ABSTRACT
In 1885, the bacterium causing “hog cholera” was isolated from infected pigs by two American veterinarians, Salmon and Smith. The bacterium was named Salmonella choleraesuis, and thereby the Salmonella genus was founded.1,2 Salmonella are gram-negative facultative anaerobic rods belonging to the Enterobacteriaceae family. The size of the rods ranges from 0.7 to 1.5 µm by 2.2−5.0 µm, producing colonies of approximately 2-4 mm in diameter. They are nonspore-forming, oxidase-negative and catalase-positive. Members of the genus are predominantly motile by petrichous ³agella, chemoorganotrophic, able to reduce nitrate to nitrite, able to grow on citrate as sole carbon source, capable of producing acid and gas from glucose, able to produce hydrogen sulŠde on triple sugar iron and decarboxylate lysine
and ornithine, and incapable of hydrolyzing indole and urea. However, deviations from these characteristics are occasionally observed.1,3
Salmonella are known to be quite resilient toward environmental in³uences, and prolonged persistence in hostile surroundings is reported.4-6 This enhanced survival supports the transmission of Salmonella from the environment to a new host.7 The optimal growth temperature for Salmonella is 37°C, but the temperature range of growth is quite broad (7°C-45°C), and the preconditioning of cells can result in growth at extreme temperatures at both ends of the scale. Growth of Salmonella in various foods has been observed down to 2°C-4°C. The normal boundaries for growth regarding water activity and pH can also be forced in either direction as a function of preconditioning.8-10 The optimum pH for growth is 6.5-7.5, but salmonellae can proliferate in the pH 4.5-9.5 range. Growth of Salmonella has not been reported
87.1 Introduction ................................................................................................................................................................... 1023 87.1.1 Biology ............................................................................................................................................................... 1023 87.1.2 ClassiŠcation ...................................................................................................................................................... 1024 87.1.3 Epidemiology ..................................................................................................................................................... 1024 87.1.4 Clinical Features ................................................................................................................................................ 1025
87.1.4.1 Clinical Features of Nontyphoid Salmonella Infections .................................................................... 1025 87.1.4.2 Enteric Fever Caused by S. enterica subsp. enterica Serovar Typhi and Serovar Paratyphi ............. 1026
87.1.5 Pathogenesis ....................................................................................................................................................... 1027 87.1.5.1 Nontyphoid Salmonella ...................................................................................................................... 1027 87.1.5.2 Typhoid Salmonella ............................................................................................................................ 1027
87.1.6 Diagnosis ........................................................................................................................................................... 1028 87.1.6.1 Conventional Techniques .................................................................................................................... 1028 87.1.6.2 Molecular Techniques ......................................................................................................................... 1029
87.2 Methods ......................................................................................................................................................................... 1030 87.2.1 Real-Time PCR Detection of Salmonella in Meat and Environmental Samples .............................................. 1030
87.2.1.1 Sample Preparation ............................................................................................................................. 1030 87.2.1.2 Detection Procedures .......................................................................................................................... 1030
87.2.2 Real-Time PCR Detection of Salmonella in Human Clinical Samples ............................................................ 1030 87.2.2.1 Sample Preparation ..............................................................................................................................1031 87.2.2.2 Detection Procedures ...........................................................................................................................1031
87.3 Conclusions and Future Perspectives............................................................................................................................. 1032 Acknowledgments ................................................................................................................................................................... 1032 References ............................................................................................................................................................................... 1032
