AIIMS Antibiotics Policy for treating Brain Abscess
All India Institute of Medical Sciences, Delhi has released AIIMS Antibiotics Policy which has been prepared by the Department of Medicine with Multidisciplinary collaboration. The guidance for Neurological Infections includes brain Abscess the salient features of which are hereunder.
Brain Abscess: A focal, intracerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a well-vascularized capsule.
When to suspect
Less than 50% of patients with brain abscess presents with the classic triad of fever, headache, and focal neurologic deficit. In addition, the clinical presentation of brain abscess in an immunocompromised patient may be masked by the diminished inflammatory response.
How to confirm
MRI & Magnetic Resonant Spectroscopy (MRS)
Anaerobic and mixed infections: along with lipid and lactate, there are peaks of succinate, acetate, lysine and multiple peaks of intracellular amino acids at 0.8 to 1.1 ppm.
TB brain abscess<: maybe single or multiple, ring-enhancing or nodular, lipid lactate peak is seen at 1.3 ppm. Mostly associated with evidence of TB in other parts of the body. Associated TB meningitis may be seen which is characterized by the presence of thick basal meningeal enhancement, hydrocephalus, parenchymal infarctions and a characteristic CSF picture +/- microbiological evidence (CB-NAAT / TB culture from CSF or other samples).
Nocardial brain abscess: Usually show single cystic ring-enhancing or multiloculated/ multiple conglomerate lesions with a necrotic core and multilobed thick walls enhancing after contrast. MRS findings reveal a lactate peak at 1.3 ppm and inverse amino acids at 0.9 ppm.
Toxoplasma: In AIDS with low CD4+ ≤ 100/mm3, usually multiple nodular ring-enhancing lesions +/- eccentric target sign, with surrounding oedema, predominantly in basal ganglia, Toxoplasma IgG usually +ve, therapeutic response to Cotrimoxazole (TMP/SMX). Decreased choline (Cho) but increased Lipids and Lactate peaks in MRS.
Stereotactic Brain Biopsy/aspiration
Gram Stain, ZN stain, modified ZN staining, Histopathology, KOH-Calcoflour White, Aerobic and Anaerobic Culture, Liquid culture for TB, CB-NAAT for MTB, Fungal Culture.
i. Empirical (Bacterial): Ceftriaxone 2 gm IV BD plus Vancomycin 1-2 gm IV BD plus Metronidazole 500mg TDS
Replace Ceftriaxone and Metronidazole with Meropenem 2g IV TDS in patients with recent hospitalization.
Add TMP-SMX 15 mg/kg IV of the trimethoprim component per day in three or four divided doses in patients with HIV/ transplant recipients/ other causes of immunosuppression.
Initial inpatient parenteral therapy:
TMP-SMX 15 mg/kg IV of the trimethoprim component per day in three or four divided doses plus
Imipenem 500 mg IV every 6 hours (Add Amikacin 7.5 mg/kg IV every 12 hours if multiple organ involvement)
Oral therapy after the initial 6 weeks of parenteral therapy and improving clinical and imaging profile: TMP-SMX +/- Amoxicillin-clavulanic acid
iii. Septate hyphae (Aspergillus/ Dematiaceous fungi):
-Start with Voriconazole IV 6 mg/kg 12 hourly load on Day 1 followed by 4 mg/kg 12 hourly
-Oral Voriconazole may be considered for long term suppressive therapy after stabilization, patients who have responded and taking well orally
-If dematiaceous fungi suspected- a combination of Voriconazole & Amphotericin B
-High dose Caspofungin (100 mg/day) or Liposomal amphotericin B (5 mg/kg daily) may be added to Voriconazole as salvage therapy
iv. Aseptate hyphae (Mucormycosis):
-Liposomal Amphotericin B 5-10 mg/kg/day
-Step down therapy with oral Posaconazole (suspension) at 200 mg 6th hourly