Which streptococcal extracellular product dissolves fibrin clots?

Streptokinase is a notable extracellular product produced by certain streptococci that plays a crucial role in dissolving fibrin clots. This enzyme acts by converting plasminogen, an inactive precursor present in blood, into plasmin, an active protease that breaks down fibrin. The dissolution of fibrin clots is significant in the context of streptococcal infections, as it facilitates the spread of the bacteria throughout the host's tissues.

In contrast, other products, such as hyaluronidase, serve different purposes. Hyaluronidase breaks down hyaluronic acid, a component of the extracellular matrix, allowing bacterial spread but does not directly dissolve fibrin clots. Bacterial proteases could break down various proteins, yet they do not specifically target fibrin in the same way as streptokinase. Streptolysin O, meanwhile, is a cytolysin that forms pores in the membranes of immunological cells, contributing to tissue destruction but without the fibrinolytic activity that characterizes streptokinase. Thus, streptokinase is the correct answer for its specific role in fibrinolysis.