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

Throat carriage rate, associated factors, and antimicrobial susceptibility pattern of group A Streptococcus among healthy school children in Jigjiga City, Eastern Ethiopia

Background

Group A Streptococcus has been recognized as an important human pathogen and it remains among the top ten causes of mortality from an infectious disease. Group A Streptococcus throat carriage plays an important role in the development of infection and transmission to contacts. In Ethiopia, there is little information about screening of children for group A Streptococcus carriage.

Objective

This study was aimed to assess the magnitude of throat carriage, associated factors, and antimicrobial susceptibility pattern of group A Streptococcus among healthy school children in Jigjiga city, Eastern Ethiopia from 12 April to 27 May 2021.

Method

A cross-sectional study was conducted enrolled by simple random sampling. Data on socio-demographic and related characteristics were gathered using pretested structured questionnaire. The throat sample was collected from 462 healthy school children and immediately transported to Jigjiga University Sultan Sheik Hassan referral hospital laboratory for investigation. Identification of group A Streptococcus was done by colony characterstics, gram staining, catalase negativity, bacitracin sensitivity, and Pyrrolidonyl arylamidase tests. Antibiotic susceptibility test was done on Muller-Hinton agar containing 5% sheep blood by modified Kirby-Bauer disc diffusion method. The data were coded, cleaned, and entered onto EpiData Version 3.1 then exported to SPSS version 26.0 for analysis. Bivariate and multivariable logistic regression through adjusted odds ratio (AOR) was used to determine the relationship between culture-positivity rates of GAS and predictor variables. A p-value < 0.05 was taken as statistically significant on multivariable analysis.

Results

The overall prevalence of group A Streptococcus throat culture rate was 10.6% (95%CI; 8.1%—13.7%). Previous family member who had a sore throat, children living with larger families (more than 11 members), and children living with non-immediate families were significantly associated with culture-positivity rates of GAS. Children who live with a family member with a sore throat compared with those who lived with in a family with no history of sore throat (AOR = 2.51; 95%CI 1.09–5.73), children who live with a large family comared to children living in families with less members (AOR = 4.64; 95% CI 1.53–14.1), and children who live with non-immediate families compared to children living with their mothers (AOR = 3.65; 95% CI 1.39 – 9.61), showed significant association with group A Streptococcus carriage rate. Resistance to all other antibiotics tested was low (< 5%). Multidrug resistance was found in 4.1% of isolates.

Conclusion

The present study showed 10.6% throat carriage of group A Streptococcus. Family member with a sore throat, having a large family, and living with non-immediate families have all been identified as independent predictors of carriage prevalence.

High risk of early sub-therapeutic penicillin concentrations after intramuscular benzathine penicillin G injections in Ethiopian children and adults with rheumatic heart disease

Introduction

Intramuscular benzathine penicillin G (BPG) injections are a cornerstone of secondary prophylaxis to prevent acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Uncertainties regarding inter-ethnic and preparation variability, and target exposure profiles of BPG injection are key knowledge gaps for RHD control.

Methods

To evaluate BPG pharmacokinetics (PK) in patients receiving 4-weekly doses in Ethiopia, we conducted a prospective cohort study of ARF/RHD patients attending cardiology outpatient clinics. Serum samples were collected weekly for one month after injection and assayed with a liquid chromatography-mass spectroscopy assay. Concentration-time datasets for BPG were analyzed by nonlinear mixed effects modelling using NONMEM.

Results

A total of 190 penicillin concentration samples from 74 patients were included in the final PK model. The median age, weight, BMI was 21 years, 47 kg and 18 kg/m², respectively. When compared with estimates derived from Indigenous Australian patients, the estimate for median (95% confidence interval) volume of distribution (V/F) was lower (54.8 [43.9–66.3] l.70kg^-1) whilst the absorption half-life (t_1/2-abs2) was longer (12.0 [8.75–17.7] days). The median (IQR) percentage of time where the concentrations remained above 20 ng/mL and 10 ng/mL within the 28-day treatment cycle was 42.5% (27.5–60) and 73% (58.5–99), respectively.

Conclusions

The majority of Ethiopian patients receiving BPG as secondary prophylaxis to prevent RHD do not attain target concentrations for more than two weeks during each 4-weekly injection cycle, highlighting the limitations of current BPG strategies. Between-population variation, together with PK differences between different preparations may be important considerations for ARF/RHD control programs.

Rheumatic heart disease (RHD) is the most common form of acquired heart disease in Ethiopia across all age groups. Monthly benzathine penicillin G (BPG) injections remains the cornerstone of secondary prophylaxis to prevent recurrent acute rheumatic fever (ARF) and progression to RHD, but data supporting the optimal dose and timing of BPG injections is a major knowledge gap for National RHD control programs, particularly amongst the highest risk groups. In this study we measured penicillin concentrations in Ethiopian patients receiving regular BPG injections. It demonstrates that that most Ethiopian patients receiving BPG as secondary prophylaxis to prevent RHD do not maintain target concentrations for more than two weeks during each 4-weekly injection cycle. This study highlights the limitation of the current BPG dosing recommendations and underpin global calls for improved penicillin formulations and better dosing and delivery strategies.

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

Background: Secondary prophylaxis against repeated attacks of acute rheumatic fever is an important intervention in patients with rheumatic heart disease (RHD), and it aims to prevent throat infection by group A β-hemolytic streptococcus (GAS); however, its implementation faces many challenges. This study aimed to assess throat colonization, antibiotic susceptibility, and factors associated with GAS colonization among patients with RHD attending care at Jakaya Kikwete Cardiac Institute in Dar-es-Salaam, Tanzania.

Methods: A descriptive cross-sectional study of RHD patients attending the Jakaya Kikwete Cardiac Institute was conducted from March to May 2018, where we consecutively enrolled all patients known to have RHD and coming for their regular clinic follow-up. A structured questionnaire was used to obtain patients' sociodemographic information, factors associated with GAS colonization, and status of secondary prophylaxis use and adherence. Throat swabs were taken and cultured to determine the presence of GAS, and isolates of GAS were tested for antibiotic susceptibility using Kirby–Bauer disk diffusion method according to the Clinical and Laboratory Standards Institute version 2015. Antibiotics of interest were chosen according to the Tanzanian Treatment Guidelines.

Results: In total, 194 patients with RHD were enrolled, their mean age was 28.4 ± 16.5 years, and 58.2% were females. Only 58 (29.9%) patients were on regular prophylaxis, 39 (20.1%) had stopped taking prophylaxis, whereas 97 (50.0%) had never been on prophylaxis. Throat cultures were positive for GAS in 25 (12.9%) patients. Patients who stopped prophylaxis were 3.26 times more likely to be colonized by GAS when compared to patients on regular prophylaxis. Majority (96%) of GAS isolates were susceptible to penicillin, ceftriaxone, and ciprofloxacin, whereas the highest resistance (20%) was observed with vancomycin. No GAS resistance was observed against penicillin.

Conclusion: The prevalence of GAS throat colonization is high among this population and is associated with stopping prophylaxis. The proportion of patients on regular secondary prophylaxis is unacceptably low, and interventions should target both patients' and physicians' barriers to effective secondary prophylaxis.

Prevalence of group A Streptococcal infection in Africa to inform GAS vaccines for rheumatic heart disease: A systematic review and meta-analysis

BACKGROUND

The prevalence of group A streptococcal (GAS) disease is estimated at >18.1 million cases with an incidence of >1.78 million cases per year. While a significant cause of mortality and morbidity on the global scale, the burden of GAS disease in Africa is unknown. We conducted a systematic review on the prevalence of GAS disease among children and adults in Africa and the frequency and distribution of emm types among isolates.

METHODS

We performed a comprehensive literature search in a number of databases, using an African search filter. Two reviewers independently selected articles meeting pre-specified criteria and extracted relevant data as per a data extraction form. We applied the random-effects meta-analysis model to aggregate GAS prevalence estimates with 95% CI for GAS prevalence, incorporating the Freeman-Tukey transformation to account for between-study variability.

RESULTS

Twenty-five studies were included. Invasive GAS disease prevalence ranged from 0.6% to 10.8% in samples from normally-sterile sites including blood, CSF and soft tissue. A single study reported a prevalence of 74% in skin infections. Prevalence of emm types varied with up to 88 different strains reported, corresponding to a vaccine coverage of 28% to 65%. The pooled prevalence of GAS in persons presenting with pharyngitis was 21% (95% CI, 17% to 26%).

CONCLUSIONS

The prevalence of GAS remains high among symptomatic individuals residing in Africa. Data on molecular strain characterisation of GAS in Africa is largely non-existent, thus the need for further studies is warranted to inform current prevention efforts including vaccine development.

Scolopendra subspinipes mutilans L. Koch Ameliorates Rheumatic Heart Disease by Affecting Relative Percentages of CD4+CD25+FoxP3 Treg and CD4+IL17 T Cells

(Scolopendra subspinipes mutilans L. Koch. (SSLK) helps reduce the risk of coronary heart disease (CHD) but its effects on rheumatic heart disease (RHD) patients remain unclear. 80 RHD patients were recruited and randomly assigned into SG (to receive SSLK treatment) and CG (to receive placebo) groups, and the intervention lasted for 3 months. The following cardiac indexes were measured, including mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), blood lactate, fatigue, shortness of breath, palpitation, and chest pain. ELISA kits were used to analyze creatine kinase isoenzyme (CK-MB), serum troponin T (cTnT), CRP, IL-1β, IL-6, and TNF-α, malondialdehyde (MDA), and superoxide dismutase (SOD). Relative percentages of CD4⁺CD25⁺FoxP3 regulatory (Treg) and CD4⁺IL-17 T cells were measured using flow cytometry. After 3-month therapy, SSLK intervention improved MAP, HR, CVP, fatigue, palpitation, and shortness breath of CHD patients, reduced the levels of blood lactate, CK-MB, cTnT, CRP, IL-1β, IL-6, TNF-α, MDA, and increased SOD level (p < 0.05). Meanwhile, SSLK treatment increased the percentages of CD4⁺CD25⁺FoxP3 Treg cells and reduced relative percentages of CD4⁺IL-17 T cells in a dose-dependent way (p < 0.05). Relative percentage of CD4⁺CD25⁺FoxP3 Treg cells had negative relationship while CD4⁺IL17 T cells had positive relationship with CK-MB, cTnT, CRP, and TNF-a (p < 0.01). SSLK ameliorated RHD by affecting the balance of CD4⁺CD25⁺FoxP3 Treg and CD4⁺IL17 T cells.

Acute Pharyngitis Associated With Streptococcus dysgalactiae Subspecies equisimilis in Children

BACKGROUND AND OBJECTIVES

The importance of Streptococcus dysgalactiae subsp. equisimilis (SDSE) in causing sporadic pharyngitis in children remains controversial. The aims of this study were (1) to report the incidence and (2) to compare the epidemiologic and clinical features of patients with SDSE to those with Streptococcus pyogenes (SP).

METHODS

A prospective study was conducted on acute pharyngitis associated with SDSE in children over a 2-year period. SDSE was identified using a phenotypic method, M protein gene (emm) analysis and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Patients with positive SDSE or SP cultures received cephalosporins for 5 days and were followed up. The emm genotyping and specific virulence genes analyses were performed.

RESULTS

From 3416 throat cultures, 67 isolates (2.0%) were identified as SDSE and 515 (15.1%) were identified as SP. The mean age of patients with SDSE (8.3 years) was older than those with SP (6.6 years; P < 0.01). There was minimal seasonal variation in the isolation rates of SDSE. The febrile patients' rates, gender distribution, cervical lymph node adenopathy rates, hospitalization rates, eradication and failure rates and the nonsuppurative sequelae between patients with SDSE and SP were similar. All SDSE isolates possessed important virulence genes. The emm genotyping of SDSE showed high strain diversity.

CONCLUSIONS

The incidence of acute pharyngitis associated with accurately identified SDSE was 2/15 of that with SP. Epidemiologic and clinical features of acute pharyngitis associated with SDSE are indistinguishable from those with SP, with the exception of age and seasonal variation.