Background: Streptococcus pyogenes (group A streptococcus, GAS) is an important human bacterial pathogen. This organism possesses many virulence factors, Streptococcal pyrogenic exotoxin one of these and the presence of virulence factors is often related to the severity of the disease.
Aim: The present study aimed to detect Streptococcal pyrogenic exotoxin (Spe) A and Spe B in isolated Streptococcus pyogenes.
Methods: Two hundred throat swab samples were collected in across sectional study from children with pharyngitis referred to Pediatric Teaching hospital and ENT hospital Wad medani, Sudan, from January to November 2021. Questionnaire was filled to collect clinical and demographic data. In order to isolate Streptococcus pyogenes, throat swabs were obtained and processed according to normal microbiological protocol. Using the Kirby Bauer disk diffusion method, antimicrobial susceptibility testing was performed on all GAS isolates in accordance with clinical laboratory standard institute (CLSI) criteria. Multiplex PCR was used to identify the Spy 1258 gene as well as the streptococcal pyrogenic exotoxins SpeA and SpeB.
Results: Amongst the Two hundred collected samples fifty-one isolates, (25.5%) were identified as S. pyogenes. Antibiotic susceptibility testing showed that all the GAS isolates were sensitive to Azithromycin and Penicillin. Sensitivity to Erythromycin, Gentamicin, Clarithromycin, Amoxicillin and Cephalexin were 88.2%, 86.3%, 45.1%, 41.2%, 13.7%, respectively. SpeA was detected in 17(33.3%) and SpeB in 48(94.1%).
Author(s) Details:
Minas Mohamed Balla
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.
Ameer Mohamed Dafalla
Department of Molecular and Immunogenetics, NCI, University of Gezira, Wad Medani, Sudan.
Recent Global Research Developments in Diagnosis and Management of Group A Streptococcal Pharyngitis
Diagnosis Guidelines:
Clinical guidelines recommend using a rapid antigen detection test (RADT) and/or bacterial culture for diagnosing GAS pharyngitis [1] .
A retrospective analysis of pharyngitis events in the United States from 2011 to 2015 found that:
Roughly 43% of cases were diagnosed by RADT, while 20% were diagnosed by RADT plus culture.
The use of nucleic acid amplification testing (NAAT) increased significantly during this period.
Diagnostic testing can help reduce inappropriate antibiotic use [1] .
Antibiotic Use:
Antibiotics are prescribed in approximately 60% of pharyngitis cases to prevent complications and address patient demands.
Diagnosis using RADT plus culture or NAAT alone was associated with lower antibiotic use [1] .
Provider Behavior:
Pediatricians were less likely than other providers to prescribe antibiotics, regardless of patient age [1] .
References
- 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
- Shulman, S. T., Bisno, A. L., Clegg, H. W., Gerber, M. A., Kaplan, E. L., Lee, G., … & Van Beneden, C. (2012). Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clinical infectious diseases, 55(10), e86-e102.
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