Novel approaches to diagnosing salmonellosis

Salmonellosis is one of the most common bacterial infections, and is associated with significant health related economic losses in the US and many parts of the world. Most disease-causing strains of the genus Salmonella belong to a single species, Salmonella enterica which has numerous serovars. Salmonella Typhi is a serovar of Salmonella enterica that causes typhoid fever. While S. Typhi circulates mostly among human subjects, salmonellosis attributed to nontyphoidal Salmonella serovars is a zoonosis mainly acquired through the consumption of contaminated foods such as meat, poultry, eggs and milk as well as produce that are contaminated on farm, during preparation or improper storage Although primarily an enteric infection, non-typhoidal salmonellosis (NTS) in healthy individuals has also been associated with severe extra-intestinal infections such as meningitis, osteomyelitis, arthritis, endocarditis, cholecystitis, urinary tract infection, and pneumonia. Clinically, salmonellosis may be manifested in three forms: 1) gastroenteritis, 2) septicemia, and 3) enteric fevers. Detection of Salmonella serovars in clinical, food, and environmental samples is critical for clinical and epidemiological decision-making process. There has been significant progress in moving from time-consuming traditional detection methods to rapid methods. Rapid methods include a large array of tests such as miniaturized biochemical kits, antibody- and DNA-based tests, and assays that are modifications of conventional tests to speed up analysis. Some of these assays have also been automated to reduce hands-on manipulations. Faster and more convenient detection and identification using reagents and tools to ensure high sensitivity and specificity is the basis for the rapid methods for Salmonella detection. This chapter discusses the officially recognized Salmonella groups and the major serovars that are most commonly encountered in human salmonellosis and reviews the common detection methods currently used for diagnosing Salmonella serovars from human clinical samples that are also applicable to samples from foods and the environment.