Persistent Bacillus cereus Bacteremia in an Immunocompetent Patient With a History of Polysubstance Abuse

Abstract

Extraintestinal infections are rare with Bacillus cereus and include endocarditis, pneumonia, and meningoencephalitis. It has been primarily reported in immunosuppressed individuals with hematological malignancies and rarely in people who inject drugs (PWIDs). Herein, we report the case of a healthy adult woman with no underlying conditions except for injection drug use who presented with signs of meningitis. A 40-year-old female intravenous (IV) drug addict presented to the hospital with a chief complaint of severe headache. She had a fever of 38 °C, and her neurological examination was unremarkable. Laboratory results were significant for a white blood cell (WBC) count of 20.0 × 10⁹/L (reference range: 4.5 to 11.0 × 10⁹/L) and urine toxicology that was positive for amphetamines and cocaine. A lumbar puncture showed a total of 1,736 nucleated cells/µL, 88% neutrophils, a glucose level of 73 mg/dL, and a significantly elevated protein level of 155 mg/dL. B. cereus grew in blood cultures and cerebrospinal fluid (CSF) cultures. Once the growth of B. cereus was identified in the CSF, intravenous vancomycin was started. After leaving against medical advice (AMA), the patient presented again to the hospital, and a lumbar puncture was repeated. Cerebrospinal fluid showed total nucleated cells of 13 cells/µL, but the patient remained bacteremic. An echocardiogram, computerized tomography (CT) of the abdomen and pelvis, and tagged white blood cell scan could not identify a source for the bacteremia. Despite receiving two weeks of IV vancomycin, her blood cultures remained consistently positive for B. cereus without identifying a clear source of infection. Although B. cereus rarely affects the central nervous system, there have been a few cases where immunosuppression has been linked to the infection. We report an unusual case of a patient who continued to be bacteremic despite a thorough search for a source of B. cereus infection and IV vancomycin treatment. As a result, we raise the possibility of addictive behavior due to the patient's pattern of leaving the hospital against medical advice and returning with recurrent bacteremia. A thorough history and careful search for a source of infection are required when B. cereus grows persistently in blood cultures.

Keywords: antibiotics therapy; bacillus cereus; gram positive bacteremia; gram-positive meningitis; polysubstance use disorder.