Co-infection et surinfection bactérienne chez les patients hospitalisés pour COVID-19: une étude rétrospective monocentrique

Introduction

Durant la pandémie de COVID-19, la prescription d’antibiotique a été importante. Cependant, les surinfections et co-infections bactériennes associées aux coronavirus sont peu décrites, et concernent principalement les patients de soins intensifs.

Matériels et méthodes

Une étude observationnelle rétrospective monocentrique a été menée dans notre CHU du 26/02/2020 au 22/04/2020. Ont été inclus tous les patients hospitalisés pour une COVID-19 (PCR respiratoire positive à SARS-CoV-2 ou atteinte scannographique compatible) hors service de réanimation et présentant une infection bactérienne documentée par un prélèvement bactériologique positif parmi: prélèvement respiratoire (ECBC, aspiration bronchique, LBA), hémoculture, antigénurie légionnelle ou pneumocoque, ou PCR nasopharyngée (Bordetella pertussis, Mycoplasma pneumoniae et légionnelle). Les données bactériologiques ont été obtenues par les laboratoires de bactériologie et virologie et les données cliniques recueillies à partir du dossier médical des patients.

Résultats

Au total, 2710 prélèvements ont été réalisés chez 778 patients hospitalisés: 957 hémocultures, 169 ECBC, 3 aspirations bronchiques, 2 LBA, 537 PCR nasopharyngées, 517 antigénuries légionnelle et 525 antigénuries pneumocoque. Quarante et un prélèvements étaient positifs (1,5 %) dont quatorze ont été considérés comme une colonisation par les cliniciens. Vingt neuf prélèvements positifs (1,1 %) ont été considérés comme pathogènes chez 27 patients (3,5 %): 15 ECBC, 2 aspirations bronchiques, 1 LBA, 7 hémocultures, 2 antigénuries et 4 PCR nasopharyngées. Parmi les 27 patients, 18 (66,7 %) avaient des comorbidités dont 10 (37 %) une pathologie respiratoire chronique. Huit patients (29,6 %) étaient sous traitement immunosuppresseur au long cours et 15 (55,6 %) ont reçu des corticoïdes ou autres traitements immunomodulateurs pour la COVID-19. Le delais entre l’apparition des symptômes de COVID-19 et la survenue de la surinfection bactérienne était en moyenne de 11 jours. Les arguments en faveur d’une surinfection étaient l’augmentation des besoins en oxygène (n = 22, 81,5 %), la toux expectorante (n= 20, 74,0 %) ou la modification de la toux (n = 5, 18,5 %) et la présence de fièvre (n= 5, 18,5 %). Un patient avait un tableau de sepsis. Les pathogènes les plus fréquemment retrouvés nétaient: Pseudomonas aeruginosa (n = 8, 29,6 %), Staphylococcus aureus (n = 5, 18,5 %), Streptococcus pneumoniae (n = 4, 14,8 %) et Enterococcus faecalis (n = 3, 11,1 %). Quatre patients (0,5 %) avaient une co-infection à bactérie intracellulaire: 2 à Bordetella pertussis et 2 à Mycoplasma pneumoniae. Aucune antigénurie légionnelle n’est revenue positive.

Conclusion

Le taux de surinfections et de co-infections bactériennes dans la COVID-19 semble faible. Ce faible taux est en faveur d’une utilisation limitée des antibiotiques dans la prise en charge de la COVID-19.

Récurrences symptomatiques de COVID-19 confirmées après guérison clinique d’un premier épisode : rechute, réinfection ou rebond inflammatoire ?

Introduction

Bien que, par analogie aux autres coronavirus, la maladie COVID-19 induite par SARS-CoV-2 ait été initialement supposée monophasique et transitoirement immunisante, de rares publications rapportent des patients avec 2^e épisode. L’objectif de cette étude est de décrire les caractéristiques cliniques, la séquence moléculaire de détection virale, et le devenir de patients présentant 2 épisodes distincts de COVID-19.

Matériels et méthodes

Une étude nationale multicentrique rétrospective observationnelle a recensé les patients présentant un 2^e épisode aigu symptomatique de COVID-19, défini par au moins un signe clinique majeur typique, et une PCR SARS-CoV-2 positive dans les voies aériennes, après :

– au moins 21 jours du début du 1^er épisode ;

– une phase de guérison clinique (retour à l’état antérieur, ou sortie de soins aigus sans oxygène), sans diagnostic différentiel infectieux, thromboembolique ou inflammatoire.

Résultats

Onze patients présentant un 2^e épisode de COVID-19 après une guérison clinique médiane [étendue] de 10 [3–27] jours ont été recensés, et 2 groupes ont été individualisés.

Dans le 1^er, 4 soignants sans comorbidités, d’âge médian 32,5 [19–43] ans, potentiellement re-exposés au SARS-CoV- (3 dans des unités de soins COVID, 1 au domicile), ont présenté aux 2 épisodes une maladie modérée suivie en ambulatoire.

Dans le 2^e groupe, 7 patients comorbides (dont 2 sous chimiothérapie), d’âges médian 73 [54–91] ans, ont été hospitalisés en soins aigus à chaque épisode. Au 1^er, 3 patients ont reçu des corticoïdes. Aucune réexposition au SARS-CoV-2 n’a été documentée, et 3 patients sont décédés, dont 2 de syndrome de détresse respiratoire aiguë sans autre cause que le SARS-CoV-2.

Au 2^e épisode, tous les scanners montraient des signes aigus de COVID-19, 4/9 PCR avaient des « cycle threshold » (CT) < 30, et 1 sur 2 cultures virales pratiquées était positive. La sérologie SARS-CoV-2 après j21 était positive pour 6 patients, et négative pour 3 (du 2^e groupe).

Conclusion

Cette étude exploratoire confirme la possibilité de récurrences de symptômes après guérison clinique d’un premier épisode de COVID-19. La positivité des PCR aux 2^e épisodes (de plusieurs gènes ou avec CT bas) et au moins une culture virale positive, sans diagnostic différentiel identifié, sont en faveur d’une origine virale à ces récurrences. Les caractéristiques des 2 groupes de patients suggèrent soit des réinfections, soit des réactivations virales. Un déficit immunitaire relatif cellulaire ou humoral (par épuisement professionnel ou immuno-senescence, ou traitements immunosuppresseurs), pourraient entraver la clairance virale ou l’efficacité immunitaire antivirale contre les réinfections à SARS-CoV-2. De plus larges études épidémiologiques, et immuno-virologiques sont nécessaires pour comprendre la fréquence et le(s) mécanisme(s) de ces récurrences.

Taste masking as a consequence of the organisation of powder mixes

Usually, chemical or technological operations are used to mask the taste of unpleasant-tasting drugs. To reduce the development cost of such drugs, we propose a new approach which does not require the modification of the existing formulation nor the use of additional costly technological operations. Different particle size fractions of two unpleasant-tasting drugs (niflumic acid and ibuprofen) were blended in binary mixes with different particle size fractions of two non-tasting excipients (ethyl cellulose and hydroxypropyl methylcellulose). By selecting the appropriate mixes of identical composition but different organisations, as predicted from surface energy data, it was possible to use the different organisations to modify the taste of the mixes for a panel of 10 healthy volunteers.

Can the organization of a binary mix be predicted from the surface energy, cohesion parameter and particle size of its components?

PURPOSE

The aim of this study was to relate the organization of several binary mixes with three physical parameters (surface energy, cohesion parameter, and particle size) of various materials blended with each other.

METHODS

Four pharmaceutical compounds were selected for their surface energies and cohesion parameters. Binary mixes were prepared from different sieved fractions. The frequency and nature of the interactions between the particles were observed by scanning electron microscopy.

RESULTS

As expected, interactions were determined by both the energetics and the relative particle size of the two compounds blended, the latter determining the mode of interaction. However, particle size was not the only factor influencing the organization of the blends as, sometimes, small particles of a material would not adhere to the coarser particles of the other. Thus, a surface energy derived parameter ¿(B/A)lambda - (A/B)lambda¿ appears to be a valuable estimating tool of the potentiality of interaction between the particles blended. No correlation between the cohesion parameters of the compounds and the organization of the resulting blends could be found.

CONCLUSIONS

Surface energy and particle size play a major role in the organization of a binary blend. However, they cannot explain separately the interactions observed between the fractions blended as reliable predictions require the use of both characteristics.

Physico-chemical characterization, preparation and performance of poly (methylidene malonate 2.1.2) nanoparticles

The present investigation confirms that initially implemented procedure to produce poly(methylidene malonate 2.1.2) (PMM 2.1.2) nanoparticles (Lescure et al. Pharm Res 1994;11:1270-77) lead to products mostly containing plasticizing oligomers which strongly lowered glass-transition temperature (Tg), dramatically reduced nanoparticle consistency and rendered them too sensitive to solubilization when diluted in an aqueous medium. From MALDI-TOF spectroscopy analysis, performed on intact colloids, emerged some structural information about these oligomeric species which could result from an intramolecular cyclization mechanism occurring soon in the course of the polymerization process. Thus, with the objective of overcoming these drawbacks, this contribution deals with the variations of manufacturing specifications such as pH and magnetic stirring speed to try and modulate molecular weight (MW) of nanoparticle constituents and reduce oligomer concentration. Although the analyses performed on these new nanoparticles were rather encouraging, the colloid formation yield became so low that it required the development of other methodologies, excluding a previous emulsion step, and allowing a controlled production of PMM 2.1.2-made nanoparticles having better physico-chemical characteristics while keeping good pharmaceutical capabilities.

The expanded Hansen approach to solubility parameters. Paracetamol and citric acid in individual solvents

In this study two solubility-parameter models have been compared using as dependent variables the logarithm of the mole fraction solubility, lnX2e, and ln(alpha)/U (originally used in the extended Hansen method), where alpha is the activity coefficient and U is a function of the molar volume of the solute and the volume fraction of the solvent. The results show for the first time the proton-donor and -acceptor hydrogen-bonding capacities of paracetamol, as measured by the acidic and basic partial-solubility parameters. The influence of solvents on the differential scanning calorimetry (DSC) pattern of the solid phases was also studied in relation to the solubility models tested. Citric acid was chosen as a test substance because of its high acidity and its proton donor capacity to form hydrogen bonds with basic solvents. The partial acidic and basic solubility parameters obtained from multiple regression were consistent with this property, validating the model chosen. The results show that the more direct lnX2e variable was more suitable for fitting both models, and the four-parameter model seemed better for describing the interactions between solvent and solute.

Influence of surface free energies and cohesion parameters on pharmaceutical material interaction parameters-theoretical simulations

PURPOSE

The aim of this study was to perform simulations of the influence of surface free energies and cohesion parameters on various interaction parameters within binary systems.

METHODS

Using predictive equations derived from surface free energies and cohesion parameters originally proposed by Wu (2, 3) and by Rowe (4), values of interfacial tension, spreading and reduced spreading coefficients, interaction parameter and strength of interaction were simulated by means of a data processor. The influence of polar and disperse fractions of the two interacting materials was also examined.

RESULTS

From the simulations, boundary conditions could be drawn: minimum interfacial tension, positive spreading coefficient, reduced spreading coefficient superior to unity, maximum value of the interaction parameter or of the strength of interaction.

CONCLUSIONS

Simulations of the various parameters will help the formulator to select proper materials, eg. an agent that will efficiently bind some powdered substrate, a film-forming agent that will properly coat given cores or a material that will enhibit high interaction with a substrate.

Immunochemical characterization of antibody-coated nanoparticles

A new method using surface plasmon resonance (SPR) through the BIAcore was used to demonstrate the specific interaction between an anti-CD4 monoclonal antibody (IOT4a), adsorbed on poly(methylidene malonate 2.1.2) (PMM 2.1.2) nanoparticles, and the CD4 molecule. The results obtained were compared with the interaction of the same immunonanoparticles with rabbit anti-mouse Fc antibodies. The molar ratio (Fc)/(Fab) was 1, suggesting that the same number of epitopes on the Fc and the Fab fragments were accessible after IOT4a adsorption onto nanoparticles. Comparing the observed association rates of free antibody and antibody adsorbed on nanoparticles, the number of molecules of IOT4a antibody on PMM 2.1.2 nanoparticles was estimated as between 2.6 and 3 per nanoparticle. The properties of the antibody-coated nanoparticles are compatible with their use as antibody-targeted pharmacophores.

Folding of the HDV antigenomic ribozyme pseudoknot structure deduced from long-range photocrosslinks

A trans-acting system has been designed in order to explore the three-dimensional structure of the anti-genomic HDV ribozyme. In this system, the substrate (SANT) is associated by base-pairing to the catalytic RNA (RzANT) forming helix H1. RzANT is able to cleave specifically the RNA substrate as well as a deoxysubstrate analogue containing a single ribocytidine at the cleavage site (position -1). This demonstrates that such deoxysubstrate analogues are valuable tools for structural studies of this ribozyme domain. They form however weak complexes with RzANT which is due in part to their ability to fold as stable hairpins unlike the RNA substrate. Using a set of full deoxy or of mixed deoxy-ribo substrate analogues site-specific substituted with the photoaffinity probe deoxy-4-thiouridine, ds4U, at a defined position, we were able to determine a number of long range contacts between the substrate and the ribozyme core. In particular, crosslinks between substrate position -1 and position -2 with residues C15, G19 and C67, thought to be involved in the ribozyme catalytic site, were detected. A three dimensional model of the antigenomic ribozyme system, derived from the structure proposed by Tanner et al. [Current Biol (1994) 4, 488-498] for the genomic system was constructed. Apart from residue deletion or insertion, only minor accommodations were needed to account for all photocrosslinks but one which is attributed to an alternative hybridization of the substrate with the ribozyme. This study therefore further supports the structure proposed by Tanner et al. for the pseudoknot model.

Analysis of human CD4-antibody interaction using the BIAcore system

Interaction between CD4 cell surface protein and HIV-bearing gp120 has been described as the initial step for HIV entry into host cells. Some anti-CD4 antibodies were shown to inhibit this interaction. Biosensor studies using the BIAcore were performed to determine kinetic and thermodynamic parameters of the interaction of one of these antibodies (i.e. IOT4a, clone 13B8-2) with immobilized recombinant soluble CD4 (rsCD4). A non-linear regression method was used to analyze the sensorgrams, showing the existence of a double exponential time curve. A KA of 5.2 x 10(7) M-1 was calculated at 25 degrees C. The complex formation was exothermic (-4.5 kcal.mol-1( and entropically positive (+20 cal.mol-1.K-1). The reaction rate (0.234 x 10(5) M-1.s-1 at 25 degrees C) as well as the enthalpy change of the activated complex (+9.7 kcal.mol-1) are not compatible with a diffusion controlled reaction. The thermodynamic values calculated from equilibrium data corresponded to those calculated from kinetic data confirming the validity of the theoretical approach. As for most antigen-antibody interactions, complex formation was enthalpy driven. The overall positive entropy contribution to the stabilization of the complex is in contrast to that observed for the lysozyme-anti-lysozyme model and is probably due to electrostatic interaction between the epitope and the antibody combining site.

In vitro and in vivo evaluation of progesterone implants based on new biodegradable poly(glutamic and glutamate esters) copolymers

New biodegradable polypeptidic copolymers of glutamic acid and tert-butyloxycarbonylmethyl glutamate were evaluated as implantable drug delivery systems. Three copolymers varying in degrees of esterification, which is inversely proportional to the number of glutamic residues, were selected for their range of hydrophilicity and biodegradation rates. Progesterone-containing implants were then prepared by means of an extrusion process and both in vitro and in vivo evaluations were performed. The effects of drug loading, nature, and pH of release medium were investigated. In vitro/in vivo correlations were established for some types of implants. Finally, mathematical fitting of the data, using published models, helped to better understand the mechanisms governing release.

Preparation and characterization of novel poly(methylidene malonate 2.1.2.)-made nanoparticles

Poly(methylidene malonate 2.1.2.) (PMM 2.1.2.) nanoparticles were prepared in phosphate buffer through emulsion polymerization of monomeric units; the kinetics of the reaction was monitored by spectrophotometry at 400 nm. Average nanoparticle sizes, molecular weights, and biodegradability of this potential drug carrier were determined under various conditions. As previously demonstrated for other similar monomers, i.e. IHCA or IBCA, pH influenced the physico-chemical characteristics of the nanoparticles obtained. Ethanol release from the ester-bearing side chains indicated that the polymers were susceptible to hydrolysis when incubated in basic pH or in rat plasma. A secondary degradation pathway, yielding formaldehyde through a reverse Knoevenagel's reaction, was minimal. Cytotoxicity studies of this new vector, in vitro, against L929 fibroblast cells demonstrated that PMM 2.1.2. nanoparticles were better tolerated than other poly(alkylcyanoacrylate) (PACA) carriers. Pharmacokinetic studies were also carried out to observe the fate of 14C-labelled PMM 2.1.2. nanoparticles after intravenous administration to rats. Forty eight hour post-injection, more than 80% of the radioactivity was recovered in urine and faeces. The body distribution of the polymer was estimated by measuring the radioactivity associated with liver, spleen, lung and kidneys. Five minutes after injection, a maximum of 24 +/- 2% of the total radioactivity was detected in the liver and less than 0.4% in the spleen. The liver-associated radioactivity decreased according to a biphasic profile and less than 8% of the total radioactivity remained after 6 days.

Long-term histopathological study of new polypeptidic biomaterials

The long-term histopathological evaluation of a new class of synthetic polypeptides, the poly(tert-butyloxycarbonylmethyl glutamates), as implantable drug delivery systems is addressed. This evaluation was performed in rat muscles over one year. The histological analysis included the measurement of many parameters, such as the type and thickness of the collagen capsule. The influence of the presence of progesterone, the selected active drug, could also be monitored over time.

Self-cleavage of a 71 nucleotide-long ribozyme derived from hepatitis delta virus genomic RNA

Self-cleavage efficiency of ribozymes derived from hepatitis delta virus (HDV) has been shown to depend on the RNA structure, which in turn may be determined by the length of the considered sequences. Here we describe the construction and functional analysis of a 71 nucleotide-long RNA genomic fragment, Rz71, which carries an 18 nucleotide deletion in a very stable GC-rich stem-loop (stem IV), predicted to be present in several computer-derived secondary structure models. Rz71 is able to undergo self-cleavage under non-denaturing conditions (the t1/2 of the reaction at 37 degrees C is 3 min). The deletion, however, is not neutral, since under the same conditions the non-deleted ribozyme cleaves to 50% in less than 15 sec. Therefore, stem-loop IV seems to play a structural role, not being directly involved in the catalytic reaction, but contributing to the correct positioning of the catalytic core of the HDV ribozyme. Rz71 is the smallest self-cleaving sub-fragment of HDV genomic RNA reported so far.

Acute histopathological response to a new biodegradable polypeptidic polymer for implantable drug delivery system

This article deals with the in vivo evaluation of a new class of synthetic polypeptides, the poly[(tert-butyloxycarbonylmethyl) glutamates], POMEG, as an injectable or implantable drug delivery system. Three different polymers, varying in their degree of esterification, were extruded either with or without progesterone, and finally implanted in rats up to 14 days. Histologic evaluation of the implant sites show evidence of the good biocompatibility of these polymers. In addition, the description of their in vivo behavior, based on microscopic observation of the implanted POMEG rods, enables one to appreciate their potential as a drug delivery system for short- or long-term therapy.

[Diagnosis of hereditary retinopathies in the dog. The value of fluorescein angiography and electrophysiology]

The diagnosis of the hereditary ocular diseases is a very actual question. These affections are divided in two parts: congenital diseases, abiotrophies. The dog that the practitioner has to examine will be: sometimes a puppy, sometimes an adult. In the puppy the diagnosis will be easy in the case of a congenital disease, it will be more difficult in the case of an abiotrophy. In the adult the practitioner will be hesitating between an hereditary or an acquired disease. In all the cases, the diagnosis of the posterior segment diseases and of the amaurosis will be made easier by the data of the fluoresceinic angiography and the electrophysiology (ERG and VEP).

Effect of lysine-acetylsalicylate and phenylbutazone premedication on the protein content of secondary aqueous humour in the dog

Inhibitory effects of the anti-inflammatory agents lysine-acetylsalicylate (LAS) and phenylbutazone (PBZ) on the breakdown of the blood-aqueous barrier by paracentesis were studied in canine eyes using protein determination of ocular fluid. In the untreated eyes the aqueous protein value was raised from 0.29 +/- 0.17 (mean +/- SD) g litre-1 at the initial paracentesis to 14.47 +/- 4.10 g litre-1 at the second paracentesis. Pretreatment with LAS or PBZ had no significant effect on the protein concentration of the primary aqueous humour. However the secondary aqueous protein concentration was only 10.05 +/- 7.00 g litre-1 with LAS and 5.80 +/- 3.83 g litre-1 with PBZ. With both drugs the maximum inhibitory effect was observed on the gammaglobulins and albumin. These results suggest that prostaglandins may be involved in the response of the canine eye to paracentesis and that premedication with LAS or PBZ may be of value in reducing postoperative ocular inflammation.