Superantigens gene profile and emm typing of Streptococcus pyogenes at a tertiary care hospital of north India

Abstract

Background: The incidence and severity of invasive group A streptococcal infection demonstrate great variability over time, which at least, in part, seems to be related to group A streptococcal type distribution among the human population. Further, emerging resistance to major antibiotics is of great concern. In view of this, we conducted a Superantigens gene profile and emm typing of GAS infections at a tertiary care hospital of north India. Methods:Molecular epidemiological study of Group A Streptococcus (GAS)was done at a tertiary care hospital of north India from Jan 2009 – Jan 2012. The confirmation of identity was done by the Vitek 2 identification cards and group A antigen detection by kit based agglutination. Antibiotic sensitivity was done for 10 selected antibiotics and theMICwas comparedbyCLSI guidelines. Detection of 11 Superantigen genes and 1 resistance gene was done by PCR. Further typing of emm type was done by conventional sequencing method. Results: A total of 180 strains of streptococcus were collected and135were identified asGAS.Noneof the isolateswere resistance to Penicillin, ampicillin, vancomycin, linezolid and ceftriaxone. A total of 69% and 38% isolates were resistant to tetracycline and erythromycin respectively. However, a lower resistance pattern of 6%, 3% and2%were seen in ciprofloxacin, levofloxacin, and clindamycin respectively. Out of 11 superantigens gene; Spe B, Z, F, Gwaspresent in between 92-86%; the prevalence of Spe C, M, h, J ranged between 22-27% and very low prevalence were observed for Spe A, I and Ssa gene. Further erm B genewere positive for 40% inGAS isolates. Emm type101 was most prevalent in GAS isolates followed by emm 110 and emm 92. Conclusion: The study shows the isolation rate of GASwas 75%, with high exotoxins and resistance geneswhichmay result inmore resistant and virulent strains. GAS vaccine coverage and control of GAS infectionswill need to take these factors and strain differences into consideration.