experience, including phase III and compassionate-use data, with these newer agents in the treatment of MRSA and VRE infections are discussed. CONCLUSIONS: The clinical experiences thus far with linezolid and quinupristin/dalfopristin for MRSA and VRE infections have demonstrated efficacy, making these agents important additions to the limited number of therapeutic alternatives for Gram-positive infections.

Acetamides↗
PubMed2002

[Susceptibility of enterococci to natural and synthetic iron chelators].

A total of 79 strains of enterococci belonging to 10 species were tested for susceptibility to natural and synthetic iron chelators. All strains produced siderophores. These enterococci were susceptible to three synthetic iron chelators only: 8-hydroxyquinoline, disodium versenate (EDTA) and o-phenanthroline. They were resistant to all other synthetic chelators: ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA), nitrilotriacetate, 2,2'-bipiridyl, salicylic acid, 8-hydroxy-5-sulphonic acid and to all natural chelators: ovotransferrine, human apotransferrine, horse apoferritine, desferrioxamine B, ferrichrome and rhodotorulic acid. The relations between susceptibility/resistance, iron assimilation and structure and stability constants of iron chelators were discussed.

Drug Resistance, Bacterial↗
PubMedDate not supplied

[Characterization of persistence factors of enterococci].

Persistence factors is some species of enterococci (E. faecium, E. faecalis, E. gallinarum), isolated from healthy children and from children with purulent inflammatory diseases, were studied. The study revealed some interspecific and intraspecific differences in the activity of these factors, linked with the presence of purulent inflammatory process induced by enterococci.

Child↗
PubMed2003

[Analysis of antimicrobial resistance of clinical isolates of enterococci from Beijing and other areas in China].

OBJECTIVE: To analyze the antimicrobial resistance of enterococci in Beijing and other areas in China. METHODS: Disk diffusion method was used to test the antimicrobial resistance of 1978 enterococcal isolates from 4 teaching hospitals in Beijing and 53 grade 3 A hospitals in other areas of China The laboratory data were analyzed by WHONET5 statistic software. RESULTS: Enterococcus. faecalis isolates and E. facium isolates accounted for 80.7% and 17.1% of the enterococcus isolates in Beijing and 79.4% and 15.2% in other areas respectively. The enterococcus isolates from urine, sputum, secretion with pus, blood, and bile accounted for 33.7%, 22.9%, 9.8%, 4.4%, and 3.0% of the enterococcus isolates in Beijing and 28.4%, 16.3%, 14.6%, 5.0%, and 4.5% in other areas respectively. The resistance rates of E. faecalis to vancomycin, teicoplanin, ampicillin, and high -level gentamicin were 2.0%, 1.4%, 17.7%, and 47.4% in Beijing, and 5.1%, 3.7%, 24%, and 49.2% in other areas; The resistance rates of E. faecium to vancomycin, teicoplanin, ampicillin, and high -level gentamicin were 1.5%, 2.6%, 64.2%, and 64.9% in Beijing, and 2.1%, 3.1%, 68.5%, and 62.3% in other areas respectively. The vancomycin-resistant rate of the total isolates of enterococci was 3.2%. CONCLUSION: Enterococcus faecalis is the main species in the enterococcus isolates from clinical samples. E. facium, as compared with E. faecalis resists many antimicrobial agents more strongly. Both of E. faecalis and E. facium show the least resistance to vancomycin and teicoplanin.

Drug Resistance, Bacterial↗
PubMed2003

Vancomycin-resistant enterococci in King Chulalongkorn Memorial Hospital: a 5-year study.

The emergence of hospital acquired infections with bacteria resistant to antimicrobials such as vancomycin resistant enterococci (VRE) has become a worldwide concern. The authors studied the prevalence and surveillance of 5 years study of VRE in King Chulalongkon Memorial Hospital and phenotype of these resistance strains. A total of enterococci 1854 isolates were collected from clinical specimens from 1995 to 1999. Screening vancomycin resistance was identified by the agar plated method and minimal inhibitory concentration (MIC) of vancomycin was determined for vancomycin-resistance strains by E-test. The results demonstated that 15 (0.81%) VRE were isolated from 1,854 specimens. Fourteen VRE were identified as Enterococcus faecium and one strain was Enterococcus faecalis. All of these strains, carrying the VanB phenotype, were susceptible to teicoplanin. Similar to other studies, most VRE strains are E. faecium. To the authors' knowledge, this is the first VRE study carried out in King Chulalongkorn Memorial Hospital. The results showed a low prevalence of VRE and surveillance of 5 years study demonstated a gradual increase of VRE. Therefore, it is important to continue periodic surveys of VRE to prevent the spread of VRE in hospitals.

Enterococcus↗
PubMedDate not supplied

[Multiplex PCR in the framework of an enterococci monitoring project].

A multiplex-PCR (MPCR) assay was optimised in the framework of an enterococci monitoring project in order to accelerate the previous time-consuming biochemical testing of enterococcal strains isolated from animal materials and food. The MPCR was optimised by variation of annealing temperature, MgCl2-concentration but more over by primer combinations and primer concentrations. Reference strains were used during the optimization. Afterwards 522 enterococcal field strains were examined by the MPCR. Ambiguous results occurred for 20 strains (17 with false-positive and 3 with false-negative results) which could be explained by the minor specificity ("EM"-primers) and sensitivity (ddlE.faecium-primers) respectively. Differences also existed between the genus-specific primers "E" and "Ent". The first mentioned primers showed weaknesses for the identification of enterococci whereas the use of the "Ent" primers inhibited other primers in the MPCR. However, the majority of the examined strains could be detected unambiguously, so that a differentiation of enterococcal isolates can be recommended by MPCR in contrast to the high time-, material- and work-consumption of conventional biochemical testings.

Bacterial Proteins↗
PubMed2004

Impact of susceptibility to antibiotics of streptococci & enterococci isolated from patients with infective endocarditis on antibiotic treatment.

BACKGROUND & OBJECTIVES: Streptococci and enterococci are the most frequent pathogens causing infective endocarditis. In order to update the recommendations for both curative and prophylaxis treatment, the susceptibility to antibiotics of the most prevalent species of Streptococcaceae isolated from the patients with infective endocarditis was determined. METHODS: Streptococcal and enterococcal isolates (n=133) isolated from confirmed cases of infective endocarditis during a one-year prospective survey conducted in 1999 in France were studied. The identification of 106 streptococci and 27 enterococci to the species level was carried out by conventional methods. Their susceptibility to ten antibiotics used in curative or prophylactic treatment was measured. Minimal inhibitory concentrations were determined by agar dilution method. RESULTS: All the streptococcal and enterococcal isolates were susceptible to 4 mg/l or less of penicillin or amoxicillin. High levels of resistance to aminoglycosides were observed in two species, Streptococcus gallolyticus subsp. gallolyticus and Enterococcus faecalis. All isolates were susceptible to glycopeptides. Resistance to erythromycin, clindamycin, and pristinamycin was restricted to some species. INTERPRETATION & CONCLUSION: Curative treatments recommended for streptococcal or enterococcal endocarditis, including penicillin, amoxicillin or vancomycin in association with gentamicin were found to be appropriate for 98.5 per cent of cases. The emergence of erythromycin resistance in oral streptococci led to the use of pristinamycin in oral prophylactic treatment in patients allergic to beta-lactams.

Anti-Bacterial Agents↗
PubMed2004

Proficiency of determination of vancomycin susceptibility in enterococci by clinical laboratories in Taiwan.

Eighty clinical microbiology laboratories in Taiwan were evaluated for proficiency in the determination of vancomycin susceptibility of enterococci. Each laboratory was given 1 vancomycin-sensitive isolate and 3 vancomycin-resistant enterococci (VRE) isolates to determine the levels of vancomycin resistance. Among a total of 240 tests performed, 153 (63.8%) correctly determined the levels of vancomycin resistance of the survey isolates. Seventy eight (98%) of the 80 laboratories accurately identified the high level of vancomycin resistant isolates [Enterococcus faecalis; minimum inhibitory concentration (MIC) >256 microg/mL]. Seventy two laboratories (90%) correctly determined the level of vancomycin resistance of another VRE with a vancomycin MIC of 64 microg/mL. Only 3 of the 80 laboratories correctly determined the intermediate-level vancomycin resistant isolates (Enterococcus casseliflavus; MIC = 8 microg/mL). Eight laboratories reported the vancomycin-susceptible isolate as being vancomycin-resistant or of intermediate susceptibility. This survey demonstrated that clinical microbiology laboratories in Taiwan are proficient in detecting high-level but not low-level VRE, suggesting a need to improve their proficiency in VRE detection.

Enterococcus↗
PubMed2003

[Detection of vancomycin-resistant enterococci by a fully automated microbiology system, RAISUS].

A fully automated microbiology system, RAISUS recently developed (Nissui Pharmaceuticals Co., Ltd., Tokyo) was evaluated for identification of enterococci and for detection of vancomycin-resistant enterococci (VRE). When a total of 124 enterococcal isolates were tested, RAISUS correctly identified 122 (98.4%) isolates. Two isolates resulted in species-identifications disagreed with the reference but agreed as belonging to the genus of Enterococcus. When a total of fifty-seven VRE isolates confirmed to be positive for vanA and/or vanB genes were tested against vancomycin, the current RAISUS susceptibility program version 1.76 could detect 41 (71.9%) isolates of VRE as having > or = 32 microg/ml MIC for vancomycin, but one was intermediate (MIC, 8.0 microg/ml) and the remaining 15 vanB-type isolates were incorrectly interpreted as vancomycin-susceptible (MIC, < or = 4.0 microg/ml). The test program based on the algorism to determine bacterial growth in the presence of vancomycin was developed and evaluated. With this test program, all the VRE isolates positive for vanA and/or vanB genes were identified as being vancomycin-resistant or intermediate interpretation. However, eight of 19 clinical isolates of E. casseliflavus and E. gallinarum intrinsically possessing vanC gene were determined as being < or = 4.0 microg/ml MIC for vancomycin. With the influence of program revision, RAISUS became to incubate the test plate longer than with the current program, but 50% of enterococcal isolates including vancomycin-resistant and vancomycin-susceptible isolates were determined within 5 hour-incubations and 90% were within 9 to 10 hour-incubations. With these results, we can conclude that the revised test program for enterococcal isolates could rapidly and correctly identify vancomycin-resistance, and will be applicable to the routine susceptibility test in clinical laboratories.

Bacteriological Techniques↗