Isolation & characterization of Bartonella sp. from optic neuritis patients

Optic neuritis (ON) is characterized by sudden and rapid impairment of vision. Bartonella henselae is a known aetiological agent of cat scratch disease (CSD), which is a common cause of neuroretinitis, the least common type of optic neuritis. The present study was carried out to determine the microbiological aetiology of optic neuritis in patients attending a tertiary care eye hospital in north India, which was later confirmed with molecular characterization.

Of the 50 patients suffering from optic neuritis reported to the Ophthalmology OPD of a tertiary care eye hospital in New Delhi, India, 29 were included in the study. Blood culture from these patients were processed for aerobic and anerobic cultures to rule out infective aetiology. Subsequently, PCR was done on archive, glycerol-stocked cultures.

Gram-negative pleomorphic coccobacilli grew in four of 29 patients tested. Characterization of these revealed Bartonella like organism as tested by the API 20E, API Staph, API Strept and RapID ANA systems. Electron microscopy revealed presence of polar flagella and bleb like projection all over the bacterial surface. PCR performed on preserved culture confirmed these as Bartonella sp.

Infections with Bartonella like organisms have not been demonstrated from India in cases of optic neuritis or in any of the other clinical syndromes in the past. The present study shows the isolation and characterization of Bartonella like organisms from optic neuritis patients. From clinical point of view it will be important to look for these organisms as aetiological agents in ON cases in order to treat with appropriate antibiotics.