Nigus Zegeye
Title: Throat Carriage Rate, Antibiotic Susceptibility pattern, emm gene typing and protein profiling of Beta-Hemolytic Streptococci in Children with Rheumatic Heart Disease
Biography
Biography: Nigus Zegeye
Abstract
Abstract Background: rheumatic heart disease is highly prevalent cardiovascular disease in Ethiopian children. Though they took monthly penicillin G prophylaxis, aggravation of rheumatic heart disease is high. Objectives: we determined the throat carriage rate, antibiotic susceptibility pattern, emm typing and protein profiling of beta hemolytic Streptococci in children with rheumatic heart disease. Methods: Throat swab from 234 children was collected and inoculated onto Sheep blood agar plates. The bacterial strains were analyzed by conventional methods as well as advanced mass spectrometry and molecular methods. Antimicrobial susceptibility testing of streptococci was performed by Kirby Bauer disc diffusion method. Anti-Streptolysin O titer determination was also done to differentiate infection from colonization. Results: Out of 234 participants, 30.74 % (71) had previous history of rheumatic fever recurrence and 38.03% (89) were referred for possible heart valve surgical intervention but only three received this treatment. Throat carriage rate of beta-hemolytic streptococci was 23.93 % (56/234). Of these, 4 were characterized as S. pyogenes (Lancefield group A) and 4 as Streptococcus dysgalactaie subsp. Equisimilis (Lancefield group A, C and G). Six different emm gene types were identified with one newly discovered subtype (stGrobn.1) associated with an Streptococcus dysgalactaie subsp. Equisimilis isolate. The Streptococcal glycosyltransferase in strain emm 68.2 had N-linked glycosylation carrying a unique HexNAc-deoxyhexose; a novel post-translational modification not previously recognized or studied. All beta- hemolytic Streptococci were susceptible to penicillin except S. agalactaie. Natural penicillin and Oxacillin discordant were found in identifying drug susceptibility pattern of isolates. About 29% (46) indicate recent streptococcal infections (ASO > 200 units/µL). Children who received antibiotic prophylaxis within two weeks and compliance showed significantly lower beta- hemolytic streptococcal throat carriage than 4 weeks of injection and non-compliance (p=0. 004 and P=0.0003 respectively). Conclusion: The strains from S. pyogenes and S. dysgalactiae assessed here had different emm gene types and PTM patterns, enabling distinction of subgroups of these closely related strains with pathogenetic potential in rheumatic fever disease. Oxacillin is not a good drug for drug susceptibility testing. Recommendation: Presence of GAS, GCS and GGS and increased ASO titer would suggest inadequate prophylaxis and may call for revision of guidelines (interval of injection, bioavailability of dugs etc.) and Treatment intervention has to be established in Ethiopia for damaged heart valves.