A Unique Case of Community Acquired Proteus mirabilis Meningitis

Proteus mirabilis, a gram-negative bacterium commonly known for causing urinary tract infections (UTI) can rarely present with central nervous system (CNS) infections. Proteus mirabilis CNS infections are usually encountered in the neonatal and infantile period and occasionally cause brain abscesses. It is an uncommon cause of adult CNS infection. We report the first case of a community-acquired Proteus mirabilis meningitis (PMM) in a patient with Proteus mirabilis UTI, urolithiasis, and bacteremia. Risk factors for gram-negative bacillary meningitis (GNBM) include extremes of age, cancer history, diabetes mellitus, UTI, and nosocomial exposure, with the latter being a more prominent cause of PMM. Compromise of the anatomical defense against CNS infections whether accidental or neurosurgical is another important cause, and approximately two-thirds of reported cases of PMM have occurred after neurosurgical procedures. PMM patients develop fever, altered consciousness, and have an acute clinical course. Antimicrobials that can be used for treatment include third-generation cephalosporins, ciprofloxacin, imipenem/ cilastatin, aztreonam, and intraventricular aminoglycosides. Despite appropriate antibiotic therapy outcomes are poor with severe neurological deficit and death commonly resulting. Nosocomial infections can be drug-resistant and multiple antibiotics should be started while awaiting culture results. Literature review reveals that treatment with intraventricular aminoglycosides when attempted has shown bacteriological cure indicating this can be an important treatment approach. Due to the acute clinical course and high morbidity and mortality, we recommend starting multiple antibiotics with different mechanisms of action as soon as the disease is suspected. Our patient was initially started on ceftriaxone, vancomycin, acyclovir, and ampicillin for UTI and meningoencephalitis. The antibiotics were later consolidated to cefepime based on blood, urine and, cerebrospinal fluid cultures growing pan-sensitive Proteus mirabilis. Her clinical condition continued to worsen and ciprofloxacin was added. However, due to the progressive decline in her condition, the family elected for inpatient hospice care and intraventricular aminoglycosides were not attempted.