European Journal of Cardiovascular Medicine

Streptococcus pyogenes, also known as Group A β-hemolytic streptococci (GABHS), is commonly found on the skin and mucous membranes of humans ⁽¹⁾. It is a significant pathogen responsible for a broad spectrum of infections, ranging from mild conditions such as pharyngitis to severe invasive diseases, due to its various virulence factors ^(1,2). GABHS contributes to about 15–30% of pharyngitis episodes in children aged 5–15 years in developing nations ⁽³⁾. The global burden of severe GABHS disease is estimated to affect nearly 18 million people ^(4). Across regions, the prevalence of GABHS pharyngitis and asymptomatic carriage varies widely, with reported rates ranging from 9% to 34.1% ⁽⁵⁾. GABHS is also a recognised cause of clusters and outbreaks of invasive infections ⁽⁶⁾. Differentiating GABHS-induced pharyngitis from non-GABHS pharyngitis based on clinical features alone is challenging. Hence, culture-based diagnostic methods remain essential for accurate identification and effective treatment, thereby preventing complications ^(1,6). Following the COVID-19 pandemic, an increase in the prevalence of GABHS pharyngitis has been observed among children under 10 years of age in developed countries ⁽⁷⁾.

However, there is a lack of recent data regarding GABHS-related pharyngitis in children in India. Therefore, this study was undertaken to assess the prevalence and antibiotic susceptibility of GABHS causing pharyngitis among children in India.

This was a prospective observational study conducted at a tertiary care hospital in Anantapuram from April 2025 to September 2025 in the Department of Microbiology and Paediatrics. Institutional Ethical Committee permission was obtained (IEC/GMCATP/2025/132).

The sample size was calculated using a single-population proportion formula, with a 5% expected margin of error (D), a 95% confidence level (z = 1.96), and a prevalence (p) of 10.7% from a study conducted in Gondar, Northwest Ethiopia ⁽⁷⁾.

N = (Za/2)² x P (1-P)/D²

N = (1.96)² x 0.107(1-0.107)/ (0.05)² = 145

A total of 147 throat swabs were collected from children aged 3 to 12 years with signs and symptoms suggestive of acute pharyngitis, as this condition is most common in this age group. Inclusion criteria were based on the IDSA (2012) and ICMR guidelines, including fever with one or more of the following signs and symptoms: sore throat, dysphagia, hoarseness, tonsillopharyngeal inflammation or exudates, palatal petechiae, anterior cervical lymphadenopathy, or a history of streptococcal pharyngitis. Children who had received injectable or oral antibiotics within 1 week before presentation were excluded from the study.

SAMPLE COLLECTION AND PROCESSING

Children who met the inclusion criteria were enrolled in the study. After obtaining informed consent from parents for children under 7 years and from patients aged 8-13 years, data were collected using a pre-structured questionnaire and clinical examinations. Under strict aseptic precautions, two throat swabs were collected from each patient, specifically from the bilateral tonsillar surfaces and the posterior pharyngeal wall, taking care to avoid contact with the soft palate and uvula. The swabs were immediately transported to the microbiology laboratory within two hours of collection.

One swab was used for direct Gram staining. At the same time, the other was inoculated onto Columbia Blood Agar (Himedia Laboratories, Mumbai, India) and incubated at 37°C for 24 hours under 5–10% CO₂ to facilitate bacterial growth. Once the incubation period was over, the plates were examined for the presence of beta-hemolytic colonies [Figure 1]. Culture plates negative for beta-hemolytic colonies were further incubated for an additional 24 hours to allow growth of slow-growing organisms. Beta-hemolytic isolates were phenotypically identified by Gram staining [Figure 2] and a negative catalase test, which distinguishes streptococci from staphylococci.

All isolates presumptively identified as β-hemolytic streptococci were tested for Bacitracin sensitivity using 0.04 U bacitracin discs (Himedia Laboratories, Mumbai, India) [Figure 3] according to the standard protocol. A bacitracin disc was placed on the inoculated medium using sterile forceps, and the plates were incubated at 37 °C overnight. Isolates showing a zone of inhibition ≥ 15 mm were considered sensitive, and presumptive identification of Group A Streptococcus (GABHS) was confirmed by a positive PYR test demonstrating L-pyrrolidonyl-β-naphthylamide (PYRase) activity.

Antibiotic susceptibility testing was performed based on the Kirby-Bauer disc diffusion method in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Colonies were inoculated onto Muller-Hinton agar supplemented with 5% blood [Figure 4] and incubated for 24 hours at 37°C. GABHS isolates were subjected to an antibiotic susceptibility test using the following antibiotic discs at their respective concentration. Penicillin (10 U), Vancomycin (30 µg), Ceftriaxone (30 μg), Erythromycin (15 μg), Clindamycin (2 μg), Chloramphenicol (30 μg), Tetracycline (30 μg), Azithromycin (15 µg) and Levofloxacin (2 μg).

STATISTICAL ANALYSIS:

Statistical analysis was performed using SPSS software, version 24. The collected data were analysed using the Chi-square test to assess associations between variables. A P-value of less than 0.05 was considered statistically significant.

Socio -Demographic Characteristics

A total of 147 throat swabs were enrolled. The male-to-female ratio was 1:1.1, and 70 (47.6%) patients were male. The mean age of the study participants was 6.59years (± 2.59SD), and 64(43.5%) were in the age group of 3-5years. Most of the children, 70(47%), were daily wage earners, and 67(45.7%) lived in kutcha houses [Figure 5].

Prevalence of Group A β-hemolytic streptococci (GABHS)

The overall prevalence of S. pyogenes was 42/147(28%), with 22/55(40%) of the isolates from female subjects. The prevalence of S. pyogenes among children between 5-10years was 22/35(62.8%) and 10-12years was 10/16(62.5%). Improper ventilation was observed in 75% of GABHS cases. Low prevalence 5/107(4.6%) in fully immunised children. [Table1]

Antibiotic Susceptibility Pattern of GABHS isolates

Overall, nine antibiotics were tested to identify the susceptibility pattern of GABHS isolates. According to the results, susceptibility was 96% to penicillin, 94% to vancomycin, 90% to ceftriaxone, 88% to clindamycin, 86% to erythromycin, 85% to chloramphenicol. In contrast, 40%, 23%, and 22% of isolates were resistant to levofloxacin, azithromycin, and tetracycline, respectively [Figure 6].

Overview Of Bacterial Isolates

GABHS was 42(28.6%), other BETA-HEMOLYTIC STREPTOCOCCI 26(17.6%), streptococcus pneumoniae 10(6.8%) and 11(7.5%) staphylococcus aureus [Table 3].

Table-1: Prevalence of GABHS

                    (* indicates significant p-value for P<0.05)

Table-2: Prevalence of Signs and Symptoms in Patients with GABHS

           (* indicates significant p-value for P<0.05)

Table 3: Overview of Bacterial Isolates

Group A Streptococcus remains an important human pathogen, capable of causing a broad range of illnesses from self-limiting pharyngitis to severe invasive disease. Its ability to colonise and breach the epithelial surfaces of the oropharyngeal and nasopharyngeal mucosa plays a central role in disease development ⁽¹⁴⁾. Early and precise identification of streptococcal pharyngitis, followed by appropriate antimicrobial therapy, is crucial to reduce the risk of both suppurative and immune-mediated complications ⁽¹³⁾. Despite this, the increasing incidence of antimicrobial resistance among GABHS isolates is a growing concern. Inappropriate antibiotic prescribing practices, particularly in resource-limited settings where empirical treatment is standard, are likely contributors to this trend ⁽¹⁵⁾. These findings emphasise the necessity of continuous surveillance of GABHS prevalence and antimicrobial susceptibility patterns to guide rational therapy and limit the emergence and spread of resistant strains.

In the present study, Group A Beta-Hemolytic Streptococcus (GABHS) was isolated in 28.6% of cases, a

prevalence comparable to that reported in previous studies conducted in India. For instance, Naveen G et al. reported a 21.25% prevalence in Karnataka ⁽¹¹⁾, and Kalpana S et al. documented a 36% prevalence in Chennai ⁽²⁾. In contrast, Sridevi R et al found a 9% prevalence in Guntur ^(6), which is less than our study. Regarding epidemiological factors, our study found a 38% prevalence of GABHS isolates, which is comparable to the 36% reported by Kalpana et al. ⁽²⁾.

This study observed a slightly higher gender difference in GABHS prevalence (31.6% in males and 29% in females), which is inconsistent with the findings of Molla Tadesse et al., who reported a slightly higher prevalence in females (12%) than males (9.8%) ⁽⁷⁾.

Sore throat was the most significantly reported symptom in our study (92.3%), followed by dysphagia (66.6%), which differs from Naveen G et al ^(1), who showed (88.23%) sore throat and Molla Tadesse et al. ⁽⁷⁾, who had enlarged tonsil (95.65%) as a significant sign and symptom.

Regarding antimicrobial susceptibility, our study demonstrated high susceptibility to penicillin and vancomycin, followed by ceftriaxone, clindamycin, and erythromycin. These findings largely align with those of Molla Tadesse et al. ⁽⁷⁾. However, azithromycin showed moderate sensitivity. In contrast, levofloxacin had the highest resistance rate, raising concerns about emerging resistance patterns and the need for judicious antibiotic use.

This study provides valuable insights into the epidemiology and antimicrobial profile of GABHS pharyngitis in children. The majority of participants were 3–5 years old, predominantly residing in kutcha houses, and often exposed to improper ventilation and prior upper respiratory infections, all of which emerged as notable risk factors. These findings highlight the importance of strengthening preventive health strategies, including routine immunisation programs and parental health education. The study supports the continued use of penicillin and erythromycin as effective empirical treatments, while emphasising the need to avoid overuse of fluoroquinolones such as levofloxacin, given the rising resistance. Regular monitoring of antibiotic susceptibility patterns is crucial to prevent treatment failures. Overall, early detection, targeted therapy, and public health initiatives are key to controlling the burden of GABHS in the paediatric population.

1. Naveen G.Peerapur BV. A Bacteriological Study of Acute Pharyngitis in Children Aged 5-15 Years with Special Reference to Streptococcal Grouping. International Journal of Current Microbiology and Applied Sciences. 2016 Aug 10;5(8):721–30.
2. Kalpana S. Isolation and Identification of Group A Streptococcal Infection Among Slum Children in the Age Group of 5-15 Years in Chennai – One Year Prospective Study. IOSR Journal of Pharmacy and Biological Sciences. 2012;2(1):27–31.
3. Pavan C, Arvind N, Vishrutha KV, Vidyalakshmi K, Shenoy S. Surveillance of Group A streptococcal throat infections among school children in Mangalore Int J Biol Med Res. 2013;4:3585–9
4. Ralph AP, Carapetis JR. Group a streptococcal disease and their global burden Curr Top Microbiol Immunol. 2013; 368:1–27
5. Haikh N, Leonard E, Martin JM. Prevalence of streptococcal pharyngitis and streptococcal carriage in children: A meta-analysis Pediatrics. 2010;126: e557–64
6. Sridevi R.Sunita Microbiological study of Pharyngitis at chinakakari, Guntur, Andrapradesh, India.
7. Tadesse M, Hailu Y, Biset S, Ferede G, Gelaw B. Prevalence, antibiotic susceptibility profile and associated factors of group A Streptococcal pharyngitis among pediatric patients with acute pharyngitis in Gondar, Northwest Ethiopia. Infect Drug Resist. 2023; 16:1637–1648. doi:10.2147/IDR.S402292
8. Jose JJM, Brahmadathan KN, Abraham VJ, Huang CY, Morens D, Hoe NP, et al. Streptococcal group A, C and G pharyngitis in school children: a prospective cohort study in Southern India. Epidemiology and Infection. 2018 Apr 4;146(7):848–53.
9. Nandi S, Kumar R, Ray P. Group A streptococcal sore throat in a periurban population of northern India: a one-year prospective study. Bulletin of the World Health Organization, 79 (6). 2009.
10. Gupta R, Prakash K, Kapoor AK. Subclinical group A streptococcal throat infection in school children. PubMed. 1992 Dec 1;29(12):1491–4.
11. https://www.who.int/europe/news-room/12-12-2022-increase-in-invasive-group-a-streptococcal-infections-among-children-in-europe--including-fatalities
12. https://www.icmr.gov.in/icmrobject/uploads/STWs/1725952349_ent_pharyngitis_and_sore_throat.pdf
13. Shulman ST, Bisno AL, Clegg HW, Gerber MA, Kaplan EL, Lee G, Martin JM, Van Beneden C. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012 Nov 15;55(10):1279-82. Doi: 10.1093/cid/cis847. Erratum in: Clin Infect Dis. 2014 May;58(10):1496. Dosage error in article text. PMID: 23091044.
14. Cunningham MW. Pathogenesis of group A streptococcal infections. Clin Microbiol Rev. 2000;13(3):470–511.
15. Devi U, Prasanta Kumar Borah, Jagadish Mahanta. The prevalence and antimicrobial susceptibility patterns of beta-hemolytic streptococci colonizing the throats of schoolchildren in Assam, India. Journal of Infection in Developing Countries. 2011 Nov 9;5(11):804–8.