What is the epidemiology of Salmonella infections?

From the Guidelines

Salmonella infections are a significant public health concern, with an estimated 1.35 million infections annually in the United States, and can be prevented through proper food handling, thorough cooking of animal products, avoiding cross-contamination in kitchens, and handwashing. The epidemiology of Salmonella shows seasonal patterns with peaks during summer months when warmer temperatures facilitate bacterial growth. Risk factors include age extremes (young children and elderly), compromised immune systems, and reduced stomach acidity. Most infections result in self-limiting gastroenteritis lasting 4-7 days with symptoms including diarrhea, fever, and abdominal cramps.

Key Points

• Treatment is generally supportive with fluid replacement, though antibiotics like ciprofloxacin (500mg twice daily for 5-7 days) or azithromycin (500mg daily for 3 days) may be necessary for severe cases or high-risk patients, as recommended by the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
• Approximately 5% of cases develop bacteremia requiring more aggressive antibiotic therapy.
• Prevention focuses on proper food handling, thorough cooking of animal products, avoiding cross-contamination in kitchens, and handwashing, as outlined in the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
• Public health surveillance systems track outbreaks to identify contamination sources and prevent further spread, making Salmonella a significant but largely preventable public health concern, as noted in the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.

Management

• The management of Salmonella infections involves supportive care with fluid replacement and electrolyte management, as well as antibiotic therapy in severe cases or high-risk patients, as recommended by the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
• The choice of antibiotic therapy depends on the severity of the infection, the patient's underlying health status, and the susceptibility of the organism to antibiotics, as outlined in the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.

Prevention

• Prevention of Salmonella infections involves proper food handling, thorough cooking of animal products, avoiding cross-contamination in kitchens, and handwashing, as outlined in the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
• Public health surveillance systems play a critical role in tracking outbreaks and identifying contamination sources to prevent further spread, as noted in the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.

From the Research

Salmonella Epidemiology

• Salmonella is a foodborne zoonotic pathogen that causes diarrheal disease in humans after consuming contaminated water, animal, and plant products 2.
• The bacterium is the third leading cause of human death among diarrheal diseases worldwide, making human salmonellosis a public health concern 2.
• The prevention of salmonellosis in humans is intricate due to several factors, including immune-stable individuals infected with S. enterica continuing to shed live bacteria without showing any clinical signs 2.

Transmission and Sources

• Asymptomatic Salmonella animals are a source of salmonellosis in humans after consuming contaminated food products 2.
• Contaminated products of plant and animal origin are a menace in food industries due to Salmonella biofilms, which enhance colonization, persistence, and survival of bacteria on equipment 2.
• The most worldwide prevalent broad-range Salmonella serovars affecting humans are Salmonella Typhimurium and Salmonella Enteritidis, with poultry products being a primary source of infection 2.

Prevention and Control

• Strategies for preventing and controlling Salmonella contamination in foods include biosecurity measures, isolation and quarantine, epidemiological surveillance, farming systems, herbs and spices, and vaccination 2.
• Other measures include the application of phages, probiotics, prebiotics, and nanoparticles reduced and capped with antimicrobial agents 2.
• The use of antibiotic drugs in treating Salmonella infection is proving less effective due to the alarming rise of antibiotic-resistant strains of Salmonella 3.
• Probiotic micro-organisms have demonstrated antagonistic properties against Salmonella and other enteropathogenic bacteria, but further studies are needed to define their potential mechanisms, efficacy, and mode of delivery 3.

Treatment

• Azithromycin is commonly used for first-line treatment of uncomplicated enteric fever, but the response to treatment may be sub-optimal in some patient groups when compared with fluoroquinolones 4.
• Azithromycin at a dose of 500mg daily is an effective treatment for fully sensitive strains of S. Typhi but is associated with delayed treatment response and prolonged bacteraemia when compared with ciprofloxacin 4.
• The susceptibility of Salmonella enterica isolates to azithromycin has been investigated, with proposed epidemiological cutoff values for wild-type Salmonella of ≤16 μg/ml of azithromycin 5.
• Treatment of Salmonella gastroenteritis with ampicillin, amoxicillin, or placebo has shown no significant benefit from antibiotic therapy on the duration of diarrhea or on the duration of recovery of Salmonella from stool cultures 6.