Molecular Epidemiology and Superantigen Gene Profiles of Streptococcus pyogenes from Pediatric Pharyngitis in Baghdad City
DOI:
https://doi.org/10.32792/utq/utjsci/v13i1.1526Keywords:
Group A Streptococcus, pharyngitis, emm typing, superantigen genes, molecular epidemiology.Abstract
Streptococcus pyogenes (Group A Streptococcus, GAS) constitutes one of the main global causative agents of paediatric pharyngitis. However, the molecular aspects of the circulating strain in Iraq remains unknown. This study aims to determine the patterns of genetic divergence, the content of the superantigen gene, and the clonal relationships of S. pyogenes pharyngeal isolates obtained from children in Baghdad City. A total of 174 isolates were collected from three hospitals. Confirmed identifications were performed using standard medical microbiology methods. Twelve virulence gene factors were identified using PCR; emm typing was performed using 5' end hypervariable region sequencing; and clonal analysis was performed using PFGE of SmaI-digested DNA and the resulting dendrograms. Among the 21 recognised emm types, the most frequent were emm12, emm22, and emm1. Core virulence genes (scpA, sagA, slo, and nga) were evenly distributed among the isolates, whereas retention of the superantigen genes was discordant. This work is novel in that it examines the molecular profile of S. pyogenes in Baghdad City and situates its diversity within a global and regional clonal framework, along with its associated virulence traits.
Received: 07-12-2025
Revised: 27-01-2026
Accepted: 18-03-2026
References
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M. Virolainen et al., “Epidemiology and emm types among group A streptococcal pharyngitis in Finland: a prospective laboratory-based study,” Eur. J. Clin. Microbiol. Infect. Dis., vol. 43, no. 2, pp. 233–241, 2024.
S. Himri et al., “The place of group A streptococci in Moroccan children with pharyngitis and emm type distribution,” 2021.
V. Iyer et al., “Group A Streptococcus infections: their mechanisms, epidemiology, and current scope of vaccines,” Cureus, vol. 14, no. 12, 2022.
S. Hamada, S. Kawabata, and I. Nakagawa, “Molecular and genomic characterization of pathogenic traits of group A Streptococcus pyogenes,” Proc. Jpn. Acad. Ser. B, vol. 91, no. 10, pp. 539–559, 2015.
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N. J. Avire, H. Whiley, and K. Ross, “A review of Streptococcus pyogenes: public health risk factors, prevention and control,” Pathogens, vol. 10, no. 2, p. 248, 2021.
L. Norton and A. Myers, “The treatment of streptococcal tonsillitis/pharyngitis in young children,” World J. Otorhinolaryngol. Head Neck Surg., vol. 7, no. 3, pp. 161–165, 2021.
T. Auala, B. L. G. Zavale, A. Ç. Mbakwem, and A. O. Mocumbi, “Acute rheumatic fever and rheumatic heart disease: highlighting the role of group A Streptococcus in the global burden of cardiovascular disease,” Pathogens, vol. 11, no. 5, p. 496, 2022.
A. Sujhithra et al., “Streptococcal pharyngitis and rheumatic fever,” J. Pure Appl. Microbiol., vol. 16, no. 1, pp. 55–62, 2022.
A. P. Ralph et al., “Potential for molecular testing for group A Streptococcus to improve diagnosis and management in a high-risk population: a prospective study,” Open Forum Infect. Dis., vol. 6, no. 4, p. ofz097, 2019.
D. D. Barth, A. Moloi, B. M. Mayosi, and M. E. Engel, “Prevalence of group A streptococcal infection in Africa to inform GAS vaccines for rheumatic heart disease: a systematic review and meta-analysis,” Int. J. Cardiol., vol. 307, pp. 200–208, 2020.
H. Bergsten and V. Nizet, “The intricate pathogenicity of Group A Streptococcus: A comprehensive update,” Virulence, vol. 15, no. 1, p. 2412745, 2024.
S. Wrighton, “Exploring monoclonal antibody action against the Group A streptococcal M protein,” 2023.
H. R. Frost et al., “Analysis of global collection of group A Streptococcus genomes reveals that the majority encode a trio of M and M-like proteins,” mSphere, vol. 5, no. 1, 2020.
T. Proft and J. D. Fraser, “Streptococcus pyogenes superantigens: biological properties and potential role in disease,” in Streptococcus pyogenes: Basic Biology to Clinical Manifestations, 2nd ed., 2022.
J. M. Loh et al., “A multivalent T-antigen-based vaccine for Group A Streptococcus,” Sci. Rep., vol. 11, no. 1, p. 4353, 2021.
T. Barnett, A. Indraratna, and M. Sanderson-Smith, “Secreted virulence factors of Streptococcus pyogenes,” in Streptococcus pyogenes: Basic Biology to Clinical Manifestations, 2nd ed., 2022.
S. A. Jasim, Z. A. Hatem, and Z. Abd Mohammed, “Virulence factors and clinical features of Streptococcus pyogenes: overview,” Ann. Romanian Soc. Cell Biol., vol. 25, no. 1, pp. 603–614, 2021.
B. Tümmler, “Molecular epidemiology in current times,” Environ. Microbiol., vol. 22, no. 12, pp. 4909–4918, 2020.
P. Konrad et al., “Long-term, single-center surveillance of non-invasive group A streptococcal infections, emm types and emm clusters,” Eur. J. Clin. Microbiol. Infect. Dis., vol. 39, no. 2, pp. 273–280, 2020.
K. M. Miller et al., “The global burden of sore throat and group A Streptococcus pharyngitis: A systematic review and meta-analysis,” EClinicalMedicine, vol. 48, 2022.
S. Esposito et al., “Recent changes in the epidemiology of group A Streptococcus infections: observations and implications,” Microorganisms, vol. 13, no. 8, p. 1871, 2025.
R. M. A. Khan, S. Anwar, and Z. A. Pirzada, “Streptococcus pyogenes strains associated with invasive and non-invasive infections present possible links with emm types and superantigens,” Iran. J. Basic Med. Sci., vol. 23, no. 1, p. 133, 2020.
M. K. Ali and F. R. Wadi, “Prevalence of asymptomatic Streptococcus pyogenes carriage and antibiotic susceptibility among schoolchildren in Baghdad, Iraq,” Int. J. Des. Nat. Ecodyn., vol. 20, no. 1, pp. 211–216, 2025.
C. L. Martini, D. N. S. Silva, A. S. Viana, P. J. Planet, A. M. S. Figueiredo, and B. T. Ferreira-Carvalho, “Streptococcus pyogenes lineage ST62/emm87: The international spread of this potentially invasive lineage,” Antibiotics, vol. 12, no. 10, p. 1530, 2023.
G. Codda, “Next generation sequencing-based detection and characterization of microbial pathogens causing invasive infections and outbreaks in ICU: Towards improved management of the high-risk patient,” 2024.
A. Efstratiou and T. Lamagni, “Epidemiology of Streptococcus pyogenes,” in Streptococcus pyogenes: Basic Biology to Clinical Manifestations, 2nd ed., 2022.
D. Kebede, A. Admas, and D. Mekonnen, “Prevalence and antibiotic susceptibility profiles of Streptococcus pyogenes among pediatric patients with acute pharyngitis at Felege Hiwot Comprehensive Specialized Hospital, Northwest Ethiopia,” BMC Microbiol., vol. 21, no. 1, p. 135, 2021.
E. Buliva et al., “Infectious disease outbreaks in the World Health Organization Eastern Mediterranean Region in 2019,” Cogent Public Health, vol. 10, no. 1, p. 2225149, 2023.
V. Iyer et al., “Group A Streptococcus infections: their mechanisms, epidemiology, and current scope of vaccines,” Cureus, vol. 14, no. 12, 2022.
K. Rampersadh et al., “Presence of Group A streptococcus frequently assayed virulence genes in invasive disease: a systematic review and meta-analysis,” Front. Cell. Infect. Microbiol., vol. 14, p. 1337861, 2024.
R. Gergova et al., “Relation between emm types and virulence gene profiles among Bulgarian Streptococcus pyogenes clinical isolates,” Infect. Dis., vol. 51, no. 9, pp. 668–675, 2019.
Q. Wu, Y. Jiang, P. Lv, and M. Chen, “Emergence of T4SS-type-ICE-carrying emm28 Streptococcus pyogenes causing invasive infection in Shanghai, China,” J. Glob. Antimicrob. Resist., vol. 41, pp. 21–28, 2025.
A. Friães, J. Melo-Cristino, and M. Ramirez, “Changes in emm types and superantigen gene content of Streptococcus pyogenes causing invasive infections in Portugal,” Sci. Rep., vol. 9, no. 1, p. 18051, 2019.
H. Li, L. Zhou, Y. Zhao, L. Ma, X. Liu, and J. Hu, “Molecular epidemiology and antimicrobial resistance of Group A Streptococcus recovered from patients in Beijing, China,” BMC Infect. Dis., vol. 20, no. 1, p. 507, 2020.
K. K. Chaudhary et al., “Assessment of Group A Streptococcus and antimicrobial resistance pattern in school going children in Morang District, Nepal,” Birat J. Health Sci., vol. 5, no. 3, pp. 1148–1154, 2020.
M. Al-Tamimi et al., “Gram-positive bacterial infections and antibiotics resistance in Jordan: current status and future perspective,” Jordan Med. J., vol. 56, no. 1, 2022.
S. DebRoy et al., “Population genomics of emm4 group A Streptococcus reveals progressive replacement with a hypervirulent clone in North America,” mSystems, vol. 6, no. 4, 2021.
L. A. Vega, H. Malke, and K. S. McIver, “Virulence-related transcriptional regulators of Streptococcus pyogenes,” 2022.
E. P. Armitage, “Epidemiology of Streptococcus pyogenes in The Gambia: investigating carriage and disease burden, transmission dynamics and diagnostic accuracy,” Ph.D. dissertation, London School of Hygiene & Tropical Medicine, 2025.
C. T. C. Pato, “Naturally occurring mutations in regulatory proteins among Streptococcus pyogenes isolates from distinct human infections,” Ph.D. dissertation, Universidade de Lisboa, 2018.
W. C. Tsai et al., “Emergence of macrolide-resistant Streptococcus pyogenes emm12 in southern Taiwan from 2000 to 2019,” J. Microbiol. Immunol. Infect., vol. 54, no. 6, pp. 1086–1093, 2021.
M. Virolainen et al., “Epidemiology and emm types among group A streptococcal pharyngitis in Finland: a prospective laboratory-based study,” Eur. J. Clin. Microbiol. Infect. Dis., vol. 43, no. 2, pp. 233–241, 2024.
S. Himri et al., “The place of group A streptococci in Moroccan children with pharyngitis and emm type distribution,” 2021.
V. Iyer et al., “Group A Streptococcus infections: their mechanisms, epidemiology, and current scope of vaccines,” Cureus, vol. 14, no. 12, 2022.
S. Hamada, S. Kawabata, and I. Nakagawa, “Molecular and genomic characterization of pathogenic traits of group A Streptococcus pyogenes,” Proc. Jpn. Acad. Ser. B, vol. 91, no. 10, pp. 539–559, 2015.
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