Although viral diseases are of greater overall significance, antibacterial vaccines are also essential.

Pasteurellosis: Fowl cholera is caused by Pasteurella multocida, an acute fatal septicemia in chickens and turkeys. P. multocida vaccines include bacterins adjuvanted with aluminum hydroxide or oil emulsions, or they may contain attenuated live organisms. Multivalent Pasteurella vaccines usually contain the commonest serotypes 1, 3, and 4. The inactivated vaccines are usually given by injection. The attenuated live vaccines (M9 or PM-1 strains) may be given by the wing web or in drinking water. Protection develops in about two weeks.
Mycoplasmosis:These diseases are caused by several pathogenic Mycoplasmas. The most important are Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS). MG causes chronic respiratory disease, whereas MS causes respiratory disease or synovitis. It is generally best to maintain mycoplasma-free flocks, but inactivated, attenuated live and fowlpox-vectored vaccines are available for use in countries where vaccination is permitted.
A fowl pox recombinant MG vaccine is also available. It is administered in the wing web. The use of the attenuated vaccines has been characterized as controlled exposure by giving a mild infection at an age when little damage occurs. Pullets are generally vaccinated between 12 to 16 weeks of age. One dose is sufficient to make the birds permanent carriers
Infectious coryza: This is an acute respiratory disease of chickens caused by Avibacterium paragallinarum. It is characterized by nasal discharge, sneezing, conjunctivitis, diarrhea, and facial swelling. Affected hens show a significant drop in egg production. Coryza may be complicated by the simultaneous presence of many other bacteria in addition to infectious bronchitis virus. There are three serovars of A. paragallinarum (A, B, and C).
Colibacillosis: Colibacillosis is caused by avian pathogenic Escherichia coli. This commonly starts as a respiratory infection and eventually leads to colisepticemia, sickness, deaths, and carcass condemnation. Colibacillosis is a leading cause of economic loss in the poultry industry.
Salmonellosis: Salmonellae present the poultry farmer with two potential problems. One is the fact that they may kill large numbers of birds. The other is that they may cause human food poisoning caused by the contamination of eggs and poultry meat with Salmonella enterica serotype Enteritidis. This is of major concern to the poultry industry for both legal and financial reasons. Young chickens may be infected by both vertical and horizontal transfer and they probably acquire the infection soon after hatching.