A case of community-acquired enterobacter aerogenes meningitis

Learning Objectives: Enterobacter aerogenes meningitis is a rare infection associated with high morbidity and mortality that usually occurs following disruption of the dura-arachnoid barrier secondary to neurologic trauma. We present the first documented case of community acquired Enterobacter a. meningitis in a patient without recent neurologic trauma. Methods: An 84-year-old female presented tachycardic but normotensive and afebrile with altered mental status. On exam she had right gaze deviation with rigidity and GCS of 8. Laboratory studies revealed a WBC of 25.5K/uL, acute kidney injury, pH 7.28, and pCO2 37.7mmHg. Head CT demonstrated a chronic infarct, but was otherwise unremarkable. In the ED, the patient was given Ativan and Keppra due to concern for seizures and was intubated for airway protection. EEG did not demonstrate epileptiform activity. Lumbar puncture was performed, patient was started empirically on antibiotics for meningitis, and she was admitted to the MICU. Cerebrospinal fluid (CSF) studies were indicative of bacterial meningitis, and CSF cultures grew Enterobacter aerogenes. Antibiotic treatment was changed to meropenem. Given the rarity of Enterobacter a. in CSF a second culture was obtained which was also positive for Enterobacter a. Blood cultures were negative. CT of the abdomen and pelvis was unremarkable, and echocardiogram showed no valvular vegetations. The patient completed a 21day course of meropenem with improvement in mental status. She was ultimately discharged to rehab after 30 days of hospital admission. Results: Enterobacter is a rarely observed cause of community acquired meningitis, especially in adults without recent neurologic injury.For Enterobacter meningitis, the most important predisposing factor is a history of neurosurgery.Other important risk factors include the presence of a CNS device or following neurotrauma. One study showed there was only a 47% rate of improvement with appropriate treatment along with a mortality rate of 21%. These meningitic strains are often resistant to third generation cephalosporins and appropriate treatment is typically with a carbapenem. In addition to its high rate of resistance, Enterobacter meningitis caries a high rate of mortality due to its associated delay in selecting appropriate antibiotic therapy. Given the critical nature of this disease process prompt recognition is prudent. While community acquired Enterobacter a. meningitis is rare, it should be considered in patients diagnosed with meningitis