Dépistage du personnel de santé exposé au SARS-CoV-2 dans un hôpital universitaire

Introduction

Dans le cadre de la pandémie mondiale au SARS-CoV-2, les personnels de santé (PS) sont professionnellement exposés à ce virus. Dans ce contexte, cette étude présente les données de surveillance de 5704 travailleurs exposés au SARS-CoV-2 d’un centre hospitalier du 17 mars au 20 avril 2020.

Matériels et méthodes

Les PS symptomatiques, les cas contacts et ceux présentant une forte anxiété ont été testés. Le diagnostic de COVID-19 a été réalisé par RT-PCR après prélèvement nasopharyngé.

Résultats

Au cours de cette période, 30,4 % (1735/5704) des PS ont bénéficié de 3057 écouvillons nasaux. Parmi ceux-ci, 8,0 % (138/1735) étaient infectés par le SRAS-CoV-2. Parmi les PS positifs au SARS-CoV-2, 21,7 % étaient asymptomatiques. Dans les unités COVID et les unités non COVID, le nombre de personnes infectées par le SARS-CoV-2 était respectivement de 5,8 % (13/223) et 8,2 % (125/1512) (p = 0,2). Parmi les PS travaillant hors des unités COVID, 6,4 % (12/188) des agents des unités pédiatriques et 8,1 % (126/1547) des agents des unités adultes ou des laboratoires étaient positifs au SARS-CoV-2 (p = 0,4). Parmi les PS des unités adultes, 6,4 % (8/125) provenaient de la médecine interne, 5,6 % (7/125) de la neurologie, 5,6 % (7/125) de la pharmacie et 5,6 % (7/125) du service médical d’urgence. Parmi les personnes atteintes du SARS-CoV2, les infirmières, les internes/médecins et les aides-soignants étaient les catégories professionnelles les plus touchées avec respectivement 30,0 % (40/138), 21,0 % (29/138) et 10,9 % (15/138). Parmi les médecins, la majorité étaient des internes (70,0 % ; 20/29). Les travailleurs de plus de 50 ans étaient moins susceptibles d’être positifs au SARS-CoV-2 (3,8 % ; 14/373) que les autres travailleurs plus jeunes (9,1 % ; 124/1362) (p < 0,001). Aucun cas grave de COVID-19 n’a été signalé dans notre population au cours de cette période.

Conclusion

Parmi les PS positifs détectés, 21,7 % (25/115) étaient asymptomatiques. Ces données soulignent l’importance du dépistage systématique des cas contacts même asymptomatiques et de l’utilisation d’équipements de protection individuelle (EPI) pour éviter la transmission. Le pourcentage des cas positifs diminuait à mesure que l’âge augmentait, en particulier après l’âge de 45 ans. Les personnels de plus de 45 ans, étant plus expérimentées et se sentant plus à risque, ont pu être mieux protégées ou affectées à des services moins à risque ou confinés à domicile. Les PS travaillant dans des unités COVID-19 n’étaient pas plus souvent infectés que ceux travaillant dans des unités non COVID-19, probablement parce qu’ils étaient plus conscients des dangers et des risques associés au SARS-CoV-2, qu’ils disposaient de plus d’équipements de protection individuelle, qu’ils les portaient de manière plus stricte et qu’ils étaient mieux informés et formés.

Mycolactone toxin induces an inflammatory response by targeting the IL-1β pathway: Mechanistic insight into Buruli ulcer pathophysiology

Mycolactone, a lipid-like toxin, is the major virulence factor of Mycobacterium ulcerans, the etiological agent of Buruli ulcer. Its involvement in lesion development has been widely described in early stages of the disease, through its cytotoxic and immunosuppressive activities, but less is known about later stages. Here, we revisit the role of mycolactone in disease outcome and provide the first demonstration of the pro-inflammatory potential of this toxin. We found that the mycolactone-containing mycobacterial extracellular vesicles produced by M. ulcerans induced the production of IL-1β, a potent pro-inflammatory cytokine, in a TLR2-dependent manner, targeting NLRP3/1 inflammasomes. We show our data to be relevant in a physiological context. The in vivo injection of these mycolactone-containing vesicles induced a strong local inflammatory response and tissue damage, which were prevented by corticosteroids. Finally, several soluble pro-inflammatory factors, including IL-1β, were detected in infected tissues from mice and Buruli ulcer patients. Our results revisit Buruli ulcer pathophysiology by providing new insight, thus paving the way for the development of new therapeutic strategies taking the pro-inflammatory potential of mycolactone into account.

Buruli ulcer is a neglected tropical disease occurring mainly in poor rural areas of West and Central Africa. This cutaneous disease is caused by Mycobacterium ulcerans, a bacterium belonging to the same family as M. tuberculosis and M. leprae. The skin lesions are caused by a cytotoxic toxin named mycolactone, also known to act as an immunosuppressor and an anti-inflammatory molecule. However, Buruli ulcer lesions are characterized by a chronic cutaneous inflammation with a recruitment of cellular immune cells trying to counteract M. ulcerans. Our work allows for a reconcilitation of previous observations. We found by in vitro experiment on macrophages that the mycolactone-containing mycobacterial extracellular vesicles produced by M. ulcerans induced the production of IL-1β, a potent pro-inflammatory molecule, while other pro-inflammatory soluble factors are inhibited. We also detected IL-1β protein in a mouse model of M. ulcerans infection as well as in biopsies of Buruli ulcer patients. The pro-inflammatory potential of mycolacone has to be taken into account to understand the full pathophysiology of Buruli ulcer.

[Genesis of specific multisite Medical Intervention Plans in the Brussels Capital Region]

After the november 19th 2015 Paris terrorist attacks, there was a clear need to update the Medical Intervention Plans (MIP) for Mass Casualty Events (MCE) in the Brussels Capital Region (BCR), because they only offered a response to single-site MCE in a peace-time context. We compared the organisation and the resources of the BCR and cities like Paris and Lille, we discussed with our french colleagues and formed a Multisite Attack Task-force that produced a specific multisite MIP, which had to be put to use only a few days after its creation.

Parasitic genotypes appear to differ in leishmaniasis patients compared with asymptomatic related carriers

For numerous infectious diseases affecting humans, clinical manifestations range from asymptomatic forms to severe pathologies. The originality of this study was its focus on asymptomatic carriers of Leishmania infantum in southern France. The fundamental interest in these asymptomatic carriers is that they can be a reservoir of potentially pathogenic microorganisms. It remains to be established whether the parasitic genomes from asymptomatic carriers differ from those of patients. Multilocus microsatellite typing was used to investigate the genetic variation among 36 French strains of L. infantum. Nine Leishmania strains isolated from blood donors (asymptomatic carriers) were compared with 27 strains of L. infantum belonging to zymodemes, MON-1, -33 and -183. These strains were isolated from HIV positive or negative patients with visceral leishmaniasis, cutaneous leishmaniasis, from canine leishmaniasis or from phlebotomine sandflies. Multilocus microsatellite typing data generated using 33 loci were analyzed by a Bayesian model-based clustering algorithm and construction of a phylogenetic tree based on genetic distances. Both analyses structured the MON-1 sample into two main clusters. Furthermore, genetic analysis demonstrated that these nine asymptomatic carrier strains are divided into two clusters grouped with the MON-1 strains. One cluster with seven strains is related to, but different from, human symptomatic strains from the Alpes-Maritimes region whereas the other cluster has the two remaining strains together with canine leishmaniasis strains as well as one strain from a visceral leishmaniasis patient. Genetic diversity among asymptomatic carrier was very weak since the nine Leishmania strains belong to only two genotypes. Genetic differentiations were evidenced between asymptomatic carrier strains and non-asymptomatic carrier strains and especially between asymptomatic carrier and HIV+ populations, although these findings require confirmation with a larger sample size. We believe that our data explore for the first time, the genetic diversity among L. infantum from asymptomatic human carriers and reveal a weak polymorphism compared with Leishmania parasites isolated from human patients.

[Detection of Mycobacterium ulcerans DNA in water bugs collected outside the aquatic environment in Benin]

Hosting of Mycobacterium ulcerans by water bugs is now well established and their vectoring role has been demonstrated experimentally. These findings were recently corroborated by detection of viable bacilli in the saliva of wild water bugs. However, the extent of water bug involvement in M. ulcerans ecology remains unclear and difficult to evaluate due to lack of understanding about water bug biology. The purpose of this study is to describe the first detection of M. ulcerans DNA in the tissue of water bugs captured outside the aquatic environment. This finding supports the hypothesis that water bug migratory behavior contributes not only to the spread of M. ulcerans but also to transmission outside the aquatic environment.

Determinants of Fi,O2 with oxygen supplementation during noninvasive two-level positive pressure ventilation

To maintain arterial oxygen saturation (Sa,O2) above 90% in patients with acute respiratory failure, oxygen (O2) is often added to the circuit of two-level noninvasive positive pressure ventilation (NPPV). However, the final inspiratory oxygen fraction (Fi,O2) is not known. To clarify this issue, the effect of different inspiratory positive airway pressures (IPAP) of the oxygen tubing connection site and the flow rate of O2, on Fi,O2 was assessed. The effects of the tidal volume (VT) and the respiratory rate on the Fi,O2 were then clarified in a model study. The Fi,O2 varied depending on the point where O2 was added to the circuit. When all other variables were constant, the connection closest to the exhaust port (ventilator side) gave the highest Fi,O2. Increases in IPAP led to decreases in Fi,O2. Finally, Fi,O2 increased with O2 flow, although it was difficult to obtain an Fi,O2 >0.30 unless very high O2 flows were used. Paradoxically, NPPV with low IPAP values and without O2 supplementation led to a Fi,O2 <0.21 at the circuit-patient interface. VT and respiratory rate did not appear to influence Fi,O2. To conclude, when using noninvasive positive pressure ventilation with two-level respirators, oxygen should be added close to the exhaust port (ventilator side) of the circuit. If inspiratory airway pressure levels are >12 cmH2O, oxygen flows should be at least 4 L x min(-1).

PaCO(2)/ETCO(2) gradient: early indicator of thrombolysis efficacy in a massive pulmonary embolism

End tidal CO(2) measurement may be helpful in detecting the efficacy of thrombolysis after a massive pulmonary embolism. We report the case of a 76-year-old man with a massive pulmonary embolism, who required early intubation and mechanical ventilation. Thrombolysis with rtpA (total dosage: 60 mg) was initiated. During this procedure, clinical data, arterial blood gases and end-tidal CO(2) with a capnograph were recorded. Before thrombolysis the P(a-ET)CO(2) gradient was raised to 25 mmHg. During thrombolysis, the clinical data improved and the P(a-ET) gradient fell to 14 mmHg. We postulate that the P(a-ET)CO(2) gradient seems to be a reasonable indicator of efficacy of thrombolysis in this setting. However, the gradient did not return to normal values (4-5 mmHg). The possible reasons for this may be that during mechanical ventilation there was a large ventilation-perfusion ratio and the cardiac output may have still reduced. With these limitations, we conclude that the P(a-ET)CO(2) gradient should be evaluated as an indicator of pulmonary reperfusion in massive pulmonary embolism.

Two-level non-invasive positive pressure ventilation in the initial treatment of acute respiratory failure in an emergency department

There are few data on the use of two-level non-invasive positive pressure ventilation (two-level nIPPV) in the initial treatment of severe acute respiratory failure in emergency departments (ED). In a prospective, non-randomized, pilot study, we assessed (1) the feasability of this method in an ED, (2) its effect on clinical and laboratory data, and (3) its effect on the need of intubation and the final outcome of patients. During a 1-year period all eligible patients admitted for acute respiratory failure, with absence of improvement after periods of specific classic treatments, were included in the study. Each patient received a specific classic treatment and two-level nIPPV with a two-level positive pressure ventilator through a face mask. We recorded parameters on admission, after 15 and 45 minutes of nIPPV and at the end of nIPPV. Sixty-two patients were included: 29 with acute pulmonary oedema (APO), 16 with acute exacerbation of chronic obstructive pulmonary disease (COPD), four with asthma, and 13 with various diseases. In the APO-group, we observed a statistically significant improvement of respiratory and pulse rates, diastolic blood pressure, pH, PaCO2 and SaO2. In acute exacerbation of COPD, we observed only a statistical improvement of respiratory and pulse rates without any significant change of PaCO2 and pH. In the two other groups, there was a clinical, gasometric and haemodynamic improvement in all patients. Four patients were intubated and 10 died, but none in the ED or in the first 24 hours after hospital admission. We were able to institute two-level nIPPV for severe acute respiratory failure in an ED without complications. Its addition to the rest of classic specific treatment seems to bring about a rapid improvement of various clinical and laboratory parameters in most patients. We found no deleterious effect of nIPPV when implemented for short periods of time in the emergency department setting.

Emergencies and somatization

The article presents the clinical profile of 72 patients with somatization seen by a psychiatric team at the request of somaticians in a emergency service in St Luc hospital (Brussels-Belgium). These include 37.5% of mood disorders, 11% of psychotic disorders and 20% of serious anxiety disorders. The psychiatric antecedents of these patients are very poor. Only the combined intervention of the somatician and the psychiatrist can improve the compliance and the level of psychiatric care which is very low.

Scintigraphy with Indium-labelled leukocytes in acute pancreatitis

The authors assessed the clinical and prognostic value of abdominal (ASCI) and pulmonary (PSCI) scintiscans with 111Indium-labelled leukocytes in the early phase of acute pancreatitis. A grading scale was constructed for both ASCI (scored 0 to 3) and PSCI (scored 0 to 2) according to the intensity of isotope fixation versus adjacent structures. Results were compared in accordance to the presence or absence of a Ranson's score greater than or equal to 3, the presence or absence of respiratory failure and of late pancreatic complications. ASCI showed an important lack of specificity making its use uninteresting. PSCI revealed a very significant correlation with evaluation by Ranson's score and appears to have a high sensitivity and specificity to evaluate the patients who will develop ARDS or risk of ARDS. This demonstrates the pathophysiological role of leukocytes in the early phase of severe acute pancreatitis. The test might also be a reliable test for the assessment of therapeutic efficiency in acute pancreatitis.