This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
True about safe CSOM: 
Select and explain. 
A. Aetiology is multiple bacteria, B. Oral antibiotics are not effective, C. Ear drops have no role, D. Otic hydrocephalus is a complication
A: Aetiology is multiple bacteria
Answer: A: Aetiology is multiple bacteria 
Explanation: (a) Aetiology is multiple bacteria(Ref. Scott Brown, 8th ed., Vol 2; 1001)CSOM is caused by mixed aerobic and anaerobic organisms. MC aerobic organism being Pseudomonas, others include Proteus, E. coli and Staph, aureus. Bacteroids are the anaerobic bacteria here.Oral antibiotics and antibiotic ear drops are given to control the infection and once the ear is dry for 6 weeks without antibiotics surgical repair is taken up.Otic hydrocephalus is a complication of unsafe CSOMResorption of bony ossicles in safe CSOM is due to repeated infections with resultant local inflammatory cytokines and local acidosis mainly in the area of low blood supply (most commonly long process of incus and incudo-stapedial joint).