Spontaneous Proteus mirabilis Meningitis in Adults Requiring an Extended Antibiotic Course: Case Report and Literature Review

Most cases of gram-negative bacillary meningitis occur in neonates and infants. Meningitis in adults caused by Proteus mirabilis has been reported rarely. Evidence-based guidelines for the treatment of adult patients with gram-negative bacillus meningitis are scarce. The optimal duration of antibiotic therapy for these patients is an unanswered question in the medical literature. This article outlines a case of community-acquired meningitis caused by P. mirabilis in an adult patient who required an extended antimicrobial treatment, after failing to a three-week antibiotic regime. Our patient, a 66-year-old man with a history of neurogenic bladder, remote spinal cord trauma, and recurrent urinary tract infections presented to the emergency department reporting a two-day history of severe headache, fever, and confusion. Cerebrospinal fluid (CSF) revealed significant neutrophil-predominant pleocytosis, low glucose level, and elevated protein level. CSF culture grew few pan-susceptible P. mirabilis. The patient initially completed 21 days of ceftriaxone guided by susceptibility testing. Nine days after finishing antibiotic therapy, the patient was readmitted with recurrent headache, fever, and neck rigidity. A new CSF study again revealed pleocytosis, elevated polymorphonuclear cells, low glucose level, and elevated protein level, but with a negative CSF culture. The patient became afebrile, and his symptoms improved after two days of ceftriaxone. He completed an additional six-week regime of ceftriaxone. On the one-month follow-up visit, the patient remained afebrile, with no recurrent symptoms. Spontaneous community-acquired P. mirabilis meningitis is rare among adult patients. Experiences in the treatment of gram-negative bacillus meningitis in adults must be shared with the scientific community to build up a better understanding of this condition. In the context of this case, sterilization of the CSF, extended antibiotic therapy, and a close post-treatment follow-up are crucial for treating this life-threatening condition.