Photo Quiz - March 2019

A 49/M with uncontrolled diabetes presented with fever (102- 103), headache and subacute onset of left sided hemiparesis. There was no history of skin and soft tissue abscess. On examination, he had no dental caries, sinusitis or ear infection. Chest X-ray was normal with no evidence of consolidation or infiltrates. His complete blood count showed TLC of 16,000 with neutrophilic predominance and raised ESR (81). HIV ELISA was negative. CT scan showed a ring enhancing space occupying lesion (RESOL) (3.4 X 3.2 X3.2 cm) in right thalamocapsular region with focal areas of cerebritis (Fig 1).

MR spectroscopy shows elevated lactate spikes (Fig 2)

What is your diagnosis? View Answer

Answer

CT guided drainage of the intracerebral lesion was performed and the pus culture grew α- haemolytic Streptococcus spp (Fig 3). With Pen E test, MIC was > 0.5 indicating a resistant streptococcus. According to the CLSI guidelines, Penicillin MIC is used for the guidance of the susceptibility of VGS in every possible case for appropriate treatment. There are no disc-diffusion criteria for VGS. Standard recommendations for treatment of ‘cryptogenic’ brain abscess are Vancomycin + Ceftriaxone + Metronidazole. As the patient patient had no risk factor for MRSA, empirical ceftriaxone 2 gm 12 hrly) and metronidazole 500 mg 6 hrly was initiated. Metronidazole was subsequently discontinued. IV ceftriaxone was continued which was shifted to oral cefixime subsequently.

Fig 3: α- haemolytic Streptococcus spp

Differential diagnosis of RESOL includes pyogenic brain abscess, tuberculoma, toxoplasmosis, tumor (astrocytoma, primary CNS lymphoma or metastasis), fungal abscess (Aspergillus, Mucor, Scedosporium) and nocardia.

Final diagnosis: Bacterial brain abscess caused by alpha hemolytic Streptococci (+- others)

Case provided by: Dr Ranjit Sah, Dr Neha Gupta, Dr Rajeev Soman, Dr Anjali Shetty, Dr Camilla Rodrigues