Salmonellosis

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Etiology/Bacteriology

Etiology

Kingdom: bacteria

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Enteroacteriales

Family: Enterobacteriacea

Genus: Salmonella

Species: Typhimurium

Bacteriology

Salmonella typhimurium are gram negative bacilli that are non-spore forming and facultatively anaerobe. This bacteria is predominately motile with peritrichous flagella

Clinical features

incidence and mortality

In the United States, approximately 40,000 cases of Salmonella typhimurium are reported annually, with 400 deaths occurring annually as a consequence of these infections. Worldwide, 93.8 million cases of Salmonella are reported annually, with approximately 155,000 deaths occurring as a consequence of these infections. [1][2]

symptoms

The symptoms of Salmonellosis generally appear 12 to 72 hours after infection. The symptoms of Salmonellosis include self-limiting diarrhea, fever, abdominal cramps, and vomiting. Symptoms generally persist for 4-7 days after infection. In immunocompromised individuals, specifically infants and elderly patients, the diarrhea may become severe enough that the individual must be hospitalized in order to replenish fluids and electrolytes via IV. Although most symptoms in non-high-risk patients will fade a week after the initial infection, it may take months to re-establish the normal gut microbiota of the digestive tract. [3[4]

Diagnosis

Salmonella typhimurium can be detected through sterile samples. The bacteria can also be detected in the blood, urine or tissues. These tests consist of growing the bacteria in pure culture [5]. Diagnostic identification can be obtained by the growth of the bacteria on MacConkey agar and Eosin Methylene Blue agar (EMB). Both of these types of media is designed to grow gram-negative bacteria and differentiate for lactose fermentation. The test results for both of the media will appear colorless and translucent, which indicates that the bacteria is lactose negative. Salmonella typhimurium produces no gas when grown in TSI media which is used to differentiate it from other Enterobacteriaceae [6]. A fecal, blood, or other sample is placed on the agar and incubated for two to three days. After that time, the specialist can properly identify the bacteria and confirm the identity by looking at the specific biochemical reactions [5].

References

CDC Website [1]

Oxford Journals of Clinical Infectious Disease [2]

CDC Website [3]

Mayo Clinic Website [4]

Marler Clark Sponsored Website [5]

Different Types of Agar [6]

Created by {Rachel Acosta, Taylor Zelnicek, and Magdalene Shaughnessy}, students of Tyrrell Conway at the University of Oklahoma.