Listeria in Adults - Truly Rare or Rarely Diagnosed in India?

Listeria monocytogenes is a facultative anaerobic intracellular Gram positive rod causing infection in pregnant women, extremes of age and immune-compromised hosts. In clinical specimens, the organisms may be gram-variable: laboratory misidentification of L. monocytogenes isolates as diphtheroids, streptococci, or enterococci is not uncommon and the isolation of a diphtheroid from blood or CSF should always alert the clinician to the possibility that the organism may be L. monocytogenes. The disease has rarely been reported in India in non-pregnant adults. We herein report four cases of L. monocytogenes infection in immune-compromised adults.