Central nervous system infections due to Abiotrophia and Granulicatella species: an emerging challenge?

Although Abiotrophia and Granulicatella species, previously referred to as nutritionally variant streptococci, were initially identified over 40 years ago, isolation of these pathogens from the central nervous system (CNS) was first noted only recently. Recognition of CNS involvement with these organisms is of great concern given the association of Abiotrophia/Granulicatella infections with increased morbidity and mortality as well as greater bacteriologic failure and relapse rates. We describe A. defectiva and G. adiacens CNS infections in two patients and review the existing literature of CNS involvement with these bacteria. The clinical presentation and initial cerebrospinal fluid analysis has varied substantially across reported patients. While most infections have been characterized primarily by a localized infection (e.g., abscess), evidence of meningitis has usually also been present. Furthermore, nearly all cases have followed neurosurgical procedures suggesting possible introduction of the organism into the CNS at the time of surgery. Given the significant negative clinical impact of Abiotrophia/Granulicatella infections, elucidation of the emerging epidemiology of CNS infections with these bacteria is warranted.