In the present study, a total of 124 strains were isolated from acute pharyngitis patients. Interestingly, 71.8% of them were emm and emmL nontypeable. The emm12 was the predominant emm type (28.6%) among the typeable GAS strains. The prevalence of emm12 was previously reported among the pharyngeal isolates of GAS from Chennai, South India . The presence of emm1, emm3, emm28, emm12, emm4 and emm11 has been reported among the North Indian GAS isolates .
In this study, stG643.0 was the predominant emm type (28.6%) among GGS strains. In contrast, two other GGS emm types, stG485 and stGLP1, were previously reported to be prevalent among 49 GGS isolates from Chennai, India . Other emm types previously reported from India  which also represented in this study were emm3 (2.9%) and stC46 (17.0%). In addition, the newly identified emm types include emm48.0 (5.7%), st3343.0 (2.9%), emm107.0 (2.9%), stS104.2 (2.9%), and emm30.11 (8.5%). According to CDC, these emm types have already been reported in United States, Mexico, Malaysia and New Zealand, but not from India. Therefore, further studies on the epidemiology of these emm types in India are needed.
The emergence of drug resistance among streptococci to macrolides (erythromycin and clarithromycin) and tetracycline are widely reported in recent years [32–34]. However, in the present study, all the streptococcal strains were susceptible to all the tested antibiotics including β-lactams, macrolides and tetracycline. Therefore, drug resistance is not a major threat among the streptococci isolated in this study population. However, untreated chronic infections may lead to severe complications such as acute rheumatic fever (ARF) and rheumatic heart disease (RHD).
SOF acts as an adhesin involved in the adherence of GAS to host cells . It has also been reported that the interaction between SOF and the host extracellular matrix protein, fibulin-1, may be involved in the adhesion of GAS to extracellular matrices of the host . Courtney et al.  reported that the SOF was expressed at a frequency of 50% among the clinical isolates of GAS. In contrast, only 14.3% of typeable GAS isolates were positive for SOF and all GCS and GGS strains were SOF-negative. Similarly, McDonald et al.  reported that most of the GCS and GGS strains of S. dysgalactiae subsp. equisimilis were SOF-negative. Therefore, SOF may not be the only factor responsible for the adhesion of GAS to the host and some other mechanisms might exist . Some of the GAS adhesins reported other than SOF include lipoteichoic acid, hyaluronic acid capsule, vitronectin-binding protein and collagen-binding protein .
We have observed significant differences in the distribution of superantigen genes between typeable and nontypeable strains. The co-occurance of number of superantigen genes was relatively more in typeable than in nontypeable strains. Among 11 superantigens, a maximum of 6 superantigens (speC, speG, speA, speH, speI and smeZ) was detected in 17.1% of typeable strains, whereas this combination was detected in only 1.1% nontypeable strains. Totally, 26 superantigen profiles have been identified among the typeable and nontypeable strains. Of these, 23 profiles were detected in nontypeable strains and 9 profiles in typeable strains. Only six superantigen profiles were identified in both typeable and nontypeable strains. Other 20 profiles were confined to either typeable or nontypeable strains. As reported previously , the most prevalent chromosomally encoded superantingens, speG and smeZ, were detected in 97.1% and 77.1% of the typeable strains, respectively. In addition, these two genes were detected in 84.3% and 83.1% of nontypeable isolates, respectively. Similarly, Proft et al.  have reported the presence of these two superantigens in all the strains of GAS.
A high occurrence of GCS (59.7%) and GGS (25.0%) among pharyngeal streptococcal isolates was observed, which is in agreement with previous reports from Spain and Australia [10, 15]. It is known that more virulent forms of GCS and GGS could have emerged through the acquisition of superantigen genes from GAS . In this study, many superantigen profiles have been identified among GCS and GGS strains and these strains could be considered as emerging pathogens.
Overall, 67 S. anginosus (52 GCS and 15 GGS) strains and 22 S. dysgalactiae subsp. equisimilis (16 GCS and 6 GGS) strains were nontypeable. Although the presence of superantigens has been reported in typeable GCS and GGS isolates, their presence in nontypeable strains has not been reported so far. However, in our study, compared to the strains of typeable S. pyogenes (GAS) and typeable as well as nontypeable S. dysgalactiae subsp. equisimilis, more numbers of superantigen profiles have been observed in nontypeable strains of S. anginosus (GCS/GGS). In a very recent study , the presence of GAS superantigens (speL, speC, speK and speM) has been reported in typeable S. dysgalactiae subsp. dysgalactiae (GCS) strains associated with bovine mastitis, but not in the human isolates of S. dysgalactiae subsp. equisimilis (GCS/GGS). We have identified the presence of superantigens in nontypeable strains of S. dysgalactiae subsp. equisimilis (GCS/GGS) associated with acute pharyngitis in humans. Therefore, our findings suggest that, like S. pyogenes, S. dysgalactiae subsp. equisimilis and S. anginosus may emerge as potential human pathogens. Some other factors might be involved in the pathogenesis of nontypeable strains in the absence of M protein. The presence of superantigens in nontypeable strains has not been reported so far. The role of superantigens in the pathogenesis of typeable GCS and GGS strains is well documented [2, 19, 20]. However, the role of superantigens in the pathogenic mechanisms of nontypeable strains is yet to be studied.