Diagnosis and Treatment
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How Can Salmonella Infections Be Diagnosed?
Diagnosing salmonellosis requires testing a clinical specimen (such as stool or blood) from an infected person to distinguish it from other illnesses that can cause diarrhea, fever, and abdominal cramps. Once Salmonella is identified in the specimen, additional testing can be done to further characterize the Salmonella.
Steps in Laboratory Testing and Reporting Salmonella
- Laboratory scientists identify Salmonella infection by culturing a patient’s sample. If Salmonella bacteria grow, then the diagnosis is confirmed, or in laboratory-terms, “culture confirmed.”
- Clinical diagnostic laboratories report the test results to the treating clinician and submit Salmonella isolates to state and territorial public health laboratories for serotyping and DNA fingerprinting.
- The public health laboratories report the results to CDC’s Laboratory-based Enteric Disease Surveillance and to PulseNet
- The public health laboratories forward atypical serotypes to CDC’s National Salmonella Reference Laboratory for more characterization or confirmation.
Serotyping Salmonella
Serotype: group within a single species of microorganisms, such as bacteria or viruses, which share distinctive surface chemical structures
Culture: Growing bacteria, viruses, and other living matter in a specific environment, such as a petri dish coated with nutrients to encourage growth
Salmonella are divided into serotypes according to structures on the bacteria’s surface. Serotyping is used in outbreak investigations to link cases of illness with similar bacteria and track them to the source (example: a contaminated food or an infected animal). Some serotypes are only found in one kind of animal or in a single place. Others are found in many different animals and all over the world. Some serotypes can cause especially severe illnesses when they infect people; most typically cause milder illnesses.
Learn more about the importance of serotyping and CDC’s Salmonella Atlas, the first-of-its-kind report that charts over 40 years of laboratory-confirmed surveillance data on 32 Salmonella serotypes.
Serotyping has played an important role in the understanding the epidemiologic and molecular characterization of Salmonella for decades. Today, modern genetic subtyping methods provide scientists with additional information to understand common serotypes and identify, investigate, and trace outbreaks.
New methods for subtyping. PulseNet is working with other Federal and State Agencies to evaluate the use of whole genome sequencing (WGS) to replace PFGE as its standard method for subtyping Salmonella and other bacteria that cause diarrheal disease. It is hoped that WGS will make the PulseNet process faster, more accurate, and more efficient.- Page last reviewed: March 9, 2015
- Page last updated: March 9, 2015
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