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PubMed2002

Prevalence of streptogramin resistance genes among Enterococcus isolates recovered from retail meats in the Greater Washington DC area.

The prevalence of streptogramin resistance genes in enterococci recovered from retail poultry in the Greater Washington DC area was examined. Forty-three chicken and 32 turkey retail samples were analysed. Thirty-one non-Enterococcus faecalis enterococcal strains were isolated that displayed MICs of quinupristin-dalfopristin and virginiamycin of > or = 4 mg/L. These included Enterococcus faecium (turkey n = 4, chicken n = 23), Enterococcus gallinarum (turkey n = 2, chicken n = 1) and Enterococcus hirae (chicken n = 1). The presence of streptogramin resistance genes was examined by PCR in all non-E. faecalis isolates. The vat(E) gene was detected in 10/23 chicken E. faecium and from 2/4 turkey E. faecium. No other streptogramin resistance genes were detected by PCR. In addition, erm(B) was detected in all the E. faecium and E. gallinarum found in turkeys and in 7/23 E. faecium found in chickens. The vat(E) gene was transferable by conjugation from only two of the 12 E. faecium isolates (one from chicken and one from turkey). This study suggests that there is a high prevalence of low-level streptogramin resistance among enterococci found in retail poultry and that other, yet to be identified, mechanisms operate in these isolates that confer streptogramin resistance in enterococci.

Animals↗
PubMed1996

Phenotypic and genotypic characterization of atypical Lactococcus garvieae strains isolated from water buffalos with subclinical mastitis and confirmation of L. garvieae as a senior subjective synonym of Enterococcus seriolicida.

During a survey of bacterial agents that cause subclinical mastitis in water buffalos, we isolated several strains of gram-positive cocci that appeared to be enterococci except that they grew very slowly at 45 degrees C and grew slowly in broth containing 6.5% NaCl. On the basis of the results of conventional physiologic tests, these strains were identified as Enterococcus durans. However, none of the strains reacted with the AccuProbe Enterococcus genetic probe. The whole-cell protein profiles of these organisms were compared with the profiles of Enterococcus and Lactococcus reference strains. apart from minor quantitative differences, the mastitis isolates had indistinguishable protein profiles that were similar to the profiles of the Lactococcus garvieae and Enterococcus seriolicida type strains. The results of DNA relatedness studies performed by using the hydroxyapatite method at 55 and 70 degrees C indicated that all of the mastitis isolates were related to the type strain of L. garvieae at the species level, despite the fact that they exhibited several uncommon phenotypic characteristics (growth at 45 degrees C, growth in broth containing 6.5% NaCl, and failure to produce acid from mannitol and sucrose). The high levels of DNA relatedness between strains of L. garvieae is a senior synonym of E. seriolicida, L. garvieae should be retained as the species name and strain ATCC 43921 should remain the type strain of this species.

Animals↗
PubMed2001

Enterococcus villorum sp. nov., an enteroadherent bacterium associated with diarrhoea in piglets.

The taxonomic positions of five enteroadherent bacterial pig isolates, showing phenotypic characteristics most similar to those of Enterococcus durans and Enterococcus hirae, were investigated in a polyphasic study that included 16S rDNA sequence analysis, DNA-DNA hybridizations, DNA base-ratio determinations, whole-cell protein fingerprinting, D11344-primed PCR typing and an extensive examination of phenotypic properties. The results demonstrated that the organisms represent a new species in the Enterococcus faecium species group, for which the name Enterococcus villorum sp. nov. is proposed. The type strain is LMG 12287T (= CCM 4887T).

Animals↗
PubMed2026

Antimicrobial Resistance in Nontyphoidal Salmonella and Clinically Relevant Enterococcus From Faecal Samples of Conservation-Priority Captive Ungulates in a United Arab Emirates Urban Zoo: A Cross-Sectional Baseline Study.

Antimicrobial resistance (AMR) is a One Health challenge driven by microbial exchange among humans, animals and the environment. Zoological institutions offer useful settings for environmental AMR surveillance. This single-zoo cross-sectional study examined the occurrence, antimicrobial susceptibility and genomic characteristics of nontyphoidal Salmonella enterica (NTS) and clinically relevant Enterococcus spp. in faecal samples from 101 clinically healthy captive ungulates representing seven conservation-priority species at a major urban zoo in the United Arab Emirates. NTS was detected in 4/101 samples (3.9%), including serovars Schwarzengrund (n = 2), Kentucky (n = 1) and Chester (n = 1). Among the four recovered NTS isolates, all met the study MDR definition within the tested panel, including a Salmonella Kentucky ST198 isolate carrying multiple resistance genes and quinolone-associated mutations. Enterococcus spp. were detected in 77/101 samples (76.2%), dominated by Enterococcus faecium and Enterococcus casseliflavus (each 41.5%). Among 33 E. faecium/Enterococcus faecalis isolates tested phenotypically, resistance was generally low, with erythromycin and ciprofloxacin resistance each observed in 9.1%. One clinically important E. faecium isolate showed glycopeptide resistance and genetic markers associated with reduced daptomycin susceptibility. These single-institution cross-sectional data provide an initial regional baseline for AMR-relevant enteric bacteria in conservation-managed ungulates and identify priorities for broader longitudinal and interface-based surveillance.

Animals↗
PubMed1994

Presence of the Listeria tetracycline resistance gene tet(S) in Enterococcus faecalis.

Two hundred thirty-eight tetracycline- and minocycline-resistant clinical isolates of Enterococcus and Streptococcus spp. were investigated by dot blot hybridization for the presence of nucleotide sequences related to tet(S) (first detected in Listeria monocytogenes BM4210), tet(K), tet(L), tet(M), tet(O), tet(P), and tet(Q) genes. The tet(S) determinant was found in 22 strains of Enterococcus faecalis, associated with tet(M) in 9 of these isolates and further associated with tet(L) in 3 of these strains. tet(M) was detected in all strains of Streptococcus spp. and in all but 10 isolates of Enterococcus spp.; tet(L) was found in 93 enterococci and tet(O) was found in single isolates of E. faecalis and Streptococcus milleri. No hybridization with the tet(K), tet(P), and tet(Q) probes was observed. Transfer of tet(S) by conjugation to E. faecalis or to E. faecalis and L. monocytogenes was obtained from 8 of the 10 E. faecalis strains harboring only this tet gene. Hybridization experiments with DNAs of four donors and of the corresponding transconjugants suggested that tet(S) was located in the chromosome. These results indicate that the genetic support of tet(S) in E. faecalis is different from that in L. monocytogenes, where it is carried by self-transferable plasmids, and confirm the notion of exchange of genetic information between Enterococcus and Listeria spp. in nature.

Conjugation, Genetic↗
PubMed1994

Overproduction of a low-affinity penicillin-binding protein and high-level ampicillin resistance in Enterococcus faecium.

Five ampicillin-resistant clinical isolates of Enterococcus faecium were analyzed for a correlation between overproduction of the low-affinity penicillin-binding protein (PBP 5) and the level of ampicillin resistance. Comparison was made with one susceptible clinical isolate and its ampicillin-resistant derivative obtained in the laboratory by selection with increasing concentrations of penicillin. Overproduction of the low-affinity PBP relative to the susceptible isolate was noted in moderately resistant strains (MIC, 32 micrograms/ml) but not in highly resistant strains (MIC, 128 micrograms/ml). Polyclonal antibodies specifically reacting with the low-affinity PBP of Enterococcus hirae, Enterococcus faecalis, and Enterococcus faecium (M. Ligozzi, M. Aldegheri, S. C. Predari, and R. Fontana, FEMS Microbiol. Lett. 83:335-340, 1991) were used to determine the amount of this PBP in the E. faecium isolates. In all strains, the antibody preparation reacted with a membrane protein of the same molecular mass as PBP 5. The amount of this protein was very small in the susceptible strain but large in all of the resistant strains. These results suggest that the highly resistant strains also overproduced the low-affinity PBP, which, compared with PBP 5 of moderately resistant strains, appeared to be modified in its penicillin-binding capability.

Ampicillin Resistance↗
PubMed2002

Heterologous expression of the Lactococcus lactis bacteriocin, nisin, in a dairy Enterococcus strain.

The bacteriocin nisin is produced only by some strains of Lactococcus lactis, and to date production in other lactic acid bacteria has not been achieved. Enterococcus sp. strain N12beta is a nisin-immune transconjugant obtained from a nisin-producing donor (L. lactis ATCC 11454) and a dairy recipient (Enterococcus sp. strain S12beta), but it does not produce nisin. In this study, using PCR amplification, we confirmed that the whole nisin operon is likely present in Enterococcus sp. strain N12beta. Northern hybridization of total RNA from strain N12beta with a nisA probe and the results of reverse transcriptase PCR showed the lack of nisA transcription in this strain. However, nisA transcription was partially restored in strain N12beta upon growth in the presence of exogenous nisin, and the nisA transcription signal was intensified after an increase in the external nisin level. Furthermore, bioassays showed that active nisin was produced in a dose-dependent fashion by strain N12beta following induction by exogenous nisin. These results indicated that expression of the nisin genes in Enterococcus sp. strain N12beta depended on autoinduction via signal transduction. However, the amount of external inducing signal required was significantly greater than the amount needed for autoinduction in L. lactis.

Bacteriocins↗
PubMed1994

Use of cephalexin-aztreonam-arabinose agar for selective isolation of Enterococcus faecium.

Cephalexin-aztreonam-arabinose agar (CAA), a new selective agar, was examined in comparison with nalidixic acid-colistin agar for the differentiation of Enterococcus faecium from other enterococci and the ability to isolate the organism from feces. Two hundred sixteen enterococcus isolates and a variety of gram-positive and gram-negative control strains were inoculated onto both media. All control strains of E. faecium were easily differentiated from Enterococcus faecalis and Enterococcus durans on the basis of arabinose fermentation on CAA. Differentiation of E. faecium from other enterococci or Streptococcus bovis was not possible on nalidixic acid-colistin agar. Increased isolation of E. faecium was demonstrated on CAA when both media were compared for the isolation of the organism from feces. CAA has been shown to possess excellent differential and selective features allowing the simple and effective isolation of E. faecium from heavily contaminated sites.

Agar↗
PubMed2000

Typing of Enterococcus faecium by polymerase chain reaction and pulsed field gel electrophoresis.

Polymerase chain reaction (PCR) with JB1 or REP consensus oligonucleotides and pulsed field gel electrophoresis (PFGE) were used to study genomic DNA extracted from 31 strains of enterococci. Eleven ATCC strains, representative of 11 species of Enterococcus, were initially tested by JB1-PCR, revealing that Enterococcus malodoratus and Enterococcus hirae presented identical banding patterns. Eight Enterococcus faecium isolates from Stanford University and 12 from São Paulo Hospital were studied by JB1-PCR, REP-PCR (1/2)R and PFGE. Among the isolates from Stanford University, 5 genotypes were defined by JB1-PCR, 7 by REP-PCR (1/2)R and 4 by PFGE. Among the isolates from São Paulo Hospital, 9 genotypes were identified by JB1-PCR, 6 by REP-PCR and 5 by PFGE. The three methods identified identical genotypes, but there was not complete agreement among them.

Bacterial Typing Techniques↗
PubMed1996

[Identification of Enterococcus species from clinical samples and their antimicrobial susceptibility].

The genus enterococcus has 12 species of which, E faecalis and E faecium are most important in human infections. A progressive resistance to penicillin and ampicillin has been detected in these species. The aim of this work was to identify Enterococcus species isolated in a hospital and to study their antimicrobial susceptibility. We studied 209 Enterococcus species coming from patients admitted to a public hospital. Their susceptibility to penicillin, ampicillin, imipenem, vancomycin, tetracycline, chloramphenicol, ciprofloxacin, gentamicin and streptomycin was determined with the agar dilution technique. Eighty seven percent of species were E faecalis and 7.1% were E fecium, other isolated species were E hirae, E casseliflaws, E avium, E solitarius and E faecalis variant. Thirty eight percent of these species were isolated from the urinary tract, 22% from the skin and 14% from surgical wounds. All E faecalis species were susceptible to penicillin, ampicillin, imipenem and vancomycin; 27.3% were susceptible to tetracycline, 54.7% to chloramphenicol and 80% to ciprofloxacin. Seventy three percent of E faecium species were susceptible to penicillin, 80% to ampicillin and 60% to imipenem. Sixty two percent of E faecalis and 42.4% of E faecium were resistant to streptomycin. It is concluded that the correct identification of Enterococcus species has therapeutic implications.

Anti-Bacterial Agents↗
PubMed1997

[Evaluation of a rapid method for the identification of the Enterococcus genus].

BACKGROUND: The evaluation of the reliability of a group of three tests: pyrrolidonil-arilamidase, rapid test in NaCl esculin broth and group D antistreptococci agglutination for the rapid identification of the Enterococcus genus were performed. METHODS: One hundred fifty-eight strains of streptococci: 110 strains of Enterococcus faecalis, 8 E. faecium, 3 E. avium, 16 Streptococcus intermedius, 7 S. salivarius, 4 S. bovis, 4 S. constellatus, 2 S. sanguis and 1 strain of S. equinus, S. mitis, S. uberis and S. mutans were studied. The tests used were: rapid test in NaCl- esculin broth, pyrrolidonyl-arilamidase and antigroup D streptococcus agglutination (Patho Dx Strep D/PYR; Diagnostic Product Corporation). All catalase-negative gram-positive cocci or coccibacilli which were positive in the three tests were considered to belong to the Enterococcus genus. The usefulness of Gram staining in culture in thioglycolate broth was also studied comparing it with the results obtained with solid medium. RESULTS: The results of the proposed identification scheme were evaluated calculating different parameters: sensitivity 98%, specificity 100%, positive predictive value, 100%, and negative predictive value 94%. No significant differences were observed between the results obtained with Gram staining with thioglycolate broth and those obtained with solid medium except in the case of the Streptococcus mutans strain. CONCLUSIONS: The application of a combination of tests: pyrroidonyl-arilamidase, antistreptococci group D agglutination and rapid test in NaCl-esculin broth to catalase-negative gram-positive cocci and coccobacilli allows reliable identification in a maximum of three hours of strains belonging to the Enterococcus genus.

Bacteriological Techniques↗
PubMed1998

Susceptibility patterns of Enterococcus spp. isolated in Poland during 1996.

Susceptibility of Enterococcus spp. isolated from various clinical specimens to different antimicrobial agents was evaluated. Of the 346 enterococcal isolates obtained from four regional Polish hospitals during 6 months of 1996, 261 (75.4%) were identified as Enterococcus faecalis, 75 (21.7%) as Enterococcus faecium and ten (2.9%) as other enterococcal species. High-level resistance to gentamicin was expressed by 33.4% of E. faecalis and 86.5% of E. faecium strains and corresponding streptomycin resistance by 43.9 and 82.4%, respectively. Over 80% of E. faecium isolates were resistant to ampicillin. None of the isolates was resistant to teicoplanin, however 7.9% of E. fecalis and 1.4% of E. faecium strains were moderately susceptible to vancomycin.

Anti-Bacterial Agents↗
PubMedDate not supplied

Enterococcus lactic acid bacteria strain SF68 and lactulose in hepatic encephalopathy: a controlled study.

Forty cirrhotic patients with non-advanced hepatic encephalopathy were randomly allocated into groups which were given orally either two capsules three times daily of a preparation of Enterococcus lactic acid bacteria strain SF68 or 30 ml lactulose four times daily. The patients were evaluated over a 10-day course of treatment and for 10 days post-treatment. The Enterococcus SF68 preparation proved to be as effective as lactulose in lowering blood ammonia, and in improving mental state and psychometric performance. Moreover, the effects of Enterococcus SF68, contrary to that of lactulose, persisted longer after treatment withdrawal. Some patients reported diarrhoea and abdominal pain with lactulose. Lactulose is a standard therapy in the treatment of patients with hepatic encephalopathy. In this study, however, the use of the Enterococcus SF68 preparation was shown to offer advantages over lactulose in these patients.

Adult↗
PubMedDate not supplied

Double-blind report on the efficacy of lactic acid-producing Enterococcus SF68 in the prevention of antibiotic-associated diarrhoea and in the treatment of acute diarrhoea.

A multicentre double-blind, placebo-controlled clinical trial, involving 123 patients at 10 centres, was carried out to assess the efficacy of a preparation of lactic acid-producing Enterococcus SF 68 in the prevention of antibiotic-associated diarrhoea and in the treatment of acute diarrhoea. In the prevention study, 45 patients being treated with antibiotics were given, concurrently, one capsule twice daily of either Enterococcus SF68 or placebo. Acute diarrhoea was present in 78 patients who were given the same treatment but three times daily. All treatments were continued for 7 days. Enterococcus SF 68 was shown to be effective in reducing the incidence of antibiotic-associated diarrhoea in comparison with placebo (8.7% compared with 27.2%, respectively). Patients with acute enteritis showed a significantly faster resolution of bowel abnormalities during treatment with Enterococcus SF68 compared with placebo.

Adult↗
PubMed1996

Structure of the low-affinity penicillin-binding protein 5 PBP5fm in wild-type and highly penicillin-resistant strains of Enterococcus faecium.

Among its penicillin-binding proteins (PBPs), Enterococcus faecium possesses a low-affinity PBP5, PBP5fm, which is the main target involved in beta-lactam resistance. A 7.7-kb EcoRI chromosomal fragment of E. faecium D63r containing the pbp5fm gene was cloned and sequenced. Two open reading frames (ORFs) were found. A 2,037-bp ORF encoded the deduced 73.8-kDa PBP5fm, the amino acid sequences of which were, respectively, 99.8, 78.5, and 62% homologous to those of the low-affinity plasmid-encoded PBP3r of Enterococcus hirae S185r and the chromosome-encoded PBP5 of E. hirae R40 and Enterococcus faecalis 56R. A second 597-bp ORF, designated psrfm, was found 2.3 kb upstream of pbp5fm. It appeared to be 285 bp shorter than and 74% homologous with the regulatory gene psr of E. hirae ATCC 9790. Different clinical isolates of E. faecium, for which a wide range of benzylpenicillin MICs were observed, showed that the increases in MICs were related to two mechanisms. For some strains of intermediate resistance (MICs of 16 to 64 micrograms/ml), the increased level of resistance could be explained by the presence of larger quantities of PBP5fm which had an affinity for benzylpenicillin (second-order rate constant of protein acylation [k+2/K] values of 17 to 25 M(-1) s(-1)) that remained unchanged. For the two most highly resistant strains, EFM-1 (MIC, 90 micrograms/ml) and H80721 (MIC, 512 micrograms/ml), the resistance was related to different amino acid substitutions yielding very-low-affinity PBP5fm variants (k+2/K < or = 1.5 M(-1) s(-1)) which were synthesized in small quantities. More specifically, it appeared, with a three-dimensional model of the C-terminal domain of PBP5fm, that the substitutions of Met-485, located in the third position after the conserved SDN triad, by Thr in EFM-1 and by Ala in H80721 were the most likely cause of the decreasing affinity of PBP5fm observed in these strains.

Amino Acid Sequence↗
PubMed1999

Evaluation of the revised MicroScan dried overnight gram-positive identification panel to identify Enterococcus species.

The revised MicroScan Dried Overnight Gram-Positive Identification panel was evaluated for its efficacy at identifying Enterococcus species in comparison with conventional biochemical tests. Supplemental testing of ampicillin-susceptible Enterococcus faecium for motility and the ability to acidify methyl-alpha-D-glucopyranoside helped recognize E. gallinarum and increased the accuracy of the panel for identifying Enterococcus species to 98.5%.

Ampicillin Resistance↗
PubMed1998

Third-generation cephalosporins and vancomycin as risk factors for postoperative vancomycin-resistant enterococcus infection.

OBJECTIVE: To examine use of third-generation cephalosporins (3GCs) alone and in association with vancomycin hydrochloride as a risk factor for vancomycin-resistant enterococcus (VRE) infection in surgical patients. DESIGN: Case-control retrospective study analyzing antibiotic use in the 30 days preceding culture of VRE or vancomycin-sensitive enterococcus from an infected site. SETTING: A large tertiary care teaching hospital. PATIENTS: Surgical inpatients with VRE infections between September 3, 1993, and January 29, 1997, were matched with patients with vancomycin-sensitive enterococcus infections. Matches were based on surgical procedure, initial infection site, and immunosuppression. Matches were found for 32 of 50 surgical patients with VRE. Twenty matched pairs of patients were recipients of solid organ transplants. MAIN OUTCOME MEASURES: Multivariate logistic regression analysis was done to examine 3GCs and vancomycin as risk factors for VRE infection. Univariate analysis of use of other antibiotic agents and demographic data was also performed. RESULTS: Multivariate analysis showed significant differences in the use of 3GCs both alone and concurrently with vancomycin. Univariate analysis also showed higher use of metronidazole, concurrent vancomycin and metronidazole, concurrent vancomycin and ceftazidime, and all antibiotics combined in patients with VRE infections. CONCLUSIONS: This matched control study showed that use of 3GCs, alone (P=.05) or concurrently with vancomycin (P=.05), was a risk factor for VRE infection in surgical patients. Judicious administration of third-generation antibiotics is warranted in surgical patients with other risk factors for VRE.

Adult↗
PubMed2002

Effect of hypoxia on the immune response of giant freshwater prawn Macrobrachium rosenbergii and its susceptibility to pathogen Enterococcus.

Giant freshwater prawns Macrobrachium rosenbergii (14-19 g) were challenged with Enterococcus (3 x 10(5) cfu prawn(-1)) previously incubated in TSB medium for 24 h, then placed in water having concentrations of dissolved oxygen (DO) at 7.75, 4.75, 2.75 and 1.75 mg l(-1). Onset of mortality occurred after 6 h exposure to 1.75 mg l(-1) DO, and after 12 h exposure to 2.75 mg 1(-1) DO. Cumulative mortality of prawns at 1.75 mg l(-1) DO was significantly higher than that at 4.75 and 2.75 mg l(-1) DO, and cumulative mortality of prawns at 4.75 and 2.75 mg l(-1) DO was significantly higher than that at 7.75 mg l(-1) DO after 96 h. The prawns (20-30 g) which had been placed in water for 0 to 120 h at 7.75, 4.75, 2.75 and 1.75 mg l(-1) DO were examined for the THC (total haemocyte counts), DHC (differential haemocyte counts), phenoloxidase activity, respiratory burst, percentage phagocytosis and clearance efficiency. No significant difference in semi-granular cells and granular cells of prawns was observed among four treatments. The prawns following 120 h exposure to 2.75 mg l(-1) DO decreased significantly the hyaline cells and THC by 39% and 36%, respectively. Phenoloxidase activity and respiratory burst decreased significantly by 33% and 11% when the prawns were exposed to 2.75 mg l(-1) DO after 24 h, respectively. Percentage phagocytosis and clearance efficiency to Enterococcus decreased significantly by 44% and 54% for the prawns following 12 h exposure to 2.75 mg l(-1) DO, respectively. It is concluded that DO as low as 2.75 mg l(-1) and 4.75 mg l(-1) causes depression in immune system of M. rosenbergii, and increases its susceptibility to Enterococcus infection.

Animals↗