# Chronic burrowing ulcer is caused by:
a) Microaerophilic streptococci
b) Peptostreptococcus
c) Streptococcus viridans
d) Streptococcus pyogenes
The correct answer is A. Microaerophilic Streptococci.
Chronic burrowing type of ulcer is due to symbiotic action of microaerophilic non-haemolytic streptococci and hemolytic Staphylococcus aureus. Clinically it is undermined ulcer with lot of granulation tissue in the floor. This condition is painful, toxaemic and the general condition of the patient deteriorates without treatment. Radical drainage is necessary for cure, antibiotics alone being useless.