Case Presentation: An 84-year-old man from China with a history of remote gastric cancer with prior subtotal gastrectomy, chronic hepatitis B virus infection on antivirals (without cirrhosis, normal liver function tests) was brought to the hospital after his family found him to be obtunded. At baseline he was independent in all iADLs. Physical exam showed normal vital signs without focal neurologic deficit or trauma. Initial laboratory studies showed a leukocytosis of 13.4 K/µL. A non-contrast head CT and brain MRI were unrevealing. On hospital day 2 he developed a high fever. Vancomycin, ceftriaxone, acyclovir, and TMP-SMX (to cover for Listeria given penicillin allergy) were started for empiric treatment of meningitis. A lumbar puncture (LP) was performed showing glucose <5.0mg/dL, protein 319 mg/dL, 82k/µL RBCs, and 13k/L WBCs with 79% PMNs; cerebrospinal fluid (CSF) cultures grew penicillin-sensitive E. coli. Infectious diseases was consulted, and antibiotics were narrowed to ceftriaxone. Urine/blood cultures were negative. By day 5, the patient’s mental status improved. CT of the abdomen, pelvis, and neck to evaluate for sources of infection were negative. Strongyloides IgG titer was negative. The patient was treated with ceftriaxone for 14 days total and had complete resolution of symptoms.

Discussion: Gram-negative organisms are a rare cause of spontaneous community-acquired meningitis. E. coli and Klebsiella are the most common gram-negative bacteria identified. The mortality rate is 47–90%. Identified comorbidities include alcoholism, cirrhosis, and diabetes mellitus. Ceftriaxone is the most common treatment recorded in the literature, though susceptibility testing should guide treatment. The optimal course of treatment has not been studied, but duration averages 15.8 days in prior reports. Ideally, clearance of the infection is verified by repeat LP. Our patient showed robust clinical improvement, and due to extreme pain during the initial LP (secondary to severe lumbar scoliosis) he declined repeat LP.
A predisposing risk for E. coli meningitis is disseminated strongyloidiasis, which should be considered in patients from endemic areas, such as China. Strongyloides stercoralis infections can be asymptomatic, but larvae auto-infect the host and can transport gut microbes hematogenously. Our patient’s IgG titer was negative, suggesting he did not have prior Strongyloides exposure. If strongyloidiasis were suspected, treatment with ivermectin and/or albendazole would be necessary. Our patient may have had relative immune compromise related to chronic HBV infection, though his HBV PCR was undetectable at the time of infection.

Conclusions: Community-acquired acute gram-negative meningitis is rare, often presents aggressively, and mortality is high. It is important for hospitalists to be aware of risk factors for gram-negative meningitis. Empiric broad spectrum antibiotics should be started, and narrowed based on susceptibility. Treatment should last 14–21 days. Patients’ serum should be tested for Strongyloides IgG if from an endemic area.