An indolent presentation of brain abscess due to a slow growing organism

Propioni bacterium propionicum is an anaerobic gram positive bacteria. It’s rarely described as to cause brain abscess. We report the isolation of this organism from a brain abscess and emphasise the problems associated with it’s diagnosis. A 62 year old lady with a history of acromegaly underwent emergency surgery for recurrent pituitary lesion felt to be apoplexy. Four weeks later she presented with headache and confusion. Co morbidities included autoimmune diseases on long term steroids and previous use of immunosuppressants. Clinical examination showed neck stiffness. Brain MRI demonstrated an enhancing lesion in the fourth ventricle causing secondary obstructive hydrocephalus requiring endoscopic third ventriculostomy. Blood tests, CSF analysis and whole body PET scan were unable to differentiate between infection and malignancy. Excision of the lesion was felt very high risk as deep in the tectal area. A sporadic trial of antibiotics, high dose steroids and immunotherapy was tried. Patient developed worsening headache with progression of the lesion. Underwent craniotomy and pus was found which isolated P. propionicum sensitive to penicillin and betalactams. Treated with intravenous meropenem for a year. There was significant reduction in the size of the abscess and hydrocephalus on brain MRI at 8 months post-diagnosis. P. propionicum has been isolated and associated with lesions of the lacrimal glands, lung and abdomen. We could find only two case reports of brain abscess due to P. propionicum. Identification of P.propionicum in the microbiology laboratory can be difficult requiring anaerobic growth conditions and extended cultures. Treatment is prolonged antimicrobial therapy.