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Different roles of enterococcus faecium from a human perspective
Södertörn University, Avdelning Naturvetenskap. Huddinge University Hospital, Karolinska Institutet.
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Food supplements containing viable bacteria, so called probiotics, have been suggested to have beneficial health effects due to their influence on the normal microflora. However, there has been safety concern regarding probiotics containing Enterococcus faecium. Although part of the normal intestinal microflora in humans, enterococci can cause infections such as urinary tract infections, septicaemia, and endocarditis. Enterococci are also inclined to develop antibiotic resistance and their hardy nature promotes survival and dissemination in the hospital setting. Although the importance of E.faecium as a bloodstream isolate is increasing, little regarding its virulence is known. One virulence trait attributed to E. faecium is the enterococcal surface protein, Esp, encoded by the esp gene. Since enterococci have different roles from the human perspective, such as occurrence in food, as probiotic strains, members of the normal intestinal microflora, and as the cause of nosocomial infections, it is important to study differences and similarities between strains of different origin. The aims of the present investigation were to study some safety aspects of a probiotic product containing Efaecium, the colonization and transmission of enterococci from a nosocomial perspective, and differences between E.faecium isolates of different origin in some characteristics of probable importance for virulence. Faecal samples were collected from healthy volunteers administered an E. faecium probiotic. Half of the volunteers received simultaneous peroral vancomycin. The E. faecium isolates were subtyped and an in vitro conjugation assay was performed. The investigated strain could survive gastrointestinal transit in humans, and intake temporarily increased the number of enterococci in the faecal microflora. The vancomycin administration prevented detection of the probiotic strain. The probiotic strain could gain the vanA gene cluster under in vitro conditions. Samples from the respiratory tract and stomach were collected from 20 consecutive patients undergoing mechanical ventilation. The enterococci isolated were subsequently subtyped. Seventeen of the 20 subjects were colonized with enterococci in the respiratory tract. Genotype analyses suggested that 13 patients were involved in a transmission event, including all patients intubated more than 12 days. The E. faecium isolates were more resistant to antimicrobial agents compared to E. faecalis. The E. faecium isolates from different origins, i.e., infections, faeces, and probiotic products, were investigated for the presence of esp, their ability to conjugate, and adhere to epithelial cells in vitro. The esp gene was significantly more common among blood isolates. E. faecium strains enriched with esp adhered significantly better, were less genetically diverse, and had a higher conjugation frequency compared to esp-negative blood isolates. Antibiotic resistance was only detected among the infection-derived isolates. The adhesion among esp-negative isolates from the normal microflora was higher compared to the esp-negative bacteraemia isolates. In conclusion, the investigated probiotic E. faecium strain can survive gastrointestinal transit in humans, and intake may transiently increase the number of enterococci in the faecal microflora. The same strain can gain the vanA operon. Enterococci are frequently disseminated between mechanically ventilated patients, and isolates from different subpopulations seem to have different characteristics in terms of occurrence of esp, adhesion properties, antibiotic resistance, and conjugation frequencies.

Place, publisher, year, edition, pages
Stockholm: Karolinska Instiutet , 2003. , 79 p.
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:sh:diva-32071ISBN: 91-7349-607-3 (print)OAI: oai:DiVA.org:sh-32071DiVA: diva2:1074655
Public defence
2003-10-15, Birkeaulan 2, F-huset, plan 5, Huddinge Universitetssjukhus, Huddinge, 10:00 (English)
Opponent
Supervisors
Available from: 2017-02-15 Created: 2017-02-15 Last updated: 2017-02-15Bibliographically approved
List of papers
1. Impact on human intestinal microflora of an Enterococcus faecium probiotic and vancomycin
Open this publication in new window or tab >>Impact on human intestinal microflora of an Enterococcus faecium probiotic and vancomycin
Show others...
2000 (English)In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 32, no 6, 627-632 p.Article in journal (Refereed) Published
Abstract [en]

The aims of this study were to evaluate the impact of a fermented milk product containing viable Enterococcus faecium on human intestinal microflora and to evaluate any risk of development of vancomycin-resistant enterococci (VRE). Twenty Danish and 20 Swedish healthy volunteers were given 150 mi of the fermented mill;. product once daily, equivalent to a daily dose of 4.5 x 10(9) to 7.5 x 10(9) CFU E. faecium, for 10 d. Half of the volunteers also received 125 mg vancomycin orally q.i.d. for 10 d. Faecal samples were collected on day 0 before intake, on day 10 directly after end of intake and on day 31, 3 weeks after the end of the experiment. There,Fas a significant increase in the total number of enterococci on day 10 (p < 0.01) in the group receiving only the E. faecium supplement, but 3 weeks later the level was as before intake. In the vancomycin group, the total number of enterococci was reduced on day 10 (p < 0.01) but had increased on day 31 (p < 0.01) in relation to day 0. In none of the Swedish and 4 of the Danish volunteers, VRE were sporadically detected, but without relation to intake of the probiotic or vancomycin. In healthy young Danish individuals the VRE carrier rate tended to be higher than previously found.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-32072 (URN)10.1080/003655400459531 (DOI)000166340400007 ()11200372 (PubMedID)2-s2.0-0034525626 (ScopusID)
Available from: 2017-02-15 Created: 2017-02-15 Last updated: 2017-02-15Bibliographically approved
2. Gastrointestinal transit survival of an Enterococcus faecium probiotic strain administered with or without vancomycin
Open this publication in new window or tab >>Gastrointestinal transit survival of an Enterococcus faecium probiotic strain administered with or without vancomycin
2002 (English)In: International Journal of Food Microbiology, ISSN 0168-1605, E-ISSN 1879-3460, Vol. 77, no 1-2, 109-115 p.Article in journal (Refereed) Published
Abstract [en]

The primary aim of this study was to evaluate if an ingested probiotic, containing viable Enterococcus faecium could survive gastrointestinal transit and if so, correlate the amount of the recovered probiotic strain with the host's own enterococci. The second aim was to investigate if simultaneous vancomycin intake influenced the survival and persistence of the probiotic strain and the stability of endogenous enterococci strains. Twenty healthy volunteers were given the probiotic product once daily for 10 days. Half of the subjects were simultaneously given vancomycin. Isolates of E. faecium strains were genotypically or phenotypically analysed with pulsed-field gel electrophoresis (PFGE) and the PhenePlate(TM) system, respectively. In eight of the ten volunteers given only the probiotic, the ingested E. faecium could be detected on day 10, while in none on day 31. From subjects given both probiotic and vancomycin no ingested E. faecium could be detected on day 10 or day 31. The estimated amount of ingested E. faecium recovered from faeces on day 10 ranged from 1.2 x 10(3) to 4.2 x 10(6) colony forming units per gram faeces, which in several cases were a substantial part of the total amount of E. faecium. The E. faecium isolated before probiotic plus vancomycin administration showed no close relationship to the ones isolated 3 weeks after ceased intake in any subjects. In conclusion, the ingested E. faecium strain can survive gastrointestinal transit. After intake, the E. faecium probiotic strain might become a large part of the total E, faecium population. The occurrence of the probiotic strain in the human gut seems to be transient after intake stop. Re-colonization of E. faecium after simultaneous probiotic plus vancomycin intake occurs mainly with strains without close genetic relationship to the strains harboured before treatment or to the ingested E. faecium strain.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15792 (URN)10.1016/S0168-1605(02)00047-8 (DOI)000176056800012 ()12076027 (PubMedID)2-s2.0-0037173481 (ScopusID)
Available from: 2012-03-08 Created: 2012-03-07 Last updated: 2017-02-15Bibliographically approved
3. Probiotic Enterococcus faecium strain is a possible recipient of the vanA gene cluster
Open this publication in new window or tab >>Probiotic Enterococcus faecium strain is a possible recipient of the vanA gene cluster
2001 (English)In: Clinical Infectious Diseases, ISSN 1058-4838, E-ISSN 1537-6591, Vol. 32, no 9, 1384-1385 p.Article in journal (Refereed) Published
Abstract [en]

The characteristics of Enterococcus faecium have led to concern regarding the safety of probiotics that contain this bacterium. The results of an in vitro filter mating assay indicate that a probiotic E. faecium strain might be a potential recipient of vancomycin resistance genes.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15857 (URN)10.1086/319994 (DOI)000168517900018 ()11303279 (PubMedID)2-s2.0-0035341415 (ScopusID)
Available from: 2012-03-12 Created: 2012-03-09 Last updated: 2017-02-15Bibliographically approved
4. Frequent transmission of enterococcal strains between mechanically ventilated patients treated at an intensive care unit
Open this publication in new window or tab >>Frequent transmission of enterococcal strains between mechanically ventilated patients treated at an intensive care unit
2002 (English)In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 40, no 6, 2084-2088 p.Article in journal (Refereed) Published
Abstract [en]

The objectives of this investigation were to study the respiratory tract colonization and transmission of enterococci between 20 patients treated with mechanical ventilation at an intensive care unit (ICU), to compare genotyping with phenotyping, and to determine the antibiotic susceptibilities of the isolated enterococci. Samples were collected from the oropharynx, stomach, subglottic space, and trachea within 24 It of intubation, every third day until day 18, and thereafter every fifth day until day 33. Enterococcal isolates (n = 170) were analyzed by pulsed-field gel electrophoresis and with the PhenePlate (PhP) system. The antimicrobial susceptibilities to five agents were determined. Seventeen of the 20 subjects were colonized with enterococci in the respiratory tract; 12 were colonized in the lower respiratory tract. Genotype analyses suggested that 13 patients were involved in a transmission event, including all patients intubated more than 12 days. In conclusion, colonization of resistant enterococci in the respiratory tract of intubated patients treated at an ICU was common. Transmission of enterococci between patients occurred frequently. Prolonged intubation period seems to be a risk factor for enterococcal cross-transmission.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15803 (URN)10.1128/JCM.40.6.2084-2088.2002 (DOI)000176159200031 ()12037069 (PubMedID)2-s2.0-0036263059 (ScopusID)
Available from: 2012-03-08 Created: 2012-03-07 Last updated: 2017-02-15Bibliographically approved
5. Bloodstream isolates of Enterococcus faecium enriched with the enterococcal surface protein gene, esp, show increased adhesion to eukaryotic cells
Open this publication in new window or tab >>Bloodstream isolates of Enterococcus faecium enriched with the enterococcal surface protein gene, esp, show increased adhesion to eukaryotic cells
2003 (English)In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 41, no 11, 5183-5185 p.Article in journal (Refereed) Published
Abstract [en]

Infection-derived Enterococcus faecium strains enriched with esp had increased ability to adhere to Caco-2 cells (P < 0.05) and were less genetically diverse than esp-negative isolates. esp-negative E. faecium fecal isolates from healthy individuals adhered significantly better than esp-negative infection isolates (P < 0.05), indicating additional factors of importance to adhesion.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15524 (URN)10.1128/JCM.41.11.5183-5185.2003 (DOI)000186665500040 ()262495 (PubMedID)2-s2.0-0242593799 (ScopusID)
Note

Som manuskript i avhandling. As manuscript in dissertation, with title:

Increased adhesion to eukaryotic cells in Enterococcus faecium bloodstream isolates enriched with enterococcal surface protein gene, esp

Available from: 2012-02-21 Created: 2012-02-21 Last updated: 2017-02-15Bibliographically approved
6. Increased conjugation frequencies in clinical Enterococcus faecium strains harbouring the enterococcal surface protein gene esp
Open this publication in new window or tab >>Increased conjugation frequencies in clinical Enterococcus faecium strains harbouring the enterococcal surface protein gene esp
2006 (English)In: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 12, no 6, 588-591 p.Article in journal (Refereed) Published
Abstract [en]

This study compared the in-vitro ability of Enterococcus faecium isolates of different origin to acquire vanA by conjugation in relation to the occurrence of the esp gene. In total, 29 clinical isolates (15/29 esp+), 30 normal intestinal microflora isolates (2/30 esp+) and one probiotic strain (esp-) were studied with a filter-mating assay. Conjugation events were confirmed by PCR and pulsed-field gel electrophoresis. Among the infection-derived isolates, the esp+ isolates had higher conjugation frequencies compared with esp- isolates (p < 0.001), with a median value of 6.4 x 10(-6) transconjugants/donor. The probiotic strain was shown to acquire vanA vancomycin resistance in in-vitro filter mating experiments.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-14298 (URN)10.1111/j.1469-0691.2006.01436.x (DOI)000237515600017 ()16700712 (PubMedID)2-s2.0-33646702110 (ScopusID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2017-02-15Bibliographically approved

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