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PubMed2001

Quantitative determination of gelatinase activity among enterococci.

Gelatinase, hemolysin and aggregation substance have all been reported to be virulence factors of enterococci. In this study, gelatinase production was investigated in isolates of Enterococcus faecalis (n=93), E. faecium (n=49) and E. avium (n=36) recovered from hospitalized patients. Gelatinase was detected in 45% of E. faecalis isolates, but could not be detected in E. faecium and E. avium. Gelatinase activity was then measured by radial diffusion for the 42 gelatinase-positive E. faecalis isolates. To convert gelatinase activity into proteinase K activity, a standard curve was produced by placing different concentrations of proteinase K into wells in the gelatine plate. Gelatinase activity per E. faecalis colony ranged from 2.6 x 10(-7) to 2.2 x 10(-5) microg/ml, proportionate to the activity of proteinase K. An approximately 84-fold difference in gelatinase concentration was observed between the colony producing the highest amount and that producing the lowest amount. This method may be useful for determining the virulence of given isolates in relation to gelatinase production as it is quick, easy and inexpensive to perform.

Adult↗

PubMed2004

Multiple-antibiotic resistance of Enterococcus spp. isolated from commercial poultry production environments.

The potential impact of food animals in the production environment on the bacterial population as a result of antimicrobial drug use for growth enhancement continues to be a cause for concern. Enterococci from 82 farms within a poultry production region on the eastern seaboard were isolated to establish a baseline of susceptibility profiles for a number of antimicrobials used in production as well as clinical environments. Of the 541 isolates recovered, Enterococcus faecalis (53%) and E. faecium (31%) were the predominant species, while multiresistant antimicrobial phenotypes were observed among all species. The prevalence of resistance among isolates of E. faecalis was comparatively higher among lincosamide, macrolide, and tetracycline antimicrobials, while isolates of E. faecium were observed to be more frequently resistant to fluoroquinolones and penicillins. Notably, 63% of the E. faecium isolates were resistant to the streptogramin quinupristin-dalfopristin, while high-level gentamicin resistance was observed only among the E. faecalis population, of which 7% of the isolates were resistant. The primary observations are that enterococci can be frequently isolated from the poultry production environment and can be multiresistant to antimicrobials used in human medicine. The high frequency with which resistant enterococci are isolated from this environment suggests that these organisms might be useful as sentinels to monitor the development of resistance resulting from the usage of antimicrobial agents in animal production.

Animal Husbandry↗

PubMed2000

Epidemiology of bacteriuria caused by vancomycin-resistant enterococci--a retrospective study.

BACKGROUND: The epidemiology of vancomycin-resistant enterococcal (VRE) bacteriuria has not been previously described. Our objectives are to describe the frequency of VRE bacteriuria, to use strict definitions to distinguish symptomatic urinary tract infection (UTI) versus urine colonization without pyuria versus asymptomatic bacteriuria with pyuria, and to describe the outcomes of each group. METHODS: We used a retrospective analysis of patients with VRE bacteriuria in an academic medical center. RESULTS: During the 18-month study period, 98 of the 107 patients (92%) with urine cultures positive for VRE (23/10,000 admissions), had charts that were available for review. In 94 of 98 patients, the organism was Enterococcus faecium, and in only 4 was Enterococcus faecalis recovered. Thirty-seven patients were colonized with VRE; 21 patients had asymptomatic bacteriuria, and the status of 27 patients was not ascertainable. Thirteen patients had VRE UTIs with two associated bacteremias and one death. Patients with UTI versus patients without UTI were more likely to have an underlying malignancy (39% vs 9%, P =.014). CONCLUSION: The majority of urine cultures yielding VRE do not represent true infection, rather colonization or asymptomatic bacteriuria.

Adolescent↗

PubMedDate not supplied

[The etiological role of enterococci in chronic obstructive bronchitis].

The role of enterococci in the development of chronic obstructive bronchitis was determined. Enterococcus faecalis, subspecies zymogens and liquefaciens, were found to be the etiological factors of chronic obstructive bronchitis both as the primary cause of the disease and, probably, the cause of secondary hospital infection. Enterococci isolated from patients had some signs of pathogenicity, their characteristic feature being multiple drug resistance. Chronic obstructive bronchitis caused by these microorganisms was accompanied by decreased immune responsiveness and the development of autoimmune processes.

Antibody Formation↗

PubMed2004

Vancomycin resistance, esp, and strain relatedness: a 1-year study of enterococcal bacteremia.

The prevalence of esp, a gene associated with infection-derived and outbreak strains, in enterococcal blood isolates from 2002 was determined. Fifty-five of 137 (40.1%) Enterococcus faecalis isolates, 30 of 58 (51.7%) E. faecium isolates, 1 of 1 E. raffinosus isolate, 0 of 4 E. gallinarum isolates, and 0 of 1 E. casseliflavus isolate were positive. esp wasn't associated with vancomycin resistance (VR) or clinical service. VR E. faecium isolates were less genetically diverse than vancomycin-susceptible strains. A large cluster of VR isolates, belonging to esp-positive E. faecium, was revealed. These data support the hypothesis that esp and VR may contribute to dissemination of particular clones.

Bacteremia↗

PubMed2004

Epidemiology of antimicrobial resistance in enterococci of animal origin.

OBJECTIVE: We evaluated the epidemiology of antimicrobial resistance in enterococci from animal farms and the potential relation of resistance to antimicrobial use. METHODS: Enterococci from faecal samples from 18 beef cattle, 18 dairy cattle, 18 swine, 13 chicken, and eight turkey farms were prospectively evaluated over a 6 year period from 1998 to 2003. RESULTS: We evaluated 1256 isolates of Enterococcus faecium and 656 isolates of Enterococcus faecalis. None was vancomycin resistant. Quinupristin/dalfopristin, gentamicin and ciprofloxacin resistance rates in E. faecium were 2%, 0% and 55% in beef cattle, 8%, 7% and 47% in dairy cattle, 21%, 1% and 47% in swine, 85%, 12% and 23% in chicken, and 52%, 13% and 24% in turkey isolates, respectively. For E. faecalis, gentamicin resistance rates were 0% in beef cattle, 24% in dairy cattle, 37% in swine, 32% in chicken, and 29% in turkey isolates, whereas 12%, 9%, 21%, 64% and none of isolates from beef, dairy, swine, chicken, and turkey farms, respectively, were resistant to ciprofloxacin. Quinupristin/dalfopristin resistance in E. faecium was more common on chicken and turkey farms using virginiamycin (P<0.0001 for both) compared with farms not using a streptogramin, gentamicin resistance was more common on dairy farms using gentamicin (P<0.0001) compared with farms not using this antibiotic, and ciprofloxacin resistance was more common on turkey and dairy farms using enrofloxacin compared with those with no enrofloxacin use (P=0.02 and P=0.04, respectively). For E. faecalis, gentamicin resistance was more frequently detected on dairy and swine farms using gentamicin (P<0.0001 and P=0.0052, respectively) and ciprofloxacin resistance was more common on beef farms using enrofloxacin (P<0.0001) compared with farms not using these antimicrobials. PFGE showed multiple strain types with some clones common between animals of the same animal species. CONCLUSIONS: This study shows the presence of a significant reservoir of antibiotic-resistant enterococci among farm animals. Resistance was more common on farms using antimicrobial agents.

Agriculture↗

PubMed2006

Bacteriocin production, plasmid content and plasmid location of enterocin P structural gene in enterococci isolated from food sources.

AIMS: To characterize bacteriocin production, antimicrobial spectrum and plasmid content in bacteriocinogenic enterococci from foods. METHODS AND RESULTS: Bacteriocinogenic Enterococcus faecium (14 isolates) and Enterococcus faecalis (three isolates) showed two different patterns of bacteriocin production in liquid broth: exponential-phase and stationary-phase production. Bacteriocin concentrates from all enterococci were inactivated by trypsin, but seldom by heat (100-117 degrees C), extremes of pH (2.0 to 9.0) or reducing agents (such as dithiothreitol). All bacteriocin concentrates were active against Listeria innocua and Listeria monocytogenes, and most were also active against many Ent. faecalis and Ent. faecium isolates. Enterococci clustered in three main groups according to their plasmid content (which included plasmids from 2.0 to 53 kb). Several isolates from different foods showed almost identical plasmid profiles. The enterocin P structural gene (entP) was detected by hybridization on plasmids of c. 19, 26 and/or 35-38 kb. CONCLUSIONS: Enterococci from food show different patterns of bacteriocin production and different plasmid content in spite of carrying similar bacteriocin-encoding genes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides information on the diversity of bacteriocinogenic enterococci from food sources carrying apparently similar enterocin genes.

Bacteriocins↗

PubMed1993

Detection of ampicillin resistance in Enterococcus spp. by disk diffusion and two commercial automated systems.

A total of 154 Enterococcus faecium and 48 Enterococcus faecalis isolates, 55% of which were ampicillin-resistant, were used to evaluate two commonly used automated systems, Vitek's GPS-TA card (bioMérieux, USA) and MicroScan's POS MIC Type 6 panel (Baxter Health-care, USA), and the NCCLS disk diffusion method for the detection of ampicillin resistance. MicroScan panels were read by the Walk/Away system and by visual inspection. The results were as follows: disk diffusion, 100% sensitive and specific; Vitek, 100% sensitive and 95% specific; and MicroScan, when read by the Walk/Away, 85% sensitive and 98% specific. When MicroScan was interpreted by visual inspection, however, sensitivity increased to 96%.

Ampicillin Resistance↗

PubMed2003

The screening of hydrogen peroxide-producing lactic acid bacteria and their application to inactivating psychrotrophic food-borne pathogens.

Lactic acid bacteria were isolated from various food samples and evaluated for hydrogen peroxide (H2O2) production. Cells suspended in 0.5% (wt/vol) glucose plus 0.5% (wt/vol) lactate (pH 7.0) were incubated for 5 h at 37 degrees C under aeration. Among 193 strains, 27 strains accumulated 201-300 ppm H2O2, and 4 strains accumulated more than 301 ppm H2O2 in the cell suspensions. Among the 9 high-level H2O2-producing strains, 8 strains were identified as Lactococcus lactis subsp. lactis. The cell-free filtrate from Lc. lactis subsp. lactis AI 62, which contained approximately 350 ppm H2O2, was evaluated for antimicrobial activity against Enterococcus faecalis, Ent. faecium, enterotoxigenic Escherichia coli, Listeria ivanovii, Staphylococcus aureus, Yersinia enterocolitica, and Aeromonas hydrophila. After 1 h incubation at 30 degrees C in the cell-free filtrate, the initial viable cell counts of the target bacteria (5.53-6.00 log cfu/mL) were reduced by 0.12-5.00 log units, except in the case of enterococci. The sensitivity varied with the bacterial species and pH. The enterococci were resistant to the treatment. Our results show that H2O2 accumulated by lactic acid bacteria in a cell suspension is very effective in reducing the viable cell count of food-borne pathogens.

Aeromonas hydrophila↗

PubMed1991

[In vitro bactericidal effect of temafloxacin and tosufloxacin against streptococci].

Tosufloxacin tosylate (TOSU) and temafloxacin hydrochloride (TEMA) were tested in vitro against 248 clinical isolates of various species of streptococci recovered in a hospital microbiology laboratory (Bellevue Regional Teaching Hospital). Species included S. pneumoniae (n = 20), group A streptococci (n = 22), group B streptococci (n = 30), group G streptococci (n = 17), group D S. bovis (n = 19), Enterococcus faecium (n = 45), Enterococcus faecalis (n = 28), S. sanguis (n = 21), S. milleri (n = 29) and S. mitis (n = 17). Activities of each of the two study drugs were evaluated comparatively with two other fluoroquinolones, i.e., ciprofloxacin (CIP) and pefloxacin (PEF). Activities of each of these four antibiotics, expressed as the MIC 90%, varied as follows according to the species of streptococci: TOSU, 0.25 to 1 mg/l, TEMA 0.5 to 2 mg/l, CIP, 1 to 4 mg/l and PEF 8 to 32 mgl. Overall, TOSU and TEMA exhibited the greatest activity of the various species. The size of the inoculum had no significant effect on MIC values.

Anti-Infective Agents↗

PubMed2005

Evaluation of the EVIGENE VRE detection kit for detection of vanA and vanB genes in vancomycin-resistant enterococci.

The aim of this study was to evaluate the performance of the EVIGENE VRE Detection kit and compare it with PCR, considered the gold standard for detection of vancomycin-resistant enterococci (VRE). The correlation between the MIC values of vancomycin and teicoplanin using the epsilon test was also determined. In the EVIGENE VRE Detection kit, DNA probes specific for bacterial target DNA sequences are bound to microwell plates. A hundred and ten VRE (104 Enterococcus faecium and six Enterococcus faecalis) and 45 vancomycin-susceptible E. faecium were tested. All VRE strains were found to be positive for the vanA genotype using the EVIGENE VRE Detection kit. All results obtained with the EVIGENE VRE Detection kit were confirmed by PCR. MIC results for the strains also correlated highly with the PCR and kit results. The EVIGENE VRE Detection kit should be used in preference to other methods for detecting resistance genes in all strains, since it is less time-consuming, does not require the handling of hazardous chemicals and has the same specificity as PCR.

Bacterial Proteins↗

PubMed1999

Antimicrobial resistance in key bloodstream bacterial isolates: electronic surveillance with the Surveillance Network Database--USA.

To assess the prevalence of antimicrobial-resistant pathogens among the most common bloodstream isolates, we examined antimicrobial susceptibility data from The Surveillance Network Database-USA, an electronic surveillance system that collects data from 118 clinical microbiology laboratories across the United States. Between 1995 and 1997, resistance to both vancomycin and ampicillin was much more prevalent among Enterococcus faecium than Enterococcus faecalis, suggesting the need for laboratories to identify to species. When staphylococcal isolates were examined for reduced susceptibility to vancomycin (minimum inhibitory concentration = 4 microg/mL), the frequency was highest in methicillin-resistant coagulase-negative staphylococci. We also learned that nonsusceptibility to ceftazidime in Klebsiella pneumoniae was more prevalent among isolates from blood (12.7%) than among isolates from urine (7.1%) or respiratory sources (9.3%). Although antimicrobial resistance is low overall for isolates of Escherichia coli from blood, the prevalence of cefoxitin resistance among ceftazidime-resistant strains (61.9%) suggests the action of mechanisms other than extended-spectrum beta-lactamase.

Anti-Bacterial Agents↗

PubMed2001

Molecular analysis of vanA enterococci isolated from humans and animals in northeastern Italy.

A total of 53 vancomycin-resistant vanA-positive enterococci isolates from poultry farms (17 Enterococcus faecium; 8 Enterococcus durans) and from different hospitals (23 E. faecium; 5 Enterococcus faecalis) in northeastern Italy were compared on the basis of their antibiotic susceptibilities, their SmaI pulsed-field gel electrophoresis (PFGE) patterns, and the organization of their Tn1546-related elements. Ampicillin resistance was similar in both groups of isolates (52 and 60.7%, respectively), whereas human strains were more resistant to high-level gentamicin and streptomycin. A total of 52% of animal strains and 60% of human strains were resistant to tetracycline, and 56% and 46.4% to quinupristin/dalfopristin, respectively. In E. faecium and E. durans animal isolates, nine and six distinct PFGE patterns, respectively, were found: in two instances indistinguishable isolates were found from different farms. In E. faecium and E. faecalis human isolates, nine and six distinct PFGE patterns, respectively, were found; among E. faecium strains, 12 were identical or closely related and were isolates from the same hospital. Elements mediating vanA-glycopeptide resistance were characterized by PCR with primers that amplified 10 overlapping fragments of Tn1546. A total of 84.6% of animal strains and 64.2% of human strains contained elements indistinguishable from the prototype Tn1546. In addition, nine different types were identified, but none was common to animal and human strains.

Animals↗

PubMed1995

The challenge of vancomycin-resistant enterococci: a clinical and epidemiologic study.

BACKGROUND: Vancomycin-resistant enterococci have been recovered with increasing frequency from hospitalized patients. Risk factors, mode of nosocomial transmission, extent of colonization in hospitalized patients, and treatment options for these organisms have not been completely delineated. METHODS: We studied 53 patients (group A) with vancomycin-resistant enterococci isolated from various clinical specimens and also surveyed for vancomycin-resistant enterococci in stool specimens submitted for Clostridium difficile toxin assays (group B). Stool specimens submitted for identification of bacterial pathogens and stool specimens from hospital employees were also analyzed for vancomycin-resistant enterococci. RESULTS: Seventy-six isolates of vancomycin-resistant enterococci were recovered in group A. Five of these patients harbored vancomycin-resistant enterococci on admission. Fifty-three of 289 group B stool specimens submitted for C. difficile toxin assays yielded vancomycin-resistant enterococci. Cephalosporins and vancomycin were the most common antimicrobial agents received by both groups of patients. Enterococcus faecium isolates were more resistant than Enterococcus faecalis isolates to antimicrobial agents. All isolates exhibited high-level aminoglycoside resistance and were not beta-lactamase producers. There were at least 15 different molecular clones of E. faecium and three of E. faecalis. Vancomycin-resistant enterococcal bacteremia was associated with a 100% in-hospital mortality rate. CONCLUSIONS: Multidrug-resistant and vancomycin-resistant enterococci have become important nosocomial pathogens that are difficult to treat. Vancomycin-resistant enterococcal bacteremia was associated with a poor prognosis. We found a high rate of colonization in patients with suspected C. difficile toxin colitis. Judicious use of vancomycin and broad-spectrum antibiotics is recommended, and strict infection control measures must be implemented to prevent nosocomial transmission of these organisms.

Adult↗

PubMed2004

Prevalence and molecular characterization of tetracycline resistance in Enterococcus isolates from food.

In the present study, a collection of 187 Enterococcus food isolates mainly originating from European cheeses were studied for the phenotypic and genotypic assessment of tetracycline (TC) resistance. A total of 45 isolates (24%) encompassing the species Enterococcus faecalis (n = 33), E. durans (n = 7), E. faecium (n = 3), E. casseliflavus (n = 1), and E. gallinarum (n = 1) displayed phenotypic resistance to TC with MIC ranges of 16 to 256 microg/ml. Eight of these strains exhibited multiresistance to TC, erythromycin, and chloramphenicol. By PCR detection, TC resistance could be linked to the presence of the tet(M) (n = 43), tet(L) (n = 16), and tet(S) (n = 1) genes. In 15 isolates, including all of those for which the MIC was 256 micro g/ml, both tet(M) and tet(L) were found. Furthermore, all tet(M)-containing enterococci also harbored a member of the Tn916-Tn1545 conjugative transposon family, of which 12 erythromycin-resistant isolates also contained the erm(B) gene. Filter mating experiments revealed that 10 E. faecalis isolates, 3 E. durans isolates, and 1 E. faecium isolate could transfer either tet(M), tet(L), or both of these genes to E. faecalis recipient strain JH2-2. In most cases in which only tet(M) was transferred, no detectable plasmids were acquired by JH2-2 but instead all transconjugants contained a member of the Tn916-Tn1545 family. Sequencing analysis of PCR amplicons and evolutionary modeling showed that a subset of the transferable tet(M) genes belonged to four sequence homology groups (SHGs) showing an internal homology of > or = 99.6%. Two of these SHGs contained tet(M) mosaic structures previously found in Tn916 elements and on Lactobacillus and Neisseria plasmids, respectively, whereas the other two SHGs probably represent new phylogenetic lineages of this gene.

Cheese↗

PubMed2006

Genotypic characterisation of vancomycin-resistant Enterococcus faecium isolates from haemato-oncological patients at Olomouc University Hospital, Czech Republic.

This study describes the first molecular characterisation of clinical isolates of vancomycin-resistant enterococci (VRE) in the Czech Republic. Of 2647 patient isolates of Enterococcus spp. from 1997-2002, 121 (4.6%) were identified as VRE. The most common isolates were VanA+ Enterococcus faecium (78%) and VanB+ Enterococcus faecalis (10%). In addition, five VanA+ E. faecium isolates were obtained from environmental and staff sampling. Macrorestriction analysis of SmaI restriction fragment length polymorphism was performed for 54 VanA+ E. faecium clinical isolates and the five VanA+ E. faecium environmental isolates. Thirty-two unique restriction endonuclease patterns were identified, including two predominant clonal types represented by five or more isolates. Two environmental VanA+ E. faecium isolates were closely related to two patient isolates, which had an identical SmaI macrorestriction pattern. The results indicated potential survival of strains in the hospital environment and possible subsequent transmission to hospitalised patients.

Cancer Care Facilities↗

PubMed1992

Rapid increase in the prevalence of high-level aminoglycoside resistance among enterococci isolated from blood cultures during 1989-1991.

At St Elizabeth Hospital Medical Center in Youngstown, Ohio, USA, the first blood culture isolate of Enterococcus faecalis with high-level gentamicin resistance (MIC > 2000 mg/L) was seen in 1985, and the prevalence of high-level gentamicin resistance among enterococci isolated from blood cultures during 1985-8 was 9%. During the period 1989-91, the prevalence of high-level gentamicin resistance among enterococci isolated from blood cultures increased to 35% (44 of 126 strains). Increases in the prevalence of high-level resistance to amikacin, tobramycin, netilmicin, kanamycin and streptomycin were also demonstrated. Ten of 44 strains (23%) with high-level gentamicin resistance did not exhibit high-level resistance to streptomycin. Of the 126 strains of enterococci, 52% had high-level resistance to at least one aminoglycoside.

Aminoglycosides↗

PubMed2004

Antimicrobial susceptibility of vancomycin-susceptible and -resistant enterococci isolated in Italy from raw meat products, farm animals, and human infections.

The susceptibility of vancomycin-resistant (VRE) and vancomycin-susceptible (VSE) enterococci to 10 antimicrobial agents was evaluated. The strains, belonging to different species, were isolated in Italy from raw meat products, farm animals, and human clinical infections in the years 1997-2000. High frequency of resistance to tetracycline and erythromycin was observed in all the groups of strains. On the contrary, chloramphenicol was the only drug that showed a relatively low rate of resistance in all the groups examined. In general, the resistance rates observed for VSE did not differ from those observed for VRE of the same species and origin. Some differences could be noticed among the different enterococcal species, with Enterococcus faecium strains being usually more resistant to beta-lactams, and Enterococcus faecalis strains more resistant to gentamicin. However, the strongest differences were observed when the strains were compared according to their source, the human isolates being usually more resistant than the isolates of animal origin. No significant difference was observed between isolates of swine and poultry origin. Among VRE E. faecium, multiple resistance was much more frequent among the human strains (90%) than among poultry (48.9%) and swine (26.5%) strains. These results show that in Italy VRE isolates from human clinical infections are usually more resistant than isolates from meat products and farm animals, and possess different antimicrobial resistance profiles.

Animals↗