The virucidal effect of platelet concentrates: preliminary study and first conclusions.

Despite the increased safety of blood components, achieved through improved donor selection and testing, transfusion recipients remain at risk of transfusion-associated diseases. Transfusion of cellular blood components has been implicated in transmission of viral, bacterial and protozoan diseases. Investigators have studied a myriad of processes for pathogen depletion and/or inactivation. No successful treatments, apart the leukodepletion, have already been identified for red cells and platelets. And more, several evidences indicate that platelets play a key role in host defence against infection. High levels of pathogens were added to single-donor platelet concentrates (PC) containing 3 to 5 10(11) platelets in 300 ml. The infectivity of each pathogen was measured with established biologic assays. The following levels of pathogen inactivation were achieved : >10(2.63) plaque-forming units (PFU) per ml of adenovirus 5 (ADV5), >10(5.6) PFU per ml of Poliovirus 1 (P1) and >10(4.1) PFU per ml of vaccinia virus (VaV). In conclusion, the PC show a potential virucidal effect. This inactivation process has been found with bacteria and still remains unknown for viruses.

Infection due to acyclovir resistant herpes simplex virus in patients undergoing allogeneic hematopoietic stem cell transplantation.

Over an eight-month period from October 1997 to May 1998, four patients who had received bone marrow transplant (BMT) from unrelated donor presented with severe mucosal cutaneous infections involving acyclovir resistant herpes simplex virus 1 (HSV-1). The four isolates were acyclovir (ACV) resistant, three of which were also foscarnet resistant as determined by the dye uptake method. The sequencing of the thymidine kinase (TK) gene did not permit to establish a relation between mutations and resistance to ACV. Three patients were considered as clinically cured of their HSV infection by replacement of ACV or foscarnet with either valacyclovir (one case) or cidofovir (two cases) but eventually two of them died of graft vs host disease. One patient died of extensive HSV infection despite administration of cidofovir. This study emphasizes the importance of monitoring the herpes virus resistance to antiviral drugs in bone marrow transplant recipients and the usefulness of the evaluation of novel antiviral drug for treatment of infections due to strains of HSV resistant to ACV and foscarnet that occur in about 5% of immunocompromised patients.

Investigation of aciclovir-resistant herpes simplex virus I infection in a bone marrow transplantation unit: genotyping shows that different strains are involved.

Over an eight-month period from October 1997 to May 1998, four patients who had received a bone marrow transplant (BMT) from an unrelated donor presented with severe mucosal cutaneous infections involving aciclovir resistant herpes simplex virus 1 (HSV-1). The emergence within a short period of resistant HSV-1 strains in the bone marrow transplantation unit raised fears of hospital-acquired infections. The hypothesis was investigated by restriction fragment length polymorphism (RFLP), sequencing of the thymidine kinase (TK) gene and genotyping of hypervariable regions of these four strains. Restriction fragment length polymorphism proved to be poorly discriminant and the TK sequence did not rule out transmission between these patients. Amplification of reiterating hypervariable genomic HSV-1 regions designated Re IV and Re VII clearly differentiated patients' strains. Thus, in this study, there was no evidence of nosocomial transmission of HSV-1 strains between the four patients.

Susceptibility of clinical strains of herpes simplex virus to three nucleoside analogues.

The susceptibility of clinical isolates of herpes simplex virus 1 (HSV1) (58 strains) and 2 (HSV2) (17 strains) from the Centre Hospitalier et Universitaire de Nancy to three nucleoside analogues was compared by the dye uptake method. As expected, all strains of HSV2 were resistant to brovavir or sorivudine. Aciclovir and penciclovir activities were comparable; 2 strains of HSV1 were resistant to these two compounds. Four strains isolated from immunocompromised patients gave different results with brovavir as compared to aciclovir; resistance to aciclovir (1 strain of HSV1) did not correlate with resistance to brovavir (3 strains of HSV1). Following up antiviral susceptibility is of interest for the detection of resistant strains in immunocompromised patients receiving prophylactic aciclovir.

A simple method for the in vitro study of the virucidal activity of disinfectants.

For the study of the virucidal activity of a disinfectant by the gel filtration or the dilution methods, the concentration of virus has to be high enough to determine a decrease in titer of at least 4 logarithm units. A filtration technique for rapid separation of the disinfectant and the virus is described that overcome this limitation. The method is applicable to any chemical compound and gives results equivalent to those of the techniques required by the French norms (NF T 72-180).

Human embryonic gastric xenografts in nude mice: a new model of Helicobacter pylori infection.

In vitro or animal models have been used to investigate the pathogenesis of Helicobacter pylori infection. However, extrapolation to humans of results obtained with these heterologous models remains difficult. We have developed a new model for the study of H. pylori infection that uses human entire embryonic stomachs engrafted in nude mice. At 80 days after implantation, 22 of these xenografts, which exhibited a mature gastric epithelium, were inoculated with 10(7) to 10(8) CFU of either H. pylori LB1, a freshly isolated H. pylori strain (n = 12), or H. pylori ATCC 49503 (n = 10). After 12-week examination, H. pylori LB1 persistently colonized the antrum of all inoculated grafts, as assessed by culture (mucus and mucosa), immunohistochemistry (mucosa), and a rapid urease test (mucus). H. pylori ATCC 49503, either before or after in vivo passage, permitted only a transient 2-week colonization in one of the five inoculated grafts in both groups. Colonization was always associated with an increase of gastric juice pH. A mild neutrophil infiltration of the gastric mucosa was noted solely in infected grafts. Transmission electron microscopy showed adherence of H. pylori organisms to epithelial cell surface. In six animals, intracytoplasmic location of this bacterium was observed in the antrum or the fundus. These results allow us to propose this model as a new ex vivo model for the study of specific H. pylori-gastric cell interactions.

[Multicenter study of the in vitro sensitivity of genital mycoplasmas to antibiotics]. / Etude multicentrique de la sensibilité in vitro des mycoplasmes génitaux aux antibiotiques.

The in vitro susceptibility of Ureaplasma urealyticum (Uu) and Mycoplasma hominis (Mh) was evaluated in a multicentric study performed in seven hospitals from different geographic areas in France. During a three month period, 324 Uu and 72 Mh clinical isolates were tested using a system ready for use, SIR Mycoplasma (Sanofi Diagnostics Pasteur). For Uu, the percentage of strains intermediate (I) or resistant (R) was as follows: doxycycline (3), minocycline (2.5), lymecycline (6.7), erythromycin (72, most I), josamycin (0.9), clindamycin (88), pristinamycin (0.3), ofloxacin (34, most I). For Mh, the percentage of strains I or R was respectively: doxycycline (2.7), minocycline (5.5), lymecycline (15.2), erythromycin (100), clindamycin (1.4), ofloxacin (2.7), josamycin (0) and pristinamycin (0). Comparable results were observed in the different geographic areas. The frequency of acquired resistances does not justify modifications in the usual treatment of genital mycoplasma infections but leads to monitor their susceptibility to antibiotics.

[Incidence of hepatitis C virus in kidney transplantation recipients]. / Incidence du virus de l'hépatite C chez les transplantés rénaux.

The investigation was carried on 122 waiting renal transplantation hospitalized patients. Detection of HCV antibodies was done before transplantation and after renal transplantation. HCV antibodies were detected by immunosorbent assay (ELISA) for C 100-3 protein of HC virus (Lab. ORTHO). Positive results were checked by a second test (immunoblot RIBA II) to detect antibodies against C100-3, 5-1-1, C33, C22 proteins of HCV genome. Before transplantation, 112 patients were negative and 10 positive. After transplantation, 104 were checked: 103 had identical serology (93- and 10+); only one patient has shown a seroconversion six months after the transplantation, demonstrating the late apparition of HCV antibodies, but immunological status of donor was unknown. Renal transplantation does not seem a risk factor of HCV contamination: only 1 seroconversion on 122 patients or 0.8%: near percentage of French blood donors (0.68%). The percentage of positivity HCV before transplantation (9%) answered with that of European hemophils (5 to 20%). Second generation tests demonstrate a better sensibility and specificity than the first.