A Retrospective Case Series Study of Alcaligenes faecalis Pneumonia

Background: The potentially developing human pathogen Alcaligenes faecalis is a Gram-negative, nonfermenting bacterium. Treatment of A. faecalis infections is frequently difficult due to increased resistance to many antibiotics, such as β-lactam antibiotics, aminoglycosides, and quinolones. In the literature, A. faecalis pneumonia has never been documented in a case series study. Here, we provide a case series study of patients with A. faecalis pneumonia. Objectives: The aim of this study was to elucidate the clinical characteristics, management strategies, and outcomes of A. faecalis pneumonia patients. Methods: Patients with A. faecalis pneumonia between January 2014 and December 2019 were included in a retrospective investigation. We examined the clinical outcomes of patients with A. faecalis pneumonia, together with the risk factors for pneumonia, prior intravenous antibiotic use within 90 days, respiratory secretion culture results, antibiotic sensitivity test results, and other variables. Results: Observations revealed eight patients with A. faecalis pneumonia, including six males and two females. The mean age of patients was 70 years. These eight patients shared risk factors for pneumonia. Six patients were discharged, and two patients died as a result of A. faecalis pneumonia. Two patients with pneumonia caused by extensively drug-resistant A. faecalis were identified. Conclusions: Rare cases of A. faecalis pneumonia have been documented in the literature. Recently, A. faecalis has developed extensive drug resistance. To treat pneumonia caused by A. faecalis with substantial antibiotic resistance, either polymyxin B or tigecycline is needed. The clinical outcome is typically satisfactory when A. faecalis pneumonia patients receive appropriate antibiotic therapy, but cases of fatal pneumonia have been documented in the literature.