Throat culture positivity rate and antibiotic susceptibility pattern of beta-hemolytic streptococci in children on secondary prophylaxis for rheumatic heart disease

Abstract

BackgroundAmong children diagnosed to have chronic rheumatic valvular heart disease (RHD) in Ethiopia, many have been observed to develop recurrence of rheumatic fever (RF) despite secondary prophylaxis. This study determined the throat culture positivity rate and drug susceptibility pattern of beta hemolytic streptococci (BHS) isolated from children attending a specialized cardiac clinic in Ethiopia.MethodsThroat swabs were collected from 233 children receiving benzathine penicillin injection as secondary prophylaxis for RHD and cultured. The bacterial isolates were characterized using Matrix Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry. Drug susceptibility was tested with the Kirby Bauer disc diffusion method. Anti-streptolysin O (ASO) titers were determined using ASO latex reagents.ResultsThe throat culture positivity rate for BHS was 24 % (56/233). Among the BHS bacterial strains isolated, four were characterized as S. pyogenes and another four as S. dysgalactiae subsp. equisimilis (Lancefield group A, C and G). All BHS were susceptible to penicillin except one isolate of S. agalactiae. Among 233 children enrolled, 46(19.7 %) showed increased ASO titer. Children who received antibiotic prophylaxis within 2-weeks of last injection had significantly lower BHS throat culture positivity rate than those injected every 4-weeks (p = 0.02). Children who missed at least one prophylaxis within the last 6 months had a higher BHS culture positivity rate than those who did not miss any (p = 0.0003).ConclusionsThe presence of groups A, C and G streptococci in the throat of children under secondary prophylaxis for RHD and increased ASO titer suggests failure of the regimen. This calls for further investigation into the causes of inadequate prophylaxis (including bioavailability of drugs used, optimal duration and patient compliance) and intervention.

Throat colonization and antibiotic susceptibility of group A β-hemolytic streptococci among rheumatic heart disease patients attending a cardiac referral hospital in Tanzania, A descriptive cross-sectional study

“…The finding that stopping ARF prophylaxis is independently associated with positive GAS throat culture results is in agreement with previous reports in literature [7,21,23,25]. In the study by…”

“…The 12.9% prevalence of throat GAS colonization found in this study is much higher than that found among 233 children with chronic RHD attending care at a cardiac clinic in Addis Ababa, Ethiopia [7].…”

“…This is more serious for those who are particularly at a greater risk due to a number of factors including their genetic susceptibility which renders them more sensitive to infection with a rheumatogenic strain of GAS [19]. Only few studies from sub-Saharan Africa have reported the prevalence of GAS colonization in the general population [17,20], in patients with pharyngotonsillitis [21,22], and among RHD patients [7]. The present study therefore adds to the current knowledge on RHD in the region by demonstrating that among RHD patients attending care at a tertiary health facility in Tanzania, throat GAS colonization is present in 12.9% and is independently associated with stopping ARF prophylaxis among these patients.…”

“…Using previous prevalence [7], a sample size of 194 RHD patient was enough to determine the prevalence of throat colonization at 95% confidence and at an error margin of 5%.…”

“…There is also limited awareness among medical personnel on the initiation and continuity of prophylaxis [5]. This causes low compliance and adherence, resulting in inadequate prophylaxis and failure to eradicate GAS from the throat [6,7].…”