Clinical impact and cost-consequence analysis of ePlex® blood culture identification panels for the rapid diagnosis of bloodstream infections: a single-center randomized controlled trial.

To assess clinical impact and perform cost-consequence analysis of the broadest multiplex PCR panels available for the rapid diagnosis of bloodstream infections (BSI). Single-center, randomized controlled trial conducted from June 2019 to February 2021 at a French University hospital with an institutional antimicrobial stewardship program. Primary endpoint was the percentage of patients with optimized antimicrobial treatment 12 h after transmission of positivity and Gram stain results from the first positive BC. This percentage was significantly higher in the multiplex PCR (mPCR) group (90/105 = 85.7% %, CI95% [77.5 ; 91.8] vs. 68/107 = 63.6%, CI95% [53.7 ; 72.6]; p < 10- 3) at interim analysis, resulting in the early termination of the study after the inclusion of 309 patients. For patients not optimized at baseline, the median time to obtain an optimized therapy was much shorter in the mPCR group than in the control group (6.9 h, IQR [2.9; 17.8] vs. 26.4 h, IQR [3.4; 47.5]; p = 0.001). Early optimization of antibiotic therapy resulted in a non-statistically significant decrease in mortality from 12.4 to 8.8% (p = 0.306), with a trend towards a shorter median length of stay (18 vs. 20 days; p = 0.064) and a non-significant reduction in the average cost per patient of €3,065 (p = 0.15). mPCR identified all the bacteria present in 88% of the samples. Despite its higher laboratory cost, the use of multiplex PCR for BSI diagnosis leads to early-optimised therapy, seems cost-effective and could reduce mortality and length of stay. Their impact could probably be improved if implemented 24/7.

Species Distribution and Comparison between EUCAST and Gradient Concentration Strips Methods for Antifungal Susceptibility Testing of 112 Aspergillus Section Nigri Isolates.

Aspergillus niger, the third species responsible for invasive aspergillosis, has been considered as a homogeneous species until DNA-based identification uncovered many cryptic species. These species have been recently reclassified into the Aspergillus section Nigri However, little is yet known among the section Nigri about the species distribution and the antifungal susceptibility pattern of each cryptic species. A total of 112 clinical isolates collected from 5 teaching hospitals in France and phenotypically identified as A. niger were analyzed. Identification to the species level was carried out by nucleotide sequence analysis. The MICs of itraconazole, voriconazole, posaconazole, isavuconazole, and amphotericin B were determined by both the EUCAST and gradient concentration strip methods. Aspergillus tubingensis (n = 51, 45.5%) and Aspergillus welwitschiae (n = 50, 44.6%) were the most common species while A. niger accounted for only 6.3% (n = 7). The MICs of azole drugs were higher for A. tubingensis than for A. welwitschiae The MIC of amphotericin B was 2 mg/liter or less for all isolates. Importantly, MICs determined by EUCAST showed no correlation with those determined by the gradient concentration strip method, with the latter being lower than the former (Spearman's rank correlation tests ranging from 0.01 to 0.25 depending on the antifungal agent; P > 0.4). In conclusion, A. niger should be considered as a minority species in the section Nigri The differences in MICs between species for different azoles underline the importance of accurate identification. Significant divergences in the determination of MIC between EUCAST and the gradient concentration strip methods require further investigation.

Chromoblastomycosis and sporotrichosis, two endemic but neglected fungal infections in Madagascar.

Chromoblastomycosis and sporotrichosis are endemic fungal infections of tropical and subtropical regions, including Madagascar. The causal fungi develop in the soil or on plants and infect humans through wounds, either directly (wounding by the plant, through thorns, for example), or through the contact of an existing wound with contaminated soil. For this reason, the lesions predominantly occur on the limbs, and these fungi principally infect people working outside with bare hands and/or feet. The subcutaneous lesions of chromoblastomycosis are initially nodular, subsequently becoming warty, tumoral, cauliflower-like and pruriginous, which promotes dissemination. The chronic nature of the infection and its progression over long periods lead to highly disabling lesions in essentially rural and agricultural populations. The lesions of sporotrichosis are also nodular, but more ulcerous, and they form an extended chain following the route of the lymph vessels. Pus, squamous or skin biopsy specimens are used for the mycological examination of these mycoses. Treatment depends on the severity and form of the lesions and is based on antifungal drugs sometimes combined with physical methods. There has been no study of these infections for more than two decades in Madagascar, despite the large numbers of cases seen by doctors in all parts of the island. The nature, diversity and distribution of the plants responsible for contamination have not been described in Madagascar. In this review, we described these two endemic mycoses in terms of their epidemiological, mycological, clinical and therapeutic characteristics, focusing particularly on Madagascar, which is one of the leading foci of these two infections worldwide.

Multicenter Comparison of the Etest and EUCAST Methods for Antifungal Susceptibility Testing of Candida Isolates to Micafungin.

In vitro susceptibility of 933 Candida isolates, from 16 French hospitals, to micafungin was determined using the Etest in each center. All isolates were then sent to a single center for determination of MICs by the EUCAST reference method. Overall essential agreement between the two tests was 98.5% at ±2 log2 dilutions and 90.2% at ±1 log2 dilutions. Categorical agreement was 98.2%. The Etest is a valuable alternative to EUCAST for the routine determination of micafungin MICs in medical mycology laboratories.

Impact of systemic antifungal therapy on the detection of Candida species in blood cultures in clinical cases of candidemia.

The diagnosis and follow-up of candidemia still rely on blood cultures (BCs). In vitro studies show that antifungals can significantly modify the result of blood culture not containing adsorbing agents. We aimed to evaluate, under clinical conditions, the impact on BC yeast detection of systemic antifungal therapy (SAT). Patients (n = 125) experiencing candidemia at Grenoble University Hospital (France) were included in a 4-year retrospective study. The Plus Aerobic/F (Aerobic) and Plus Anaerobic/F (Anaerobic) bottles, which both contain adsorbing resins and the non-resin selective Mycosis IC/F (Mycosis) bottles, were compared using multivariate hierarchical models adjusted for clinical characteristics. The positivity rate (PR) is decreased in patients with SAT (p < 0.01), abdominal surgery (p = 0.01), and hemodialysis (p = 0.02). In all bottles, SAT reduces PR by a factor of 0.16 (95 % CI: [0.08; 0.32]) and increases the time to positivity (TTP) by a factor of 1.76 ([1.30; 2.40]; p < 0.01). In the presence of SAT, TTP is higher in non-resin bottles (Mycosis) than in resin bottles (RR = 1.76, [1.30; 2.40]); however, the TTP in nonresin and resin bottles remains comparable. Although discordant results are observed with and without SAT (37 and 58 % respectively), we showed that the presence of SAT decreases significantly the agreement rate by a factor of 0.29 (CI: [0.12; 0.68]). The combination of Anaerobic and Mycosis bottles allowed a 100 % positivity rate for C. glabrata. SAT significantly affects BC results. Because they provide additional and complementary results, this study supports the concomitant use of resin and selective bottles, especially in patients receiving SAT.

Pneumocystis jirovecii (Pj) quantitative PCR to differentiate Pj pneumonia from Pj colonization in immunocompromised patients.

Conventional polymerase chain reaction (PCR) in respiratory samples does not differentiate between Pneumocystis pneumonia (PCP) and Pneumocystis jirovecii (Pj) colonization. We used Pj real-time quantitative PCR (qPCR) with the objective to discriminate PCP from Pj colonization in immunocompromised patients. All positive Pj qPCR [targeting the major surface glycoprotein (MSG) gene] obtained in respiratory samples from immunocompromised patients presenting pneumonia at the Grenoble University Hospital, France, were collected between August 2009 and April 2011. Diagnoses were retrospectively determined by a multidisciplinary group of experts blinded to the Pj qPCR results. Thirty-one bronchoalveolar lavages and four broncho aspirations positive for the Pj qPCR were obtained from 35 immunocompromised patients. Diagnoses of definite, probable, and possible PCP, and pneumonia from another etiology were retrospectively made for 7, 4, 5, and 19 patients, respectively. Copy numbers were significantly higher in the "definite group" (median 465,000 copies/ml) than in the "probable group" (median 38,600 copies/ml), the "possible group" (median 1,032 copies/ml), and the "other diagnosis group" (median 390 copies/ml). With the value of 3,160 copies/ml, the sensitivity and specificity of qPCR for the diagnosis of PCP were 100 % and 70 %, respectively. With the value of 31,600 copies/ml, the sensitivity and specificity were 80 % and 100 %, respectively. The positive predictive value was 100 % for results with more than 31,600 copies/ml and the negative predictive value was 100 % for results with fewer than 3,160 copies/ml. qPCR targeting the MSG gene can be helpful to discriminate PCP from Pj colonization in immunocompromised patients, using two cut-off values, with a gray zone between them.

In vitro differential phenotypic characteristics among Type-II Toxoplasma gondii strains from congenital toxoplasmosis in humans.

In France, more than 80% of human congenital toxoplasmosis is attributable to Toxoplasma gondii strains belonging to the type-II lineage, whereas 3 main lineages have been described in Europe. Cell invasion, parasite replication, and cyst formation of type-II strains isolated from congenital infections were compared in a human cell model. The phenotype patterns of the 4 type-II strains studied differed from each other; the 2 strains responsible for asymptomatic infection formed significantly fewer cysts than the 2 strains isolated from symptomatic toxoplasmosis. The capacity to form cysts was different among the type-II strains studied and may be related to the clinical form.

[Real-time PCR in the diagnosis of toxoplasmosis: the way to standardisation?]. / Apport de la PCR quantitative dans le diagnostic de la toxoplasmose: la voie de la standardisation?

Severity of toxoplasmosis is highly correlated to the immune status of the infected individual. Foetus and immunocompromised patient are mostly at risk to develop life threatening forms. In this situation, serological diagnosis gives poor information. DNA detection using polymerase-chain-reaction technology (PCR) has significantly improved the management of this disease. Even so, the growing number of conventional PCR assays has finally led to variable performance results. Real-Time PCR (RT-PCR) in toxoplasmosis has been developed since 2000. This new technology can improve standardisation. Moreover, quantification of parasitic load in samples becomes possible. This review describes the main RT-PCR procedures actually under use and the studies comparing different target genes. The effective benefit of quantification is also discussed. Reducing number of procedures and more systematic external quality control should be considered, in order to improve reliability in PCR results, which has undoubtedly become a major tool in toxoplasmosis diagnosis.

AGS3, an alpha(1-3)glucan synthase gene family member of Aspergillus fumigatus, modulates mycelium growth in the lung of experimentally infected mice.

The cell wall of human fungal pathogen Aspergillus fumigatus protects the fungus against threats from environment and interacts with the host immune system. Alpha(1-3)glucan is the major polysaccharide of Aspergillus fumigatus cell wall, and it has been shown to contribute to the virulence of diverse fungal pathogens. In A. fumigatus, three putative alpha(1-3)glucan synthase genes AGS1, AGS2 and AGS3 have been identified. AGS1 is responsible for cell wall alpha(1-3)glucan biosynthesis, but strains with deletions of either AGS1 or AGS2 are not defective in virulence [Beauvais, A., Maubon, D., Park, S., Morelle, W., Tanguy, M., Huerre, M., Perlin, D.S., Latgé, J. P., 2005. Two alpha(1-3) glucan synthases with different functions in Aspergillus fumigatus. Appl. Environ. Microbiol. 71, 1531-1538]. In contrast, we present evidence that AGS3 is also responsible for cell wall alpha(1-3)glucan biosynthesis and can modulate the virulence of A. fumigatus. An AGS3 deletion strain was found to produce faster and more robust disease than the parental strain in an experimental mouse model of aspergillosis. The apparent hyper-virulence in the AGS3-deleted mutant was correlated with an increased melanin content of the conidial cell wall, a better resistance to reactive oxygen species and a quicker germination rate. These results suggest an indirect role for AGS3 in virulence through an adaptive mechanism.

Two alpha(1-3) glucan synthases with different functions in Aspergillus fumigatus.

Alpha(1-3) glucan is a main component of the Aspergillus fumigatus cell wall. In spite of its importance, synthesis of this amorphous polymer has not been investigated to date. Two genes in A. fumigatus, AGS1 and AGS2, are highly homologous to the AGS genes of Schizosaccharomyces pombe, which encode putative alpha(1-3) glucan synthases. The predicted Ags proteins of A. fumigatus have an estimated molecular mass of 270 kDa. AGS1 and AGS2 were disrupted in A. fumigatus. Both Deltaags mutants have similar altered hyphal morphologies and reduced conidiation levels. Only Deltaags1 presented a reduction in the alpha(1-3) glucan content of the cell wall. These results showed that Ags1p and Ags2p were functionally different. The cellular localization of the two proteins was in agreement with their different functions: Ags1p was localized at the periphery of the cell in connection with the cell wall, whereas Ags2p was intracellularly located. An original experimental model of invasive aspergillosis based on mixed infection and quantitative PCR was developed to analyze the virulence of A. fumigatus mutant and wild-type strains. Using this model, it was shown that the cell wall and morphogenesis defects of Deltaags1 and Deltaags2 were not associated with a reduction in virulence in either mutant. This result showed that a 50% reduction in the content of the cell wall alpha(1-3) glucan does not play a significant role in A. fumigatus pathogenicity.