Untargeted next-generation sequencing-based first-line diagnosis of infection in immunocompromised adults: a multicentre, blinded, prospective study.

OBJECTIVE: Infections are the major cause of morbidity and mortality in immunocompromised patients. Improving microbiological diagnosis in these patients is of paramount clinical importance. METHODS: We performed this multicentre, blinded, prospective, proof-of-concept study, to compare untargeted next-generation sequencing with conventional microbiological methods for first-line diagnosis of infection in 101 immunocompromised adults. Patients were followed for 30 days and their blood samples, and in some cases nasopharyngeal swabs and/or biological fluids, were analysed. At the end of the study, expert clinicians evaluated the results of both methods. The primary outcome measure was the detection rate of clinically relevant viruses and bacteria at inclusion. RESULTS: Clinically relevant viruses and bacteria identified by untargeted next-generation sequencing and conventional methods were concordant for 72 of 101 patients in samples taken at inclusion (κ test=0.2, 95% CI 0.03-0.48). However, clinically relevant viruses and bacteria were detected in a significantly higher proportion of patients with untargeted next-generation sequencing than conventional methods at inclusion (36/101 (36%) vs. 11/101 (11%), respectively, p <0.001), and even when the latter were continued over 30 days (19/101 (19%), p 0.003). Untargeted next-generation sequencing had a high negative predictive value compared with conventional methods (64/65, 95% CI 0.95-1). CONCLUSIONS: Untargeted next-generation sequencing has a high negative predictive value and detects more clinically relevant viruses and bacteria than conventional microbiological methods. Untargeted next-generation sequencing is therefore a promising method for microbiological diagnosis in immunocompromised adults.

Live rubella virus vaccine long-term persistence as an antigenic trigger of cutaneous granulomas in patients with primary immunodeficiency.

Granulomas may develop as a response to a local antigenic trigger, leading to the activation of macrophages and T-lymphocytes. Primary immunodeficiency (PID) is associated with the development of extensive cutaneous granulomas, whose aetiology remains unknown. We performed high-throughput sequencing of the transcriptome of cutaneous granuloma lesions on two consecutive index cases, and RT-PCR in a third consecutive patient. The RA27/3 vaccine strain of rubella virus-the core component of a universally used paediatric vaccine-was present in the cutaneous granuloma of these three consecutive PID patients. Controls included the healthy skin of two patients, non-granulomatous cutaneous lesions of patients with immunodeficiency, and skin biopsy samples of healthy individuals, and were negative. Expression of viral antigens was confirmed by immunofluorescence. Persistence of the rubella vaccine virus was also demonstrated in granuloma lesions sampled 4-5 years earlier. The persistence of the rubella virus vaccine strain in all three consecutive cutaneous granuloma patients with PID strongly suggests a causal relationship between rubella virus and granuloma in this setting.

Electrical properties of the starfish oocyte membranes.

The electrical parameters of both vitelline and plasma membranes have been measured in Marthasterias glacialis oocytes. Voltage-current relationship was studied by an original method using a single intracellular micro-electrode. The analysis of V-I curves obtained by this method reveals rectifying properties of the plasma membrane. Bath application of 1-methyladenine, the hormone wich controls meiosis reinitiation, triggers without lag a partial depolarization of the plasma membrane, whereas the total ionic conductance undergoes typical variations.

[Passive electrical constants of skeletal muscular fibres studied in different muscles of normal and thiamine deficient rats (author's transl)]. / Constantes électriques passives des fibres musculaires squelettiques du rat: etude sur divers muscles normaux et carencés en thiamine

10 Some effects of thiamine deficiency were studied in three skeletal rat muscles, having different proportions of "fast" and "slow" fibres: extensor longus digiti IV (a nearly pure fast muscle), soleus (having a predominant population of slow fibres) and diaphragm muscle (mixed fibre population). 20 Cross section area of fibres (fig. 2) is reduced in thiamine deficient animals, mostly for fast fibres having a glycolytic metabolism, the histochemical profile of which tends to become similar to that of slow fibres, in which oxydative metabolism is predominant, as shown by a marked increase in succinodehydrogenase activity. 30 Measurements of resting potential E, of membranes time constant tau and of fibre input resistance R were performed in normal and thiamine deficient muscles (table I). R and tau were obtained from square pulse analysis, using a double shifted sampling method permitting the use of a single microelectrode. E is not greatly affected by thiamine deficiency. tau changes appear not to be significant, except for fast fibres from extensor longus muscle, where tau is slightly reduced. R is increased in thiamine deficient animals (fig. 3). 40 Changes in R and tau do not exactly follow the predictions of cable theory, if one assumes that a purely dimensional factor is involved. Thus, the view that thiamine deficiency does not change basic passive electrical constants of fibres (membrane specific resistance and capacity, myoplasm resistivity) can be considered only as a first approximation. 50 R and tau values obtained in normal muscles are larger than data taken from other studies. The reasons for this discrepancy are discussed. It is suggested that diet differences may play a role.