The expansion of the microbiological spectrum of brain abscesses with use of multiple 16S ribosomal DNA sequencing.

Background. Brain abscess is commonly treated using empirically prescribed antibiotics. Thus, a comprehensive study of bacterial organisms associated with brain abscess is essential to define the best empirical treatment for this life-threatening condition. Methods. We prospectively compared cultures to single and multiple sequenced 16S ribosomal DNA polymerase chain reaction amplifications (by cloning and/or pyrosequencing) of cerebral abscesses in 20 patients from 2 hospitals in Marseilles, France, during the period January 2005 through December 2007. Results. The obtained cultures identified significantly fewer types of bacteria (22 strains) than did molecular testing (72 strains; P = .017, by analysis of variance test). We found that a patient could exhibit as many as 16 different bacterial species in a single abscess. The obtained cultures identified 14 different species already known to cause cerebral abscess. Single sequencing performed poorly, whereas multiple sequencing identified 49 species, of which 27 had not been previously reported in brain abscess investigations and 15 were completely unknown. Interestingly, we observed 2 patients who harbored Mycoplasma hominis (an emerging pathogen in this situation) and 3 patients who harbored Mycoplasma faucium, which, to our knowledge, has never been reported in literature. Conclusions. Molecular techniques dramatically increased the number of identified agents in cerebral abscesses. Mycoplasma species are common and should be detected in this situation. These findings led us to question the accuracy of the current empirical treatment of brain abscess.