Bacillus cereus Bacteremia and pneumocystis jirovecii pneumonia in a patient with CD20-positive B-cell acute lymphoblastic leukemia: an intensive care unit case report
DOI:
https://doi.org/10.71112/6r7kw134Keywords:
acute lymphoblastic leukemia, febrile neutropenia, Bacillus cereus, Pneumocystis jirovecii, septic shock, acute respiratory distress síndrome, intensive careAbstract
Introduction: Severe infections in patients with acute lymphoblastic leukemia receiving chemotherapy represent an oncohematologic emergency. Profound neutropenia modifies clinical presentation, promotes invasive bacterial infections, and facilitates opportunistic pneumonia, including Pneumocystis jirovecii pneumonia. Bacillus cereus, sometimes interpreted as a contaminant, may behave as an invasive pathogen in immunocompromised hosts.
Case report: We report the case of a 40-year-old woman with recently diagnosed CD20-positive common B-cell precursor acute lymphoblastic leukemia after GATLA-based chemotherapy. She was admitted with fever, gastrointestinal symptoms, severe pancytopenia, and profound neutropenia. During hospitalization she developed septic shock, acute kidney injury, metabolic acidosis, and hyperlactatemia. Blood culture yielded Bacillus cereus, and molecular testing later detected Pneumocystis jirovecii, with chest computed tomography showing diffuse bilateral pulmonary consolidations. She progressed to severe hypoxemic respiratory failure and severe acute respiratory distress syndrome requiring endotracheal intubation, invasive mechanical ventilation, prone positioning, sedation, neuromuscular blockade, vasopressor support, and directed antimicrobial therapy.
Discussion: This case highlights the diagnostic and therapeutic complexity of sepsis in neutropenic oncohematologic patients, where Bacillus cereus bacteremia and Pneumocystis jirovecii pneumonia may coexist and precipitate severe ARDS. It also emphasizes that Bacillus cereus should not be dismissed as a contaminant in patients with profound neutropenia, intravascular devices, or clinical deterioration.
Conclusion: In patients with acute leukemia and profound neutropenia, Bacillus cereus should be considered a potentially invasive pathogen when sepsis, bacteremia, or pulmonary involvement is present. Early investigation for opportunistic infections, timely intensive care support, and targeted antimicrobial therapy are essential to prognosis.
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