American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · May 2021
Polyclonality, Shared Strains, and Convergent Evolution in Chronic CF S. aureus Airway Infection.
Rationale: Staphylococcus aureus is the most common respiratory pathogen isolated from patients with cystic fibrosis (CF) in the United States. Although modes of acquisition and genetic adaptation have been described for Pseudomonas aeruginosa, resulting in improved diagnosis and treatment, these features remain more poorly defined for S. aureus. Objectives: To characterize the molecular epidemiology and genetic adaptation of S. aureus during chronic CF airway infection and in response to antibiotic therapy. ⋯ Unlike P. aeruginosa, S. aureus genetic diversity was unconstrained, with an ongoing flow of new genetic elements into the population of isolates from children with CF. Conclusions: CF airways are frequently coinfected by multiple, genetically distinct S. aureus lineages, indicating that current clinical procedures for sampling isolates and selecting antibiotics are likely inadequate. Strains can be shared by patients in close domestic or clinical contact and can undergo convergent evolution in key persistence and antimicrobial-resistance genes, suggesting novel diagnostic and therapeutic approaches for future study.
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Am. J. Respir. Crit. Care Med. · May 2021
Quantitative Assessment of Viral Dispersion Associated with Respiratory Support Devices in a Simulated Critical Care Environment.
Rationale: Patients with severe coronavirus disease (COVID-19) require supplemental oxygen and ventilatory support. It is unclear whether some respiratory support devices may increase the dispersion of infectious bioaerosols and thereby place healthcare workers at increased risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Objectives: To quantitatively compare viral dispersion from invasive and noninvasive respiratory support modalities. ⋯ At the intubating position, bacteriophage concentrations associated with HFNO (2.66 × 104 plaque-forming units [PFU]/L of air sampled), nasal prongs (1.60 × 104 PFU/L of air sampled), nonrebreather face masks (7.87 × 102 PFU/L of air sampled), and bilevel positive airway pressure (1.91 × 102 PFU/L of air sampled) were significantly higher than those associated with invasive ventilation (P < 0.05 for each). The difference between bacteriophage concentrations associated with helmet ventilation with a PEEP valve (4.29 × 10-1 PFU/L of air sampled) and bacteriophage concentrations associated with invasive ventilation was not statistically significant. Conclusions: These findings highlight the potential differential risk of dispersing virus among respiratory support devices and the importance of appropriate infection prevention and control practices and personal protective equipment for healthcare workers when caring for patients with transmissible respiratory viral infections such as SARS-CoV-2.
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Am. J. Respir. Crit. Care Med. · May 2021
The Association of Aging Biomarkers, Interstitial Lung Abnormalities, and Mortality.
Rationale: The association between aging and idiopathic pulmonary fibrosis has been established. The associations between aging-related biomarkers and interstitial lung abnormalities (ILA) have not been comprehensively evaluated. Objectives: To evaluate the associations among aging biomarkers, ILA, and all-cause mortality. ⋯ Causal inference analysis showed that the association of age with ILA was mediated by IL-6 (P < 0.0001) and TNFR (P = 0.002) and was likely mediated by GDF15 (P = 0.008) in the FHS and was mediated by GDF15 (P = 0.001) in the COPDGene Study. Conclusions: Some aging-related biomarkers are associated with ILA. GDF15, in particular, may explain some of the associations among age, ILA, and mortality.
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Am. J. Respir. Crit. Care Med. · May 2021
Episodic Aspiration with Oral Commensals Induces a MyD88-dependent, Pulmonary Th17 Response that Mitigates Susceptibility to Streptococcus pneumoniae.
Rationale: Cross-sectional human data suggest that enrichment of oral anaerobic bacteria in the lung is associated with an increased T-helper cell type 17 (Th17) inflammatory phenotype. Objectives: In this study, we evaluated the microbial and host immune-response dynamics after aspiration with oral commensals using a preclinical mouse model. Methods: Aspiration with a mixture of human oral commensals (MOC; Prevotella melaninogenica, Veillonella parvula, and Streptococcus mitis) was modeled in mice followed by variable time of killing. ⋯ MOC aspiration before a respiratory challenge with S. pneumoniae led to a decrease in hosts' susceptibility to this pathogen. Conclusions: Thus, in otherwise healthy mice, a single aspiration event with oral commensals is rapidly cleared from the lower airways but induces a prolonged Th17 response that secondarily decreases susceptibility to S. pneumoniae. Translationally, these data implicate an immunoprotective role of episodic microaspiration of oral microbes in the regulation of the lung immune phenotype and mitigation of host susceptibility to infection with lower-airway pathogens.