Detection of biofilm-producing and methicillin resistance genes in Staphylococcus epidermidis isolated from healthy humans and in blood culture tests.

The detection of biofilm-producing (ica AB) and methicillin resistance genes (mec A) was investigated in 70 blood culture isolates of Staphylococcus epidermidis and in 66 and 51 isolates from human hands and the vestibules of the nose, respectively, of 77 healthy subjects who gave consent. Of the 70 strains isolated from blood culture testing, both ica AB and mec A were detected in 36 (51.4%), and neither was detected in 4 (5.7%). The mec A gene only was detected in 30 (42.9%), but no isolate from blood culture testing possessed the ica AB gene alone. In contrast, of the 66 isolates from healthy hands, only one isolate (1.5%) possessed both genes, whereas neither was detected in 56 (84.8%), but the mec A gene was detected in 9 (13.6%). Of the 51 isolates from the nasal vestibules, both genes were detected in 12 (23.5%), and neither in 15 (29.4%). Moreover, the mec A gene was detected in 17 (33.3%). Thus, S. epidermidis strains that normally inhabit the nasal vestibule were found to carry the ica AB and mec A genes more frequently than those that inhabit the fingers. The ica AB and mec A genes were detected in S. epidermidis isolated in blood culture tests from patients diagnosed with sepsis associated with catheter-related bloodstream infection (CR-BSI). Both genes were detected in 7 (70.0%) of 10 isolates, and the mec A gene alone was detected in 3 (30.0%). In fact, we could not detect any strain carrying only the ica AB gene from S. epidermidis, an infecting organism of CR-BSI. This suggests that surviving strains carrying the mec A gene cause severe infection on empirical administration of an antibacterial drug, although biofilm formation by the ica AB gene is also important for CR-BSI. Based on these findings, most strains of S. epidermidis causing CR-BSI are biofilm-producing beta-lactam-resistant (methicillin-resistant) bacteria. When S. epidermidis is isolated from blood culture testing, the identification of both ica AB and mec A genes may be significant with regard to judging whether the detected strain is the etiologic agent of CR-BSI.

Plantar pressure distribution during gait in athletes with functional instability of the ankle joint: preliminary report.

This study addressed the hypothesis that gait characteristics differ between normal subjects and athletes suffering from functional instability (FI) of the ankle joint. FI of the ankle joint is one of the most common residual disabilities after an acute ankle sprain. However, the influences of the FI of the ankle joint on the gait characteristics are not well understood. Athletes suffering from FI of the ankle joint and healthy control subjects were examined. Pressure, area, and force during gait were measured using a pressure measuring system. These in vivo plantar pressure measurements were performed during free walking. The foot angle and the pronation-supination index were calculated. Those in the FI group were found to exhibit a significantly lower dynamic foot angle and a greater pronation-supination index at the midsupport phase of gait than those in the control group. The results showed increased adduction-supination of the foot at the stance phase of gait in those with FI of the ankle joint.

Tartrate-resistant acid phosphatase-positive cells in the synovial-cartilage junction and bone marrow during the progression of collagen-induced arthritis in adult rats.

We investigated the time-course changes in bone destruction in rats with collagen-induced arthritis (CIA). The synovial-cartilage junction (SCJ) and epiphyseal bone marrow of the femoral posteromedial condyle in CIA rats were evaluated histologically and immunohistologically at 2, 3, 4, 6, and 8 weeks after sensitization. Two weeks after sensitization, tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells formed resorption lacunae on the lateral side of the cortical bone under the SCJ. No resorption lacunae were observed in bone marrow. Three weeks after sensitization, resorption lacunae on the lateral side of the cortical bone expanded, but no bone marrow invasion by pannus was observed. In bone marrow, many TRAP-positive multinuclear cells appeared and formed resorption lacunae in subchondral bone. Four weeks after sensitization, cortical bone was destroyed, and pannus had invaded the bone marrow. After six weeks, trabecular bone and subchondral bone plate were extensively resorbed by TRAP-positive cells. Bone destruction in CIA began with the appearance of TRAP-positive cells on the lateral side of the cortical bone under the SCJ, followed by the TRAP-positive multinuclear cells in bone marrow, which were morphologically unconnected to the SCJ lesions. These histological findings suggested that bone destruction in the early stage of arthritis occurred in two anatomically different regions.