Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “enterococci”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2002

Effects of flavophospholipol on resistance in fecal Escherichia coli and enterococci of fattening pigs.

A "plasmid-curing effect" of multiresistant Escherichia coli by flavophospholipol, an antibiotic used as an antimicrobial growth promoter (AMGP) in animal feeds, has been reported to occur in vitro and in vivo under experimental conditions. In this study, the effect of flavophospholipol under field conditions was studied. The prevalence and degree (proportion of resistant strains to the total numbers present per gram of feces) of resistance of indicator bacteria, E. coli and enterococci, was determined in fecal samples from three groups of pigs that were fed a commercial finisher feed without any AMGP. Group A was the negative control group without any AMGP, group B received the same feed with 9 mg of flavophospholipol/kg of feed (study group), and group C received the same feed with 15 mg of avoparcin/kg (positive control). Fecal samples from each pig were collected at the start and at the end of the study and assessed for the prevalence and degree of resistance against antibiotics commonly used either for therapy in pig medicine or as an AMGP. Before the start of the study, all pigs were colonized with multiresistant E. coli by mixing three resistant pig isolates through their feed after disturbance of the colonization resistance of the intestinal flora by a 3-day course of lincomycin and spectinomycin. At the end of the study, the overall prevalence and degree of resistance of E. coli in the fecal flora had increased significantly in groups A and C but remained at the same level as at the start of the study in group B. The prevalence of vancomycin resistance was 44 and 41% in groups A and B, respectively, but only very low numbers of vancomycin-resistant enterococci (VRE) per gram of feces were found. In the avoparcin-fed group, the prevalence was 72%, and in 57% of the samples, more than 50% of all enterococci present were vancomycin resistant. The prevalence of resistant Enterococcus faecalis increased only in the flavophospholipol-exposed group, from 23% before the start of the study to 43% at the end of the study. It was concluded that flavophospholipol effectively suppressed the augmentation and dissemination of multiresistant E. coli in the intestinal flora of fattening pigs. Avoparcin use strongly selected for VRE carriage and excretion. Therefore, as neither flavophospholipol nor any related molecule is used therapeutically, no cross-resistance with therapeutic antibiotics exists and no transmissible resistance has been shown; the major decrease in resistance in intestinal E. coli of flavophospholipol-fed animals seemed to outweigh the small increase in the risk of transfer of flavophospholipol-resistant E. faecalis from animals to humans via the food chain.

Animal Feed↗
PubMed1975

Effect of pH and human serum on the susceptibility of group D streptococci (Enterococci) to ampicillin in vitro.

The in vitro susceptibility of group D streptococci (enterococci) to ampicillin was studied comparing the results obtained in Mueller-Hinton broth (MHB) with those obtained in normal human serum (NHS). The rate of enterococcal killing was consistently faster in NHS than in MHB at equivalent ampicillin concentrations. Whereas an increasing media pH appeared to decrease the susceptibility of enterococci to ampicillin by determinations of the minimum bactericidal concentration (MBC) of ampicillin, an opposite increase in susceptibility was observed when the rate of bactericidal activity was studied. This difference may be explainable by the instability of ampicillin at higher pH values. In both MHB and NHS a paradoxical decrease in the rate and extent of enterococcal killing occurred as the ampicillin concentration was increased above the minimally effective concentration. These results demonstrate the inadequacies of the MBC test system and the need for standardizing test media used for determining the susceptibility of enterococci to ampicillin.

Ampicillin↗
PubMed1975

Studies of cephalothin: aminoglycoside synergism against enterococci.

Combinations of cephalothin and aminoglycoside antibiotics are not currently used in the therapy of serious enterococcal infections, because clinical trials of these combinations have been unsuccessful. Studies of 28 enterococci isolated from patients with enterococcal bacteremia suggested three possible mechanisms for this in vivo antibiotic failure: (i) a relatively high level of resistance to cephalothin among all enterococci and especially those characterized as Streptococcus faecium, (ii) a significant incidence of high-level resistance to the aminoglycosides among certain strains of enterococci, and (iii) a failure of synergism to occur when cephalothin concentrations fall below the minimal inhibitory concentration of the enterococcus, as occurs during the in vivo metabolism and excretion of this antibiotic when given in standard doses for endocarditis.

Aminoglycosides↗
PubMed2006

Ecology of antibiotic resistance genes: characterization of enterococci from houseflies collected in food settings.

In this project, enterococci from the digestive tracts of 260 houseflies (Musca domestica L.) collected from five restaurants were characterized. Houseflies frequently (97% of the flies were positive) carried enterococci (mean, 3.1 x 10(3) CFU/fly). Using multiplex PCR, 205 of 355 randomly selected enterococcal isolates were identified and characterized. The majority of these isolates were Enterococcus faecalis (88.2%); in addition, 6.8% were E. faecium, and 4.9% were E. casseliflavus. E. faecalis isolates were phenotypically resistant to tetracycline (66.3%), erythromycin (23.8%), streptomycin (11.6%), ciprofloxacin (9.9%), and kanamycin (8.3%). Tetracycline resistance in E. faecalis was encoded by tet(M) (65.8%), tet(O) (1.7%), and tet(W) (0.8%). The majority (78.3%) of the erythromycin-resistant E. faecalis isolates carried erm(B). The conjugative transposon Tn916 and members of the Tn916/Tn1545 family were detected in 30.2% and 34.6% of the identified isolates, respectively. E. faecalis carried virulence genes, including a gelatinase gene (gelE; 70.7%), an aggregation substance gene (asa1; 33.2%), an enterococcus surface protein gene (esp; 8.8%), and a cytolysin gene (cylA; 8.8%). Phenotypic assays showed that 91.4% of the isolates with the gelE gene were gelatinolytic and that 46.7% of the isolates with the asa1 gene aggregated. All isolates with the cylA gene were hemolytic on human blood. This study showed that houseflies in food-handling and -serving facilities carry antibiotic-resistant and potentially virulent enterococci that have the capacity for horizontal transfer of antibiotic resistance genes to other bacteria.

Animals↗
PubMed1979

Repair detection procedure for enumeration of fecal coliforms and enterococci from seafoods and marine environments.

The repair detection procedure of Speck et al. (Appl. Microbiol. 29:549-550, 1975) was adapted for the enumeration of coliforms, fecal coliforms, and enterococci in seafood and environmental samples. Samples were pour plated with Trypticase soy agar, followed by a 1- to 2-h incubation to effect repair; the plates were then overlaid with the selective medium and incubated. Violet red bile agar and an incubation temperature of 45 degrees C were used as the selective conditions for fecal coliforms, and KF streptococcal agar was used for the enumeration of enterococci. The method was more efficient than the standard most-probable-number method for fecal coliform enumeration and also allowed enumeration of the injured cells, which might have remained undetected when selective medium in the most-probable-number method was used. The repair detection method effectively recovered the injured portion of the population of enterococci capable of growing on KF streptococcal agar. The repair enumeration method was not suitable for coliforms in marine samples because associative marine bacteria mimicked coliforms in violet red bile agar plates incubated at 35 degrees C. The marine bacteria did not grow at 45 degrees C and therefore did not interfere with fecal coliform enumeration.

Escherichia coli↗
PubMed1994

Sunlight inactivation of enterococci and fecal coliforms in sewage effluent diluted in seawater.

Inactivation (loss of culturability) by sunlight of enterococci and fecal coliforms within sewage effluent diluted in seawater was investigated in field experiments. In most experiments, 500-ml flasks of pure silica were used to confine activated sludge effluent diluted to 2% (vol/vol) in seawater. Inactivation of bacteria in these flasks (diameter, 0.1 m) was faster than in either open chambers (depth, 0.25 m) or patches of dyed effluent (depth of order, 1 m), probably because of the longer light paths in the latter two types of experiment, which caused greater attenuation of sunlight. Inactivation of 90% of enterococci generally required 2.3 times the insolation required for 90% inactivation of fecal coliforms, because of both the presence of larger initial shoulders on survival curves and a lower final inactivation rate. Two parameters are required to model inactivation of enterococci, a shoulder constant as well as a rate coefficient. The depth dependence of inactivation rate for both fecal indicators matched the attenuation profile of UV-A radiation at about 360 nm. Inactivation by UV-B radiation (290 to 320 nm), which penetrates much less into seawater, is of minor importance compared with the UV-A and visible radiation in sunlight, contrary to expectations in consideration of published action spectra for bacterial inactivation.

Journal Article↗
PubMed1968

Significance of coliforms and enterococci in fish products.

Coliforms, more recently fecal coliforms, and enterococci are often used to assess the hygienic quality of foods. Although these bacteria serve rather successfully as an index of fecal pollution of water supplies, their usefulness in measuring fecal pollution in foods is less than satisfactory. The ratio and correlation of coliforms and enterococci in fish-fillet and lobster-meat samples led us to conclude that these organisms originated from improperly sanitized working surfaces, where they survive and multiply, and not from fecal pollution. Therefore, the presence of coliforms and enterococci in fish fillets and lobster meat reflects the quality of fish-plant sanitation and not the direct fecal pollution of these products.

Enterobacteriaceae↗
PubMed1972

Enterococci in insects.

Enterococci were obtained from 213 of 403 insects cultured during a 14-month period, in numbers from 10(3) to 3 x 10(7)/g of insect. Insects were taken only from nonurban, wild, and cultivated fields and woods. In species of insects carrying them, enterococci were not always present in every individual cultured, and often more than one species of enterococcus occurred within a species. Enterococci were obtained from certain insects taken in the field during the dormant season, suggesting their role as overwintering agents. They were generally present in species feeding on nectar, succulent plant parts, and on and ir forest litter, but not from insects feeding on less succulent leaves and stems. Streptococcus faecalis was recovered from 32%, Streptococcus faecium from 22.4%, and Streptococcus faecium var. casseliflavus from 43.5% of members of the 37 taxa of insects. S. faecalis and S. faecium var. casseliflavus exhibit a high percent of conformity to the properties published for them. The heterogeneity in properties of S. faecium is similar to that found for the species taken from plants. Many fail to grow in broth at 45 C or in broth containing 6.5% NaCl; 50% of the cultures ferment both melezitose and melibiose, and a few ferment neither sugar. The remainder ferment melibiose only. Failure to reduce methylene blue in milk by S. faecalis and S. faecium is correlated with the inability to ferment lactose. More than 93% of the cultures of S. faecalis digest casein in milk from the top downward, following the production of a soft, flowing curd. Because this property is not characteristic of S. faecalis taken from humans, the reaction in litmus milk is suggested as a means of differentiation between cultures of remote and innocent origin in nature and recent, human pollution.

Animal Feed↗
PubMed1961

Detection and enumeration of fecal indicator organisms in frozen sea foods. II. Enterococci.

Consistently high recoveries of enterococci as compared to the low numbers of coliforms obtained from the same samples of frozen sea foods are indirect evidence that enterococci are better indicators of contamination in such foods. The use of azide dextrose broth, modified by the incorporation of bromthymol blue, and of ethyl violet azide broth as presumptive and confirmation tests, respectively, were found to be highly specific for the detection and enumeration of enterococci in these samples. Tetrazolium agar medium, when used as a third step after the confirmation test, provides a reliable differentiation of Streplococcus faecalis types from other group D streptococci. A simple procedure is described for further identification of S. faecalis varieties and other enterococcal species. Incidence of biotypes within certain species is noted and relationships of these subgroups to the organisms described by other workers is discussed. The striking resistance of all group D streptococci to dihydrostreptomycin and polymyxin B seems to offer promise for evolving a new selective medium for these organisms.

Culture Media↗
PubMed1961

Studies on Media for Enumerating Enterococci in Frozen Vegetables.

A study was made of the relative sensitivity and specificity of presumptive and confirmatory media for the most probable number enumeration of enterococci in frozen vegetables. Azide dextrose broth yielded the highest numbers of confirmable enterococci and its sensitivity was shown to be comparable to nonselective media. The use of ethyl violet azide broth as a confirmatory medium resulted in a significant number of false positive tests. Growth in broth containing 6.5% sodium chloride incubated at 45 C for 2 days was found to be a more specific confirmatory test for enterococci.

Journal Article↗
PubMed1961

Occurrence of Enterococci: Bud, Blossom, and Soil Studies.

The occurrence of enterococci (group D streptococci) on buds and flowers of plants and in soils has been studied. They were recovered from 27.5% of the flowers of seven species of plants, and from 6.8% of the buds of the same plants. They were recovered from 34% of the flowers of nonagricultural plants, from 32.2% of the flowers of ten species of agricultural dicotyledonous plants, and from 10.4% of the flowers of five species of grasses and cereals. The enterococci were invariably present or invariably absent from all samples taken from very few species. They occurred in small numbers on enclosed tassels and silks of corn of 22 of 60 samples, and in greater numbers on 90% or more of these after their floral parts had emerged. Interposition of a mechanical barrier reduced the incidence of recovery from flowers. The occurrence in soil, generally at a low level of population, may be correlated with occurrence on the plant growing on the soil or with nearby enterococcal-bearing plants. It is concluded that enterococci may be regarded as temporary residents on plants, capable of limited reproduction, and that they are disseminated among plants by the action of insects and wind, and spread to the ground by these agencies, gravity, and rain.

Journal Article↗
PubMed1994

Virulence of enterococci.

Enterococci are commensal organisms well suited to survival in intestinal and vaginal tracts and the oral cavity. However, as for most bacteria described as causing human disease, enterococci also possess properties that can be ascribed roles in pathogenesis. The natural ability of enterococci to readily acquire, accumulate, and share extrachromosomal elements encoding virulence traits or antibiotic resistance genes lends advantages to their survival under unusual environmental stresses and in part explains their increasing importance as nosocomial pathogens. This review discusses the current understanding of enterococcal virulence relating to (i) adherence to host tissues, (ii) invasion and abscess formation, (iii) factors potentially relevant to modulation of host inflammatory responses, and (iv) potentially toxic secreted products. Aggregation substance, surface carbohydrates, or fibronectin-binding moieties may facilitate adherence to host tissues. Enterococcus faecalis appears to have the capacity to translocate across intact intestinal mucosa in models of antibiotic-induced superinfection. Extracellular toxins such as cytolysin can induce tissue damage as shown in an endophthalmitis model, increase mortality in combination with aggregation substance in an endocarditis model, and cause systemic toxicity in a murine peritonitis model. Finally, lipoteichoic acid, superoxide production, or pheromones and corresponding peptide inhibitors each may modulate local inflammatory reactions.

Animals↗
PubMed2000

Prophylactic and therapeutic efficacy of antibodies to a capsular polysaccharide shared among vancomycin-sensitive and -resistant enterococci.

Enterococci are important nosocomial pathogens that are increasingly difficult to treat due to intrinsic and acquired resistance to antibiotics, including vancomycin. A recently described capsular polysaccharide (CP) isolated from Enterococcus faecalis 12030 was used to evaluate the potential efficacy of active or passive immunotherapy regimens as adjunctive treatments. Evaluation of protective efficacy was carried out in immunocompetent mice challenged intravenously (i.v.) with live enterococci. In nonimmune mice, i.v. inoculations resulted in high levels of bacteria in kidneys, spleens, and livers 5 days after challenge. Mice immunized with four 10-microg doses of CP antigen/mouse were protected against challenge with the homologous E. faecalis strain. High-titer opsonic immunoglobulin G was also induced by immunizing rabbits with the purified CP, and passive transfer of this antiserum to mice produced significantly lower bacterial counts in organs than did normal rabbit serum or sterile saline. Antibodies to the polysaccharide isolated from E. faecalis 12030 were protective against Enterococcus faecalis OG1RF and against two serologically related, vancomycin-resistant Enterococcus faecium clinical isolates. Antibodies to this CP antigen were also effective as a therapeutic reagent in mice when passive therapy was initiated 48 h after live bacterial challenge. These data indicate that CP antigens from enterococci are potential targets of protective antibodies and that these antibodies may be useful for prophylaxis and treatment of enterococcal infections.

Animals↗
PubMed1973

Differentiation of some enterococci by gas chromatography.

Relative fatty acid compositions of 37 enterococci were examined by gas chromatography. Streptococcus faecalis, S. faecium, and S. faecium var. durans yielded similar fatty acid patterns. Strains of S. faecium var. casseliflavus, and a motile yellow-pigmented streptococcus, contained very low levels of C(19:0) cyclopropane fatty acid and four unidentified components, compared to the other strains of enterococci examined. There were no significant differences in the fatty acid patterns of enterococci grouped according to plant, animal, or human source.

Chromatography, Gas↗
PubMed1964

ISOLATION AND IDENTIFICATION OF ENTEROCOCCI FROM THE INTESTINAL TRACT OF THE RAT.

Rogers, C. G. (Department of National Health and Welfare, Ottawa, Ontario, Canada), and W. B. Sarles. Isolation and identification of enterococci from the intestinal tract of the rat. J. Bacteriol. 88:965-973. 1964.-Surface inoculation was employed in a comparison of three selective media, M-enterococcus (M) agar, thallium acetate-glucose (TITG) agar, and KF-streptococcus (KF) agar, for enumeration and isolation of enterococci from contents of the digestive tract of the rat. Similar yields of enterococcus colonies were obtained with M, TITG, and KF agar. When cecal contents were examined, species identification of 120 isolates, 40 from each medium, revealed only minor differences in selective activity. Streptococcus faecalis and its variety zymogenes represented 55 to 63% of the isolates from each medium; the remaining strains resembled S. durans or S. faecium. More than 99% of the isolates failed to survive the heat-tellurite tolerance test. Periodic analyses of intestinal contents from young rats indicated that enterococci became established in the gut from 10 to 14 days after birth. The species isolated most frequently on M agar was S. faecalis var. zymogenes. When rats were fed a purified diet with casein as the source of nitrogen, S. faecalis var. zymogenes predominated among isolates from contents of the small intestine plated on M agar. This species was largely replaced by others resembling S. durans or S. faecium when mixtures of l-amino acids provided the dietary nitrogen. Nineteen enterococcus isolates, representing all that met the Sherman criteria, required arginine, glutamic acid, histidine, isoleucine, leucine, methionine, tryptophan, and valine; of these, two strains required in addition threonine, glycine, and lysine; four required threonine and glycine; two, threonine and lysine; and one, threonine.

Agar↗
PubMed1987

Sodium chloride-esculin hydrolysis test for rapid identification of enterococci.

The ability of enterococci to cause severe disease in humans and their relative resistance to chemotherapeutic agents make it desirable to rapidly differentiate these organisms from other streptococci. We developed and evaluated a test that within 2 h distinguishes enterococci from other alpha-, beta-, or nonhemolytic streptococci in a buffered solution containing 0.2% esculin and 5% sodium chloride. All 239 strains of enterococci tested gave a positive reaction within 2 h, whereas 95 of 96 isolates of other streptococci remained negative at 4 h.

Esculin↗
PubMed1992

Antimicrobial susceptibility patterns of common and unusual species of enterococci causing infections in the United States. Enterococcal Study Group.

We collected 705 isolates of enterococci (1 per patient) from cultures of a variety of anatomic sites from patients at eight tertiary-care hospitals in six geographic regions of the United States. A total of 632 (90%) Enterococcus faecalis, 58 (8%) E. faecium, 5 E. gallinarum, 4 E. avium, 3 E. casseliflavus, 1 E. raffinosus, and 1 E. hirae isolate and 1 biochemical variant of E. faecalis were identified; 606 (86%) of these isolates were associated with clinical infections. The most common sites of isolation were the urinary tract (402 [57%]), nonsurgical wounds (94 [13%]), the bloodstream (74 [10%]), and surgical wounds (62 [9%]). High-level resistance to gentamicin or streptomycin or both was detected in 265 (38%) of the isolates. We identified two E. faecalis isolates resistant to vancomycin (MICs, 32 and 128 micrograms/ml) and 11 beta-lactamase-producing E. faecalis isolates. E. faecium isolates were significantly more resistant than E. faecalis isolates to penicillin, ampicillin, piperacillin, imipenem, and ciprofloxacin (P less than 0.001). The MICs for the 15 non-E. faecalis, non-E. faecium enterococci indicated variable resistance to ciprofloxacin and the penicillins. Antimicrobial susceptibility patterns vary among species of enterococci, and these organisms, while commonly resistant to high-level aminoglycosides, can also acquire resistance to vancomycin or the ability to produce beta-lactamase. Because of these diverse antimicrobial resistance mechanisms, successful treatment and control of enterococcal infections with current antimicrobial agents are becoming increasingly difficult.

Adolescent↗
PubMed1994

Rapid detection of vancomycin-resistant enterococci.

Campylobacter blood agar with clindamycin incubated in 6% CO2 served as a medium to both screen for vancomycin resistance and select for presumptive enterococci. Colonies that grew on the medium were specifically identified as enterococci within 30 min by the pyroglutamyl-beta-naphthylamide and rapid bile esculin tests. The combination of a selective medium plus rapid enzyme substrate tests offered an inexpensive means to enumerate vancomycin-resistant enterococci from specimens by using readily available reagents.

Drug Resistance, Microbial↗