The respiratory tract microbiome, the pathogen load, and clinical interventions define severity of bacterial pneumonia

Pérez-Cobas, Ana Elena; Ginevra, Christophe; Rusniok, Christophe; Jarraud, Sophie; Buchrieser, Carmen

doi:10.1016/j.xcrm.2023.101167

Cited by 3 publications

(3 citation statements)

References 66 publications

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“…The analysis of the sputum microbiome in patients affected by pneumonia showed a polymicrobial flora. In some cases, Legionella was found to be only a minority of the total amount of bacteria in patients diagnosed with LD [ 35 , 36 ]. This bacterium is more difficult to grow than other co-pathogens.…”

Section: Discussionmentioning

confidence: 99%

Therapeutical strategies in cavitary legionnaires’ disease, two cases from the field and a systematic review

Moretti,

De Boek,

Ilsen

et al. 2023

Ann Clin Microbiol Antimicrob

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Background Legionnaires’ Disease (LD) rarely evolves into pulmonary abscesses. The current systematic review has been designed to explore therapeutical strategies in pulmonary cavitary LD. Methods A research strategy was developed and applied to the databases Embase, Pubmed, and Web of Science from the 1st of January 2000 to the 1st of November 2022. Original articles, case series, case reports, and guidelines written in English, French, German, Italian, and Dutch were considered. Furthermore, medical records of patients treated at the University Hospital UZ Brussel for LD cavitary pneumonia, between the 1st of January 2016 to the 1st of January 2022, were reviewed. Results Two patients were found by the UZ Brussel’s medical records investigation. Through the literature review, 23 reports describing 29 patients, and seven guidelines were identified. The overall evidence level was low. Result of synthesis (case reports) The median age was 48 years and 65% were male. A polymicrobial infection was detected in 11 patients (44%) with other aerobic bacteria being the most commonly found. At diagnosis, 52% of patients received combination therapy, and fluoroquinolones were the preferred antimicrobial class. Anaerobic coverage was neglected in 33% of patients. Result of synthesis (guidelines) Three guidelines favor monotherapy with fluoroquinolones or macrolides, while one suggested an antimicrobial combination in case of severe LD. Four guidelines recommended anaerobic coverage in case of lung abscesses. Conclusion To date, the evidence supporting cavitary LD treatment is low. Monotherapy lowers toxicity and might be as effective as combination therapy. Finally, anaerobes should not be neglected. Graphical Abstract

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Section: Discussionmentioning

confidence: 99%

Therapeutical strategies in cavitary legionnaires’ disease, two cases from the field and a systematic review

Moretti,

De Boek,

Ilsen

et al. 2023

Ann Clin Microbiol Antimicrob

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“…The respiratory tract microbiome (RTM) balance is impaired in the case of severe LD. There is a low microbial diversity in patients with invasive mechanical ventilation (IMV) and the presence of opportunistic pathogens (fungi, archaea, and protozoa) seem to contribute to the progress of pneumonia [ 41 ]. As the Legionella biomass has been found to correlate with disease severity and has been linked to co-morbidities, the quantification of the pathogen should be included among the procedures in patient monitoring.…”

Section: Pathogenesis Of Legionnaires’ Diseasementioning

confidence: 99%

“…The impact of dual infection usually worsens the patients’ prognosis. Some opportunistic bacterial and fungal pathogens such as Pseudomonas , Stenotrophomonas , Candida or Aspergillus may also be found as co-infection or superinfection microorganisms [ 41 , 76 ]. In cases of LD, physicians should consider multiple pathogen infections.…”

Section: Clinical Picturementioning

confidence: 99%

Severe Legionnaires’ disease

Rello,

Allam,

Ruiz-Spinelli

et al. 2024

Ann. Intensive Care

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Background Legionnaires’ disease (LD) is a common but under-diagnosed cause of community-acquired pneumonia (CAP), although rapid detection of urine antigen testing (UAT) and advances in molecular testing have improved the diagnosis. LD entails intensive care unit (ICU) admission in almost one-third of cases, and the mortality rate ranges from 4% to 40%. This review aims to discuss recent advances in the study of this condition and to provide an update on the diagnosis, pathogenesis and management of severe LD. Results The overall incidence of LD has increased worldwide in recent years due to the higher number of patients with risk factors, especially immunosuppression, and to improvements in diagnostic methods. Although LD is responsible for only around 5% of all-cause CAP, it is one of the three most common causes of CAP requiring ICU admission. Mortality in ICU patients, immunocompromised patients or patients with a nosocomial source of LD can reach 40% despite appropriate antimicrobial therapy. Regarding pathogenesis, no Legionella-specific virulence factors have been associated with severity; however, recent reports have found high pulmonary Legionella DNA loads, and impairments in immune response and lung microbiome in the most severe cases. The clinical picture includes severe lung injury requiring respiratory and/or hemodynamic support, extrapulmonary symptoms and non-specific laboratory findings. LD diagnostic methods have improved due to the broad use of UAT and the development of molecular methods allowing the detection of all Lp serogroups. Therapy is currently based on macrolides, quinolones, or a combination of the two, with prolonged treatment in severe cases. Conclusions Numerous factors influence the mortality rate of LD, such as ICU admission, the underlying immune status, and the nosocomial source of the infection. The host immune response (hyperinflammation and/or immunoparalysis) may also be associated with increased severity. Given that the incidence of LD is rising, studies on specific biomarkers of severity may be of great interest. Further assessments comparing different regimens and/or evaluating host-directed therapies are nowadays needed. Graphical Abstract

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Optimization of lung tissue pre-treatment by bead homogenization for subsequent culturomics

Anduni,

Molina,

Zazueta

et al. 2024

Sci Rep

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The discovery that the lung harbors a diverse microbiome, as revealed by next-generation sequencing, has significantly altered our understanding of respiratory health and disease. Despite the association between the lung microbiota and disease, the nature of their relationship remains poorly understood, and culture isolation of these microorganisms could help to determine their role in lung physiology. Current procedures for processing samples from the lower respiratory tract have been shown to affect the viability of microorganisms, so it is crucial to develop new methods to improve their survival. This study aimed to improve the isolation and characterization of lung microorganisms using a bead-beating homogenization method in a mouse model. Microsphere diameter and bead-beating time affected the survival of the microorganisms ( E. coli , S. aureus and C. albicans ). Using 2.3 mm diameter microspheres for 60 s of bead-beating promoted the survival of both bacteria and yeast strains. After intratracheal instillation of these microorganisms in mice, approximately 70% of the cells were recovered after the tissue homogenization. To assess the efficiency of the proposed method, the diversity of bacteria was compared between the homogenate and lung tissue samples. Ninety-one genera were detected in the lung tissue, and 63 in the homogenate. Bacterial genera detected in the homogenate represented 84% of the total abundance of the microbiota identified in the lung tissue. Taken together, these results demonstrate that the tissue homogenization process developed in this study recovered the majority of the microorganisms present in the lung. This study presents a bead-beating homogenization method for effective cultivation of lung tissue microorganisms, which may help to improve the understanding of host–microbe interactions in the lung.

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The respiratory tract microbiome, the pathogen load, and clinical interventions define severity of bacterial pneumonia

Cited by 3 publications

References 66 publications

Therapeutical strategies in cavitary legionnaires’ disease, two cases from the field and a systematic review

Therapeutical strategies in cavitary legionnaires’ disease, two cases from the field and a systematic review

Severe Legionnaires’ disease

Optimization of lung tissue pre-treatment by bead homogenization for subsequent culturomics

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