<P> Salmonellosis is known to be able to cause back pain or spondylosis . It can manifest as five clinical patterns: gastrointestinal tract infection, enteric fever, bacteremia, local infection, and the chronic reservoir state . The initial symptoms are nonspecific fever, weakness, and myalgia among others . In the bacteremia state, it can spread to any parts of the body and this induces localized infection or it forms abscesses . The forms of localized Salmonella infections are arthritis, urinary tract infection, infection of the central nervous system, bone infection, soft tissue infection, etc . Infection may remain as the latent form for a long time, and when the function of reticular endothelial cells is deteriorated, it may become activated and consequently, it may secondarily induce spreading infection in the bone several months or several years after acute salmonellosis . </P> <P> A hallmark of Salmonella pathogenesis is the ability of the bacterium to survive and proliferate within phagocytes . Phagocytes produce DNA damaging agents such as nitric oxide and oxygen radicals as a defense against pathogens . Thus, Salmonella species must face attack by molecules that challenge genome integrity . Buchmeier et al. showed that mutants of Salmonella enterica lacking RecA or RecBC protein function are highly sensitive to oxidative compounds synthesized by macrophages, and furthermore these findings indicate that successful systemic infection by S. enterica requires RecA and RecBC mediated recombinational repair of DNA damage . </P> <P> Salmonella enterica, through some of its serotypes such as Typhimurium and Enteriditis, shows signs of the ability to infect several different mammalian host species, while other serotypes such as Typhi seem to be restricted to only a few hosts . Some of the ways that Salmonella serotypes have adapted to their hosts include loss of genetic material and mutation . In more complex mammalian species, immune systems, which include pathogen specific immune responses, target serovars of Salmonella through binding of antibodies to structures like flagella . Through the loss of the genetic material that codes for a flagellum to form, Salmonella can evade a host's immune system . In the study by Kisela et al., more pathogenic serovars of S. enterica were found to have certain adhesins in common that have developed out of convergent evolution . This means that, as these strains of Salmonella have been exposed to similar conditions such as immune systems, similar structures evolved separately to negate these similar, more advanced defenses in hosts . There are still many questions about the way that Salmonella has evolved into so many different types but it has been suggested that Salmonella evolved through several phases . As Baumler et al. have suggested, Salmonella most likely evolved through horizontal gene transfer, formation of new serovars due to additional pathogenicity islands and through an approximation of its ancestry . So, Salmonella could have evolved into its many different serotypes through gaining genetic information from different pathogenic bacteria . The presence of several pathogenicity islands in the genome of different serotypes has lent credence to this theory . </P> <P> In addition to its importance as a pathogen, Salmonella enterica serovar Typhimurium has been instrumental in the development of genetic tools that led to an understanding of fundamental bacterial physiology . These developments were enabled by the discovery of the first generalized transducing phage, P22, in Typhimurium that allowed quick and easy genetic exchange that allowed fine structure genetic analysis . The large number of mutants led to a revision of genetic nomenclature for bacteria . Many of the uses of transposons as genetic tools, including transposon delivery, mutagenesis, construction of chromosome rearrangements, were also developed in Typhimurium . These genetic tools also led to a simple test for carcinogens, the Ames Test . </P>

What is the name of the bacteria that causes salmonella