m Rapid development within the field of massive parallel sequencing (MPS) is about to bring this technology within reach for diagnostic microbiology laboratories. We wanted to explore its potential for improving diagnosis and understanding of polymicrobial infections, using bacterial brain abscesses as an example. We conducted a prospective nationwide study on bacterial brain abscesses. Fifty-two surgical samples were included over a 2-year period. The samples were categorized as either spontaneous intracerebral, spontaneous subdural, or postoperative. Bacterial 16S rRNA genes were amplified directly from the specimens and sequenced using Ion Torrent technology, with an average of 500,000 reads per sample. The results were compared to those from culture-and Sanger sequencing-based diagnostics. Compared to culture, MPS allowed for triple the number of bacterial identifications. Aggregatibacter aphrophilus, Fusobacterium nucleatum, and Streptococcus intermedius or combinations of them were found in all spontaneous polymicrobial abscesses. F. nucleatum was systematically detected in samples with anaerobic flora. The increased detection rate for Actinomyces spp. and facultative Gram-negative rods further revealed several species associations. We suggest that A. aphrophilus, F. nucleatum, and S. intermedius are key pathogens for the establishment of spontaneous polymicrobial brain abscesses. In addition, F. nucleatum seems to be important for the development of anaerobic flora. MPS can accurately describe polymicrobial specimens when a sufficient number of reads is used to compensate for unequal species concentrations and principles are defined to discard contaminant bacterial DNA in the subsequent data analysis. This will contribute to our understanding of how different types of polymicrobial infections develop. O ur understanding of polymicrobial infections has been hindered by our limited possibilities for describing them. Recent investigations of bacterial brain abscesses using universal amplification of the bacterial 16S rRNA gene, followed by Sanger sequencing of cloned amplicons, have revealed that only a fraction of the bacteria present are identified by culture (1, 2). Nevertheless, this approach has limitations when it comes to detecting smaller subpopulations in a multispecies community, unless very high numbers of clones are sequenced (3). This is problematic, since the species structure of an abscess may change over time and pathogens important for establishing the infection potentially remain at only low concentrations in the more mature abscesses. Furthermore, the species that are important for maintaining and expanding the abscess might primarily exist close to the abscess wall and do not necessarily dominate in the pus obtained by aspiration. Rapid development within the field of massive parallel sequencing technologies (MPS) is about to provide the diagnostic laboratories with tools that can characterize even the most complex microbial communities. The aim of the present study was to use recent adva...

Infections caused by Burkholderia pseudomallei are rare in nonendemic areas, such as Scandinavia. We report the first two cases of melioidosis in Norway presenting with bacteraemia and splenic and prostatic abscesses, respectively.