Transcriptional Regulator PerA Influences Biofilm-Associated, Platelet Binding, and Metabolic Gene Expression in Enterococcus faecalis

Enterococcus faecalis is an opportunistic pathogen and a leading cause of nosocomial infections, traits facilitated by the ability to quickly acquire and transfer virulence determinants. A 150 kb pathogenicity island (PAI) comprised of genes contributing to virulence is found in many enterococcal isolates and is known to undergo horizontal transfer. We have shown that the PAI-encoded transcriptional regulator PerA contributes to pathogenicity in the mouse peritonitis infection model. In this study, we used whole-genome microarrays to determine the PerA regulon. The PerA regulon is extensive, as transcriptional analysis showed 151 differentially regulated genes. Our findings reveal that PerA coordinately regulates genes important for metabolism, amino acid degradation, and pathogenicity. Further transcriptional analysis revealed that PerA is influenced by bicarbonate. Additionally, PerA influences the ability of E. faecalis to bind to human platelets. Our results suggest that PerA is a global transcriptional regulator that coordinately regulates genes responsible for enterococcal pathogenicity

Intravenous to Oral Antimicrobial Stepdown Implementation at the Calgary General Hospital, Calgary, Alberta

Peer Reviewe

Masticator space abscess derived from odontogenic infection: imaging manifestation and pathways of extension depicted by CT and MR in 30 patients

Propagation of odontogenic masticator space abscesses is insufficiently understood. The purpose was to analyse pathways of spread in 30 patients with odontogenic masticator space abscess. The imaging findings in 30 patients (CT in 30, MR in 16 patients) were retrospectively analysed. CT and MR imaging depicted a masticator space abscess within: medial pterygoid muscle in 13 patients (43.3%), lateral masseter and/or pterygoid muscle in 14 (46.7%) and superficial temporal muscle in 3 patients (10%). In the lateral masticator space intra-spatial abscess extension occurred in 7 of 14 patients (50%). The sub-masseteric space provided a pathway in seven (70%). Extra-spatial extension involved the submandibular space only in 3 of 14 patients (21.4%). Medial masticator space abscesses exhibited extra-spatial spread only. Extension affected the parapharyngeal space and/or soft palate in 7 of 13 lesions (53.8%). MR imaging in comparison to CT increased the number of abscess locations from 18 to 23 (27.8%) and regions affected by a cellular infiltrate from 12 to 16 (33.3%). The sub-masseteric space served as a previously underestimated pathway for intra-spatial propagation of lateral masticator abscesses. Medial masticator space abscesses tend to display early extra-spatial parapharyngeal space and/or soft palate extension