Lower airway microbiota compositions differ between influenza, COVID-19 and bacteria-related acute respiratory distress syndromes

BACKGROUND

Acute respiratory distress syndrome (ARDS) is responsible for 400,000 deaths annually worldwide. Few improvements have been made despite five decades of research, partially because ARDS is a highly heterogeneous syndrome including various types of aetiologies. Lower airway microbiota is involved in chronic inflammatory diseases and recent data suggest that it could also play a role in ARDS. Nevertheless, whether the lower airway microbiota composition varies between the aetiologies of ARDS remain unknown. The aim of this study is to compare lower airway microbiota composition between ARDS aetiologies, i.e. pulmonary ARDS due to influenza, SARS-CoV-2 or bacterial infection.

METHODS

Consecutive ARDS patients according to Berlin's classification requiring invasive ventilation with PCR-confirmed influenza or SARS-CoV-2 infections and bacterial infections (> 105 CFU/mL on endotracheal aspirate) were included. Endotracheal aspirate was collected at admission, V3-V4 and ITS2 regions amplified by PCR, deep-sequencing performed on MiSeq sequencer (Illumina®) and data analysed using DADA2 pipeline.

RESULTS

Fifty-three patients were included, 24 COVID-19, 18 influenza, and 11 bacterial CAP-related ARDS. The lower airway bacteriobiota and mycobiota compositions (β-diversity) were dissimilar between the three groups (p = 0.05 and p = 0.01, respectively). The bacterial α-diversity was significantly lower in the bacterial CAP-related ARDS group compared to the COVID-19 ARDS group (p = 0.04). In contrast, influenza-related ARDS patients had higher lung mycobiota α-diversity than the COVID-19-related ARDS (p = 0 < 01).

CONCLUSION

Composition of lower airway microbiota (both microbiota and mycobiota) differs between influenza, COVID-19 and bacterial CAP-related ARDS. Future studies investigating the role of lung microbiota in ARDS pathophysiology should take aetiology into account.

The gut microbiota composition is linked to subsequent occurrence of ventilator-associated pneumonia in critically ill patients

Ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in critically ill-ventilated patients. Oropharyngeal and lung microbiota have been demonstrated to be associated with VAP occurrence, but the involvement of gut microbiota has not been investigated so far. Therefore, the aim of this study is to compare the composition of the gut microbiota between patients who subsequently develop VAP and those who do not. A rectal swab was performed at admission of every consecutive patient into the intensive care unit (ICU) from October 2019 to March 2020. After DNA extraction, V3-V4 and internal transcribed spacer 2 regions deep-sequencing was performed on MiSeq sequencer (Illumina) and data were analyzed using Divisive Amplicon Denoising Algorithm 2 (DADA2) pipeline. Among 255 patients screened, 42 (16%) patients with invasive mechanical ventilation for more than 48 h were included, 18 (43%) with definite VAP and 24 without (57%). Patients who later developed VAP had similar gut bacteriobiota and mycobiota α-diversities compared to those who did not develop VAP. However, gut mycobiota was dissimilar (β-diversity) between these two groups. The presence of Megasphaera massiliensis was associated with the absence of VAP occurrence, whereas the presence of the fungal genus Alternaria sp. was associated with the occurrence of VAP. The composition of the gut microbiota, but not α-diversity, differs between critically ill patients who subsequently develop VAP and those who do not. This study encourages large multicenter cohort studies investigating the role of gut-lung axis and oropharyngeal colonization in the development of VAP in ICU patients. Trial registration number: NCT04131569, date of registration: 18 October 2019. IMPORTANCE The composition of the gut microbiota, but not α-diversity, differs between critically ill patients who subsequently develop ventilator-associated pneumonia (VAP) and those who do not. Investigating gut microbiota composition could help to tailor probiotics to provide protection against VAP.

Bridging gut microbiota composition with extended-spectrum beta-lactamase Enterobacteriales faecal carriage in critically ill patients (microbe cohort study)

BACKGROUND

The worldwide dissemination of extended spectrum beta-lactamase producing Enterobacteriales (ESBL-E) is of major concern. Microbiota may play a role in the host resistance to colonization with ESBL-E, but the underlying mechanisms remain unknown. We aimed to compare the gut microbiota composition between ESBL-producing E. coli or K. pneumoniae carriers and ESBL-E non-carriers according to the bacterial species.

RESULTS

Among 255 patients included, 11 (4,3%) were colonized with ESBL-producing E. coli and 6 (2,4%) with ESBL-producing K. pneumoniae, which were compared with age- and sex-matched ESBL-E non carriers. While no significant differences were found between ESBL-producing E. coli carriers and non-carriers, gut bacteriobiota α-diversity was decreased in ESBL-K. pneumoniae faecal carriers compared both with non-carriers (p = 0.05), and with ESBL-producing E. coli carriers. The presence of Sellimonas intestinalis was associated with the absence of ESBL-producing E. coli fecal carriage. Campylobacter ureolyticus, Campylobacter hominis, bacteria belonging to Clostridium cluster XI and Saccharomyces sp. were associated with the absence of ESBL-producing K. pneumoniae faecal carriage.

CONCLUSIONS

The composition of the gut microbiota differs between ESBL-producing E. coli and K. pneumoniae faecal carriers suggesting that microbial species should be taken into account when investigating the role of gut microbiota in resistance to gut colonization with ESBL-E.

TRIAL REGISTRATION NUMBER

NCT04131569, date of registration: October 18, 2019.

Lung Mycobiota α-Diversity Is Linked to Severity in Critically Ill Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) affects more than 200 million people worldwide. The chronic course of COPD is frequently worsened by acute exacerbations (AECOPD). Mortality in patients hospitalized for severe AECOPD remains dramatically high, and the underlying mechanisms are poorly understood. Lung microbiota is associated with COPD outcomes in nonsevere AECOPD, but no study specifically investigated severe AECOPD patients. The aim of this study is thus to compare lung microbiota composition between severe AECOPD survivors and nonsurvivors. Induced sputum or endotracheal aspirate was collected at admission from every consecutive severe AECOPD patient. After DNA extraction, the V3-V4 and ITS2 regions were amplified by PCR. Deep-sequencing was performed on a MiSeq sequencer (Illumina); the data were analyzed using DADA2 pipeline. Among 47 patients admitted for severe AECOPD, 25 (53%) with samples of sufficient quality were included: 21 of 25 (84%) survivors and 4 of 25 (16%) nonsurvivors. AECOPD nonsurvivors had lower α-diversities indices than survivors for lung mycobiota but not for lung bacteriobiota. Similar results were demonstrated comparing patients receiving invasive mechanical ventilation (n = 13 [52%]) with those receiving only noninvasive ventilation (n = 12 [48%]). Previous systemic antimicrobial therapy and long-term inhaled corticosteroid therapy could alter the lung microbiota composition in severe AECOPD patients. In acidemic AECOPD, lower lung mycobiota α-diversity is linked to the severity of the exacerbation, assessed by mortality and the requirement for invasive mechanical ventilation, whereas lung bacteriobiota α-diversity is not. This study encourages a multicenter cohort study investigating the role of lung microbiota, especially fungal kingdom, in severe AECOPD. IMPORTANCE In AECOPD with acidemia, more severe patients-i.e., nonsurvivors and patients requiring invasive mechanical ventilation-have lower lung mycobiota α-diversity than survivors and patients receiving only noninvasive ventilation, respectively. This study encourages a large multicenter cohort study investigating the role of lung microbiota in severe AECOPD and urges investigation of the role of the fungal kingdom in severe AECOPD.

[Macroscopic and microscopic study of the right coronary artery after radiofrequency catheter ablation of cavotricuspid isthmus in an experimental model]

INTRODUCTION AND OBJECTIVES

The right coronary artery (RCA) is found in the AV groove, just below the ablation target of atrial flutter, the cavotricuspid isthmus (ICT). After radiofrequency (RF) ablation with standard catheters, there have been no reports of complications, but it may not be successful in 10% of the cases. However, the use of irrigated tip catheters, which create deeper lesions, might potentially damage the coronary tree.

METHODS

We analyzed the effects of ICT RF ablation on the coronary tree, with macroscopic and microscopic anatomopathological study. Ablation on ICT was performed using an irrigated tip catheter in 16 pigs and was randomly compared with a standard ablation catheter. There were no clinical problems, modifications of ST or new arrhythmias during the ablation. The heart was extracted at 1 week.

RESULTS

The macroscopic study demonstrated that the right coronary artery was preserved, along the ICT, surrounded by the epicardial fat. The microscopic study showed an inflammatory reaction in the epicardial fat that reached the adventitia of the coronary artery, but never produced necrosis in 14 cases. The muscular wall of the artery had signs of focal inflammation without endothelium involvement in 2 cases. However, we found a subepicardial vein completely damaged by the radiofrequency.

CONCLUSIONS

Although the right coronary artery is located just below the isthmus, no necrosis was observed in any case. However, there was an inflammatory reaction that focally reached the muscular wall. The veins may be damaged in RF ablation, perhaps due to the different blood flow of each vessel.

[Radiofrequency ablation of recurrent monomorphic ventricular tachycardia in a patient with severe systemic scleroderma]

A case of progressive systemic scleroderma in a 33 year-old woman who was referred to our Arrhythmia Unit due to daily palpitations and dizziness is presented. The 24-hour Holter recording showed monomorphic ventricular tachycardia which lasted several minutes. Hemodynamic study showed dilated right chambers and right ventricular dysfunction, without pulmonary hypertension. Left ventricular angiography and coronary arteries were normal. During programmed electrical stimulation, two different ventricular tachycardia were induced and ablated with radiofrequency on the right ventricle. The patient remains free of recurrence of tachycardia after (10 months of follow up). Patients with progressive systemic scleroderma may present several different cardiac arrhythmias. Involvement of the right ventricle is particularly frequent as is the origin of ventricular tachycardia in this ventricle. Radiofrequency catheter ablation is safe and effective in the management of these patients.

Comparison of multiplane and biplane transesophageal echocardiography in the assessment of aortic stenosis

The aim of the study was to compare the accuracy of multiplane transesophageal echocardiography (TEE) with the more conventional biplane technique in the direct assessment of aortic valve area in patients with aortic stenosis. Short-axis images of the aortic valve adequate for measuring aortic valve area were obtained in all 81 patients studied by multiplane TEE but in only 56 of 64 patients (88%) using the biplane approach. The correlation coefficient for aortic valve area determined by multiplane TEE (r = 0.89; SEE = 0.04 cm2) was higher (p < 0.01) than biplane TEE (r = 0.74; SEE = 0.06 cm2). Correlations were higher for bicuspid valves (multiplane, r = 0.93; biplane, r = 0.75) than tricuspid valves (multiplane, r = 0.87; biplane, r = 0.75). Our study has demonstrated the superiority of multiplane TEE to both biplane TEE and transthoracic echocardiography (TTE) in the direct evaluation of aortic valve area in patients with aortic stenosis.

Tuberculous cardiac tamponade and AIDS

Tuberculosis, usually extrapulmonary, is often associated with AIDS but tuberculous pericarditis is a rare manifestation in this group. We report three patients with tuberculous pericarditis as the first manifestation of AIDS.

Right atrial diverticulum and hypertrophic cardiomyopathy

This report describes the case of a young man with a right atrial diverticulum and hypertrophic cardiomyopathy who died suddenly. The relationship of congenital diverticulosis of the heart with hypertrophic cardiomyopathy is discussed.

[Echocardiography with intravenous dipyridamole infusion in the assessment of ischemic cardiopathy. A comparison with the stress test]

BACKGROUND

Diagnosis of ischemic cardiomyopathy by noninvasive methods is a challenge for the clinician. Echocardiography with intravenous administration of dipyridamole has been proposed as an alternative to exercise stress test in this setting.

METHODS

Intravenous administration of dipyridamole (0.84 mg/kg in 6 minutes) with two-dimensional echocardiography and 12-lead electrocardiographic monitoring was performed in 50 patients. The test was considered positive when contractility of any of the left ventricular segments decreased, at least, one grade. In that moment, dipyridamole administration was stopped and aminophylline (40-240 mg over 1 to 3 minutes) was given. All patients underwent exercise stress test and coronary angiography.

RESULTS

Significant coronary artery disease (70% stenosis in, at least, one of the major vessels) was demonstrated in 32 patients. Twenty of these had a positive dipyridamole echocardiography test (62%) and 23 had a positive exercise stress test (71%). None of the patients without significant coronary artery disease had a positive dipyridamole echocardiography test and 5 patients (23%) has a positive exercise stress test. Dipyridamole echocardiography test had and overall sensitivity of 60% and a specificity of 100%. Exercise stress test had an overall sensitivity of 75% (NS) and a specificity of 67% (p less than 0.01). Dipyridamole echocardiography test was well tolerated: there were no complications during the test. One patient had a transitory type I second-degree AV block.

CONCLUSIONS

Dipyridamole echocardiography is a high specificity test for coronary artery disease and has a similar sensitivity than exercise stress test. It is well tolerated and in the authors' experience there were no complications.

[Mitral valve aneurysm. Its diagnosis by transesophageal echocardiography]

Aneurysm of the mitral valve is a rare complication of infectious endocarditis. We report a 65-years-old woman with left heart failure and mitral regurgitation secondary to a mitral valve aneurysm. The diagnosis was made by transesophageal echocardiography.

[Gm1 gangliosidosis types 1 and 2 (author's transl)]

Two cases of gangliosidosis due to aggregates of Gm1 are described. The first patient was a female infant with noticeable retardation in psychomotor development, coarse facies, hepatomegaly, and X-rays showing skeletal anomalies in the large bones, vertebral column, cranium and ribs. She died at the age of 10 months of a septic condition. The second patient was a male infant; deterioration in psychomotor development was first noticed 8 months after birth and this progressed slowly to arrive at a vegetative state with convulsions and myoclonus. The child died at the age of 4 years. There were no signs of enlargement of visceral organs but a cherry red stain was observed in the ophthalmologic examination. In the first case, necropsy revealed the presence of a deposit substance in the histiocytes of the hepatic sinusoids, spleen, pancreas, thymus, septi and pulmonary alveoli, intestinal lamina propria, epithelial cells of the renal glomeruli, and in the neurons and glial cells of the brain. The same deposits were observed only in the neurons and glial cells in the second case. Ultrastructural examination showed the presence of typical cytoplasmic membranous bodies in the central nervous system of both patients. The beta-galactosidase activity in the urine of both patients during life was zero. There was a higher than normal total amount of gangliosides in brain tissue samples from both (1906.7 and 2459.9 NANA/g respectively) as compared with normal values (724.0). This increase was proportional to the rise in Gm1 ganglioside (76.8 and 89.6 percent molar respectively) as compared to control (27.0). These clinical, morphologic, and biochemical data characterize both types 1 and 2 of gangliosidosis due to Gm1 aggregates.

[Kinsbourne's disease. Study of four cases (author's transl)]

Four children who at ages from five months to three years developed an acute (one case), subacute (two cases) and chronic form (one case) clinical picture of ataxia, myoclonus, ocular dyskinesia and behaviour disorder are reported. In one of them there was, in addition mental retardation. Response to treatment with ACTH was successful. Clinical and evolutive characteristics of this process as well as the variety of ocular manifestations are emphasized.