E. Coli mortality is difficult to treat. Antibiotic treatments are often very effective, during the treatment, but once you stop and the underlying, primary cause is still present, the mortality comes back. Use of antibiotics is not always possible, because of the withdrawal time of the products used. Especially in layers, a treatment becomes very expensive when you have to destroy all the eggs produced during 10-12 days.
Alternative treatments, like spraying with disinfectants, and drinking water sanitation, with H2O2/ per acetic acids combination, with organic acids or with chlorine are also widely used.