Question

1.what are the morphologies, physiology, virulence factors and diseases caused by Group A Streptococci, and What are they cause by Streptococcus pneumoniae? 2. Describe in detail both direct and indirect ELISA immunoassays?

Answer 1

1. Morphology of Group A Sterptococci i.e of Streptococcus pyogenes is spherical in nature which occurs in chain like formations.The virulence factors of Group A Streptococci includes M protein, haemolysins and several other enzymes. They cause infections of the throat and skin ranging from very mild conditions to severe life threatning conditions. The prominent infections of GAS includes the strep throat, scarlet fever. These are among the non invasive ones which are less severe and more common. The invasive infections include toxic shock syndrome, necrotising fascilitis, pneumonia and bacteremia. Some strans cause severe infection. They enter the parts of the body such as blood, lungs, fat tissue. They often lead to shock, multiorgan failure and death.

Streptococcus pneumoniae is a gram positive bacteria which is alpha haemolytic or beta haemolytic in nature. They are diplococci in nature i.e they occur in pairs, do not form spores and are non motile. They have a polysachharide capsule which acts as a virulence factor for the bacterium. It typically colonizes the respiratory tract, sinuses and nasal cavity. It is is the main cause of pneumonia and meningitis in children. Persons infected with HIV develop septicemia. It also causes other pneumococcal infections like bronchitis, rhinitis, acute sinusitis, otitis media, conjunctivitis, meningitis etc.