This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': "True statements about Pneumococcus are all except \nSelect and explain. \nA. Pneumolysin a thiolactivated toxin, exes a variety of effect on ciliary & PMN's, B. Autolysin may contribute to the pathogenesis of pneumococcal disease by lysing the bacteria, C. Anticapsular antibodies are serotype specific, D. The virulence of pneumococci is dependent only on the production of the capsular polysaccharide", 'role': 'user'}, {'content': "Answer: D \nExplanation: The virulence of Streptococcus pneumoniae depends on; Capsular polysaccharide, because of its acidic and hydrophilic propeies, protects the cocci from phagocytosis. Capsulated streptococcus pneumoniae are not phagocytosed efficiently in fluid media or exudates, however, they are susceptible to surface phagocytosis, being engulfed against a firm surface, such as a fibrin clot or epithelium. The enhanced virulence of type 3 Streptococcus pneumoniae is due to the abundance of its capsular material. Non-capsulated strains are avirulent. Pneumolysin: a membrane damaging toxin. Cytotoxic, complement activating propeies and is immunogenic. Autolysin: by releasing bacterial components in infected tissues, it may also contribute to virulence. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 226", 'role': 'assistant'}]