Streptococcal pyoderma is a matter of great concern, since the organism possess several virulence factors which are both anchored on the cell surface and are also secreted by the bacteria. Βeta-hemolytic streptococci (BHS) are prevalent in pyodermal infections. Streptococcus pyogenes have several extracellular products and express a virulence factor- serum opacity factor (SOF) which opacifies mammalian serum by interacting with high-density lipoprotein. It is a large extracellular and surface bound protein of Group A streptococci (GAS), which is capable of binding fibronectin. The present study was carried out to determine the prevalence of (SOF) producing hemolytic streptococci in pyoderma cases and the commonly involve serogroups.103 pyodermal patients in the age group of 1- 50 years and with the clinical presentation of pyoderma comprised the study group. Paired swabs from the lesions were obtained by standard methods from each patient. One swab was subjected to Gram staining and observed microscopically for the presence of Gram positive cocci in chains. Other swab was inoculated on crystal violet blood agar for isolation of BHS. The blood agar plates were incubated overnight in an atmosphere containing 5- 10% C02 in a candle jar. β- Hemolytic colonies obtained were identified as per standard methods. SOF in the culture supernatant was obtained by centrifugation of overnight cultures and addition of 10μl of culture supernatant to 100μl of horse serum (Hi Media) in a microtitre plate. Plates were sealed and incubated overnight in a moist chamber at 37°C. Following incubation 100 μl of normal saline was added to each well and results were read visually and opacity was scored as 0 to 4+. Serogrouping of β -hemolytic colonies isolated was performed by rapid latex agglutination test (Remel Streptex kit) as per the procedure. Among the BHS isolates the predominant group identified belong to Group A streptococci. Among those Group A isolates 83% of them were able to produce serum opacity factor.
