Asian Research Thesis Index

Abstract

S. pyogenes or Group A streptococci (GAS) is a notorious and significant human pathogen. S. pyogenes infections broadly range from superficial skin infections, and noninvasive infections (pharyngitis, scarlet fever) to life threatening invasive infections like streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis (NF). Such infections are often followed by post-streptococcal sequelae, including rheumatic heart disease and acute glomerulonephritis. Among other beta hemolytic streptococcal groups, group D streptococci (GDS) are the frequent cause of hospital-acquired urinary tract infections and bacteremia. S. agalactiae or GBS is a leading cause of infections among pregnant women and neonates, whereas Group C and G streptococci are recognized as the emerging pathogens. S. pyogenes possess a number of cell associated (M protein, F protein, hyaluronic acid, lipoteichoic acid) and secreted virulence factors including streptococcal pyrogenic exotoxins (Spe), Streptolysin S and O, C5a peptidase, DNase and streptococcal inhibitor of complement responsible for the variety of infections. Particularly, M protein and Spe, exhibiting superantigenic activity (SAg) are considered as the major virulence factors of S. pyogenes. M protein, encoded by emm gene serves an important surveillance tool to monitor GAS diversity, epidemiology, disease patterns, dynamics of transmission and formulation of indigenous vaccine. SAgs are low molecular weight, highly potent extracellular products, usually associated with severity of infections. However, to our knowledge no data is available from Pakistan regarding the prevalent emm types and SAgs genes distribution. Therefore, this study was designed to monitor the prevalence and epidemiology of β-hemolytic streptococci, antibiotic resistance pattern, molecular mechanism of drug resistance, emm genotypes and superantigens profile in Pakistan. Hence this would be the first comprehensive report about GAS epidemiology, chemotherapy and pathogenesis from Pakistan. This study would further help us in understanding the possible links among invasive and noninvasive streptococcal diseases with emm types and superantigens.

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