This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
Clostridial organism are 
Select and explain. 
A. Gram-positive aerobes, B. Gram-positive anaerobes, C. Gram-positive aerobes, D. Gram-negative anaerobes
B: Gram-positive anaerobes
Answer: B: Gram-positive anaerobes 
Explanation: The genus Clostridium consists of Gram-positive, anaerobic and spore forming bacilli.Eg: C.tetani, C.perfringens, C.difficile,C.botulinum etc. These are responsible for tetanus, gas gangrene and food poisoning. Reference : page 251 Ananthanarayan and Panicker's Textbook of Microbiology 9th edition.