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PubMed1997

Comparison of agar-based media for primary isolation of glycopeptide-resistant enterococci.

OBJECTIVE: To compare four vancomycin-containing agar media for the isolation of glycopeptide-resistant enterococci (GRE) from clinical fecal specimens: kanamycin---aesculin---azide (KAA) agar; bile---aesculin---polymixin (BAP) agar; aztreonam---amphotericin blood (CBAA) agar; and neomycin blood (CBN) agar. METHODS: Fecal specimens from 125 patients were inoculated onto each medium. Media were examined for enterococci after incubation for up to 48 h. Enterococci were identified to species level, and glycopeptide phenotypes were determined by measuring minimum inhibitory concentrations of vancomycin and teicoplanin. RESULTS: GRE were isolated from 44/125 samples. Enterococcus faecalis and Enterococcus faecium isolates, expressing glycopeptide resistance of the VanA or VanB phenotypes, were recovered from 27/33 (82%) specimens on BAP medium, 26/33 (79%) on KAA medium, and 21/33 (64%) on CBN and CBAA media. Enterococcus gallinarum and Enterococcus casseliflavus isolates expressing low-level glycopeptide resistance (VanC phenotype) were recovered from 14/15 (93%) specimens on CBAA medium, 7/15 (47%) on KAA and CBN media, and 6/15 (40%) on BAP medium. CONCLUSIONS: The media tested in this study, with the exception of CBN medium, detected at least 75% of patients colonized by GRE. Further development of BAP, CBAA and KAA media is warranted to improve growth and selectivity.

Journal Article↗

PubMed2002

Quantitative determination of bile salt hydrolase activity in bacteria isolated from the small intestine of chickens.

A quantitative assay based on high-performance liquid chromatography analysis of bile salts and bacterial protein determination was established for investigating bile salt hydrolase (BSH) activity in bacteria isolated from the small intestine of chickens. Bacteria were isolated using various media and were subsequently grouped according to cell morphology, fermentation profile, and 16S ribosomal DNA sequence. Representative isolates from each bacterial group were assayed for BSH activity. The isolates differed in BSH activity with respect to the state of growth and preculturing with and without taurochenodeoxycholate. The highest levels of BSH activity were found with Enterococcus faecium and Clostridium perfringens.

Amidohydrolases↗

PubMed2002

Sequential emergence of antibiotic resistance in enterococcal bloodstream isolates over 25 years.

We determined the antibiotic susceptibilities of 1,785 enterococcal bloodstream isolates collected over 25 years. Antibiotic resistance emerged at a greater rate in Enterococcus faecium than in other enterococcal species, and E. faecium isolates became proportionally more common over time. Our findings confirm the pattern of emerging antibiotic resistance among enterococci and highlight the increasing importance of E. faecium as a cause of bloodstream infection.

Colorado↗

PubMed1991

Genetic transformation of various species of Enterococcus by electroporation.

A transformation system for Enterococcus faecalis was developed which uses untreated (i.e., non-protoplasted) cells and the electroporation technique. The optimized protocol resulted in transformation efficiencies of up to 4 x 10(6) transformants per microgram of plasmid DNA. All strains of E. faecalis tested could be transformed by this method, albeit with differing transformation efficiencies. Using the protocol optimized for E. faecalis we successfully transformed Enterococcus faecium, E. hirae, E. malodoratus and E. mundtii.

Cell Division↗

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↗

PubMed2004

Activity of daptomycin against multi-resistant Gram-positive bacteria including enterococci and Staphylococcus aureus resistant to linezolid.

The activity of daptomycin was assessed against 545 isolates of Gram-positive bacteria including enterococci, coagulase-positive and -negative staphylococci, beta-haemolytic streptococci, viridans streptococci and coryneforms. The panel of isolates was biased towards those with resistance to first-line antimicrobial agents and included linezolid-resistant enterococci and Staphylococcus aureus. MICs of daptomycin were < or =1mg/l for all the staphylococci, streptococci, and coryneforms, except for two isolates of Corynebacterium aquaticum, for which MICs were 8 mg/l. Daptomycin MICs were < or =2 and < or =4 mg/l for Enterococcus faecalis and Enterococcus faecium, respectively.

Acetamides↗

PubMed2005

Antimicrobial resistance of enterococcal blood isolates at a pediatric care hospital in India.

Enterococci are one of the leading causes of nosocomial infections. In recent years, enterococci have become increasingly resistant to a wide range of antimicrobial agents. From April to October 2001, a study was conducted to speciate and determine the antimicrobial susceptibility of 50 isolates of enterococci from bacteremic children. These isolates were tested for antimicrobial susceptibility to the commonly used antibiotics. Screening for vancomycin resistance was done by the agar screen method, and the results were confirmed by determining the minimum inhibitory concentration (MIC) using the agar dilution method. It was observed that 33 isolates were Enterococcus faecium, followed by E. faecalis (10), E. durans (4), and E. dispar (3). Seventy-two percent of strains were resistant to ampicillin, 46% to amoxicillin + clavulanic acid, 72% to ciprofloxacin, 54% to doxycyclin, and 74% to erythromycin. Sixty-six percent of isolates showed high-level gentamicin resistance and 42% showed high-level streptomycin resistance. Four strains showed raised MIC to vancomycin (8 microg/ml). It was concluded that multidrug resistant E. faecium is emerging as an important agent of bacteremia in children.

Child↗

PubMed2003

Prevalence and antimicrobial resistance of enterococcus species isolated from retail meats.

From March 2001 to June 2002, a total of 981 samples of retail raw meats (chicken, turkey, pork, and beef) were randomly obtained from 263 grocery stores in Iowa and cultured for the presence of Enterococcus spp. A total of 1,357 enterococcal isolates were recovered from the samples, with contamination rates ranging from 97% of pork samples to 100% of ground beef samples. Enterococcus faecium was the predominant species recovered (61%), followed by E. faecalis (29%), and E. hirae (5.7%). E. faecium was the predominant species recovered from ground turkey (60%), ground beef (65%), and chicken breast (79%), while E. faecalis was the predominant species recovered from pork chops (54%). The incidence of resistance to many production and therapeutic antimicrobials differed among enterococci recovered from retail meat samples. Resistance to quinupristin-dalfopristin, a human analogue of the production drug virginiamycin, was observed in 54, 27, 9, and 18% of E. faecium isolates from turkey, chicken, pork, and beef samples, respectively. No resistance to linezolid or vancomycin was observed, but high-level gentamicin resistance was observed in 4% of enterococci, the majority of which were recovered from poultry retail meats. Results indicate that Enterococcus spp. commonly contaminate retail meats and that dissimilarities in antimicrobial resistance patterns among enterococci recovered from different meat types may reflect the use of approved antimicrobial agents in each food animal production class.

Animals↗

PubMed1995

vanA genes in vancomycin-resistant clinical isolates of Oerskovia turbata and Arcanobacterium (Corynebacterium) haemolyticum.

We report the cloning and sequencing of vanA genes present in the high-level vancomycin- and teicoplanin-resistant clinical isolates Oerskovia turbata 892 and Arcanobacterium (Corynebacterium) haemolyticum 872. The presence of vanA was detected by Southern blotting and PCR and confirmed by DNA sequencing. vanA-like sequences were encoded on plasmids of 15 and 20 kb respectively. The A. haemolyticum 872 DNA sequence was identical to the published vanA sequence of vancomycin-resistant Enterococcus faecium BM4147, but the O. turbata 892 sequence showed three coding changes. Induction experiments indicated that vancomycin resistance in A. haemolyticum 872 and O. turbata 892 was constitutive. SDS-PAGE analysis of membrane proteins showed the presence of a c. 39 kD protein in both clinical isolates whose expression was unaltered in the presence of vancomycin, while a similar protein in E. faecium BM4147 was inducible. Since A. haemolyticum and O. turbata are naturally susceptible to vancomycin, the high-level constitutive resistance seen in these isolates appears to be mediated by vanA. This is the first report confirming the presence of vanA in genera other than Enterococcus.

Actinomycetaceae↗

PubMed2006

Genetic relatedness and antimicrobial resistance determinants among clinical isolates of enterococci from Cuba.

This study describes the genetic relationships and antimicrobial resistance determinants found among 99 clinical isolates of enterococci from 15 different hospitals in Cuba. Pulsed-field gel electrophoresis SmaI analysis demonstrated a high degree of genetic diversity. A limited number of multiresistant Enterococcus faecalis clones, showing resistance to three or more families of antimicrobial agents, were detected simultaneously in different institutions, suggesting inter-hospital circulation of selected clones, and/or selection of particular clones following their introduction into the hospital environment. Antimicrobial resistance determinants, including erm(B), aac(6')-aph(2'), aph(3'), ant(6), vanB (E. faecalis) and vanA (Enterococcus faecium) were detected by PCR in various isolates.

Aminoglycosides↗

PubMed2006

Genotypic and phenotypic heterogeneity in Enterococcus isolates from Batzos, a raw goat milk cheese.

This study investigated the genotypic and phenotypic diversity in 34 isolates of enterococci obtained during ripening of Batzos cheese from raw goat milk and characterized phenotypically as Enterococcus durans. RAPD-PCR, plasmid profiling and PFGE were used to study the genetic variability and distinguish closely related isolates. Species recognition by means of RAPD-PCR was in agreement with the phenotypic identification for 29 strains. One strain was characterized as Lactococcus lactis subsp. lactis by RAPD-PCR and four strains were grouped with the Enterococcus faecium reference strain. All strains were vancomycin sensitive, while 10 strains showed beta-haemolytic reaction on human blood and the majority of them (88.9%) showed decarboxylase activity on tyramine. All strains exhibited antagonistic activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli and Listeria monocytogenes and the majority inhibited Enterococcus faecalis. Isolates displayed weak acidifying ability and low proteolytic activities when grown in milk for 24h. However, their caseinolytic activity after growth in milk for seven days was significant with preference for alphas-casein degradation.

Animals↗

PubMed2003

Evolution of microbial populations during traditional Feta cheese manufacture and ripening.

In three different dairies (A, B and C) located in Peloponess region (Southern Greece), traditional Feta cheese trials took place February to March using mixtures of sheep's and goat's milk. Only small variations in the evolution of microbial groups were observed during the whole ripening period. The main groups, such as thermophilic cocci, mesophilic lactococci, thermophilic lactobacilli, nonstarter lactic acid bacteria (NSLAB), presumptive Leuconostoc, enterococci and micrococci, reached their highest levels during the first 16 days, and then declined approximately 1-2 log units until the end of ripening. The remaining groups investigated, comprising yeasts, coliforms and Escherichia coli, were highest at day 4. The yeasts remained constant, while coliforms and E. coli decreased sharply and were not detectable after 120 days of ripening. A number of 146 isolates (dairy A) taken from all stages of the manufacturing and ripening process were purified and studied. Lactobacillus plantarum (58/146) and isolates of related species Lactobacillus pentosus and Lactobacillus paraplantarum (16/146) were the most common microorganisms found during cheese ripening. Streptococcus thermophilus (23/146) and Lactobacillus delbrueckii subsp. bulgaricus (20/146) were detected in high levels up to 20 days, and then gradually reduced. Enterococcus faecium (29/146) was found in all manufacturing and ripening stages.

Animals↗

PubMed2000

Isolation and characterization of glycopeptide-resistant enterococci from hospitalized patients over a 30-month period.

In February 1996, a Hospital Infection Control Practices Advisory Committee-style screening program was commenced to isolate and subsequently characterize glycopeptide-resistant enterococci (GRE) from patients at a hospital trust in Glasgow, Scotland. Over the next 30 months, GRE were isolated from 154 patients. GRE were isolated from patients in traditionally high-risk areas such as the renal unit and intensive care unit and also in areas considered to be lower risk, including medical wards and associated long-stay geriatric hospitals. The majority (90%) of isolates were Enterococcus faecium vanB. The remaining isolates consisted of seven E. faecalis (vanA), three E. gallinarum (vanC), and a further six E. faecium (five vanA, one both vanA and vanB) isolates. Analysis of SmaI-digested DNA by pulsed-field gel electrophoresis revealed that 34 of 40 (85%) VanB E. faecium isolates were identical or closely related, while 11 of 13 (85%) VanA GRE were distinct. High-level aminoglycoside resistance was seen in less than 8% of isolates. VanB E. faecium isolates were almost uniformly resistant to ampicillin and tetracycline. In this study, GRE have been isolated over a prolonged period from a broad range of patients. Glycopeptide resistance within the study hospital trust appeared to be mainly due to the clonal dissemination of a single strain of E. faecium VanB.

Aminoglycosides↗

PubMed1996

In vitro activity of the trinem sanfetrinem (GV104326) against gram-positive organisms.

The in vitro activity of the trinem sanfetrinem (formerly GV104326) (GV) was compared with that of vancomycin, ampicillin, and/or nafcillin against 287 gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and multiresistant enterococci, by the agar and microbroth dilution methods. GV demonstrated 2 to 16 times more activity than ampicillin and nafcillin against the majority of these organisms. The MIC range of GV was 16 to 64 micrograms/ml for 19 Enterococcus faecium strains that were highly resistant to ampicillin (ampicillin MIC range, 64 to 512 micrograms/ml) and vancomycin resistant and 0.25 to 32 micrograms/ml for resistant Rhodococcus spp. Similar activities (+/-1 dilution) were observed by either the agar or the broth microdilution method. GV demonstrated bactericidal activity against a beta-lactamase-producing Enterococcus faecalis strain and against two methicillin-susceptible Staphylococcus aureus strains in 10(5)-CFU/ml inocula. Synergy between GV and gentamicin was observed against an E. faecalis strain that lacked high-level gentamicin resistance. The activity of GV suggests this compound warrants further study.

Ampicillin↗

PubMed2005

[Pathogenic characters of infected bacteria after liver transplantation].

OBJECTIVE: To analyze the main pathogens of infection after the liver transplantation and their antibiotic resistant patterns. METHODS: The main pathogens of infection after the liver transplantation were retrospectively analyzed. Using 3-dimensional tests, ESBLs (extended-spectrum beta-lactamase), and AmpC were detected among the Gram negative bacilli. beta-Lactamase and Van gene in Enterococcus were determined by the standard agar dilution susceptibility tests and Nitrocefin respectively. RESULTS: The main infected strains were Enterococcus faecalis (15.0%), Enterobacter cloacae (13.9%), fungus (13.3%), and Escherichia coli (10.7%) after the liver transplantation. Among them, 32.4% of Enterobacter cloacae and 36.8% of Escherichia coli produced ESBLs; 33.8% of Enterobacter cloacae and 10.5% of Escherichia coli. produced AmpC beta-lactamases. The detectable rate of VanA gene in Enterococcusfaecalis and Enterococcus faecium was 7.5% and 11.1%; VanB was 3.8% and 7.4%; VanC was 1.3% and 0, respectively. CONCLUSION: The infection mainly occurs in the intestinal tract after the liver transplantation. The production of ESBLs and AmpC beta-lactamases is the main mechanism of antibiotic resistance. The increased detectable rate of vancomycin-resistant Enterococcus should be paid attention to.

Adolescent↗

PubMed1990

Properties of cell wall-associated DD-carboxypeptidase of Enterococcus hirae (Streptococcus faecium) ATCC 9790 extracted with alkali.

DD-Carboxypeptidase (DD-CPase) activity of Enterococcus hirae (Streptococcus faecium) ATCC 9790 was extracted from intact bacteria and from the insoluble residue (crude cell wall fraction) of mechanically disrupted bacteria by a brief treatment at pH 10.0 (10 mM glycine-NaOH) at 0 degrees C or by extraction with any of several detergents. Extractions with high salt concentrations failed to remove DD-CPase activity from the crude wall fraction. In contrast to N-acetylmuramoylhydrolase (both muramidase 2 and muramidase 1) activities, DD-CPase activity failed to bind to insoluble cell walls or peptidoglycan matrices. Thus, whereas muramidase 1 and muramidase 2 activities can be considered to be cell wall proteins, the bulk of the data are consistent with the interpretation that the DD-CPase of this species is a membrane protein that is sometimes found in the cell wall fraction, presumably because of hydrophobic interactions with other proteins and cell wall polymers. The binding of [14C]penicillin to penicillin-binding protein 6 (43 kilodaltons) was proportional to DD-CPase activity. Kinetic parameters were also consistent with the presence of only one DD-CPase (penicillin-binding protein 6) in E. hirae.

Cell Membrane↗

PubMed2007

Bacteriocin activity of enterococci from rabbits.

The antimicrobial spectrum of bacteriocin-producing enterococcal isolates from rabbits faeces, the biochemical characterization of bacteriocins, and their molecular mass and the presence of structural genes for bacteriocin production were investigated. Among enterococci selected from rabbit faeces, six strains of Enterococcus faecium (EF2019, EF1819, EF2119, EF1839, EF529, EF24/10) showed inhibitory activity against the indicators E. avium EA5, Listeria innocua LMG13568 and Listeria monocytogenes CCM4699 and against other enterococci and staphylococci tested. The molecular mass of bacteriocin-like substances ranged from 3 to 10 kDa. The presence of the structural genes for enterocins (ent) A, P and L50B was detected in all enterococci tested. However, no strain possessed the gene for ent B. E. faecium EF2019 showed the broadest inhibitory activity. A proteinaceous substance produced by the EF2019 strain was partially purified. This is a thermostable substance that is stable at pH 4.0, 7.0 and 9.0. Its production starts in the early logarithmic growth phase and culminates in the late logarithmic growth phase of the EF2019 strain. Partially purified bacteriocin (PPB) EF2019 added to the growing strain L. innocua LMG13568 (after 4 h) inhibited its growth as early as 1 h after addition with a decrease of 1.5 log cycles (5 h of cultivation). This effect was extended up to 24 h. The bacteriocinogenic E. faecium EF2019 strain and/or bacteriocin EF2019 could be utilized against contaminant bacteria, e.g. in rabbitries. More detailed studies under in vitro and in vivo conditions are in progress.

Animals↗

PubMed1992

Emergence and nosocomial transmission of ampicillin-resistant enterococci.

Between 1986 and 1988, the incidence of ampicillin-resistant enterococci increased sevenfold at a university-affiliated hospital. Forty-three patients acquired nosocomial infections with ampicillin-resistant enterococci, most of which were also resistant to mezlocillin, piperacillin, and imipenem. An analysis of plasmid and chromosomal DNAs of isolates revealed that the increase was due to an epidemic of 19 nosocomial infections that yielded closely related strains of Enterococcus faecium and to a significant increase in the incidence of nonepidemic, largely unrelated strains of ampicillin-resistant enterococci. The nonepidemic strains were identified as E. faecium, E. raffinosus, E. durans, and E. gallinarum. A logistic regression analysis revealed that patients with nonepidemic resistant strains were 16 times more likely than controls to have received preceding therapy with imipenem. In our institution, the increase in the incidence of ampicillin-resistant enterococci appears to be due to the selection of various strains of resistant enterococci by the use of imipenem and to the nosocomial transmission of E. faecium and E. raffinosus.

Adult↗