Genotypic homogeneity of nosocomial Pseudomonas aeruginosa O12 strains demonstrated by analysis of protein profiles, DNA fingerprints and rRNA gene restriction patterns

The spread in Europe of a single multiresistant strain of Pseudomonas aeruginosa serotype O12 has been suggested. This bacterium was responsible for a nosocomial outbreak in our hospital in 1988-1989. Three different epidemiological methods were used to analyze 30 strains isolated during five consecutive years. Protein profile analysis and chromosomal DNA fingerprinting with four different enzymes revealed closely related patterns. rRNA gene restriction fragment length analysis performed with a digoxigenin-labelled probe showed identical hybridization patterns with four to six bands according to the endonuclease used. Combination of the three typing methods showed genotypic homogeneity of these Pseudomonas aeruginosa O12 strains, despite a relative increase in their antibiotic resistance.

Staphylococcal vaccine development: review of past failures and plea for a future evaluation of vaccine efficacy not only on staphylococcal infections but also on mucosal carriage

Staphylococcal disease represents a universal burden including acute, life-threatening infections as well as chronic infections usually associated with foreign materials. Infections occur notably in permanent carriers of Staphylococcus aureus. To date, all the attempts to develop an efficacious vaccine against S. aureus have failed. Failures in vaccine clinical trials might be related to a focus on single targets and development of humoral-based vaccines rather than vaccines with a combination of antigens stimulating both humoral and cellular immunity. The end points of these unsuccessful trials were a reduction in mortality or bacteremia, whereas the patient's decolonization was not assessed. Adopting the latter point of view, the aim of this article is to discuss nasal mucosal decolonization as a complementary marker of vaccine efficacy for clinical research in vaccine development.

Comparative evaluation of immunoglobulin M neutralizing antibody response in acute-phase sera and virus isolation for the routine diagnosis of enterovirus infection

A total of 314 patients exhibiting symptoms consistent with a viral disease provided, during the early stage of hospitalization, at least one specimen from a peripheral site (throat or stools or both) and a serum specimen in order to evaluate the neutralizing immunoglobulin M (IgM) antibody response in acute-phase serum in comparison with virus isolation for the rapid diagnosis of enterovirus (EV) infection. IgM antibodies were fractionated by ion-exchange chromatography and tested by seroneutralization against the various types of EV that have been recently circulating. A total of 189 patients (60%) were negative, and 21 (7%) were positive by both methods; in 51 patients (16%), a virus was isolated without IgM antibody response; 53 patients (17%) showed the opposite pattern. In all age groups except for children under 6 months, the frequency of positive results was higher with IgM serology than with virus isolation (27 and 22%, respectively). Apart from meningitis, for which isolation was more efficient, the other clinical conditions were associated with similar percentages of positivity by both methods. Regarding the 21 cases with positive results by the two techniques, the same serotype was detected in 9 cases and different serotypes were detected in 12, suggesting crossreactivities. Thus, IgM neutralizing antibody response on acute-phase serum appears to be of limited value in the rapid diagnosis of acute EV infection but may prove useful for the investigation of the wide range of chronic diseases associated with EV.

Reduction of Yersinia enterocolitica load in deliberately inoculated blood: the effects of blood prestorage temperature and WBC filtration

BACKGROUND

Yersinia enterocolitica is known to cause severe infections in patients who receive transfusions.

STUDY DESIGN AND METHODS

The aim of the study was to define the best strategy for reducing the bacterial load in blood that was deliberately contaminated with Y. enterocolitica by combining prestorage temperature and WBC filtration with conditions of blood processing close to those applied in blood banks.

RESULTS

The effects of three prestorage temperatures (4 degrees C, 20 degrees C, 37 degrees C) were evaluated at various times after infection. The best reduction of bacterial load was achieved after 3 hours at 20 degrees C. In further experiments, conducted according to the former specifications, filtration of whole blood from eight and six donors with an inoculum of 100 and 500 to 1000 CFUs per mL, respectively, resulted in a total inhibition of bacterial growth up to 42 days after infection. After fractionation of blood components, in contrast to plasma and RBCs, filtration was shown to reduce dramatically the bacterial growth in buffy coats, demonstrating that the antibacterial effect of filtration was supported by the removal of infected WBCs from blood samples.

CONCLUSION

These results provide support for the systematic use of blood filtration in the preparation of blood components to prevent Y. enterocolitica infection of patients receiving transfusions.

[High prevalence and incidence of hepatitis C virus infections among dialysis patients in the East-Centre of Tunisia]

Hemodialysed patients are recognised as a group at increased risk of infection with hepatitis C virus (HCV). The aim of this study was to determine the prevalence and incidence of HCV infection among dialysis patients of the east-centre part of Tunisia. Two hundred and seventy-six patients dialysed until 2001 were recruited within seven hemodialysis units located in the cities of Sousse, Monastir and Mahdia. The serum markers of HCV infection were tested over the period of March 2000-December 2002, by a 3rd generation ELISA test for antibodies and by qualitative RT-PCR technique for viral RNA. The prevalence of anti-HCV antibodies and of HCV RNA was 32.6% (90 patients) and 25.7% (71 patients), respectively. Between 1998 and 2002, 20 new infections were documented in five of the seven dialysis units corresponding to an incidence of 2.34% per year, with an average time of contamination after the beginning of dialysis of 4.6 years. If all the infections are assessed to have occurred during dialysis, the density of incidence of HCV contamination was 4.4% per year of dialysis. A high correlation was noticed between the presence of HCV markers in serum and the duration of dialysis (F = 34.15, P < 0.0001). In the absence of other risk factors (transfusion, drug-addiction), these results plead for the nosocomial transmission of the observed HCV infections. A phylogenetic analysis of the E2 hypervariable region of the viral genome is in progress to confirm this assumption.

Development and Validation of a Laboratory-Developed Multiplex Real-Time PCR Assay on the BD Max System for Detection of Herpes Simplex Virus and Varicella-Zoster Virus DNA in Various Clinical Specimens

A multiplex real-time PCR (quantitative PCR [qPCR]) assay detecting herpes simplex virus (HSV) and varicella-zoster virus (VZV) DNA together with an internal control was developed on the BD Max platform combining automated DNA extraction and an open amplification procedure. Its performance was compared to those of PCR assays routinely used in the laboratory, namely, a laboratory-developed test for HSV DNA on the LightCycler instrument and a test using a commercial master mix for VZV DNA on the ABI7500fast system. Using a pool of negative cerebrospinal fluid (CSF) samples spiked with either calibrated controls for HSV-1 and VZV or dilutions of a clinical strain that was previously quantified for HSV-2, the empirical limit of detection of the BD Max assay was 195.65, 91.80, and 414.07 copies/ml for HSV-1, HSV-2, and VZV, respectively. All the samples from HSV and VZV DNA quality control panels (Quality Control for Molecular Diagnostics [QCMD], 2013, Glasgow, United Kingdom) were correctly identified by the BD Max assay. From 180 clinical specimens of various origins, 2 CSF samples were found invalid by the BD Max assay due to the absence of detection of the internal control; a concordance of 100% was observed between the BD Max assay and the corresponding routine tests. The BD Max assay detected the PCR signal 3 to 4 cycles earlier than did the routine methods. With results available within 2 h on a wide range of specimens, this sensitive and fully automated PCR assay exhibited the qualities required for detecting simultaneously HSV and VZV DNA on a routine basis.

Is transfusion-transmitted dengue fever a potential public health threat?

Dengue is an arboviruses due to single-stranded enveloped ribonucleic acid viruses, named dengue viruses (DENV), that include four serotypes and are mainly transmitted via the bite of mosquitoes of the genus Aedes (A. aegypti and A. albopictus). The distribution of the disease was historically limited to intertropical areas; however, during the last thirty years, the perimeter of the disease extended considerably and temperate areas are now at risk of outbreaks. The present global burden of dengue is considerable: 2.5 billion people over more than 100 countries are concerned; 50 to 100 million infections occur every year, with a number of fatal cases of approximately 20000. Although frequently asymptomatic or limited to a mild fever, dengue is responsible for severe cases mainly consecutive to the occurrence of hemorrhagic complications that can lead to shock and death, notably in children from poor-resource settings. The place of DENV as a transfusion-transmitted pathogen has been recognized only in 2008. At the present time, only five cases of transfusion-transmitted dengue, including one case of dengue hemorrhagic fever, have been formerly documented. This review provides a general overview of dengue, its viruses and their vectors. It replaces the disease in the context of other viral diseases transmitted by arthropods. It discusses the threat of dengue on the supply of blood products in endemic and non endemic areas. Finally, it describes the specific and non specific measures available for improving the security of blood products with regards to this emerging risk. Interestingly, in 2009, the American Association of Blood Banks placed DENV in the highest category of emerging infectious agents for their potential impact on transfusion recipient safety for the next years in North America.

Differentiation of Pseudomonas aeruginosa strains by ribotyping: high discriminatory power by using a single restriction endonuclease

The genotypic diversity of 40 presumably epidemiologically unrelated strains of Pseudomonas aeruginosa belonging to nine different O-serotypes was analysed according to ribosomal DNA fingerprints. Ribotyping was performed with a digoxigenin-labelled DNA probe and four restriction endonucleases. Characteristic banding patterns of three to 12 bands were obtained with the different endonucleases. Among the 40 strains, eight, nine, 10 and 29 different ribotypes were differentiated with EcoRI, the combination EcoRI+HindIII, BamHI and PvuII, respectively. Poor correlations were noted between the results of serotyping and those of ribotyping. With the latter method, indices of discrimination were calculated for each enzyme from the data of the 40 unrelated strains: the values ranged from 0.678 for EcoRI to 0.979 for PvuII. Epidemiologically related samples were also tested; this enabled assessment of whether the method was able to cluster strains from a common origin with each of the enzymes tested. Ribotyping with PvuII endonuclease is proposed for screening large numbers of P. aeruginosa strains in epidemiological studies. Additional enzymes could be used to further increase the discrimination between isolates found to be indistinguishable with PvuII enzyme.

Multicenter quality control for the detection of hepatitis C virus RNA in seminal plasma specimens

The discrepant results available in the literature about the presence of hepatitis C virus (HCV) RNA in seminal plasma of men chronically infected by this agent are related, at least in part, to the molecular techniques used and particularly to the wide range of protocols dedicated to RNA extraction. In order to evaluate these protocols and to standardize the method of detection of HCV RNA in this fluid, a panel of coded specimens was tested blindly in 12 French laboratories; it included 14 seminal plasma specimens and four water controls spiked with HCV RNA ranging from 10 to 20000 IU/ml and two HCV-negative seminal plasma specimens. The extraction step was performed according to methods using either silica beads (NucliSens [Organon Teknika S.A., Fresnes, France]; RNA viral kit [Qiagen, Courtaboeuf, France]) or guanidinium thiocyanate (Amplicor HCV assay; Roche Diagnostics, Meylan, France), preceded or not by a centrifugation of the seminal plasma. For the amplification step, all the laboratories performed the same reverse transcription-PCR technique (Amplicor HCV Cobas assay). The percentage of correct results ranged from 53.3 to 100, the poorest results being obtained when no centrifugation step preceded the Amplicor extraction protocol. The rate of correct results was significantly higher in laboratories using a preliminary centrifugation of the specimen (P = 0.034 by chi-square test). By contrast, the overall number of correct results was not correlated to the initial volume of sample used for the test. These results allowed us to validate standardized techniques adapted to the performance of this test on a routine basis, especially in men infected with HCV and involved in programs of medically assisted reproduction.

Evaluation of an immunomagnetic separation assay in combination with cultivation to improve Legionella pneumophila serogroup 1 recovery from environmental samples

AIMS

Legionella isolation from environmental samples is often difficult because of the presence of heterotrophic-associated bacteria that frequently overgrow when using standard culture (ISO 11731, 1998; NF T90-431, 2003) methods. To improve Legionella pneumophila recovery from complex water samples (water from cooling towers, biofilms), we evaluated an immunomagnetic separation (IMS) assay using a monoclonal antibody raised against the lipopolysaccharide of Leg. pneumophila sg1 in combination with culture.

METHODS AND RESULTS

This study was conducted on 51 environmental specimens. The comparison between IMS-culture and standard culture (ISO 11731, 1998; NF T90-431, 2003) methods was made using ISO 17994, 2004 criteria for establishing equivalence between microbiological methods based on the upper and lower (XH and XL) values of the relative difference (95% confidence limit) and D as maximum acceptable deviation (value of the confidence limit).

CONCLUSIONS

We found that the average performance of IMS culture was higher than the reference method.

Comparison of a rapid culture method combining an immunoperoxidase test and a group specific anti-VP1 monoclonal antibody with conventional virus isolation techniques for routine detection of enteroviruses in stools

In order to shorten the time required for the detection of enteroviruses in stool specimens, an 18-h immunoperoxidase test combining low-speed centrifugation and the use of a group specific anti-VP1 monoclonal antibody (5-D8/1, Dako) was developed. This rapid culture assay (RCA) was compared blindly to a conventional culture assay (CCA) on a panel of 180 children's stool specimens received for routine diagnosis of enterovirus infection. The same cell lines (human embryonic fibroblasts and KB continuous cell line) were used in both tests. Discrepancies in results were analysed by a PCR technique with primers located in a conserved part of the 5' non-coding region of the enterovirus genome. Fourteen specimens were positive and 158 were negative with both tests. Four samples were positive with the RCA yet negative with the CCA and 3 others showed the opposite pattern; an additional sample positive by RCA was uninterpretable by CCA due to bacterial contamination. Subsequent PCR testing of these 8 samples showed no discrepancies; all were positive. Using CCA as the reference, the sensitivity and specificity of RCA were 77.8 and 98% respectively. Kinetic studies using enterovirus isolates demonstrated that RCA was much more sensitive than CCA during the first three days of culture. These results further suggested that RCA sensitivity could be improved by a factor of at least 10 times by prolonging the incubation period by 24 hr. With this change, the RCA assay described below is suggested as a rapid alternative to CCA for the routine diagnosis of enterovirus infection in stool specimens. When an identification at the serotype level is required, samples found positive using RCA could then be subjected to CCA.

Arbitrarily-primed PCR confirms the differentiation of strains of Ureaplasma urealyticum into two biovars

Fourteen serotypes are currently recognized in the Ureaplasma urealyticum species. These serotypes have been divided into two genomic clusters or biovars by a large number of typing methods. The parvo-biovar includes strains of serotypes 1, 3, 6 and 14 and the T960-biovar, strains belonging to the ten other serotypes. In this study, arbitrarily primed polymerase chain reaction (AP-PCR) has been applied to the analysis of reference strains of the 14 U. urealyticum serotypes. By using two different sets of 10-mer oligonucleotide primers, the method allowed the clear differentiation between the two known biovars of the species. However, further differentiation within a same biovar was only achieved for a few standard strains of the T960-biovar analysed by using a pairwise combination of primers. The reproducibility of AP-PCR profiles was shown on strains tested after repeated subcultures and with different thermal cyclers. Additional experiments were performed on forty isolates of U. urealyticum recovered from subjects of various origins. They confirmed that AP-PCR was able to identify the strains at the biovar level. With reference to the other typing methods, AP-PCR is easy to perform and can be applied to large numbers of strains for epidemiological purposes.

Evaluation of a prototype HCV NS5b assay for typing strains of hepatitis C virus isolated from Tunisian haemodialysis patients

Hepatitis C virus (HCV) strains isolated from 68 haemodialysis Tunisian patients exhibiting chronic infection were genotyped targeting the NS5b region of the HCV genome using a prototype assay developed by Bayer HealthCare-Diagnostics (TRUGENE NS5b HCV). The overall results were compared to those obtained with another assay of the same company based on sequencing of the 5' non-coding region (TRUGENE HCV 5'NC genotyping kit). All strains could be typed by the 5'NC typing kit, but only 62 (91; 2%) by the NS5b prototype assay. All the 62 strains typed by both methods exhibited the same pattern at the type level: 57 were type 1, 3 were type 2, and 2 were type 4. At the subtype level, eight strains that gave undetermined results by the 5'NC kit were successfully typed by the NS5b kit; eight additional strains exhibited discrepant results. The overall agreement between the two assays was 74.2% at the subtype level. In conclusion, the NS5b region appears to be much more accurate than the 5'NC region to subtype HCV strains, especially in those isolated from patients attending haemodialysis centres where the subtype distribution suggests frequent nosocomial transmissions.

Platelet toll-like receptors are crucial sensors of infectious danger moieties

In addition to their haemostatic role and function in the repair of damaged vascular epithelium, platelets play a defensive role in innate immunity, having the capacity to produce and secrete various anti-infectious factors, as well as cytokines, chemokines and related products, to interact with other immune cells to modulate immune responses to pathogens. Thus, it is now widely acknowledged that platelets participate in inflammatory processes and infection resolution, most notably by expressing and using receptors to bind infectious pathogen moieties and contributing to pathogen clearance. The ability of platelets to sense external danger signals relates to the expression of certain innate immunity receptors, such as toll-like receptors (TLRs), and the activation of efficient cell signalling machinery. TLR engagement triggers platelet response, which results in adapted degranulation according to: the type of TLR engaged, the nature of the ligand and the milieu; together, the TLR-mediated event and other signalling events may be followed by aggregation. Platelets thus use complex tools to mediate a whole range of functions upon sensing danger. By linking the inflammatory and haemostatic platelet response to infection, TLRs play a central role. The extent of the inflammatory response to pathogen clearance is still a debatable issue and is discussed in this short review.

Are polymorphisms of the immunoregulatory factor CD40LG implicated in acute transfusion reactions?

The CD40 ligand (CD40L/CD154), a member of TNF superfamily, is notably expressed on activated CD4+ T-cells and stimulated platelets. CD40L is linked to a variety of pathologies and to acute transfusion reactions (ATR). Mutations in this gene (CD40LG) lead to X-linked hyper-IgM syndrome. Some CD40LG polymorphisms are associated with variable protein expression. The rationale behind this study is that CD40L protein has been observed to be involved in ATR. We wondered whether genetic polymorphisms are implicated. We investigated genetic diversity in the CD40LG using DHPLC and capillary electrophoresis for screening and genotyping (n = 485 French and Tunisian blood donors). We identified significant difference in the CD40LG linkage pattern between the two populations. Variant minor alleles were significantly over-represented in Tunisian donors (P<0.0001 to 0.0270). We found higher heterogeneity in the Tunisian, including three novel low frequency variants. As there was not a particular pattern of CD40LG in single apheresis donors whose platelet components induced an ATR, we discuss how this information may be useful for future disease association studies on CD40LG.

Characterization of unrelated strains of Staphylococcus schleiferi by using ribosomal DNA fingerprinting, DNA restriction patterns, and plasmid profiles

The molecular characteristics of 31 unrelated strains of Staphylococcus schleiferi isolated from 13 hospitals between 1973 and 1991 were determined by ribosomal DNA fingerprinting by using a digoxigenin-labeled DNA probe, genomic DNA restriction patterns, and plasmid profiles. Only six strains harbored one or two plasmids. DNA restriction analysis, which was carried out with five endonucleases (EcoRI, HindIII, PstI, PvuII, and ClaI), did not allow us to discriminate between isolates. Ribotyping with HindIII, ClaI, or EcoRI enzymes generated six, seven, and nine distinct patterns, respectively. With the combination ClaI-EcoRI, 13 ribotypes were obtained among the 31 strains, suggesting a relative heterogeneity within the species. Moreover, all strains shared two or three common bands, according to the endonuclease used, which were relatively specific for S. schleiferi in comparison with the ribosomal banding patterns described for other coagulase-negative staphylococci. These results illustrate that ribotyping can be used for the epidemiological investigation of S. schleiferi isolates and possibly for taxonomic analysis in this species.

CAPRISA 018: a phase I/II clinical trial study protocol to assess the safety, acceptability, tolerability and pharmacokinetics of a sustained-release tenofovir alafenamide subdermal implant for HIV prevention in women

INTRODUCTION

Young African women bear a disproportionately high risk for HIV acquisition. HIV technologies that empower women to protect themselves are needed. Safe, potent antiretroviral agents such as tenofovir alafenamide (TAF), formulated as long-acting subdermal implants, offer an innovative solution.

METHODS AND ANALYSIS

CAPRISA 018 is a phase I/II trial to evaluate the safety, acceptability, tolerability and pharmacokinetics (PKs) of a TAF free base subdermal silicone implant containing 110 mg of TAF with an anticipated 0.25 mg/day release rate.The phase I trial (n=60) will assess the safety of one implant inserted in six participants (Group 1), followed by dose escalation components (Groups 2 and 3) assessing the safety, tolerability and PK of one to four TAF 110 mg implants releasing between 0.25 mg and 1 mg daily in 54 healthy women at low risk for HIV infection. Data from this phase I trial will be used to determine the dosing, implant location and implant replacement interval for the phase II trial.The phase II component (Group 4) will assess extended safety, PK, tolerability and acceptability of the implant in 490 at risk women, randomised in a 1:1 ratio to the TAF implant and placebo tablet or to the placebo implant and an oral pre-exposure prophylaxis tablet. Safety will be assessed by calculating the percentage change in creatinine clearance from baseline at weeks 4, 12, 24, 36, 72, 96 and 120, compared with the percentage change in the control group.

ETHICS AND DISSEMINATION

The South African Health Products Regulatory Authority and the University of KwaZulu-Natal's Biomedical Research Ethics Committee have approved the trial. Results will be disseminated through open access peer reviewed publications, conference presentations, public stakeholder engagement and upload of data into the clinical trials registry.

TRIAL REGISTRATION NUMBER

PACTR201809520959443.

Staphylococcus aureus colonization and non-influenza respiratory viruses: Interactions and synergism mechanisms

Viral infections of the respiratory tract can be complicated by bacterial superinfection, resulting in a significantly longer duration of illness and even a fatal outcome. In this review, we focused on interactions between S. aureus and non-influenza viruses. Clinical data evidenced that rhinovirus infection may increase the S. aureus carriage load in humans and its spread. In children, respiratory syncytial virus infection is associated with S. aureus carriage. The mechanisms by which some non-influenza respiratory viruses predispose host cells to S. aureus superinfection can be summarized in three categories: i) modifying expression levels of cellular patterns involved in S. aureus adhesion and/or internalization, ii) inducing S. aureus invasion of epithelial cells due to the disruption of tight junctions, and iii) decreasing S. aureus clearance by altering the immune response. The comprehension of pathways involved in S. aureus-respiratory virus interactions may help developing new strategies of preventive and curative therapy.

Altered release of regulated upon activation, normal T-cell expressed and secreted protein from human, normal platelets: contribution of distinct HIV-1MN gp41 peptides

Platelets can bind HIV and, in turn, be altered in with respect to and function during HIV progression. This study examines the secretion of normal platelets after exposure to recombinant HIV-1MN gp120 or gp41 peptides. There was a modest but significant decrease in regulated upon activation, normal T-cell expressed and secreted protein production in the presence of two out of 10 peptides, which was restored by monoclonal antibodies to gp41. Our data provide novel information on possible primary interactions between platelets and HIV env proteins.

Multicenter evaluation of the ENTEROVIRUS R-gene real-time RT-PCR assay for the detection of enteroviruses in clinical specimens

BACKGROUND

The rapid molecular diagnosis of enteroviral meningitis has been shown important for an adequate management of the patients.

OBJECTIVES

A new CE-marked real-time RT-PCR assay (ENTEROVIRUS R-gene, Argene) was evaluated in two university hospital virology laboratories.

STUDY DESIGN

Reactivity, analytical sensitivity and specificity were evaluated using 54 prototype and 173 clinical human enterovirus (HEV) strains, a 12-sample HEV proficiency panel, and 30 non-HEV microorganisms. The clinical performance of the ENTEROVIRUS R-gene assay was evaluated by testing 197 cerebrospinal fluid (CSF) and 103 respiratory specimens, comparatively to the routinely used diagnostic techniques.

RESULTS

Sixty-four out of the 65 HEV serotypes tested were detected. The analytical sensitivity ranged between 10(-2.64) and 10(2.39)TCID(50)/50 microl. Cross-reactivity was observed with four human rhinoviruses. On 59 CSF specimens analyzed prospectively, the results of the ENTEROVIRUS R-gene assay showed a 94.8% concordance with those of the Smart enterovirus (EV) assay (Cepheid). On 138 CSF specimens tested retrospectively, the results of the ENTEROVIRUS R-gene assay showed a 97.1% concordance with those of either the GeneXpert EV assay (Cepheid) or the in-house RT-PCR HEV assays used at the time of specimen collection. On 103 respiratory specimens, the concordance between the results of the ENTEROVIRUS R-gene assay and those of the routine RT-PCRs or viral culture was 90.2% and 96.1% before and after retest, respectively.

CONCLUSIONS

The new test was found able to detect a large panel of enterovirus serotypes; it was sensitive when used on clinical specimens; and, easy and rapid to perform on a routine basis.

[Emergent viral threats in blood transfusion]

During the last 20 years, the safety of blood products increased dramatically with regard to the infectious risk and notably to that represented by retroviruses (HIV and HTLV) and hepatitis B and C viruses. The aim of this review is to identify the residual and emergent viral threats that could be responsible for the occurring of new contaminations in the receivers of blood products. Beside many other viruses (HHV-8, erythrovirus B19, hepatitis A and E viruses...), a special attention has been paid to emerging arbovirus diseases (West Nile virus infection, dengue, chikungunya) that threaten to occur in the French metropolitan area following the implantation in Europe of the mosquito Aedes albopictus, the main vector of dengue and chikungunya in temperate regions. Another blood-linked risk, notably in United Kingdom and France, is the prion agent responsible for the variant form of the Creutzfeldt-Jakob disease. The review is concluded by a brief overview of the measures aimed to control these emergences, including the exclusion of at-risk donors, the diagnostic tests able to detect a specific agent, the leukocyte reduction of labile blood products, and the physical or chemical treatments aiming the nonspecific inactivation of infectious agents potentially present in blood without impairing significantly the physiological properties of blood compounds. The ability to control prospectively the new viral risks linked to blood products is a challenge for the preservation of the confidence of both clinicians and receivers in the safety of blood transfusion.

Conversion of prevalence survey data on nosocomial infections to incidence estimates: a simplified tool for surveillance?

We calculated the incidence of nosocomial infection in 2 intensive care units (ICUs) on the basis of prevalence data recorded from 1997 through 2002 and compared these estimates to cumulative incidences measured in the 2 ICUs during the same period to investigate the feasibility and the reliability of converting prevalence data to incidence estimates. Decreases in the calculated and measured incidences over time in the ICUs were found to be statistically significantly related.