**8. Acknowledgement**

Authors would like to acknowledge European Union project ProSafeBeef (ref. Food-CT-2006-36241) within the 6th Framework Programme for the financial support of some of the studies on *Salmonella* biofilms performed on our lab.

## **9. References**

168 Salmonella – A Dangerous Foodborne Pathogen

that only lacked the 3′ part of the *luxS* coding sequence, were found to be able to form mature wild-type biofilms on polystyrene, despite the fact that these strains were unable to produce AI-2. These authors concluded that a small regulatory RNA molecule, MicA, encoded in the *luxS* adjacent genomic region, rather than LuxS itself, infuences *S*. Typhimurium biofilm formation phenotype. On the other hand, Prouty et al. (2002) showed that a *S*. Typhimurium *luxS* insertion mutant formed scattered biofilm on gallstones with little apparent EPS even after 14 days of incubation. Yoon & Sofos (2008) showed that biofilm formation by *S.* Thompson on stainless steel, under monoculture conditions (72 h at 25°C), was similar between AI-2 positive and negative strains. Altogether, these results demonstrate that the relationship between biofilm formation and the presence of an active

The third QS system of *Salmonella* uses the two component system PreA/B (Bearson & Bearson 2008; Merighi et al., 2006). PreA/B is similar to the *luxS*-dependent two component QseB/QseC of enterohemorrhagic *E. coli*, which has been shown to sense the QS signal AI-3, as well the eukaryotic hormones epinephrine and norepinephrine (Sperandio et al., 2002; Walters & Sperandio, 2006). In *S*. Typhimurium, the histidine sensor kinase QseC, which is able to detect norepinephrine, has been implicated in the regulation of virulence traits, such as motility and *in vivo* competitive fitness in pigs (Bearson & Bearson, 2008). Even though the role of AI-3/epinephrine/norepinephrine signaling system in the formation of biofilm by *Salmonella* is still unknown, given that motility is usually an important biofilm determinant in many bacterial species, it is quite possible that this third QS system may also

Biofilms are commonly defined as communities of microorganisms attached to a surface and producing an extracellular matrix, in which these microorganisms are embedded. Biofilms are very diverse and unique, not just to the microorganism, but to the particular environment in which they are being formed. This makes *in vitro* characterization of biofilms difficult and requires the establishment of laboratory conditions that mimic the natural setting being studied. Pathogenic biofilms have been of considerable interest in the context of food safety and have provoked interest of many research groups. In particular, biofilm formation by *Salmonella* is a serious concern in food industry, since the persistence of this bacterium in biofilms formed on food-contact surfaces may become a constant source of

The discovery of bacterial biofilms in medical and industrial ecosystems has created an urgency to identify and characterize factors that are necessary for biofilm development, which may serve as targets for biofilm prevention and treatment. Thus, researchers in the fields of clinical, food, water, and environmental microbiology have begun to investigate microbiological processes from a biofilm perspective. As the pharmaceutical, health-care and food industries embrace this approach, novel strategies for biofilm formation and control will undoubtedly emerge. Particularly challenging is the attempt to understand the complexicity of the interactions within a biofilm community, since these interactions between the different species influence the final outcome of this community. Communication between species may include extracellular compounds whose sole role is to influence gene expression, metabolic cooperativity and competition, physical contact, and the production of antimicrobial exoproducts. One or all of these interactions may be

LuxS system and AI-2 in *S. enterica* is not clear and further research is needed.

affect *Salmonella* biofilm formation.

**7. Conclusions** 

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**9** 

*Brazil* 

**Important Aspects of Salmonella in the** 

 Antonio Guilherme M. De Castro1 and Ana Lucia S. P. Cardoso1 *1Biological Institute - Advanced Technological Research Center of the Poultry Agribusiness - Agriculture Secretariat of the State of Sao Paulo, Descalvado/SP* 

The objective of this review was to discuss relevant issues related to the pathogeny, epidemiology and antimicrobial resistance of *Salmonella* spp. Due to its economic importance, and because it poses risks to human health, *Salmonella* spp. is one of the most frequently studied enteropathogens. Nowadays, the disease is considered to be a consequence of interrelated factors, such as food, the environment, vectors, men, utensils

*Salmonellae* are widely distributed in nature. The main reservoir of these bacteria is the intestinal tract of men and warm-and cold-blooded animals (Jakabi et al., 1999), except for fish, mollusks and crustaceans, which may get contaminated after being fished. Among warm-blooded animals, chickens, geese, turkeys and ducks are the most important reservoirs. Domestic animals, such as dogs, cats, turtles and birds may be carriers, and pose

The natural habitat of *Salmonella* may be divided into three categories based on the specificity of the host and clinical pattern of the disease: highly adapted to men: *Salmonella* Typhi and *Salmonella* Paratyphi A, B and C, agents of typhoid fever; highly adapted to animals: *Salmonella* Dublin (bovines), *Salmonella* Choleraesuis and *Salmonella* Typhisuis (swine), *Salmonella* Pullorum and *Salmonella* Gallinarum (birds), responsible for animal paratyphoid. The third category includes most of the serovars that affect men and animals, called zoonotic *Salmonella*, responsible for worldwide-distributed foodborne diseases, and detected in most species of animals used for human consumption, wild and domestic

*Salmonellae* are short bacilli, 0.7-1.5 x 2.5 μm, Gram-negative, aerobic or facultative anaerobic, positive catalase, negative oxidase; they ferment sugars with gas production, produce H2S, are nonsporogenic, and are normally motile with peritricheal flagella, except for *Salmonella* Pullorum and *Salmonella* Gallinarum, which are nonmotile (Forshell & Wierup, 2006).

and equipments, the production line, animal transit and animal reservoirs.

great risk, mainly to kids (Franco & Landgraf, 1996).

**1. Introduction** 

**2. General aspects** 

animals (Gantois et al., 2009).

**Poultry Industry and in Public Health** 

Eliana N. Castiglioni Tessari1, Ana Maria Iba Kanashiro1,

Greice F. Z. Stoppa1, Renato L. Luciano1,

