Fig. 7.

This figure shows representative microscopic images of Giemsa eosin-stained methyl methacrylate–embedded mouse femoral sections of Hi-SA5458-infected animals and Lo-SA5464-infected animals 14 days postoperatively (bone is stained pink, connective and soft tissue are rose, and cell nuclei are dark blue; the fracture site is either complete or only its trans part is shown). Marked tissue necrosis above the plate was visible in (A, black arrowheads) Hi-SA5458-infected animals and (B, black arrowheads) Lo-SA5464-infected animals. In Hi-SA5458 (C, black arrowheads), necrosis inside the bone marrow was present. Giemsa-positive coccoid bacteria were visible in (C, red square, see inset) Hi-SA5458-infected animals and less present in (D) Lo-SA5464-infected animals. (E) In animals infected with Hi-SA5458, mainly polymorphonuclear cell infiltration was observed, accompanied by (E, red square, inset) Giemsa-positive coccoid bacteria. In (E) Hi-SA5458-infected animals, the straight cutting lines on the bone stumps indicate no new bone formation, while (E, red circles) the presence of empty lacunae indicates osteonecrosis. In contrast, osteonecrosis in (F) Lo-SA5464-infected animals was less pronounced (F, black circles; lacunae are occupied by osteocytes), and the cutting lines were not completely straight but (F, black dashed polygon) limited new bone formation was recorded. Additionally, inflammation in (F) Lo-SA5464-infected animals was characterized by mixed infiltration mainly with mononuclear cells (no Giemsa-positive coccoid bacteria were found in this field of view). Artefacts: Cyan blue–stained, round structures in the soft tissue (A, B) were monofilament sutures placed postmortem to fix the soft tissue to avoid shrinkage artefacts. Images were taken at 2 x (A and B: scale bar 1 mm), 7.5 x (C and D: scale bar 200 mm), 40 x (E and F: scale bar 50 mm), and 100 x oil (insets: scale bar 20 mm). A color image accompanies the online version of this article.