Evaluation of clinical characteristics of Legionella pneumophila pneumonia diagnosed by metagenomic Next-Generation Sequencing:A retrospective study

PurposeThis study aimed to summarize the clinical characteristics and outcomes of Legionella pneumophila (L. pneumophila) pneumonia to assist clinicians in accurately and early identifying this disease. The findings provide evidence to guide decision-making for L. pneumophila infection and improve treatment success rates. Patients and methodsA retrospective analysis of clinical data was conducted on 19 patients diagnosed with L. pneumophila infection at our hospital using Metagenomic next-generation sequencing (mNGS). ResultsThe study included 16 male and 3 female participants, with an average age of 59.5{+/-}16.2 years. The majority of participants were immunocompromised (13/19). The most common symptoms included fever (n=11) with a median peak value of 39.5{degrees}C, cough (n = 15), expectoration (n = 14), dyspnea (n = 10), poor appetite (n = 9), fatigue (n = 8), and headache (n = 3). Elevated levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were observed in all patients, while procalcitonin (PCT) and lactate dehydrogenase (LDH) levels were significantly higher in the severe group compared to the non-severe group. Lymphocyte count levels were also significantly lower in the severe group (P<0.05). Common CT manifestations included flake high-density shadows (n = 17), pleural effusion (n = 11), consolidation (n = 4), ground-glass exudation (n = 4), and bronchial inflation signs (n = 3). The most prevalent underlying diseases were hypertension (n = 9), diabetes (n = 8), AIDS (n = 6), COPD (n = 5), and malignancies (n = 3). Common complications included acute liver injury (n=7), acute respiratory failure (n=6), electrolyte disorders (n=5), sepsis (n=3), MODS (n=2), and ARDS (n=1). The majority of patients received treatment with quinolones (16/19), with six patients requiring mechanical ventilation therapy. Tragically, 2 patients in the severe pneumonia group succumbed to sepsis and multiple organ failure. ConclusionL. pneumophila pneumonia is an acute respiratory infection. If not promptly diagnosed, patients may develop severe pneumonia, multiorgan failure, or face fatal outcomes. mNGS can be used for rapid and accurate diagnosis of L. pneumophila infections, thereby improving treatment outcomes. Early initiation of quinolones or combination therapy with other medications has demonstrated a significant therapeutic benefit for patients with L. pneumophila pneumonia.