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PubMed1998

Comparative in vitro and bactericidal activity of oxazolidinone antibiotics against multidrug-resistant enterococci.

Increasing resistance among enterococci poses a considerable therapeutic problem. In this study, we evaluated the comparative in vitro activity of two investigational oxazolidinone antibiotics, eperezolid and linezolid, versus clinical isolates of multidrug-resistant enterococci. One hundred isolates (16 Enterococcus faecalis, 69 E. faecium, 10 E. gallinarum, 2 E. casseliflavus, 1 E. avium, 1 E. hirae, and 1 E. raffinosus) evaluated were collected from diverse geographic areas in North America and Europe from 1991 to 1995. Eperezolid MIC50 and MIC90 were 1.0 microgram/mL and 2.0 micrograms/mL (1.0-2.0 micrograms/mL range). Linezolid MIC50 and MIC90 were 2.0 micrograms/mL and 2.0 micrograms/mL (0.5-2.0 micrograms/mL range), respectively. MICs were the same at 10(3) CFU/mL and 10(8) CFU/mL initial inoculum. In time-kill experiments using 10 strains and concentrations of 4 micrograms/mL, 8 micrograms/mL, and 16 micrograms/mL (achievable serum concentrations) of eperezolid and linezolid there was a 2 log10 reduction of growth for 2 of 10 isolates tested using eperezolid and a 1 log10 reduction for 50% of isolates with both agents. There was indifferent bactericidal killing when either oxazolidinone was combined with gentamicin, ampicillin, or streptomycin for isolates lacking these resistances. This study demonstrates these oxazolidinone agents to have excellent in vitro activity versus multidrug-resistant enterococci.

Ampicillin↗
PubMed2000

Epidemiology and ecology of enterococci, with special reference to antibiotic resistant strains, in animals, humans and the environment. Example of an ongoing project within the European research programme.

The objectives of the present study are to generate knowledge of the ecology and epidemiology of enterococci in the food chain by studying the following: (1) the population structure (in measures of abundance, number of vancomycin resistant strains, antibiotic resistance patterns, diversity, and stability) among enterococcal populations in different geographical regions and in different links of the food chain (2) possible transmission of strains through the food chain and between hospital environments and the food chain (3) the association between vancomycin resistance and individual strains of enterococci and (4) the diversity of the drug resistance genes in enterococci. So far, 1578 samples have been collected from different countries within the EU (Sweden, Denmark, UK and Spain), and from different habitats (pig farms, carcasses in slaughter houses, soil, manure, water, sewage, and humans). Total and vancomycin resistant enterococcal populations in each sample have been enumerated and more than 12000 isolates have been characterised by phenotyping. Representative isolates are further species identified and characterised by genotyping and MIC determination and from antibiotic resistant isolates the resistance genes are characterised.

Animals↗
PubMed2000

Acquired and intrinsic glycopeptide resistance in enterococci.

Enterococci are Gram-positive cocci responsible for severe human infections, such as endocarditis, meningitis, and septicemia and constitute an increasingly frequent cause of nosocomial infections. Enterococci are resistant to nearly all classes of drugs including, since 1986, glycopeptides. Vancomycin and teicoplanin act by blocking cell wall formation and resistance is due to synthesis of modified late peptidoglycan precursors. Glycopeptide resistance can be intrinsic or acquired and strains may be resistant to vancomycin and teicoplanin, or to vancomycin only. Five types of glycopeptide resistance and their biochemical mechanisms have been described in enterococci. Clinical isolates that are dependent on vancomycin for growth have been isolated. Data suggest a dual origin for resistance: glycopeptide-producing organisms or enterococcal species intrinsically resistant to these drugs.

Anti-Bacterial Agents↗
PubMed1995

Susceptibility of staphylococci and enterococci to glycopeptides comparison of 3 test methods.

The significance of grampositive bacteria, especially staphylococci and enterococci, as nosocomial pathogens has increased in the last decade. Furthermore, resistance to commonly used antibiotics like beta-lactams has also become more common and even resistance to glycopeptides has been observed. We evaluated the susceptibility of 150 staphylococcal clinical isolates (52 S. epidermidis, 52 S. haemolyticus, 10 S. saprophyticus, 10 S. hominis, 4 S. warneri, 4 S. simulans, 4 S. capitis and 14 S. aureus) and of 50 enterococci (49 E. faecalis, 1 E. faecium) to the glycopeptides, vancomycin and teicoplanin. The data from the agar dilution test used as reference method were compared with the results from the E test and the agar disk diffusion test. Concerning vancomycin, no resistance among all the staphylococcal isolates was observed whereas one single enterococcal strain (E. faecium) proved to be resistant. The overall resistance of staphylococcal isolates against teicoplanin was about 10.7% (15 S. haemolyticus, 1 S. epidermidis) being mainly due to the high proportion of S. haemolyticus strains (52 out of 150) among the staphylococcal isolates. Teicoplanin resistance among the enterococci was not detected. For vancomycin, a very close correlation between the MICs from the agar dilution test and the E test was noticed. As concerns teicoplanin, the MICs from the E-test were usually somewhat lower than those obtained by the agar dilution test. No correlation was found between the MICs of resistant and intermediate staphylococcal strains and the results from the teicoplanin agar disk diffusion test. For routine teicoplanin susceptibility testing of staphylococci, the determination of the MIC (e.g., by the E test) is much more reliable for detecting resistant strains than the agar disk diffusion test.

Anti-Bacterial Agents↗
PubMed1989

Few-minutes tests for the identification of group A streptococci and enterococci with chromogenic substrates.

The usefulness of paper strip tests for rapid identification of Streptococcus pyogenes and enterococci cultured on blood agar plates was investigated. The paper strips used contain dried chromogenic substrates for pyrrolidonyl peptidase (PYRase) and beta-glucosidase (beta-Gluc). Material from only a few colonies needed to be applied to the test strips. The reactions could be read after two min (PYRase) and 5-7 min (beta-Gluc), respectively. Results from testing 503 streptococcal strains were evaluated. The reactions proved very useful for rapid differentiation of S. pyogenes and enterococci from human sources. Nearly all strains of these streptococcal species showed positive reactions in the PYRase test whereas only the enterococci (E. faecalis and E. faecium) were positive for both enzymes.

Chromogenic Compounds↗
PubMed2001

Vancomycin-resistant enterococci: why are they here, and where do they come from?

Vancomcyin-resistant enterococci (VRE) have emerged as nosocomial pathogens in the past 10 years, causing epidemiological controversy. In the USA, colonisation with VRE is endemic in many hospitals and increasingly causes infection, but colonisation is absent in healthy people. In Europe, outbreaks still happen sporadically, usually with few serious infections, but colonisation seems to be endemic in healthy people and farm animals. Vancomycin use has been much higher in the USA, where emergence of ampicillin-resistant enterococci preceded emergence of VRE, making them very susceptible to the selective effects of antibiotics. In Europe, avoparcin, a vancomycin-like glycopeptide, has been widely used in the agricultural industry, explaining the community reservoir in European animals. Avoparcin has not been used in the USA, which is consistent with the absence of colonisation in healthy people. From the European animal reservoir, VRE and resistance genes have spread to healthy human beings and hospitalised patients. However, certain genogroups of enterococci in both continents seem to be more capable of causing hospital outbreaks, perhaps because of the presence of a specific virulence factor, the variant esp gene. By contrast with the evidence of a direct link between European animal and human reservoirs, the origin of American resistance genes remains to be established. Considering the spread of antibiotic-resistant bacteria and resistance genes, the emergence of VRE has emphasised the non-existence of boundaries between hospitals, between people and animals, between countries, and probably between continents.

Animal Husbandry↗
PubMed1989

High-level vancomycin-resistant enterococci causing hospital infections.

Nosocomial infection or colonization due to enterococci with high-level resistance to vancomycin (minimal inhibitory concentrations [MICs] between 64 and greater than 2000 mg/L) has occurred in 41 patients with renal disease. These vancomycin-resistant enterococci were cultured from many sources including blood. All but one strain contained one or more plasmids ranging in molecular weight from 1.0 to 40 Megadaltons (MDa). Vancomycin resistance was transferable by conjugation to a susceptible recipient strain of Enterococcus faecalis but this was not always associated with plasmid DNA. The emergence of transferable high-level vancomycin resistance in enterococci causing significant clinical infections is of particular importance since vancomycin is widely regarded as a reserve drug for the management of infections with multi-resistant Gram-positive organisms.

Acute Kidney Injury↗
PubMed1997

In vitro susceptibility studies and detection of vancomycin resistance genes in clinical isolates of enterococci in Nagasaki, Japan.

Glycopeptide resistance in enterococci is now a cause of clinical concern in the United States and Europe. However, details of vancomycin resistance in enterococci in Japan have been unknown. We measured minimum inhibitory concentrations (MICs) of various antimicrobial agents for a total of 218 clinical strains of enterococci isolated in our hospital in 1995-6 in addition to 15 strains with known genotypic markers of resistance. We also screened vancomycin resistance genes using a single step multiplex-PCR. In clinical isolates, only two strains of Enterococcus gallinarum were of intermediate resistance to vancomycin (MIC, 8 micrograms/ml), while the others were all susceptible. Glycopeptides (vancomycin and teicoplanin) and streptogramins (RP 58500 and RPR 106972) showed potent antimicrobial effects for the isolates. In addition, ampicillin was also potent for Enterococcus faecalis, while ampicillin, minocycline and gentamicin were potent for Enterococcus avium. No vanA or vanB genes were detected, while vanC1 and vanC23 genes were detected from two and four strains, respectively. Our results suggest that incidence of VRE in Japan may be estimated as still very low at this time.

Anti-Bacterial Agents↗
PubMed2001

Rapid immunodiagnosis of streptococci and enterococci in blood cultures.

We evaluated a procedure for rapid identification of blood culture isolates of pneumococci, enterococci and beta-haemolytic streptococci groups A, B, C, and G. Immunological tests were applied directly to blood culture medium and included a quellung reaction for pneumococci, and latex agglutination tests (LAT) for pneumococcal antigen and Lancefield antigens A, B, C, D and G. During a one-year trial period with approximately 12,000 blood culture sets (BacT/Alert, Organon-Teknika), 208 sets showed pure growth of gram-positive cocci in pairs or chains by direct microscopy. Overall, a correct diagnosis was noted for 103 (63.2%, 95% CI: 55.3-70.6%) of 163 sets yielding pneumococci, beta-haemolytic streptococci, or enterococci. A procedure excluding Lancefield antigens only A, B, and D was implemented during a one-year follow-up period. With this simplified procedure positive and negative predictive values, respectively, were 1.00 and 0.87 for pneumococci, 1.00 and 0.94 for beta-haemolytic streptococci group A, 0.60 and 1.00 for beta-haemolytic streptococci group B, and 0.91 and 0.88 for enterococci. We conclude that rapid identification of gram-positive cocci is feasible and may improve the information given to clinicians at the first notification of positive blood cultures.

Bacteremia↗
PubMed2002

Modified pulsed-field gel electrophoresis protocol for typing of enterococci.

Controlling the spread of vancomycin-resistant enterococci (VRE) is an important task in hospital epidemiology. Pulsed-field gel electrophoresis (PFGE) has become the golden standard for molecular epidemiological characterisation of enterococcal isolates. For separation of DNA fragments by PFGE, different electrophoresis conditions have been recommended, but none of these protocols allows a satisfactory separation of both small and large DNA fragments of enterococci simultaneously. In this study we have speeded up the preparation of chromosomal DNA and defined new electrophoresis conditions that enhance separation of small and large DNA fragments for subtyping of enterococci with a 24 h PFGE.

Bacterial Typing Techniques↗
PubMed2002

Characterization of yellow-pigmented and motile enterococci isolated from intestines of the garden snail Helix aspersa.

AIMS: Enterococci associated with garden snails (Helix aspersa) were studied in order to obtain reliable species identification and characterization. METHODS AND RESULTS: Twelve yellow-pigmented and motile enterococci, isolated from the intestines of garden snails, were phenotypically close to Enterococcus casseliflavus, but they showed certain unusual biochemical characteristics. tRNA intergenic length polymorphism analysis (tDNA-PCR) divided all strains studied into two groups, in full agreement with biochemical test results. 16S rDNA sequencing, DNA base composition analysis and DNA-DNA hybridization results showed unambiguously that the enterococci studied belonged to the species Ent. casseliflavus. The representative strains of described ecovars were deposited in the Czech Collection of Microorganisms (CCM) as Ent. casseliflavus CCM 4868, 4869, 4870 and 4871. CONCLUSIONS: Enterococcus casseliflavus associated with garden snails can be subdivided into groups. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterococcus casseliflavus differs from other enterococcal species in that it is typically associated with plants, soil, water and invertebrate animals. The different groups that can be found in these widely occurring bacteria are possibly source-specific ecovars, as exemplified by the Ent. casseliflavus inhabiting the intestines of snails.

Animals↗
PubMed1999

Antimicrobial susceptibility of enterococci recovered from commercial swine carcasses: effect of feed additives.

Enterococcus faecium is an important nosocomial pathogen often displaying multiple antibiotic resistance. The increase in clinical isolates can be attributed in part to hospital practices in antibiotic usage, but there is concern that antibiotic-resistant strains might also originate in animals fed rations containing antibiotic growth promoters. Ingestion of meat from carcasses contaminated with faecal enterococci might then result in human colonization or resistance gene transfer to human enterococci. Because there are few comparisons of bacteria isolated from matched animals that have, or have not, been fed a diet containing antibiotic, two such groups of pig carcasses were sampled at a commercial abattoir. Forty isolates from each group of pigs were tested for their resistance to avilamycin and tylosin. Although a modest number of pigs was examined, and the number of strains of E. faecium tested was small, there was no evidence that the feeding of a growth promoter caused selection of enterococci resistant to tylosin or avilamycin.

Abattoirs↗
PubMedDate not supplied

Enterococci: new aspects of an old organism.

Enterococci are a long-known cause of bacterial endocarditis and a more recently recognized cause of nosocomial infection and superinfection. While much is known about the many antibiotic resistances of enterococci, less is known about the organism itself and how it causes disease. This article presents a brief overview of enterococci and its possible virulence factors and summarizes the authors' efforts to understand the features of this organism that may contribute to its disease potential.

Animals↗
PubMed1999

Efficacy of hand disinfectants against vancomycin-resistant enterococci in vitro.

Vancomycin-resistant enterococci (VRE) may be spread within a hospital via the contaminated hands of the healthcare worker. Effective hand disinfectants are necessary to break chains of transmission. We determined the bactericidal activity of 1-propanol, chlorhexidine digluconate (0.5 and 4%). Sterillium (45% 2-propanol, 30% 1-propanol and 0.2% mecetronium etilsulphate), Skinsept F (70% 2-propanol, 0.5% chlorhexidine digluconate and 0.45% hydrogen peroxide) and Hibisol (70% 2-propanol and 0.5% chlorhexidine gluconate) against 11 clonally distinct enterococcal isolates in a quantitative suspension test. Four isolates were vancomycin susceptible, four were vanA and the remainder vanB positive. Eight isolates were identified as Enterococcus faecium, two as Enterococcus faecalis and one as Enterococcus gallinarum. The investigator was blinded to the species and the genotype. Four parallel experiments were carried out for each isolate, each preparation, each dilution and each reaction time. 1-Propanol (60%), Sterillium, Skinsept F and Hibisol were all highly bactericidal after 15 and 30 s against VRE and vancomycin-susceptible enterococci (VSE) with reduction factors (RF) > 6.4, even in dilution of 50% (v/v). No significant difference was observed between vanA isolates, vanB isolates and VSE. Chlorhexidine digluconate (0.5% and 4%) was found to be less bactericidal after 30, 60 and 300 sec (RF < or = 2.5). The vanB genotype isolates were found to be significantly more susceptible to chlorhexidine (0.5%) than the vanA isolates (60 sec; one-way ANOVA model; P = 0.05). After 300 sec the vanB genotype isolates were found to be significantly more susceptible to chlorhexidine (0.5%) than the other two genotype isolates (P = 0.016). The vanA isolates were found to be significantly more susceptible to chlorhexidine (4%) than the vanB isolates (300 s; P = 0.024). E. faecium was found to be less susceptible to chlorhexidine than E. faecalis at all concentrations and reaction times, but significant differences between RF were only observed at 60 sec for both chlorhexidine concentrations (P < 0.05; t-test for independent samples). Propanol is much more effective against enterococci than chlorhexidine and combination of the two may be useful in providing an immediate and long lasting effect.

Analysis of Variance↗
PubMed2001

Identification and antibiotic resistance of faecal enterococci isolated from water samples.

We have isolated 47 strains of presumptive faecal streptococci from different water samples. Identification was made by the method of Facklam et al. (1989). Antibiotic resistance was studied on Mueller-Hinton Agar. Twelve antibiotics were tested. High-level aminoglycoside resistance (HLAR) and resistance to glycopeptides were studied. Biochemical identification of presumptive faecal streptococci isolates gave the following results: 19 Enterococcus faecalis, 12 E. faecium, 8 E. hirae, 4 E. durans and 4 E. mundtii. E. mundtii is not included among faecal enterococci. None of the strains were resistant to glycopeptides (vancomycin and teicoplanin). Three strains of Enterococci showed HLAR. Two of them were isolated from coastal bathing waters and the other from wastewater. This suggests that water could contribute to spread of HLAR enterococci and it should be a matter of concern for public health authorities.

Aminoglycosides↗
PubMed2006

Shortcut detection of the vanB gene cluster in enterococci by a duplex real-time PCR assay.

AIM: To develop a robust, simple and rapid method for detection of vanB in enterococci. METHODS: A real-time duplex PCR assay for the simultaneous detection of Enterococcus faecium and vanB resistance genotype in enterococci was developed in conjunction with a simple method for DNA extraction. The assay was tested on 130 fresh plate cultures of clinical isolates of enterococci and other Gram-positive bacteria. RESULTS: Forty-eight isolates of vanB E. faecium from 32 different patients and three isolates of vanB E. faecalis were detected within 1 hour. All isolates of E. faecium were identified correctly. CONCLUSION: This simple method for the detection of resistance mediated by vanB is a potentially useful method that is suitable for use in the diagnostic microbiology laboratory.

Anti-Bacterial Agents↗
PubMed1999

A comparison of polymerase chain reaction and phenotyping for rapid speciation of enterococci and detection of vancomycin resistance.

This study aimed to ascertain the ability of the microbiology laboratory to detect and identify catalase-negative Gram-positive cocci with particular reference to vancomycin-resistant enterococci (VRE). Twenty-seven reference strains and 42 prospectively collected catalase-negative Gram-positive cocci were screened by agar dilution breakpoint susceptibility and linked biochemical methods in routine use. Ability to speciate organisms was then compared using: (i) a multiplex polymerase chain reaction, designed to detect gene sequences specific to Enterococcus faecalis and E. faecium, and vancomycin resistance (van) genes; (ii) a commercial "API 20 strep" (iii) an algorithm using individual tests from a commercial API 20 strep strip; and (iv) the same algorithm utilising traditional phenotyping methods. All vancomycin resistant catalase-negative Gram-positive cocci were detected by an agar dilution screening plate containing 4 micrograms/ml of vancomycin. Polymerase chain reaction (PCR) detected all enterococci with van genes, speciated all vancomycin-sensitive E. faecalis and E. faecium isolates and excluded non-enterococcal vancomycin-resistant catalase-negative Gram-positive cocci. Algorithm-based methods speciated 41 of the 42 study isolates (98%). The API 20 strep correctly identified only 25 (60%) of these organisms, 38 of which were vancomycin-sensitive E. faecalis. VRE are detected by current screening methods for vancomycin-resistant catalase-negative Gram-positive cocci in this laboratory. API 20 strep, currently used to speciate catalase-negative Gram-positive cocci, is less reliable and should be replaced. Algorithm-based phenotyping by either method tested is more reliable for speciation than API 20 strep in its recommended form. Compared to the other methods tested, PCR is a rapid, accurate and inexpensive method of detecting and speciating vancomycin-resistant enterococci and it provides important extra information impacting on clinical therapy and infection control.

Algorithms↗
PubMed2001

Fecal carriage of vancomycin- and ampicillin-resistant Enterococci observed in Swedish adult patients with diarrhea but not among healthy subjects.

During a 1-y prospective study between 1 October 1996 and 30 September 1997, fecal samples from 786 adult patients with diarrhea and 203 healthy control subjects were screened for vancomycin-resistant Enterococci (VRE) and ampicillin-resistant Enterococci (ARE). The carriage rates of VRE and ARE were 0.4% and 6%, respectively among patients and 0% among controls. The 3 VRE isolates were all VanA and were obtained from patients who had been abroad (Thailand, Spain, France) within the previous 3 months. Thirteen of the 45 patients with ARE (29%) had been abroad within 2 weeks of the onset of diarrhea. These findings suggest a potential risk of introduction of antibiotic-resistant Enterococci in Swedish hospitals by patients receiving treatment for diarrhea after traveling abroad.

Adolescent↗