<prompt> True about safe CSOM:Aetiology is multiple bacteriaOral antibiotics are not effectiveEar drops have no roleOtic hydrocephalus is a complication  <response>: a Aetiology is multiple bacteriaRef. Scott Brown, 8th ed., Vol 2; 1001CSOM 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. 