Bacteria Genomes - MYCOPLASMA SYNOVIAE

Mycoplasma are members of the class Mollicutes, meaning soft skin. Along with the other members of this class (Acholeplasma, Anaeroplasma, Asteroleplasma, Spiroplasma, and Ureaplasma) Mycoplasma are characterised by their unusually small genomes as well as their complete lack of a bacterial cell wall. Wall-less bacteria are much more difficult to kill because they lack the lipid layer surrounding them.

19 avian mycoplasma serotypes are known in chickens, of these, only 2 have a pathogenic importance. Mycoplasma synoviae is one, the other, Mycoplasma Gallisepticum is more pathogenic.

Mycoplasma synoviae causes an acute to chronic infection of chickens and turkeys that produces exudative tendonitis and bursitis; it now occurs most frequently as a subclinical infection of the upper respiratory tract. Mycoplasma synoviae infection can also cause a complication of airsacculitis in association with Newcastle disease or infectious bronchitis. Systemic infection can lead to the condition known as infectious synovitis. The synovial membranes of the bird become inflamed, predominantly those of the tendons of the legs, especially the hock (causing tenosynovitis) and over the breast (causing a sternal bursitis) as breast blisters. Mild air sac disease leading to poor growth or precipitation of viral respiratory disease and leg problems with significant mortality may also be observed.

M. synoviae infection occurs primarily in chickens and turkeys, but ducks, geese, guinea fowl, parrots, pheasants, and quail may also be susceptible. and it is present in most poultry-producing countries, especially in commercial layer flocks.

Infection rates may be very high. Spread is generally rapid within and between houses on a farm, whilst illness is variable and mortality less than 10%. Infection is via the conjunctiva or upper respiratory tract with a long incubation period, 11–21 days following contact exposure. Transmission may be transovarian, or lateral via respiratory aerosols and direct contact.

Isolates of M. synoviae show considerable variation in their ability to cause disease. Severity of infection is greatly influenced by infection with other mycoplasmas, viruses and bacteria.

References:

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/203505.htm
http://www.thepoultrysite.com/diseaseinfo/Default.asp?Display=99
Microbiology 151 (2005), 935-940; DOI 10.1099/mic.0.27109-0