Utility of beta-glucan for the diagnosis of invasive fungal infections

(1,3)-b-D-glucan is a component of the fungal cell wall. New assays have made it possible to detect this molecule in a variety of clinical samples such as blood, cerebrospinal fluid, and bronchioalveolar lavage fluid. Detection of this molecule through several assays has been validated as an adjunct method to diagnose invasive fungal infections. With several decades of data and recent positive meta-analyses, these assays have now been sufficiently studied and are ready to enter the mainstream of diagnosis in medical mycology.

Decrease in the prevalence of hepatitis B and a low prevalence of hepatitis C virus infections in the general population of the Seychelles.

A serological survey of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections was carried out on a random sex- and age-stratified sample of 1006 individuals aged 25-64 years in the Seychelles islands. Anti-HBc and anti-HCV antibodies were detected using commercially available enzyme-linked immunosorbent assays (ELISA), followed by a Western blot assay in the case of a positive result for anti-HCV. The age-adjusted seroprevalence of anti-HBc antibodies was 8.0% (95% CI: 6.5-9.9%) and the percentage prevalence among males/females increased from 7.0/3.1 to 19.1/13.4 in the age groups 25-34 to 55-64 years, respectively. Two men and three women were positive for anti-HCV antibodies, with an age-adjusted seroprevalence of 0.34% (95% CI: 0.1-0.8%). Two out of these five subjects who were positive for anti-HCV also had anti-HBc antibodies. The seroprevalence of anti-HBc was significantly higher in unskilled workers, persons with low education, and heavy drinkers. The age-specific seroprevalence of anti-HBc in this population-based survey, which was conducted in 1994, was approximately three times lower than in a previous patient-based survey carried out in 1979. Although there are methodological differences between the two surveys, it is likely that the substantial decrease in anti-HBc prevalence during the last 15 years may be due to significant socioeconomic development and the systematic screening of blood donors since 1981. Because hepatitis C virus infections are serious and the cost of treatment is high, the fact that the prevalence of anti-HCV antibodies is at present low should not be an argument for not screening blood donors for anti-HCV and eliminating those who are positive.

The course of malaria in mice: major histocompatibility complex (MHC) effects, but no general MHC heterozygote advantage in single-strain infections.

A general MHC-heterozygote advantage in parasite-infected organisms is often assumed, although there is little experimental evidence for this. We tested the response of MHC-congenic mice (F2 segregants) to malaria and found the course of infection to be significantly influenced by MHC haplotype, parasite strain, and host gender. However, the MHC heterozygotes did worse than expected from the average response of the homozygotes.

Characteristics and outcome of 27 elbow periprosthetic joint infections: results from a 14-year cohort study of 358 elbow prostheses.

Elbow arthroplasty is increasingly performed in patients with rheumatic and post-traumatic arthritis. Data on elbow periprosthetic joint infection (PJI) are limited. We investigated the characteristics and outcome of elbow PJI in a 14-year cohort of total elbow arthroplasties in a single centre. Elbow prosthesis, which were implanted between 1994 and 2007 at Schulthess Clinic in Zurich, were retrospectively screened for infection. PJI was defined as periprosthetic purulence, the presence of sinus tract or microbial growth. A Kaplan-Meier survival method and Cox proportional hazard analysis were performed. Of 358 elbow prostheses, PJI was identified in 27 (7.5%). The median patient age (range) was 61 (39-82) years; 63% were females. Seventeen patients (63%) had a rheumatic disorder and ten (37%) had osteoarthritis. Debridement and implant retention was performed in 78%, followed by exchange or removal of the prosthesis (15%) or no surgery (7%).The relapse-free survival (95% CI) was 79% (63-95%) after 1 year and 65% (45-85%) after 2 years. The outcome after 2 years was significantly better when patients were treated according to the algorithm compared to patients who were not (100% vs. 33%, p <0.05). In 21 patients treated with debridement and retention, the cure rate was also higher when the algorithm was followed (100% vs. 11%, p <0.05). The findings of the present study suggest that the treatment algorithm developed for hip and knee PJI can be applied to elbow PJI. With proper patient selection and antimicrobial therapy, debridement and retention of the elbow prosthesis is associated with good treatment outcome.

Nouvelles méthodes pour le diagnostic des infections liées aux implants [New methods for the diagnosis of implant-associated infections]

For successful treatment of prosthetic joint infection, the identification of the infecting microorganism is crucial. Cultures of synovial fluid and intraoperative periprosthetic tissue represent the standard method for diagnosing prosthetic joint infection. Rapid and accurate diagnostic tools which can detect a broad range of causing microorganisms and their antimicrobial resistance are increasingly needed. With newer diagnostic techniques, such as sonication of removed implants, microcalorimetry, molecular methods and mass spectrometry, the sensitivity has been significantly increased. In this article, we describe the conventional and newer diagnostic techniques with their advantages and potential future applications.

Physiopathologie et prévention des infections liées aux accès vasculaires [Pathophysiology and prevention of intravascular catheter-related infection]

Les infections liées aux accès vasculaires sont à l'origine d'une proportion importante des infections nosocomiales. Elles comprennent leur colonisation par des micro-organismes, les infections du site d'insertion et les bactériémies et fongémies qui leur sont associées ou attribuées. Une bactériémie complique l'insertion de 3 à 5 % des voies veineuses, correspondant à une incidence de 2 à 14 épisodes pour 1000 jourcathéters. Cette proportion ne représente toutefois que la partie visible de l'iceberg puisque la plupart des épisodes de sepsis clinique sans foyer infectieux associé sont également considérés comme liés aux accès vasculaires. Après un rappel de leur physiopathologie, cet article passe en revue les éléments importants pour leur prévention, y compris ceux concernant l'utilisation de cathéters imprégnés de désinfectants ou d'antibiotiques. Pour terminer, nous discutons en détail les stratégies préventives globales. Fondées sur la prise en compte d'un ensemble d'éléments spécifiques, ces approches sont centrées sur l'éducation du personnel au respect des règles d'hygiène de base et sur l'introduction de recommandations précises pour l'insertion et l'utilisation des accès vasculaires.

CHARACTERIZATION OF NrsZ, A NOVEL SMALL REGULATORY NON-CODING RNA INVOLVED IN THE ADAPTATION OF PSEUDOMONAS AERUGINOSA PAO1

The opportunistic ubiquitous pathogen Pseudomonas aeruginosa strain PAOl is a versatile Gram-negative bacterium that has the extraordinary capacity to colonize a wide diversity of ecological niches and to cause severe and persistent infections in humans. To ensure an optimal coordination of the genes involved in nutrient utilization, this bacterium uses the NtrB/C and/or the CbrA/B two-component systems, to sense nutrients availability and to regulate in consequence the expression of genes involved in their uptake and catabolism. NtrB/C is specialized in nitrogen utilization, while the CbrA/B system is involved in both carbon and nitrogen utilization and both systems activate their target genes expression in concert with the alternative sigma factor RpoN. Moreover, the NtrB/C and CbrA/B two- component systems regulate the secondary metabolism of the bacterium, such as the production of virulence factors. In addition to the fine-tuning transcriptional regulation, P. aeruginosa can rapidly modulate its metabolism using small non-coding regulatory RNAs (sRNAs), which regulate gene expression at the post-transcriptional level by diverse and sophisticated mechanisms and contribute to the fast physiological adaptability of this bacterium. In our search for novel RpoN-dependent sRNAs modulating the nutritional adaptation of P. aeruginosa PAOl, we discovered NrsZ (Nitrogen regulated sRNA), a novel RpoN-dependent sRNA that is induced under nitrogen starvation by the NtrB/C two-component system. NrsZ has a unique architecture, formed of three similar stem-loop structures (SL I, II and II) separated by variant spacer sequences. Moreover, this sRNA is processed in short individual stem-loop molecules, by internal cleavage involving the endoribonuclease RNAse E. Concerning NrsZ functions in P. aeruginosa PAOl, this sRNA was shown to trigger the swarming motility and the rhamnolipid biosurfactants production. This regulation is due to the NrsZ-mediated activation of rhlA expression, a gene encoding for an enzyme essential for swarming motility and rhamnolipids production. Interestingly, the SL I structure of NrsZ ensures its regulatory function on rhlA expression, suggesting that the similar SLs are the functional units of this modular sRNA. However, the regulatory mechanism of action of NrsZ on rhlA expression activation remains unclear and is currently being investigated. Additionally, the NrsZ regulatory network was investigated by a transcriptome analysis, suggesting that numerous genes involved in both primary and secondary metabolism are regulated by this sRNA. To emphasize the importance of NrsZ, we investigated its conservation in other Pseudomonas species and demonstrated that NrsZ is conserved and expressed under nitrogen limitation in Pseudomonas protegens Pf-5, Pseudomonas putida KT2442, Pseudomonas entomophila L48 and Pseudomonas syringae pv. tomato DC3000, strains having different ecological features, suggesting an important role of NrsZ in the adaptation of Pseudomonads to nitrogen starvation. Interestingly the architecture of the different NrsZ homologs is similarly composed by SL structures and variant spacer sequences. However, the number of SL repetitions is not identical, and one to six SLs were predicted on the different NrsZ homologs. Moreover, NrsZ is processed in short molecules in all the strains, similarly to what was previously observed in P. aeruginosa PAOl, and the heterologous expression of the NrsZ homologs restored rhlA expression, swarming motility and rhamnolipids production in the P. aeruginosa NrsZ mutant. In many aspects, NrsZ is an atypical sRNA in the bacterial panorama. To our knowledge, NrsZ is the first described sRNA induced by the NtrB/C. Moreover, its unique modular architecture and its processing in similar short SL molecules suggest that NrsZ belongs to a novel family of bacterial sRNAs. -- L'agent pathogène opportuniste et ubiquitaire Pseudomonas aeruginosa souche PAOl est une bactérie Gram négative versatile ayant l'extraordinaire capacité de coloniser différentes niches écologiques et de causer des infections sévères et persistantes chez l'être humain. Afin d'assurer une coordination optimale des gènes impliqués dans l'utilisation de différents nutriments, cette bactérie se sert de systèmes à deux composants tel que NtrB/C et CbrA/B afin de détecter la disponibilité des ressources nutritives, puis de réguler en conséquence l'expression des gènes impliqués dans leur importation et leur catabolisme. Le système NtrB/C régule l'utilisation des sources d'azote alors que le système CbrA/B est impliqué à la fois dans l'utilisation des sources de carbone et d'azote. Ces deux systèmes activent l'expression de leurs gènes-cibles de concert avec le facteur sigma alternatif RpoN. En outre, NtrB/C et CbrA/B régulent aussi le métabolisme secondaire, contrôlant notamment la production d'importants facteurs de virulence. En plus de toutes ces régulations génétiques fines ayant lieu au niveau transcriptionnel, P. aeruginosa est aussi capable de moduler son métabolisme en se servant de petits ARNs régulateurs non-codants (ARNncs), qui régulent l'expression génétique à un niveau post- transcriptionnel par divers mécanismes sophistiqués et contribuent à rendre particulièrement rapide l'adaptation physiologique de cette bactérie. Au cours de nos recherches sur de nouveaux ARNncs dépendant du facteur sigma RpoN et impliqués dans l'adaptation nutritionnelle de P. aeruginosa PAOl, nous avons découvert NrsZ (Nitrogen regulated sRNA), un ARNnc induit par la cascade NtrB/C-RpoN en condition de carence en azote. NrsZ a une architecture unique, composée de trois structures en tige- boucle (TB I, II et III) hautement similaires et séparées par des « espaceurs » ayant des séquences variables. De plus, cet ARNnc est clivé en petits fragments correspondant au trois molécules en tige-boucle, par un processus de clivage interne impliquant l'endoribonucléase RNase E. Concernant les fonctions de NrsZ chez P. aeruginosa PAOl, cet ARNnc est capable d'induire la motilité de type « swarming » et la production de biosurfactants, nommés rhamnolipides. Cette régulation est due à l'activation par NrsZ de l'expression de rhlA, un gène essentiel pour la motilité de type swarming et pour la production de rhamnolipides. Étonnamment, la structure TB I est capable d'assurer à elle seule la fonction régulatrice de NrsZ sur l'expression de rhlA, suggérant que ces molécules TBs sont les unités fonctionnelles de cet ARNnc modulaire. Cependant, le mécanisme moléculaire par lequel NrsZ active l'expression de rhlA demeure à ce jour incertain et est actuellement à l'étude. En plus, le réseau de régulations médiées par NrsZ a été étudié par une analyse de transcriptome qui a indiqué que de nombreux gènes impliqués dans le métabolisme primaire ou secondaire seraient régulés par NrsZ. Pour accentuer l'importance de NrsZ, nous avons étudié sa conservation dans d'autres espèces de Pseudomonas. Ainsi, nous avons démontré que NrsZ est conservé et exprimé en situation de carence d'azote par les souches Pseudomonas protegens Pf-5, Pseudomonas putida KT2442, Pseudomonas entomophila L48, Pseudomonas syringae pv. tomato DC3000, quatre espèces ayant des caractéristiques écologiques très différentes, suggérant que NrsZ joue un rôle important dans l'adaptation du genre Pseudomonas envers la carence en azote. Chez toutes les souches étudiées, les différents homologues de NrsZ présentent une architecture similaire faite de TBs conservées et d'espaceurs. Cependant, le nombre de TBs n'est pas identique et peut varier de une à six copies selon la souche. Les différentes versions de NrsZ sont clivées en petites molécules dans ces quatre souches, comme il a été observé chez P. aeruginosa PAOl. De plus, l'expression hétérologue des différentes variantes de NrsZ est capable de restaurer l'expression de rhlA, la motilité swarming et la production de rhamnolipides dans une souche de P. aeruginosa dont nrsZ a été inactivé. Par bien des aspects, NrsZ est un ARNnc atypique dans le monde bactérien. À notre connaissance, NrsZ est le premier ARNnc décrit comme étant régulé par le système NtrB/C. De plus, son unique architecture modulaire et son clivage en petites molécules similaires suggèrent que NrsZ appartient à une nouvelle famille d'ARNncs bactériens.

Effectiveness of organised versus opportunistic mammography screening.

BACKGROUND: Detailed comparison of effectiveness between organised and opportunistic mammography screening operating in the same country has seldom been carried out. PATIENTS AND METHODS: Prognostic indicators, as defined in the European Guidelines, were used to evaluate screening effectiveness in Switzerland. Matching of screening programmes' records with population-based cancer registries enabled to compare indicators of effectiveness by screening and detection modality (organised versus opportunistic screening, unscreened, interval cancers). Comparisons of prognostic profile were also drawn with two Swiss regions uncovered by service screening of low and high prevalence of opportunistic screening, respectively. RESULTS: Opportunistic and organised screening yielded overall little difference in prognostic profile. Both screening types led to substantial stage shifting. Breast cancer prognostic indicators were systematically more favourable in Swiss regions covered by a programme. In regions without a screening programme, the higher the prevalence of opportunistic screening, the better was the prognostic profile. CONCLUSIONS: Organised screening appeared as effective as opportunistic screening. Mammography screening has strongly influenced the stage distribution of breast cancer in Switzerland, and a favourable impact on mortality is anticipated. Extension of organised mammography screening to the whole of Switzerland can be expected to further improve breast cancer prognosis in a cost-effective way.

Complicated intra-abdominal infections in Europe: preliminary data from the first three months of the CIAO Study.

The CIAO Study is a multicenter observational study currently underway in 66 European medical institutions over the course of a six-month study period (January-June 2012).This preliminary report overviews the findings of the first half of the study, which includes all data from the first three months of the six-month study period.Patients with either community-acquired or healthcare-associated complicated intra-abdominal infections (IAIs) were included in the study.912 patients with a mean age of 54.4 years (range 4-98) were enrolled in the study during the first three-month period. 47.7% of the patients were women and 52.3% were men. Among these patients, 83.3% were affected by community-acquired IAIs while the remaining 16.7% presented with healthcare-associated infections. Intraperitoneal specimens were collected from 64.2% of the enrolled patients, and from these samples, 825 microorganisms were collectively identified.The overall mortality rate was 6.4% (58/912). According to univariate statistical analysis of the data, critical clinical condition of the patient upon hospital admission (defined by severe sepsis and septic shock) as well as healthcare-associated infections, non-appendicular origin, generalized peritonitis, and serious comorbidities such as malignancy and severe cardiovascular disease were all significant risk factors for patient mortality.White Blood Cell counts (WBCs) greater than 12,000 or less than 4,000 and core body temperatures exceeding 38°C or less than 36°C by the third post-operative day were statistically significant indicators of patient mortality.

Upper and lower respiratory tract viral infections and acute graft rejection in lung transplant recipients.

Background: Lung transplant recipients are frequently exposed to respiratory viruses and are particularly at risk for severe complications. The aim of this study was to assess the association among the presence of a respiratory virus detected by molecular assays in bronchoalveolar lavage (BAL) fluid, respiratory symptoms, and acute rejection in adult lung transplant recipients. Methods: Upper (nasopharyngeal swab) and lower (BAL) respiratory tract specimens from 77 lung transplant recipients enrolled in a cohort study and undergoing bronchoscopy with BAL and transbronchial biopsies were screened using 17 different polymerase chain reaction-based assays. Result: BAL fluid and biopsy specimens from 343 bronchoscopic procedures performed in 77 patients were analyzed. We also compared paired nasopharyngeal and BAL fluid specimens collected in a subgroup of 283 cases. The overall viral positivity rate was 29.3% in the upper respiratory tract specimens and 17.2% in the BAL samples (). We observed a significant association P < .001 between the presence of respiratory symptoms and positive viral detection in the lower respiratory tract (Pp. 012). Conversely, acute rejection was not associated with the presence of viral infection (odds ratio, 0.41; 95% confidence interval, 0.20-0.88). The recovery of lung function was significantly slower when acute rejection and viral infection were both present. Conclusions: A temporal relationship exists between acute respiratory symptoms and positive viral nucleic acid detection in BAL fluid from lung transplant recipients. We provide evidence suggesting that respiratory viruses are not associated with acute graft rejection during the acute phase of infection.

Impact of chlorhexidine-impregnated sponges on catheter-related infections rate

INTRODUCTION. Multimodal strategy targeted at prevention of catheter-related infection combine education to general measures of hygiene with specific guidelines for catheter insertion and dressing (1). OBJECTIVES. In this context, we tested the introduction of chlorhexidine(CHX)-impregnated sponges (2). METHODS. In our 32-beds mixed ICU, prospective surveillance of primary bacteremia and of microbiologically documented catheter-related bloodstream infections (CRBSI) is performed according to standardized definitions. New guidelines for central venous catheter (CVC) dressing combined a CHX-impregnated sponge (BioPatch_) with a transparent occlusive dressing (Tegaderm _) and planning for refection every 7 days. To contain costs, Biopatch_ was used only for internal jugular and femoral sites. Other elements of the prevention were not modified (overall compliance to hand hygiene 65-68%; non coated catheters except for burned patients [173 out of 9,542 patients];maximal sterile barriers for insertion; alcoholic solution ofCHXfor skin disinfection). RESULTS. Median monthly CVC-days increased from 710, to 749, 855 and 965 in 2006, 2007, 2008 and 2009, respectively (p\0.01). Following introduction of the new guidelines (4Q2007), the average monthly rate of infections decreased from 3.7 (95% CI: 2.6-4.8) episodes/1000 CVC-days over the 24 preceding months to 2.2 (95% CI: 1.5-2.8) over the 24 following months (p = 0.031). Dressings needed to be changed every 3-4 days. The decrease of catheter-related infections we observed in all consecutive admitted patients is comparable to that recently showed in a placeborandomized trial2. Further generalization to all CVC and arterial catheters access may be justified. CONCLUSIONS. Our data strongly suggest that combined with occlusive dressings, CHXimpregnated sponges for dressing of all CVC catheters inserted in internal jugular and/or femoral sites, significantly reduces the rate of primary bacteremia and CRBSI. REFERENCES. (1) Eggimann P, Harbarth S, Constantin MN, Touveneau S, Chevrolet JC, Pittet D. Impact of a prevention strategy targeted at vascular-access care on incidence of infections acquired in intensive care. Lancet 2000; 355:1864-1868. (2) Timsit JF, Schwebel C, Bouadma L, Geffroy A, Garrouste-Org, Pease S et al. Chlorhexidine- impregnated sponges and less frequent dressing changes for prevention of catheter-related infections in critically ill adults: a randomized controlled trial. JAMA 2009; 301(12):1231-1241.

Frequent accesses to totally implanted vascular ports in pediatric oncology patients are associated with higher infection rates.

PURPOSE: Totally implanted vascular (TIVA) ports are used in children for repeated blood samples or intravenous treatments. We have recently published a prospective evaluation of surgical incidents and early complications associated with these devices. This work is the final part of the same study, assessing late complications over a follow-up of 2 yrs. METHODS: From January 2006 to January 2008, children older than 1 yr of age with a diagnosis of solid or blood cell malignancy were included. Insertion technique and care of the device were standardized. Every manipulation was prospectively recorded by specialized nurses. Obstruction was documented clinically. When bacteremia was suspected, routine central and peripheral blood cultures were drawn. RESULTS: Forty-five consecutive patients were enrolled in the study. Mean age at the time of the procedure was 8.5 yrs. There was no catheter-related infection within the first 4 weeks post-surgery. No device had to be removed because of infection or obstruction during follow-up. Frequent accesses to the port (=3 per day over a 10-day period) were associated with an 8-fold risk of infection. CONCLUSION: Insertion and use of TIVA devices were frequently associated with complications. No device had to be removed because of infection or obstruction over the follow-up period, although no prophylactic antibiotic agent was used. Restrictive use of antibiotics may prevent opportunistic infection. Frequent access to the device was significantly associated with line infection (odds ratio=8.43). No risk factor was identified for obstruction which occurred at a rate of 5.3 per 10,000 accesses.