Collected from Children with Pharyngitis : A Part from the Book Chapter : Evaluating the Molecular Identification of Streptococcus pyogenes Isolated from Children with Pharyngitis in Gezira State, Sudan

Background: Streptococcus pyogenes (Group A streptococcus) is an important Gram-positive human pathogen that affects the upper respiratory tract, such as the tonsils and pharynx, and also induces post-infection diseases such as rheumatic fever and glomerulonephritis. The infection rate is more than 600 million infections annually resulting in more than 500,000 deaths a year.

Aim: This study aims to isolate Streptococcus pyogenes from children with pharyngitis and to evaluate the molecular identification of S. pyogenes compared with conventional methods.

Methods: A cross-sectional study was conducted on a total of 200 throat swab samples which were collected from children with pharyngitis referred to Wad Medani Pediatric Teaching Hospital and Wad Medani ENT hospital from January to November 2021. Demographic and clinical data were collected by questionnaire. Throat swabs were tested with the standard microbiological techniques to isolate Group A streptococcus (GAS). Antimicrobial susceptibility testing was performed on all GAS isolates using the Kirby Bauer disk diffusion method according to Clinical Laboratory Standard Institute (CLSI) guidelines. Additionally, PCR was used to identify the Spy 1258 gene of isolated bacteria. Statistical analysis was done by SPSS statistical software.

Results: From all throat swab samples screened, 51 isolates (25.5%) were identified as GAS. The study showed the Spy 1258 gene specific for S. pyogenes only when tested for other species including Staphylococcus aureus, Coagulase negative staphylococci, other streptococci, E. coli and human DNA. Antibiotic susceptibility testing revealed that all the GAS isolates were sensitive to Penicillin and Azithromycin. Sensitivity to Erythromycin, Gentamicin, Clarithromycin, Amoxicillin and Cephalexin were 88.2%, 86.3%, 45.1%, 41.2%, 13.7%, respectively. Based on PCR identification of Spy 1258 gene the percentage of isolated bacteria was 21%.

Conclusion: The rate of isolated Streptococcus pyogenes was 25.5% by conventional methods and 21% by PCR. The bacteria were sensitive to Penicillin and Azithromycin. The Spy 1258 gene was specific for the detection of Streptococcus pyogenes.

Author(s) Details:

Minas Mohamed Balla Yousif
Department of Microbiology, Faculty of Science, University of Gezira, Wad Medani, Sudan.

Adil Mergani
Department of Molecular and Immunogenetics, NCI, University of Gezira, Wad Medani, Sudan.

Mohamed Elamin A. M. E. Medani
Pediatric Cardiologist, Faculty of Medicine, University of Gezira, Wad Medani, Sudan.

Adam Dawoud Abakar
Department of Medical Parasitology, Faculty of Medical Laboratory Science, University of Gezira, Wad Medani, Sudan.

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Recent Global Research Developments in Acute Streptococcal Pharyngitis in Children

Global Burden and Incidence Rates: A systematic review and meta-analysis highlighted the significant global burden of sore throat and group A Streptococcus (Strep A) pharyngitis. The study found a pooled incidence rate of 22.1 episodes per 100 child-years for Strep A sore throat [1] .

Diagnosis and Management: Research in the United States from 2011 to 2015 evaluated the diagnosis and treatment of acute pharyngitis. The study emphasized the importance of rapid antigen detection tests (RADT) and nucleic acid amplification testing (NAAT) in reducing inappropriate antibiotic use [2] .

Clinical Guidelines and Antibiotic Use: A comprehensive review of clinical guidelines and antibiotic treatment for pharyngitis in children and adults underscored the need for standardized diagnostic methods to prevent overuse of antibiotics [3] .

Diagnostic Methods: A study reviewed various diagnostic methods, including clinical scoring systems and RADTs, for group A beta-hemolytic streptococci (GABHS). The research highlighted the effectiveness of these methods in accurately diagnosing streptococcal pharyngitis [4] .

Impact of Vaccines: Research funded by the Wellcome Trust explored the potential impact of future Strep A vaccines on the global burden of sore throat and pharyngitis. The study called for methodologically standardized studies to better quantify the disease burden and evaluate vaccine efficacy [1] .

References

1. Miller, K. M., Carapetis, J. R., Van Beneden, C. A., Cadarette, D., Daw, J. N., Moore, H. C., … & Cannon, J. W. (2022). The global burden of sore throat and group A Streptococcus pharyngitis: A systematic review and meta-analysis. EClinicalMedicine, 48.
2. Luo, R., Sickler, J., Vahidnia, F. et al. Diagnosis and Management of Group a Streptococcal Pharyngitis in the United States, 2011–2015. BMC Infect Dis 19, 193 (2019). https://doi.org/10.1186/s12879-019-3835-4
3. Pellegrino, R., Timitilli, E., Verga, M.C. et al. Acute pharyngitis in children and adults: descriptive comparison of current recommendations from national and international guidelines and future perspectives. Eur J Pediatr 182, 5259–5273 (2023). https://doi.org/10.1007/s00431-023-05211-w
4. Mustafa Z and Ghaffari M (2020) Diagnostic Methods, Clinical Guidelines, and Antibiotic Treatment for Group A Streptococcal Pharyngitis: A Narrative Review. Front. Cell. Infect. Microbiol. 10:563627. doi: 10.3389/fcimb.2020.563627

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