Impact of HLA-G polymorphism on the outcome of allogeneic hematopoietic stem cell transplantation for metastatic renal cell carcinoma.

Renal cell carcinoma (RCC) is particularly sensitive to immune intervention. HLA-G, a non-classical HLA class I molecule with immunomodulatory properties, has been studied with regard to outcome after hematopoietic stem cell transplantation (HSCT), in particular the 14 bp insertion/deletion polymorphism in the 3' untranslated region. Here we analyzed n=56 patients affected by metastatic RCC who received an allogeneic HSCT between 1998 and 2006 in Milano, Marseille, Clermont-Ferrand and Stockholm. The 14 bp polymorphism was analyzed in correlation with overall survival (OS), PFS, acute and chronic GvHD. With a median follow-up of 13 years, a trend towards better outcome was observed when homozygosity for the 14bp-del allele was present: multivariate hazard ratio was 0.50 (95% confidence interval (CI): 0.23-1.13; P=0.10) and 0.57 (95% CI: 0.26-1.26; P=0.17) for OS and PFS, respectively, when 14bp-del/del was compared with 14bp-ins/X. Further exploratory analysis revealed a significant association between T/C at p3003 and improved OS (P=0.05) and PFS (P=0.006) compared with T/T. To our knowledge this is the first study on HLA-G and outcome after HSCT for a solid malignancy. After a coordinated multicenter study, we found that the more tolerogenic polymorphisms (14bp-del/del) is associated with better PFS and OS. The finding on p3003 deserves further investigation.

Prospective comparison of PCR-based vs late mRNA-based preemptive antiviral therapy for HCMV infection in patients after allo-SCT.

Human CMV (HCMV)-directed preemptive therapy has helped to improve the outcome following allo-SCT. In this study, we evaluated the safety and efficacy of a late mRNA-based (NucliSens CMV pp67) anti-HCMV treatment strategy. A prospective randomized multicenter pilot trial was performed comparing PCR-based, with late mRNA-based preemptive HCMV-directed antiviral therapy in patients after allo-SCT. In all, 133 patients were randomized in three different centers at the time of transplant, 130 of whom are evaluable. Viral screening was performed weekly. Antiviral therapy was initiated at the second consecutive positive PCR result, or at the first detection of late mRNA. The therapy was stopped if clearance of HCMV DNA or late mRNA was demonstrated after 14 days of antiviral therapy. If HCMV infection persisted, antiviral therapy was continued in a reduced dose. The median duration of antiviral therapy during the first treatment episode was 28 days for PCR-, and 19 days for mRNA-screened patients (P<0.02). However, the overall duration of antiviral therapy, as well as the incidence of HCMV disease and the OS at day 100 after transplantation was comparable between the two study groups. We conclude that late mRNA-based anti-HCMV therapy may show comparable safety and efficacy with PCR-based therapy in patients after allo-SCT.

A prospective randomized study using N-acetyl-L-cysteine for early liver toxicity after allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (ASCT) and its conditioning with chemoradiotherapy often results in liver toxicity, the most severe form being veno-occlusive liver disease (VOD). N-acetyl-L-cysteine (NAC), an antioxidant glutathione precursor, may provide protection from liver toxicity. Patients with elevated bilirubin (>26 mmol/l) and/or elevated (ALT) (>1.4 microkat/l) and/or aspartate aminotransferase (AST) (>1.4 microkat/l) levels were randomized to treatment with NAC or no treatment. Among 522 transplanted patients, 160 were included in the trial. NAC was given, 100 mg/kg per day, as a 6-h i.v. infusion until normalization of bilirubin, ALT and AST values. Maximum bilirubin level was the same in patients randomized to NAC (n=72) or controls (n=88). Increase and recovery of ALT and AST were the same in patients randomized to NAC or controls. There were two patients in the NAC group who developed VOD, as compared to three of the controls. To conclude, NAC does not improve liver toxicity after ASCT.

Cyclosporine A (CsA) 2-h concentrations vary between patients without correlation to graft-versus-host disease after allogeneic haematopoietic stem cell transplantation.

Cyclosporine A (CsA) therapy based on 2-h concentrations (C2) after oral administration has demonstrated low acute rejection rates after solid organ transplantation. We analysed the correlation between C2 and trough (C0) levels of oral CsA therapy in samples obtained twice in consecutive weeks from 58 patients during their first admission for allogeneic haematopoietic stem cell transplantation. Also 8-h concentration curves were obtained from 23 patients. The mean (range) CsA dose was 332 (167-763) and 255 (113-575) mg/day for patients with matched unrelated donor (MUD) and human leukocyte antigen identical sibling donor (Sib), respectively. Median (range) C0 and C2 were 254 (145-332) and 898 (419-1466) ng/ml in MUD patients, and 130 (93-265) and 554 (196-988) ng/ml in Sib patients. In MUD patients with either aGVHD grade < II or > or = II, the median C2 were 915 (419-1466) and 890 (519-1399) ng/ml, respectively. In Sib patients with aGVHD grade < II or grade > or = II, the median C2 were 552 (404-718) and 539 (196-988) ng/ml, respectively. The median C2 levels were comparable in patients with or without severe infections. Interindividual variations in CsA uptake and metabolism may explain the wide variation of C2 levels without prediction for increased risk for severe aGVHD or infectious complication when C0 guided the CsA dosing.

Fludarabine-based disease-specific conditioning or conventional myeloablative conditioning in hematopoietic stem cell transplantation for treatment of non-malignant diseases.

Fludarabine-based conditioning (FBC) was given to 24 patients and conventional myeloablative conditioning (MC) to 33 patients, most children, before hematopoietic stem cell transplantation (HSCT) for non-malignant diseases. The donors were human leukocyte antigen (HLA)-A, -B, -DRbeta1-identical related (33%) or unrelated (67%). In the FBC group, two grafts failed versus three in the MC group; all were successfully regrafted. Fever was more common in the MC patients (P=0.003). Bacteremia occurred in 25% of the FBC group and 50% in the MC group (P=0.1). In the FBC group, platelet engraftment was faster and transfusions were fewer (P<0.05). Mucositis and renal function were similar in the two groups. The MC group had higher maximum bilirubin (P=0.03) and less often normal spirometry (P=0.04) after HSCT. A 7-year-old girl in the MC group had permanent alopecia. No patients had severe acute graft-versus-host disease (GVHD). Chronic GVHD was rare. Complete donor CD3+ chimerism was more common in the MC group (P=0.01), but CD33+ engraftment was better with FBS (P=0.03). Treatment-related mortality was 4 and 15%, and 5-year survival was 89 and 85% in the FBC and MC groups. Although survival was similar, FBC is a promising alternative to MC in non-malignant disorders.

Allogeneic haematopoietic stem cell transplantation for metastatic renal carcinoma in Europe.

BACKGROUND: An allogeneic antitumour effect has been reported for various cancers. We evaluated the experience of allogeneic haematopoietic stem cell transplantation (HSCT) for renal cell carcinoma (RCC) in 124 patients from 21 European centres. PATIENTS AND METHODS: Reduced intensity conditioning and peripheral blood stem cells from an HLA-identical sibling (n = 106), a mismatched related (n = 5), or an unrelated (n = 13) donor were used. Immunosuppression was cyclosporine alone, or combined with methotrexate or mycophenolate mofetil. Donor lymphocyte infusions (DLI) were given to 42 patients. The median follow-up was 15 (range 3-41) months. RESULTS: All but three patients engrafted. The cumulative incidence of moderate to severe, grades II-IV acute GVHD was 40% and for chronic GVHD it was 33%. Transplant-related mortality was 16% at one year. Complete (n = 4) or partial (n = 24) responses, median 150 (range 42-600) days post-transplant, were associated with time from diagnosis to HSCT, mismatched donor and acute GVHD II-IV. Factors associated with survival included chronic GVHD (hazards ratio, HR 4.12, P < 0.001), DLI (HR 3.39, P < 0.001), <3 metastatic sites (HR 2.61, P = 0.002) and a Karnofsky score >70 (HR 2.33, P = 0.03). Patients (n = 17) with chronic GVHD and given DLI had a 2-year survival of 70%. CONCLUSION: Patients with metastatic RCC, less than three metastatic locations and a Karnofsky score >70% can be considered for HSCT. Posttransplant DLI and limited chronic GVHD improved the patient survival.

T-cell receptor Vbeta repertoire after myeloablative and reduced intensity conditioning allogeneic haematopoietic stem cell transplantation.

T cells play an important role in the adaptive immune system. After haematopoietic stem cell transplantation (HSCT), T-cell function is impaired. This is reflected by the emergence of opportunistic infections, infections that are often difficult to treat because of the patient's insufficient immune function. T-cell receptor reconstitution was studied using CDR3 spectratyping to analyze the diversity of the T-cell repertoire at 3, 6 and 12 months after myeloablative and reduced intensity conditioning (RIC) HSCT in 23 patients. Immune function in vitro was tested by lymphocyte stimulation at 3, 6 and 12 months after HSCT. Lower diversity in the CDR3 repertoire was demonstrated in CD4+ cells after RIC HSCT at 3 and 6 months and in CD8+ cells at 3 months compared with healthy donors. After myeloablative HSCT, lower diversity was seen at 3, 6 and 12 months in CD4+ cells and at 6 and 12 months in CD8+ cells after HSCT. Acute and chronic graft-versus-host-disease (GVHD) did not affect diversity. Responses to phytohaemagglutinin (PHA), Concanavalin A (Con A) and Staphylococcus aureus protein A were significantly lower compared with healthy donors during the first 6 months after RIC HSCT. After myeloablative HSCT, lymphocyte response to Con A was significantly lower at 3 months compared with healthy donors. Decreased responses to cytomegalovirus and varicella zoster virus antigens were seen in patients suffering from acute GVHD grade II or chronic GVHD. The T-cell repertoire is skewed under the first year after HSCT, and immune reconstitution after HSCT with myeloablative and RIC conditioning seems to be comparable. GVHD, infections and age are more important for immune reconstitution than type of conditioning.

Reconstitution of the Ig heavy chain CDR3 repertoire after allogeneic haematopoietic stem cell transplantation with myeloablative or reduced-intensity conditioning regimens.

The objective of this study was to investigate B-lymphocyte reconstitution in patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) after myeloablative conditioning (MAC) or reduced-intensity conditioning (RIC) regimens. B-lymphocyte reconstitution was studied by monitoring the CDR3 repertoire with spectratyping. We demonstrate a delay in the recovery of the B-lymphocyte repertoire, measured by variation in size distribution of the immunoglobulin H CDR3 in patients conditioned with RIC compared to MAC. We found no general explanation for this finding, but when clinical data for each patient were studied in detail, we could identify a cause for the oligoclonality of the B-lymphocyte repertoire after HSCT with RIC for each of the patients. Older patients and donors, low cell dose at transplantation, relapse, graft-versus-host disease (GVHD) and its treatment as well as cytomegalovirus infection and its treatment are all possible causes for the restriction of the B-lymphocyte repertoire observed in this study. Taken together, reconstitution of the B-lymphocyte repertoire after HSCT is a process dependent on multiple factors and differs between patients. The conditioning regimen may be of importance, but data from this study suggest that individual factors and the various complications occurring after HSCT are more likely to determine the development of the B-lymphocyte repertoire.

Measles immunity after allogeneic stem cell transplantation; influence of donor type, graft type, intensity of conditioning, and graft-versus host disease.

During follow-up after allogeneic stem cell transplantation (SCT), patients frequently lose their immunity to infectious agents such as measles. The aim of this study was to analyze the influence of different factors on measles immunity. In total, 395 patients with a disease-free survival of at least 1 year were included. Measles vaccination was given at 2 years after SCT to children and young adults without chronic GVHD or ongoing immunosuppression. In all, 264 patients had matched sibling donors and 131 either mismatched family or unrelated donors. Totally, 318 patients received bone marrow and 77 peripheral blood stem cells. Overall, 375 patients had undergone myeloablative and 20 nonmyeloablative conditioning. Out of 395 patients, 133 (34%) were seronegative to measles. In multivariate models, younger age or being vaccinated to measles, rather than previous measles disease, before transplantation were risk factors both for becoming seronegative and to have doubtfully protective immunity to measles. Acute GVHD grade II-IV was a risk factor for seronegativity and blood stem cells a risk factor for doubtfully protective immunity. Children and young adults previously immunized to measles have a high risk for becoming vulnerable to a measles infection. Since measles is again circulating in many countries and measles is a serious infection after SCT, vaccination should be considered.

N-acetyl-L-cysteine does not affect the pharmacokinetics or myelosuppressive effect of busulfan during conditioning prior to allogeneic stem cell transplantation.

Busulfan is currently used as a main component in the conditioning regimen prior to allogeneic stem cell transplantation (SCT). Several studies have shown a correlation between exposure to busulfan and transplantation-related liver toxicity, such as venoocclusive disease (VOD) in patients undergoing SCT. Busulfan is metabolized mainly through glutathione (GSH). During high-dose therapy, busulfan may deplete hepatocellular levels of GSH. As part of the conditioning therapy, busulfan is usually followed by high doses of cyclophosphamide. The activation of cyclophosphamide yields a cytotoxic metabolite, 4-hydroxy cyclophosphamide, which is highly reactive and detoxified through GSH. According to recent studies using cell lines and animal models N-acetyl-L-cysteine (NAC), a GSH precursor, does not hamper the myeloablative effect of busulfan during conditioning. In the present study, we administered NAC during conditioning to 10 patients at risk of VOD due to pretransplant liver disorders or elevated liver enzymes. No side effects related to the NAC infusions were observed and busulfan concentrations were not affected. All patients became pancytopenic and engrafted with 100% donor cells. None of the patients developed VOD or liver failure. Increased liver enzymes during conditioning decreased or normalized in all patients. We suggest that NAC therapy is safe and does not impair the myeloablative effect of busulfan during conditioning prior to SCT.

G-CSF given after haematopoietic stem cell transplantation using HLA-identical sibling donors is associated to a higher incidence of acute GVHD II-IV.

The effect of granulocyte colony-stimulating factor (G-CSF), given after transplantation, was studied in 155 patients transplanted with haematopoietic stem cells (HSCT) from HLA-identical sibling donors at Huddinge University Hospital between 1993 and 2001. Only patients with haematological malignancies were included. Conditioning consisted of total-body irradiation in 118 and busulphan in 37 patients. They were all given methotrexate combined with cyclosporine as graft-versus-host disease (GVHD) prophylaxis. Of the 155 patients, 66 (43%) received G-CSF after HSCT. Those given G-CSF had a significantly shorter time to neutrophil engraftment (P <0.001). G-CSF treatment had no effect on erythrocyte transfusions, platelet engraftment and infections. However, patients treated with G-CSF had a significantly higher incidence of grades II-IV acute GVHD than those not given this treatment (34 vs 9%, P <0.001). The multivariate analysis showed that the effect of G-CSF was independent of other known risk factors for grades II-IV acute GVHD. Death from GVHD occurred in four and two cases (P=0.06) in the two groups, respectively. The cumulative incidences of transplant-related mortality, survival, chronic GVHD, relapse and relapse-free survival were similar in both groups. In conclusion, G-CSF given after HLA-identical sibling HSCT was associated with a higher risk of grades II-IV acute GVHD, but not transplant-related mortality.

Low-intensity conditioning and hematopoietic stem cell transplantation in patients with renal and colon carcinoma.

We have evaluated whether allogeneic hematopoietic stem cell transplantation (HSCT) could induce an antitumor effect in patients with metastatic solid tumors. A total of 12 HLA-identical siblings and 6 HLA-A-, -B- and -DR beta 1-compatible unrelated grafts were used. Diagnoses were adenocarcinoma of kidney (n=10), colon (n=6), breast (n=1) and cholangiocarcinoma (n=1). Conditioning was fludarabine 30 mg/m(2)/day for 3 days and 2 Gy of total body irradiation. Recipients of unrelated HSCT were also given thymoglobuline and two additional days of fludarabine. The median CD34+ cell dose was 7.5 x 10(6)/kg. Immunosuppression was mycophenolate mofetil and cyclosporin. Among all, 12 patients became complete donor chimeras within a median of 28, 29 and 65 days for B, myeloid and T cells, respectively. Two patients rejected the grafts, one developed marrow aplasia and three were mixed chimeras. The probability of grades II-IV acute graft-versus-host-disease (GVHD) was 57%. Regression of all tumor metastases was seen in one patient with colon carcinoma. Another patient with colon and two with renal carcinoma had regression of lung metastases, but progression of metastases in the liver and/or bone. Necrosis of lung metastasis was found in one further patient with renal carcinoma who died of graft-versus-host-disease (GVHD). In all, 10 patients died; four of transplant-related complications, one of trauma and five of progressive disease. Thus, progression was common after allogeneic HSCT in unselected patients with advanced solid tumors. However, the regression of some metastases associated with GVHD provides suggestive evidence that the GVHD effect may occur in renal and colon adenocarcinoma using reduced intensity conditioning.

The graft-versus-leukaemia effect in haematopoietic stem cell transplantation using unrelated donors.

We studied the graft-versus-leukaemia (GVL) effect in 185 patients with haematological malignancies who underwent unrelated donor haematopoietic stem cell transplantation (HSCT) at Huddinge University Hospital between May 1991 and June 2001. Ninety-five were in first CR/CP and 90 in later stages. Most (86%) of them had a HLA-A, -B and -DRbeta1 matched donor. Conditioning usually consisted of total body irradiation and cyclophosphamide, and GVHD prophylaxis of cyclosporine and methotrexate. In the multivariate risk-factor analysis of relapse, we found that disease stage beyond CR1/CP1 (P = 0.02), acute GVHD 0-I (P = 0.02), absence of chronic GVHD (P = 0.02) and ALL (P = 0.02) were independent risk factors for relapse. The incidence of relapse in those with acute GVHD grade II was 18% vs 46% in those with no or grade I (P = 0.04). In patients with or without chronic GVHD, the incidences of relapse were 32% and 48%, respectively (P < 0.01). The best RFS was seen in patients with chronic GVHD. No difference in RFS was seen in patients with no, mild or moderate acute GVHD. Risk factors for relapse after HSCT with unrelated donors were: acute lymphoblastic leukaemia, disease stage beyond CR1/CP1, absence of chronic GVHD and no, or mild acute GVHD. Overall and relapse-free survival were not improved by the occurrence of acute GVHD.

Treatment of severe acute graft-versus-host disease with anti-thymocyte globulin.

Severe acute graft-versus-host disease (GVHD) is one of the major complications after haematopoietic stem-cell transplantation (HSCT). Treatment of severe GVHD is difficult and the condition is often fatal. One proposed method of improving the therapy is to include anti-thymocyte globulin (ATG). Here, we will report our results in 29 patients using ATG as part of treatment for severe steroid-resistant acute GVHD. Four patients suffered from grade II, 13 from grade III and 12 from grade IV GVHD. Median time to grade II GVHD was 24 d (range 7-91 d) and to grade III was 29 d (range 8-55 d) after HSCT. Five different ATG preparations were used, rabbit ATG (R-ATG), BMA 031, OKT3, ATG-Fresenius and Thymoglobuline. All patients had skin involvement, 26 also had gut involvement and 25 had liver involvement. The rate of response to treatment was best in skin involvement (72%), while liver and gut involvement showed lower response rates (38%). Eleven patients survived more than 90 d, 7 of them developed chronic GVHD, 1 developed mild GVHD, 1 developed moderate GVHD and 5 developed severe GVHD. Survival at 100 d was 37% and at 1 yr it was 12%. Most patients died of GVHD, with virus or fungal infections as contributing causes of death. To conclude, treatment of severe acute GVHD is difficult and ATG, in our hands, adds nothing to conventional pharmacological treatment.

Mixed chimaerism is common at the time of acute graft-versus-host disease and disease response in patients receiving non-myeloablative conditioning and allogeneic stem cell transplantation.

We report the clinical outcome and results of chimaerism analysis in various cell lineages of 30 patients given non-myeloablative conditioning, followed by allogeneic stem cell transplantation (SCT). The commonest diagnoses were chronic myelogenous leukaemia (n = 11) and solid tumours (n = 11). Twenty-one patients received SCT from human leucocyte antigen (HLA)-identical siblings and nine from matched unrelated donors. Median patient age was 53 (28-77) years. Four non-myeloablative protocols were used, including fludarabine (30 mg/m2 x 3-6), busulphan (4 mg/kg x 2), cyclophosphamide (Cy) (30 mg/kg/day x 2) or total body irradiation (2 Gy), and anti-thymocyte globulin. The patients were analysed by polymerase chain reaction (PCR) analysis of minisatellites on days 14, 21 and 28, then every other week up to 3 months and monthly thereafter. All samples were cell separated for T, B and myeloid cells using immunomagnetic beads. Eighteen patients were alive at a median follow-up of 11 (6-20) months. Acute graft-versus-host disease (GVHD) occurred in 22 patients. Eighteen of the 22 patients with acute GVHD showed mixed chimaerism (MC) in the T-cell fraction at the time of acute GVHD. However, all patients with acute GVHD showed donor chimaerism (DC) in the T-cell fraction median 76 (7-414) days after onset versus three out of eight patients without acute GVHD, P < 0.001]. Disease response was diagnosed in 15 patients, median 100 (37-531) days after SCT. At the time of disease response, six out of 15 patients showed MC in the T-cell fraction. In conclusion, mixed chimaerism in the T-cell fraction is common at the time of acute GVHD and disease response in patients conditioned with non-myeloablative therapy.

Ecological disturbances in intestinal microflora caused by clinafloxacin, an extended-spectrum quinolone.

BACKGROUND: The quinolones developed over the past few years have enhanced in vitro activity and a broader spectrum of antimicrobial activity compared to many other antimicrobial agents including the older quinolones. The present study focuses on the effect of clinafloxacin, a member of the new broad-spectrum quinolone class of antibiotics, on the normal intestinal microflora. SUBJECTS AND METHODS: A total of 12 healthy volunteers received clinafloxacin orally, 200 mg twice daily for 7 days. Fecal specimens were collected at defined intervals before, during and after the administration in order to study the effect of clinafloxacin on the intestinal microflora and to correlate this effect with fecal clinafloxacin concentrations. Intestinal microorganisms isolated before, during and 2 weeks after clinafloxacin administration were tested for their suseptibility to clinafloxacin. RESULTS: Oral administration of clinafloxacin resulted in high drug levels in feces (mean value 176.2 mg/kg on day 7) and pronounced ecological disturbances. The aerobic microflora was eradicated in 11 of the 12 subjects and the anaerobic microflora was strongly suppressed during administration. There was a significant emergence of clinafloxacin-resistant Bacteroides spp. strains (MIC > or = 4 mg/ml) during administration. The elevated MIC values still remained 2 weeks after discontinuation of the antibiotic (p < 0.001). CONCLUSION: The emergence of clinafloxacin-resistant Bacteroides spp. demonstrates the necessity of restricting prescription for particular indications in order to preserve the efficacy of the highly active broad-spectrum quinolones.

Pharmacokinetics and comparative effects of telithromycin (HMR 3647) and clarithromycin on the oropharyngeal and intestinal microflora.

The pharmacokinetics in plasma and saliva of a new ketolide, telithromycin (HMR 3647), and the effect on the normal oropharyngeal and intestinal microflora were studied in healthy volunteers and compared with those of clarithromycin. Ten subjects received 800 mg telithromycin perorally once daily and 10 other subjects received 500 mg clarithromycin bid for 10 days. Blood, saliva and faecal specimens were collected at defined intervals before, during and after administration for pharmacokinetic and microbiological analyses. In subjects receiving telithromycin, the mean C:(max), AUC and C:(24) (24 h) in saliva exceeded the values obtained from plasma, while saliva and serum pharmacokinetic parameters were in the same range for the clarithromycin group. The quantitative ecological disturbances in the normal microflora during administration of telithromycin were moderate and comparable to those associated with clarithromycin administration. No overgrowth of yeasts or Clostridium difficile occurred. Emergence of resistant strains was seen in both treatment groups. Administration of both telithromycin and clarithromycin was associated with significant increases in MICs for intestinal Bacteroides isolates, which persisted 2 weeks after discontinuation of treatment. In addition, a significant emergence of highly clarithromycin-resistant alpha-haemolytic streptococci, intestinal enterococci and Enterobacteriaceae was detected at day 10 in the clarithromycin group. In conclusion, administration of telithromycin resulted in high drug levels in saliva, which indicates a good therapeutic profile for throat infections. Telithromycin seems to have a more favourable ecological profile compared with clarithromycin in terms of resistance development in the normal microflora.

Impact on human intestinal microflora of an Enterococcus faecium probiotic and vancomycin.

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 ml of the fermented milk 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 was 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.