Low transmission risk of Pseudomonas aeruginosa in a bronchiectasis clinic based on the knowledge of bacterial population biology

[Management of adult bronchiectasis - Consensus-based Guidelines for the German Respiratory Society (DGP) e. V. (AWMF registration number 020-030)]

Bronchiectasis is an etiologically heterogeneous, chronic, and often progressive respiratory disease characterized by irreversible bronchial dilation. It is frequently associated with significant symptom burden, multiple complications, and reduced quality of life. For several years, there has been a marked global increase in the prevalence of bronchiectasis, which is linked to a substantial economic burden on healthcare systems. This consensus-based guideline is the first German-language guideline addressing the management of bronchiectasis in adults. The guideline emphasizes the importance of thoracic imaging using CT for diagnosis and differentiation of bronchiectasis and highlights the significance of etiology in determining treatment approaches. Both non-drug and drug treatments are comprehensively covered. Non-pharmacological measures include smoking cessation, physiotherapy, physical training, rehabilitation, non-invasive ventilation, thoracic surgery, and lung transplantation. Pharmacological treatments focus on the long-term use of mucolytics, bronchodilators, anti-inflammatory medications, and antibiotics. Additionally, the guideline covers the challenges and strategies for managing upper airway involvement, comorbidities, and exacerbations, as well as socio-medical aspects and disability rights. The importance of patient education and self-management is also emphasized. Finally, the guideline addresses special life stages such as transition, family planning, pregnancy and parenthood, and palliative care. The aim is to ensure comprehensive, consensus-based, and patient-centered care, taking into account individual risks and needs.

Pseudomonas aeruginosa population genomics among adults with bronchiectasis across Germany

Genome sequencing of 130 Pseudomonas aeruginosa isolates from 110 bronchiectasis patients identified a few dominant clones common in the global bacterial population and numerous rare clones infrequently seen in the environment or other human infections https://bit.ly/3lIfD2X.

Phenotypic and Genomic Comparison of the Two Most Common ExoU-Positive Pseudomonas aeruginosa Clones, PA14 and ST235

Genotyping of 2,882 Pseudomonas aeruginosa isolates that had been collected during the last 40 years identified the ExoU-positive lineages PA14 (ST253) and ST235 as the second and third most frequent clones in the P. aeruginosa population. Both clones were approximately 2-fold more frequently detected in animate habitats than in soil or aquatic habitats. While ST253 clone isolates were causing mainly acute and chronic infections in humans, ST235 isolates had been preferentially collected from hospitalized patients with severe acute infections, particularly, keratitis, urinary tract infections, burn wounds, and ventilator-associated pneumonia. The two major exoU clones differed substantially in the composition and flexibility of the accessory genome and by more than 8,000 amino acid sequences. Pronounced sequence variation between orthologs was noted in genes encoding elements of secretion systems and secreted effector molecules, including the type III secretion system, indicating the modes of action of the different clones. When comparing representatives of the two clones in batch culture, the PA14 strain orchestrated the quorum sensing circuitry for the expression of pathogenic traits and stopped growing in batch culture when it entered the stationary phase, but the quorum sensing-deficient ST235 strain expressed high type III secretion activity and continued to grow and to divide. In summary, unrestricted growth, high constitutive type III secretion activity, and facilitated uptake of foreign DNA could be major features that have made ST235 a global high-risk clone associated with poor outcomes of acute nosocomial infections.IMPORTANCE The ubiquitous and metabolically versatile environmental bacterium Pseudomonas aeruginosa can cause infections in a wide variety of hosts, including insects, plants, animals, and humans. P. aeruginosa is one of the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens that are the major cause of nosocomial infections in the United States and are a threat all over the world because of their capacity to become increasingly resistant to all available antibiotics. Most experimental work on P. aeruginosa has been performed with reference strains PAO1 and PA14, providing deep insight into key metabolic and regulatory pathways thought to be applicable to all P. aeruginosa strains. However, this comparative study on the two most common exoU-positive clones taught us that there are major lineages in the population such as the global high-risk clone ST235 that exhibit uncommon traits of lifestyle, genome mobility, and pathogenicity distinct from those in our knowledge gained from the studies with the reference strains.