P055 Title: Standard rate of ASLO in healthy children with streptococcal (angina) or post-streptococcal (RAA) infection in Morocco

Abstract

Abstract Background The antistreptolysins O “ASLO” are anti streptococcal antibodies directed against streptolysin O. The assay of ASLO can provide proof of infection of streptococcal origin. However, it cannot confirm the presence of RAA or the degree of severity of the disease. A level of ASLO less than or equal to a critical threshold of 200 IU/ml is considered normal in children. Several factors influence the ASLO title and therefore their standard rate such as age, geographic location and seasonal variation. The objective of this study is to determine the upper normal limit (ULN) of ASLO in healthy children with angina or RAA at the CHU Hassan II of Fez in Morocco. Methods This is a cross-sectional study carried out from January 2016 to July 2019 in the cardiopediatric unit of CHU Hassan II and the Anarjiss health center in Fez. Patients below 18 years of age were included in this study. The children are classified into 3 groups: group 1: 152 children with RAA and who are diagnosed according to the modified Jones criteria, group 2: 177 children with angina, group 3: 157 healthy children who did not have an RAA, a history of recurrent or recent pharyngitis. Patient data is collected on operating sheets. Statistical analysis was performed using SPSS v 21 software. To establish a normal upper limit for ASLOs, the 90 percentile was used as it is a value below which at least 90% of cases studied in each group. Results The most common age group in the 3 groups is the age group between 5 and 15 years old. The frequency of children of urban origin is greater than that of rural origin in all the groups studied. The ULN is 421.4U/ml in the group of normal children, 641.95 U/ml in the RAA group and 561.8 U/ml in the group of children with pharyngitis. The study of changes in ASLO rates over time shows that they increase significantly in angina and tend to decrease in RAA. The LSN of ASLOs by gender shows that it is higher for boys than for girls. The ULN according to the residence shows that it is higher in urban areas. As well as the LSN of ASLO according to the season shows that it is higher in the cold period, especially in winter and spring (P < 0.001). With regard to age, the ULN of ASLOs is higher in the 5–15 age group. Conclusion In this study, it can be concluded that an ASLO level less than or equal to 400 U/ml is the critical threshold in a normal child, while an ASLO level >400 U/ml is considered pathological in children. children in Morocco.