Pulmonary abscess due to Rothia mucilaginosa: A rare case in an immunocompetent patient

Rothia mucilaginosa is a germ rarely involved in pulmonary abscesses, especially in immunocompetent patients. We report the case of a 69-year-old man, a former smoker, admitted for fever, productive cough, and purulent sputum for the past 15 days. Clinical examination revealed moderate fever, tachycardia, and tachypnea, along with abnormal auscultatory findings in the right lower lung. Blood tests showed leukocytosis with a predominance of neutrophils. Imaging studies revealed an 8 cm hydro-aerial collection, suggesting a pulmonary abscess.

Despite antimicrobial treatment including third-generation cephalosporins, ciprofloxacin, and metronidazole, the patient continued to exhibit symptoms. Blood gas analysis revealed severe hypoxia and hypercapnia. A thoracic ultrasound identified a cystic formation, leading to chest drainage on the sixth day of hospitalization, resulting in the extraction of 1.5 liters of purulent fluid.

The cytobacteriological examination of the fluid confirmed the presence of Rothia mucilaginosa, with no signs of malignancy or fungal infection. Following drainage, both clinical and radiological improvement was observed, highlighting the importance of early diagnosis and therapeutic intervention in the management of pulmonary abscesses, particularly in at-risk patients.