The relative localization patterns of class B penicillin-binding proteins Pbp2x and Pbp2b were used as positional indicators of septal and peripheral (side-wall-like) peptidoglycan (PG) synthesis, respectively, in the midcell regions of Streptococcus pneumoniae cells at different stages of division. We confirm that Pbp2x and Pbp2b are essential in the strain D39 genetic background, which differs from that of laboratory strains. We show that Pbp2b, like Pbp2x and class A Pbp1a, follows a different localization pattern than FtsZ and remains at division septa after FtsZ reappears at the equators of daughter cells. Pulse-experiments with fluorescent D-amino acids (FDAAs) were performed in wild-type cells and in cells in which Pbp2x activity was preferentially inhibited by methicillin or Pbp2x amount was depleted. These experiments show that Pbp2x activity separates from that of other PBPs to the centers of constricting septa in mid-to-late divisional cells resolved by high-resolution 3D-SIM microscopy. Dual-protein and protein-fluorescent vancomycin 2D and 3D-SIM immunofluorescence microscopy (IFM) of cells at different division stages corroborate that Pbp2x separates to the centers of septa surrounded by an adjacent constricting ring containing Pbp2b, Pbp1a, and regulators, StkP and MreC. The separate localization of Pbp2x suggests distinctive roles in completing septal PG synthesis and remodeling.

Level II.

PURPOSE: Trending the pediatric-adjusted shock index (SIPA) after admission has been described for children suffering severe blunt injuries (i.e. injury severity score (ISS)>15). We propose that following SIPA in children with moderate blunt injuries, as defined by ISS 10-14, has similar utility. METHODS: The trauma registry at a single institution was queried over a seven year period. Patients were included if they were between 4-16 years old at the time of admission, sustained a blunt injury with an ISS 10-14, and were admitted less than 12 hours after their injury (n=501). Each patient's SIPA was then calculated at 0, 12, 24, 36, and 48 hours (h) after admission and then categorized as elevated or normal at each time frame based upon previously reported values. Trends in outcome variables as a function of time from admission for patients with an abnormal SIPA to normalize as well as patients with a normal admission SIPA to abnormal were analyzed. RESULTS: In patients with a normal SIPA at arrival, elevation within the first 24h of admission correlated with increased length of stay (LOS). Increased transfusion requirement, incidence of infectious complications, and need for in-patient rehabilitation were also seen in analyzed subgroups. An elevated SIPA at arrival with increased length of time to normalize SIPA correlated with increased length of stay LOS in the entire cohort and in those without head injury, but not in patients with a head injury. No deaths occurred within the study cohort. CONCLUSIONS: Patients with an ISS 10-14 and a normal SIPA at time of arrival who then have an elevated SIPA in the first 24h of admission are at increased risk for morbidity including longer LOS and infectious complications. Similarly, time to normalize an elevated admission SIPA appears to directly correlate with LOS in patients without head injuries. No correlations with markers for morbidity could be identified in patients with a head injury and an elevated SIPA at arrival. This may be due to small sample size, as there were no relations to severity of head injury as measured by Head Abbreviated Injury Scale (Head AIS) and the outcome variables reported. This is an area of ongoing analysis. This study extends the previously reported utility of following SIPA after admission into milder blunt injuries

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