Background:A previous cross-sectional study reported that pathogenic factors associated with Osgood-Schlatter disease (OSD) in adolescent athletes include increased quadriceps muscle tightness, lower leg malalignment, and development of apophysitis in the tibial tuberosity.Purpose:To confirm these pathogenic factors associated with OSD in a longitudinal study with regard to physical function and performance.Study Design:Cohort study; Level of evidence, 2.Methods:In this study, 37 boys (mean age, 10.2 ± 0.4 years) were recruited from 2 soccer teams at an elementary school. This cohort study was conducted over an observation period of 1 year, with measurements recorded at baseline, followed by screening for OSD every 6 months. Variables evaluated at baseline included physical function (morphometry, joint flexibility, and lower extremity alignment), presence of Sever disease, and kicking motion.Results:Pathogenic factors associated with OSD in the support leg of adolescent male soccer players included height, weight, body mass index, quadriceps femoris muscle tightness in the kicking and support legs, and gastrocnemius muscle tightness, soleus muscle tightness, and medial longitudinal arch in the support leg. Additional factors included a diagnosis of Sever disease and distance from the lateral malleolus of the support leg’s fibula to the center of gravity during kicking.Conclusion:The onset of OSD was found to be affected by many factors, including developmental stage, physical attributes, and pre-existing apophysitis. In particular, a diagnosis of Sever disease and backward shifting of the center of gravity during kicking increased the risk of the subsequent onset of OSD, suggesting that these factors are very important as a possible focus for interventions.
Rhodococcus equi was isolated from the lungs of six foals with bronchopneumonia. All isolates expressed 15-17-kd antigens by immunoblot analysis and contained a virulence-associated plasmid of 85 or 90 kb. Immunohistochemically, R. equi from all pulmonary lesions showed the expression of 15-17-kd antigens mainly in the phagocytic cells. The specific monoclonal antibody to 15-17-kd antigens of R. equi (MAb 10G5) may be an aid in the diagnosis of R. equi-induced pneumonia.
ABSTRACT. Although isolation of Rhodococcus equi from tracheobronchial aspirates is thought to be a definitive diagnosis of R. equi pneumonia in foals, virulence of isolates from the aspirates of infected foals remains obscure. In the present study, transtracheal aspirates were collected from thirty-one 1-to 6-month-old foals, which showed clinical signs of respiratory tract infection, and R. equi isolates were analyzed for the presence of virulence plasmids and virulence-associated antigens. Moreover, this method was compared with a serodiagnosis by an enzyme-linked immunosorbent assay (ELISA) to evaluate the sensitivity of the ELISA. Of the 31 foals, 21 revealed positive cultures for R. equi. Of the 21 foals, 20 (95%) had an ELISA OD value of 0.3 (positive limit of this test) or higher at the initial medical examination. All of the isolates from the aspirates were virulent R. equi, which contained virulence plasmids and expressed virulence-associated antigens. In the remaining 10 foals showing a negative culture for R. equi, 3 foals had positive ELISA titers. Six foals died during the treatment, and necropsy revealed that 5 of the 6 foals had R. equi infection characterized by large abscesses in the lungs, and 3 of the 5 foals also had intestinal lesions. All clinical isolates from the lesions of the foals were virulent R. equi. These results support the assumption that isolates from the transtracheal aspirates of infected foals are virulent R. equi and the sensitivity of ELISA might demonstrate a serodiagnostic value for early diagnosis of R. equi infection in foals. -KEY WORDS: foal, Rhodococcus equi, tracheal aspirate, virulence.
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