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At least 109 records · Page 6Linked to original sources
PubMed2000

[Prevalence of Enterococcus faecalis and Enterococcus faecium with high resistance to aminoglycosides in the cities of Resistencia and Corrientes, Republic of Argentina].

BACKGROUND: The objective of this study was characterize the prevalence of high-level aminoglycosides resistance (HLRA) in Enterococcus faecalis and E. faecium, determine the relationship between high-level gentamicin resistance (HLGR) and other aminoglycosides, and their distribution according clinical samples (blood, urine and others). MATERIALS AND METHOD: A total of 177 strain (157 E. faecalis and 20 E. faecium) isolated from 1996 to 1998 were studied. They were identified by using classic methods. Their susceptibility to gentamicin, streptomycin, and kanamycin was tested by the disk diffusion technique using high-level disks in agar Müller Hinton. RESULTS: E. faecalis showed HLRG of 28.7%, streptomycin 28.7% and kanamycin 37.6%, E. faecium showed 50%, 40%, and 60% respectively. The strains with HLRA have a tendency to high-level resistances to streptomycin and kanamycin (p < 0.0005). Statistical analysis demonstrated significative differences among strains with HLRA isolated from blood, urine and other clinical samples (p < 0.0005 to gentamicin and streptomycin and 0.004 < p < 0.007 to kanamycin). CONCLUSIONS: The prevalence of HLRA enterococci found in the area os this study, justify its detection, particularity in cases of serious infections.

Aminoglycosides↗
PubMed2005

[Factors of virulence and mechanisms of resistance to aminoglycosides in clinical isolates of Enterococcus faecalis and Enterococcus faecium with high-level gentamicin resistance].

Enterococcus faecalis and E. faecium are grampositive commensal bacteria that may become pathogenic under the selection pressure. In view of natural resistance and effective mechanisms of genetic transfer, the treatment of enterococcal diseases is rather complicated. Aminoglycosides are clinically relevant antimicrobials that are frequently prescribed in practice since having good pharmacokinetics and showing synergism with beta-lactam and glycopeptides. One of the major mechanisms involved in aminoglycoside resistance is inactivation of the antibiotic agent by aminoglycoside-modifying enzymes (AGMEs) differing in the capacity for inactivation of specific types of aminoglycosides. The factors of virulence are also involved in enterococcal pathogenicity but their role in the pathogenesis of infectious diseases remains unclear. Production of beta-hemolysin (Hly), gelatinase (Gel), and aggregation substance (AS), and synthesis of enterococcal surface protein (Esp) are among the most frequently studied potential virulence factors.

Drug Resistance, Bacterial↗
PubMed2002

Characterization of anti-Listeria monocytogenes bacteriocins from Enterococcus faecalis, Enterococcus faecium, and Lactococcus lactis strains isolated from Raïb, a Moroccan traditional fermented milk.

Seventy-four samples of raïb, a Moroccan traditional fermented milk, were screened for their anti-Listeria monocytogenes activity. Nine lactic acid bacteria with antilisterial activity were isolated and identified as Lactococcus lactis [4], Enterococcus faecium [4], and E. faecalis [1]. Antibacterial spectra, determined against 45 target strains, led to the selection of four antibacterial-producing strains, which were further characterized. Their anti-microbial agents, inactivated by one or more proteases, were designed as bacteriocins. Lactococcin R9/2 and R10/1 showed the broadest range of inhibitory action. Anti-bacterial spectra and physico-chemical properties suggest that these bacteriocins were similar to nisin. Enterocin R69 had a specificity of action against Listeria spp., whereas Enterocin R18 had a broad spectrum of activity. Lc. lactis R9/2 and E. faecalis R18 were able to coagulate sterilised UHT milk at 30 degrees C in 24 h and induced a 2 log reduction in L. monocytogenes ATCC 15313 population.

Animals↗
PubMed2001

Rapid identification of Enterococcus durans and Enterococcus hirae by PCR with primers targeted to the ddl genes.

Species-specific PCR assays with primers targeted to D-alanine:D-alanine ligase (ddl) encoding genes were developed for the identification of Enterococcus durans and E. hirae. The specificity of the primers was validated in a multiplex PCR on well characterised E. durans (n=30) and E. hirae (n=16) strains, all of which were identified correctly. This PCR procedure offers a reliable and rapid alternative to conventional phenotypic methods for speciation of these enterococci of growing clinical importance.

Bacterial Typing Techniques↗
PubMed2003

Effectiveness of selected materials against Enterococcus faecalis: part 3. The antibacterial effect of calcium hydroxide and chlorhexidine on Enterococcus faecalis.

It has been found that Enterococcus faecalis is most commonly isolated in failed endodontic treatment. Irrigation with chlorhexidine gluconate has been suggested based on its antimicrobial effect and substantivity. Calcium hydroxide also is an effective antimicrobial agent because of its high alkalinity. The purpose of this study was to test the individual and combined effect of calcium hydroxide and chlorhexidine against E. faecalis. The agar-diffusion test was performed on Mueller-Hinton plates. Paper disks were impregnated with: (a) CaOH powder with sterile water; (b) Pulpdent; (c) 0.12% Peridex; (d) CaOH powder with Peridex; and (e) Pulpdent with Peridex. Ampicillin served as a control. The plates were incubated at 37 degrees C for 72 h. Peridex showed significantly larger zones of inhibition compared with CaOH. No statistically significant difference was found between Peridex and the combination of CaOH and Peridex.

Analysis of Variance↗
PubMed1992

The autolytic ('suicidase') system of Enterococcus hirae: from lysine depletion autolysis to biochemical and molecular studies of the two muramidases of Enterococcus hirae ATCC 9790.

Autolysis of Enterococcus hirae ATCC 9790 is the result of the action of endogenous enzymes that hydrolyze bonds in the protective and shape-maintaining cell wall peptidoglycan. It is thought that these potentially suicidal enzymes play a positive role(s) in wall growth and division and are expressed as autolysins when cell wall assembly and/or repair are inhibited. E. hirae possesses two potentially autolytic enzymes, both of which are muramidases. Although they hydrolyze the same bond as hen egg-white lysozyme, both are high-molecular-mass, complex enzymes. Muramidase-1 is synthesized as a zymogen, requiring protease activation. It is a glucoenzyme that is also multiply nucleotidylated with an unusual nucleotide, 5-mercaptouridine monophosphate. Muramidase-2 is almost certainly a product of a separate gene. The deduced amino acid sequence of a cloned gene for extracellular muramidase-2 showed several unusual features. It appears to be a two-, or perhaps three-domain protein with a putative glycosidase-active site near the N-terminal end and six 45-amino-acid-long repeats at the C-terminal end which are presumed to be involved with high-affinity binding to the insoluble peptidoglycan substrate. Muramidase-2 binds penicillin with low affinity. The presence of several amino acid groupings characteristic of serine-active site beta-lactam-interactive proteins is consistent with the possible presence of a penicillin-binding, third domain. Indirect evidence consistent with a role(s) for these enzymes in cell wall growth and division has been obtained. However, proof of such role(s) awaits modern genetic, molecular, and biochemical analyses.

Amino Acid Sequence↗
PubMed1998

Screening systems for detecting inhibitors of cell wall transglycosylation in Enterococcus. Cell wall transglycosylation inhibitors in Enterococcus.

We devised two screening systems to detect cell wall transglycosylation inhibitors. One screen utilizes a mutant of Enterococcus faecalis strain A256 that is dependent on vancomycin or moenomycin for growth. In the absence of transglycosylation inhibitors the strain fails to grow, while in the presence of inhibitors, cells are rescued. A second screening organism E. faecalis strain MDD212 utilizes a translational fusion of the lacZ gene to the vanH promoter in a derivative of E. faecalis that contains a vancomycin resistance determinant. Induction of beta-galactosidase occurs when cells are exposed to inhibitors of transglycosylation. Our natural products drug source of fungal fermentations was tested with these screens. Several cultures that produced the same family of compounds, called the thielavins, were detected. Thielavin B inhibited the formation of peptidoglycan in an in vitro assay, suggesting that these screening systems can detect compounds that interfere with cell wall transglycosylation.

Base Sequence↗
PubMed1991

Comparison of Enterococcus raffinosus with Enterococcus avium on the basis of penicillin susceptibility, penicillin-binding protein analysis, and high-level aminoglycoside resistance.

We reidentified our laboratories' collections of 57 enterococcal isolates previously classified as Enterococcus avium by the API Rapid Strep identification system (Analytab Products, Plainview, N.Y.) with the identification criteria recommended by Facklam and Collins (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27: 731-734, 1989). Thirty isolates were identified as true E. avium, 25 isolates were identified as E. raffinosus, and 2 isolates were identified as E. pseudoavium. E. raffinosus could be differentiated from E. avium on the basis of penicillin susceptibility, as follows: MIC for 50% of E. raffinosus isolates tested (MIC50), 32 micrograms/ml; MIC90, 64 micrograms/ml (range, 4 to 64 micrograms/ml); E. avium MIC50, 1 microgram/ml; MIC90, 2 micrograms/ml (range, 0.5 to 2 micrograms/ml). No strains produced detectable beta-lactamase. Penicillin-binding protein (PBP) analysis of all E. raffinosus isolates demonstrated the unique pattern reported previously (M. D. Collins, R. R. Facklam, J. A. E. Farrow, and R. Williamson, FEMS Microbiol. Lett. 57:283-288, 1989); however, a number of newly identified PBPs were noted. Of 25 isolates, 13 had an additional PBP of 77 kDa (designated PBP 6*), while all isolates possessed a 52-kDa PBP (PBP 7) and a 46-kDa PBP (PBP 8). The presence or absence of PBP 6* did not correlate with penicillin susceptibility; however, PBP 7 demonstrated many features suggestive of low penicillin-binding affinity and may represent a possible mechanism for the relative resistance of this species to penicillin, although this hypothesis remains speculative since attempts to develop a penicillin-hypersusceptible E. raffinosus mutant were unsuccessful. E. raffinosus isolates were significantly more likely to exhibit high-level resistance to kanamycin than E. avium strains were (P < 0.001; chi-square); however, no strains demonstrated high-level resistance to gentamicin. No trend toward increasing penicillin resistance was noted among this collection of E. avium and E. raffinosus isolates collected over the past 35 and 14 years, respectively. Relative resistance to penicillin may be a helpful differentiating feature between E. avium and E. raffinosus when assessment of raffinose metabolism is not possible or is indeterminant.

Aminoglycosides↗
PubMed2004

The tyrosine decarboxylation test does not differentiate Enterococcus faecalis from Enterococcus faecium.

According to the current edition of the Bergey's Manual of Systematic Bacteriology [11] the tyrosine decarboxylation test allows the differentiation of enterococci. Tyrosine is decarboxylated to the biogenic amine tyramine by E. faecalis and not by E. faecium strains. In the present study we sequenced the16S rDNA of two tyramine-producing strains, BIFI-56 and BIFI-58, presumptively classified as E. faecalis. Their 16S rDNA were identical to the same fragment from the E. faecium type strain. Several E. faecium strains were then checked for their ability to decarboxylate tyrosine and also a putative tyrosine decarboxylase-coding gene was PCR amplified from these strains. All the strains confirmed as E. faecium produced tyramine and possessed a DNA fragment coding for a putative tyrosine decarboxylase. The concordance of the two methods allows us to conclude that the tyrosine decarboxylase test cannot be used in the differentiation of E. faecalis from E. faecium since at least some E. faecium strains are tyramine producers.

Bacterial Typing Techniques↗