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PubMed2003

Sudden increase of vancomycin-resistant enterococcal infections in a Korean tertiary care hospital: possible consequences of increased use of oral vancomycin.

A sudden increase in vancomycin-resistant enterococci (VRE) infections was noted in 1998 in a tertiary care hospital in Korea. All of the VRE isolated in 1998 in the hospital were VanA type and most were multidrug-resistant Enterococcus faecium. The increase in VRE was probably due to the increased use of oral vancomycin to treat Clostridium difficile infections and clonal as well as horizontal spread. More restricted oral vancomycin use and stricter infection control measures are required to achieve a better control of the spread of VRE.

Administration, Oral↗

PubMedDate not supplied

In vitro evaluation of high-level, gentamicin-resistant enterococci isolated from bacteremic patients.

We attempted to characterize the susceptibility of high-level, gentamicin-resistant (HLGR, minimum inhibitory concentration [MIC] > 2000 micrograms/ml) enterococcal blood isolates and evaluated a small subset of these isolates for bactericidal synergy. Thirteen Enterococcus faecalis and three Enterococcus faecium isolates that were HLGR were prospectively collected. Standard broth macrodilution techniques were used to determine the MICs and minimum bactericidal concentrations to a variety of antibiotics. Two isolates were evaluated for synergy by time-kill curve methods using combinations of penicillin and streptomycin, teicoplanin and rifampin, and vancomycin and ciprofloxacin. Teicoplanin was the most active antibiotic tested, with all isolates exhibiting susceptibility to this agent. Four E. faecalis isolates and one E. faecium isolate expressed only low-level resistance to streptomycin (LLSR, MICs 32-64 micrograms/ml). Penicillin and streptomycin produced bactericidal synergy in the LLSR isolate. The other antibiotic combinations did not result in bactericidal synergy in the two isolates tested. For HLGR enterococci that are only LLSR, the combination of penicillin-streptomycin appears to provide adequate bactericidal activity. Teicoplanin may potentially be useful for streptomycin-resistant HLGR isolates.

Anti-Bacterial Agents↗

PubMed1996

Escherichia coli transcytosis in a Caco-2 cell model: implications in neonatal necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is a serious gastrointestinal disorder of preterm infants. Other than an association with prematurity and gastrointestinal feeding, no single factor or mechanism has been consistently linked to this disease. We have previously demonstrated that Escherichia coli isolates obtained from the stool of infants with NEC caused NEC-like injury in a weanling rabbit ileal loop model; this injury, in turn, could be blocked by coinfection with selected Gram(+) bacteria (Enterococcus faecium) isolated from asymptomatic controls. Using Caco-2 cells in a trans-well system, we now demonstrate that the same E. coli isolates can cross epithelial cell monolayers in the absence of ultrastructural change or damage. These results with E. coli contrast with those seen with Salmonella typhimurium, which passed through the monolayer at a higher rate and were associated with striking ultrastructural damage. Transcytosis of E. coli was reduced 3-5-fold in the presence of E. faecium previously shown to block NEC-like injury in the loop model. There was a mild increase in the rate of E. coli transcytosis when studies were conducted with younger, undifferentiated cells; these immature cells had no brush border, had decreased production of brush border-specific enzymes, but retained well defined tight junctions, as demonstrated by transepithelial electrical resistance and electron microscopy. A further reduction/ complete blockage of E. coli transcytosis was observed when E. faecium was used as the coinfectant in studies with these undifferentiated cells. We hypothesize that the ability of E. coli to cross epithelial cell layer is a critical initial step in the cascade of events which lead ultimately to NEC; blockage or reduction in E. coli transcytosis in the presence of certain Gram(+) organisms may play a significant role in prevention of NEC.

Analysis of Variance↗

PubMedDate not supplied

Improved DNA probe detection of Listeria monocytogenes in enrichment culture after physical-chemical fractionation.

Bacterial detection in foods by nucleic acid probes is limited by microflora competition during selective enrichment. Probe target concentration by extraction and fractionation of enrichments may diminish this limitation. The 1-h AccuProbe chemiluminescent culture identification test for Listeria monocytogenes was used as a model. Its high detection threshold provides a stringent challenge for evaluating enrichment work-up protocols. Detection of L. monocytogenes, at 1-4 colony-forming units/g food, was not consistently possible in 48 h enrichment cultures using AccuProbe. Concentration by cell sedimentation was occasionally helpful but the volume of co-sedimented food limited concentration to about 10-fold. To improve concentration, enrichment sediments were sonicated or enzymatically lysed to release the probe's target, r-RNA. The RNA was separated from non-RNA material by extraction with phenol and precipitation with ethanol. Enrichments (250 mL) were concentrated 2500-fold, and the limitation was food RNA volume. A strongly competitive Enterococcus faecium food isolate was used to demonstrate the effect of artificial competition on the kit's ability to detect L. monocytogenes in enrichments. High competitor concentrations repressed the level of the target below the detection threshold, but concentration of r-RNA enabled detection of L. monocytogenes. The effectiveness of this enrichment sample work-up was demonstrated with naturally contaminated hummus.

Bacteriological Techniques↗

PubMed2006

Genotypic diversity and epidemiology of high-level gentamicin resistant Enterococcus in a Chinese hospital.

OBJECTIVE: To investigate the antibiotics resistance of Enterococcus, the aminoglycoside-modifying enzymes (AME) and homology of high-level gentamicin resistant (HLGR) Enterococcus in clinical specimens for the implementation of effective infection control measures. METHODS: The resistance of 13 antimicrobial agents was determined by Kirby-Bauer (K-B) or agar dilution method. And the HLGR and high-level streptomycin resistant (HLSR) isolates were screened by agar screen. Production of beta-lactamases was tested by the nitrocefin disc method. The aminoglycoside-modifying enzyme genes were detected by polymerase chain reaction (PCR). Pulsed-field gel electrophoresis (PFGE) was used to analyze the homology of HLGR isolates from in-patients. RESULTS: No isolates resistant to linezolid, vancomycin and teicoplanin were found. Ampicillin-resistant isolates did not produce beta-lactamases and 68 HLGR isolates were screened at the rate of 64.2%. The positive rate of aac(6')-Ie-aph(2'')-Ia was 86.8% and 3 isolates had the new AME gene designated aph(2'')-Ie mostly similar to aph(2'')-Id. Among 51 HLGR isolates from in-patients, PFGE grouped 17 Enterococcus faecalis (E. faecalis) isolates into 4 clusters (A-D), and 33 Enterococcus faecium (E. faecium) isolates into 8 clusters (A-H), of which the A cluster is the main. CONCLUSIONS: HLGR has become the important antibiotic resistance pathogen causing nocosomial infection. And the aac(6')-Ie-aph(2'')-Ia gene was the main aminoglycoside-modifying enzyme gene leading to HLGR.

Acetyltransferases↗

PubMed2004

Synthesis of mosaic peptidoglycan cross-bridges by hybrid peptidoglycan assembly pathways in gram-positive bacteria.

The peptidoglycan cross-bridges of Staphylococcus aureus, Enterococcus faecalis, and Enterococcus faecium consist of the sequences Gly(5), l-Ala(2), and d-Asx, respectively. Expression of the fmhB, femA, and femB genes of S. aureus in E. faecalis led to the production of peptidoglycan precursors substituted by mosaic side chains that were efficiently used by the penicillin-binding proteins for cross-bridge formation. The Fem transferases were specific for incorporation of glycyl residues at defined positions of the side chains in the absence of any additional S. aureus factors such as tRNAs used for amino acid activation. The PBPs of E. faecalis displayed a broad substrate specificity because mosaic side chains containing from 1 to 5 residues and Gly instead of l-Ala at the N-terminal position were used for peptidoglycan cross-linking. Low affinity PBP2a of S. aureus conferred beta-lactam resistance in E. faecalis and E. faecium, thereby indicating that there was no barrier to heterospecific expression of resistance caused by variations in the structure of peptidoglycan precursors. Thus, conservation of the structure of the peptidoglycan cross-bridges in members of the same species reflects the high specificity of the enzymes for side chain synthesis, although this is not essential for the activity of the PBPs.

Amino Acid Sequence↗

PubMed1998

[Vancomycin resistant enterococcus in France. High prevalence in a young ambulatory care patient population].

OBJECTIVE: Assess the prevalence of asymptomatic carriage of vancomycin-resistant Enterococci in a population of healthy young French subjects. METHODS: Stool samples obtained from 100 persons living in south-eastern France (20 sampling sites) were directly seeded on enriched selective media containing 6 mg/l vancomycin. Bacterial species and their resistant gene were identified with classical methods and multiplex genomic amplification. RESULTS: The incidence of asymptomatic carriage was 17% with a homogeneous geographic distribution of the resistant strains. Nine Enterococcus faecium van A strains and 8 E. gallinarum van C1 strains were isolated. CONCLUSION: These findings demonstrate carriage of vancomycin-resistant Enterococci in a population of young ambulatory subjects in France. The incidence observed was much higher than in an earlier study conducted in France. These results might be explained by a much more sensitive detection technique. Care should be taken to avoid dissemination in hospital settings.

Adult↗

PubMed2005

Potential human health benefits of antibiotics used in food animals: a case study of virginiamycin.

Risk management of food-animal antibiotics has reached a crucial juncture for public health officials worldwide. While withdrawals of animal antibiotics previously used to control animal bacterial illnesses are being encouraged in many countries, the human health impacts of such withdrawals are only starting to be understood. Increases in animal and human bacterial illness rates and antibiotic resistance levels in humans in Europe despite bans on animal antibiotics there have raised questions about how animal antibiotic use affects human health. This paper presents a quantitative human health risk and benefits assessment for virginiamycin (VM), a streptogramin antibiotic recommended for withdrawal from use in food animals in several countries. It applies a new quantitative Rapid Risk Rating Technique (RRRT) that estimates and multiplies data-driven exposure, dose-response, and consequence factors, as suggested by WHO (2003) to estimate human health impacts from withdrawing virginiamycin. Increased human health risks from more pathogens reaching consumers if VM use is terminated (6660 estimated excess campylobacteriosis cases per year in the base case) are predicted to far outweigh benefits from reduced streptogramin-resistant vancomycin-resistant Enterococcus faecium (VREF) infections in human patients (0.27 estimated excess cases per year in the base case). While lack of information about impacts of VM withdrawal on average human illnesses-per-serving of food animal meat precludes a deterministic conclusion, it appears very probable that such a withdrawal would cause many times more human illnesses than it would prevent. This qualitative conclusion appears to be robust to several scientific and modeling uncertainties.

Animal Husbandry↗

PubMed2002

Synthesis of novel nocathiacin-class antibiotics. Condensation of glycolaldehyde with primary amides and tandem reductive amination of amadori-rearranged 2-oxoethyl intermediates.

Nocathiacin I (1) and nocathiacin IV (2) are novel indole-containing thiazolyl peptide antibiotics, which exhibit potent activity against key Gram-positive bacterial pathogens, including multi drug-resistant Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecium. New nocathiacins 7-12 were prepared from 2 by a condensation with glycolaldehyde followed by tandem reductive amination of the 2-oxoethyl intermediate 4. The latter was formed via Amadori rearrangement from initial 2-hydroxyethylideneamide 3. This transformation readily tolerates the complex architecture of nocathiacins and allows selective incorporation of water solubilizing groups to the primary amide in 2 without protecting group manipulation.

Acetaldehyde↗

PubMed2003

Lactobacillus ruminis is a predominant lactic acid producing bacterium in the caecum and rectum of the pig.

AIMS: To identify the predominant lactic acid producing bacteria in the small intestine, caecum and the rectum of the healthy pig. METHODS AND RESULTS: Samples obtained from the large intestine of healthy pigs post-mortem were cultured using a modified agar-MRS medium in roll tubes. Thirteen isolates were selected on the basis of their morphological characteristics and Gram stain reaction for gene sequencing. These isolates were characterized by DNA sequence analysis of 16S rDNA. Eight isolates were identified as Lactobacillus ruminis, two as Enterococcus faecium, one as Mitsuokella multiacidus and two as Escherichia coli. CONCLUSION: This is the first report of Lact. ruminis as the dominant lactic acid bacteria in the large intestine of the pig. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that Lact. ruminis is a dominant bacterium in the large intestine of the healthy pig. Future work should focus on the role of this bacterium in relation to the physiological function of the intestine and the health of the animal.

Animals↗

PubMedDate not supplied

[AF, a new bacterial preparation based on lactobacilli and its biological properties].

A highly efficient bacterial composition "AF" which includes representatives of two genera of microorganisms Enterococcus faecium and Lactobacillus acidophilus has been created as a result of analysis of biological properties of a number of strains of lactic-acid bacteria. Their biological properties--antagonistic activity in respect to pathogenic and conditionally pathogenic microorganisms, ability to adhesion and function in the intestine, sensitivity to antibiotics, etc., have been studied in the laboratory conditions. Prospects of the use of the given composition in production of milk products of functional effects have been shown.

Animals↗

PubMed1995

Plasmid-mediated vanB glycopeptide resistance in enterococci.

Enterococcus faecium, which was highly resistant to vancomycin (MIC 256 mg/liter), but susceptible to teicoplanin (MIC 2 mg/liter), caused two distinct episodes of infection on a renal unit in the United Kingdom. Pulsed field gel electrophoresis (PFGE) indicated that a single strain caused the first episode, while the second episode, which occurred 1 year later, involved multiple strains, all of which were distinct from the original strain. Vancomycin resistance in all but one of these strains was mediated by transferable plasmids that carried the vanB glycopeptide resistance gene. Transfer either of resistance plasmids or the vanB resistance determinant itself to different strains occurred during the second episode. Plasmid-mediated vanB resistance has not been widely documented. A retrospective study of a reference collection revealed two other vanB-encoding plasmids from an E. faecalis and an E. faecium referred from two further UK centers. Although restriction analysis indicated no similarity between the plasmids from the three different centers, all contained a 2.1-kb EcoRV fragment that hybridized with a probe for the vanB gene. This suggests that there has been dissemination of a conserved glycopeptide resistance determinant, of which vanB is a part.

Anti-Bacterial Agents↗

PubMed2004

In-vitro activity of nitrofurantoin in enterococcus urinary tract infection.

OBJECTIVE: To compare in-vitro antimicrobial susceptibility of nitrofurantoin against commonly used antimicrobials for the treatment of urinary tract infection caused by enterococci. METHODS: A total of 144 enterococci (Enterococcus faecalis, n=130, Enterococcus faecium, n=14) isolated and confirmed by biochemical tests at the department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, for a period of three years were included in the study. The antimicrobial susceptibility tests of isolated organisms were performed by standard disc diffusion method as recommended by NCCLS. In addition to nitrofurantoin (NIT), doxycycline (DOX), co-trimoxazole (COT), ampicillin (AMP), imipenem (IPM) and vancomycin (VAN) were used for antimicrobial susceptibility testing. RESULTS: One hundred and twenty seven (88%) isolates of Enterococci were susceptible to NIT while 72% (n = 103) to AMP, 13% to COT, 11% to DOX, 91% to IPM and 99% to VAN. Among the strains resistant to AMP, COT, DOX, IPM and VAN, 50-88% were susceptible to NIT. CONCLUSION: Nitrofurantoin is an effective antimicrobial in vitro and can be used for treatment of Enterococcus urinary tract infections.

Anti-Bacterial Agents↗

PubMedDate not supplied

Survival of streptococcus in optisol-GS medium.

BACKGROUND: Donor cornea contamination as a cause of endophthalmitis is one of the most serious complications of penetrating keratoplasty. Optisol-GS corneal storage medium with the combination of gentamicin and streptomycin was designed to provide wider antibiotic coverage, most notably against streptococcal species. However, many enterococci are resistant to streptomycin and genta micin. METHODS/RESULTS: We report a case in which Enterococcus faecium was isolated from cultures of the donor limbus prior to corneal excision and again from preoperative cultures of the donor corneal rim despite 5 days of preservation in Optisol-GS. The isolate was found to be resistant to both gentamicin and streptomycin. CONCLUSIONS: This case illustrates the need to raise awareness that streptococcus can remain a viable contaminant of donor corneas despite storage in Optisol-GS medium.

Chondroitin Sulfates↗

PubMed1994

Influence of pH on the production of enterocin 1146 during batch fermentation.

The production of enterocin 1146, a bacteriocin from Enterococcus faecium DPC1146, was studied during batch fermentation at pH 5, 5.5, 6 and 6.5. The bacteriocin was produced throughout the growth of the micro-organism, showing primary metabolite kinetics. Bacteriocin production stopped at the end of growth and was followed by a decrease in activity due primarily to adsorption on the cells of the producer. The optimal pH for enterocin 1146 production was 5.5, because of higher bacteriocin yield per unit of biomass and slower adsorption/degradation, while optimal pH for growth was between 6.0 and 6.5.

Adsorption↗

PubMed1993

Epithelial cells secrete the chemokine interleukin-8 in response to bacterial entry.

Bacterial invasion of mucosal surfaces results in a rapid influx of polymorphonuclear leukocytes. The chemotactic stimulus responsible for this response is not known. Since epithelial cells are among the first cells entered by many enteric pathogens, we investigated the ability of epithelial cells to provide an early signal for the mucosal inflammatory response through the release of chemotactic cytokines. As shown herein, the chemokine interleukin-8 (IL-8), a potent chemoattractant and activator of polymorphonuclear leukocytes, was secreted by intestinal and cervical epithelial cells in response to bacterial entry. Moreover, a variety of different bacteria, including those that remain inside phagosomal vacuoles, e.g., Salmonella spp., and those that enter the cytoplasm, e.g., Listeria monocytogenes, stimulated this response. Increased IL-8 mRNA levels could be detected within 90 min after infection. Neither bacterial lipopolysaccharide nor noninvasive bacteria, including Escherichia coli and Enterococcus faecium, induced an IL-8 response. Moreover, tumor necrosis factor alpha, which is known to be expressed by some epithelial cells, was not detected in the culture supernatants after bacterial entry, and addition of anti-tumor necrosis factor alpha antibodies had no effect on the IL-8 response following bacterial entry. These data suggest the novel concept that epithelial cells serve as an early signaling system to host immune and inflammatory cells in the underlying mucosa following bacterial entry.

Bacterial Physiological Phenomena↗

PubMed2001

[Intracranial epidural abscess in a newborn secondary to skin catheter].

Intracranial epidural abscesses are uncommon lesions, being more frequents in older children and adults. They commonly arise as a result of direct extension of a preexisting infection and rarely present with focal deficit. We present a case of a 11-days old preterm infant who developed an intracranial epidural abscess as a result of an infected scalp vein catheter. The diagnosis was made on the basis of the cranial ultrasound and CT scan images. An identified strain of Enterococcus faecium was cultured from all the samples. The patient underwent a right frontal craniotomy with drainage of the abscess and a 2-week total course of intravenous antibiotics was administrated. CT scan imaging 3 week after the procedure demonstrated no evidence of residual lesion. When present, a scalp vein catheter, in absence of others predisponing factors, must be considered as an etiologic agent for an intracranial epidural abscess in this age-group.

Catheterization↗

PubMed2004

Streptomyces africanus sp. nov., a novel streptomycete with blue aerial mycelium.

An actinomycete with blue aerial mycelium and yellow substrate mycelium was isolated from a suburban soil sample collected in Cape Town, South Africa and named strain CPJVR-HT. The colour of the substrate mycelium was not sensitive to changes in pH. The organism produced spiny spores in Spirales spore chains. Chemical taxonomy indicated that it is a member of the genus Streptomyces. Strain CPJVR-HT grew at 45 degrees C and did not produce melanin or any diffusible pigments. It exhibited weak antibacterial activity against a clinical isolate of Enterococcus faecium, but no antibacterial activity against Escherichia coli ATCC 25922 or Pseudomonas aeruginosa ATCC 27853. Analysis of its 16S rRNA gene sequence, DNA-DNA hybridization studies and the results of physiological tests showed that this strain represents a novel species of Streptomyces, for which the name Corynebacterium aurimucosum [corrected] nov. is proposed. The type strain is CPJVR-HT (= NRRL B-24243T [corrected] = DSM 41829T).

Antibiosis↗