In Vivo Tracking of Streptococcal Infections of Subcutaneous Origin in a Murine Model

Abstract

Purpose Generation of plasmin in vivo by Streptococcus pyogenes is thought to localize the active protease complexes to the pathogen surface to aid in tissue dissemination. Here, we chose to follow cutaneous streptococcal infections by the use of non-invasive bioluminescence imaging to determine if this pathogen can be followed by this approach and the extent of bacterial spread in the absence of canonical plasminogen activation by streptokinase. Procedures Mice were injected subcutaneously with either bioluminescent strains of streptococci, namely Xen20 and Xen10 or S. pyogenes ALAB49. Bioluminescence imaging was performed daily and results were correlated with microbiological and histological analyses. Results Comparative analysis of chronologic non-invasive datasets indicated that Xen20 did not disseminate from the initial infection site. Contrary to this, microbiological and histological analyses of Xen20 mice for total bacterial burden indicated sepsis and widespread pathogen involvement. Conclusions The use of bioluminescence in microbe-based studies requires genomic and pathologic characterization to correlate imaging results with underlying pathology.

Sugar shock: Probing Streptococcus pyogenes metabolism through bioluminescence imaging

“…Our previous results indicated that the luminescence of Strep. Xen20 did not accurately reflect bacterial load in vivo and suggested this may be due to a D -glucose-mediated inhibitory effect (4). To confirm this finding on a static medium, we plated Strep .…”

“…Competition for carbon sources and energy may affect the survival of Streptococcus pyogenes ( S. pyogenes ) during an infection. Previously we found that a luxABCDE -incorporated S. pyogenes had reduced light production in D -glucose enriched medium (4). Although this trait is less desirable for Strep.…”

“…Previously, we studied a luxABCDE- modified Streptococcus pyogenes Xen20 ( Strep . Xen20) to track the spread of cutaneous infection in wild type mice (4). By ex vivo colony forming units (CFU) determination and Gram-staining histology, we noted live Streptococcus present in the distal organs of the infected animals.…”

Sugar Shock: Probing Streptococcus pyogenes Metabolism Through Bioluminescence Imaging

“…Our previous results indicated that the luminescence of Strep. Xen20 did not accurately reflect bacterial load in vivo and suggested this may be due to a D -glucose-mediated inhibitory effect ( Davis et al, 2015 ). To confirm this finding on a static medium, we plated Strep .…”

“…Previously, we studied a luxABCDE -modified S. pyogenes Xen20 ( Strep . Xen20) to track the spread of cutaneous infection in wild-type mice ( Davis et al, 2015 ). By ex vivo colony forming units’ (CFUs) determination and Gram-staining histology, we noted live Streptococcus present in the distal organs of the infected animals.…”