Target next-generation sequencing for the accurate diagnosis of Parvimonas micra lung abscess: a case series and literature review.

Background: Parvimonas micra (P. micra) has been identified as a pathogen capable of causing lung abscesses; however, its identification poses challenges due to the specialized culture conditions for anaerobic bacterial isolation. Only a few cases of lung abscesses caused by P. micra infection have been reported. Therefore, we describe the clinical characteristics of lung abscesses due to P. micra based on our case series. Methods: A retrospective analysis was conducted on eight patients who were diagnosed with lung abscesses attributed to P. micra. Detection of P. micra was accomplished through target next-generation sequencing (tNGS). A systematic search of the PubMed database using keywords "lung abscess" and "Parvimonas micra/Peptostreptococcus micros" was performed to review published literature pertaining to similar cases. Results: Among the eight patients reviewed, all exhibited poor oral hygiene, with four presenting with comorbid diabetes. Chest computed tomography (CT) showed high-density mass shadows with necrosis and small cavities in the middle. Bronchoscopic examination revealed purulent sputum and bronchial mucosal inflammation. Thick secretions obstructed the airway, leading to the poor drainage of pus, and the formation of local abscesses leading to irresponsive to antibiotic therapy, which finally protracted recovery time. P. micra was successfully identified in bronchoalveolar lavage fluid (BALF) samples from all eight patients using tNGS; in contrast, sputum and BALF bacterial cultures yielded negative results, with P. micra cultured from only one empyema sample. Following appropriate antibiotic therapy, seven patients recovered. In previously documented cases, favorable outcomes were observed in 77.8% of individuals treated with antibiotics and 22.2% were cured after surgical interventions for P. micra lung abscesses. Conclusions: This study enriches our understanding of the clinical characteristics associated with lung abscesses attributed to P. micra. Importantly, tNGS has emerged as a rapid and effective diagnostic test in scenarios where traditional sputum cultures are negative. Encouragingly, patients with lung abscesses caused by P. micra infection exhibit a favorable prognosis with effective airway clearance and judicious anti-infective management.

Effect of Metagenomic Next-Generation Sequencing on Clinical Outcomes of Patients with Severe Community-Acquired Pneumonia in ICU: A Multicenter Randomized Controlled Trial.

BACKGROUND: Metagenomic next-generation sequencing (mNGS) was previously established as a method that can increase the pathogen identification rate in patients with severe community-acquired pneumonia (SCAP). RESEARCH QUESTION: What is the impact on clinical outcomes of mNGS of BALF in ICU patients with SCAP? STUDY DESIGN AND METHODS: A multicenter, randomized, open-label clinical trial was conducted in 10 ICUs. Patients were randomized in a 1:1 ratio to undergo BALF with the conventional microbiological tests (CMTs) only (CMT group) or both BALF with mNGS and CMTs (mNGS group). The primary outcome was the time to clinical improvement, defined as the time from randomization to either an improvement of two points on a six-category ordinal scale or discharge from the ICU, whichever occurred first. RESULTS: A total of 349 patients were randomized between January 1, 2021, to November 18, 2022, of whom 170 were assigned to the CMT group and 179 to the mNGS group. In the intention-to-treat analysis, the time to clinical improvement was better in the mNGS group than that in the CMT group (10 d vs. 13 d, difference: -2.0 [95% CI = -3.0 to 0.0]). Similar results were obtained in the per-protocol analysis. The proportion of patients with clinical improvement within 14 d was significantly higher in the mNGS group (62.0%) than that in the CMT group (46.5%). There was no significant difference in other secondary outcomes. CONCLUSION: MNGS combined with CMTs reduced the time to clinical improvement for patients with SCAP, compared to the use of CMTs alone.