From the Guidelines
The recommended method for testing for Salmonella infection is a stool culture, which is considered the gold standard diagnostic test, as supported by the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1. To conduct this test, a healthcare provider will collect a stool sample from the patient, which is then sent to a laboratory where technicians attempt to grow and identify Salmonella bacteria.
Key Considerations for Testing
- Blood cultures may also be performed, particularly in cases of typhoid fever or when the infection has potentially spread beyond the intestines, as recommended for certain high-risk patients, including those with signs of septicemia, immunocompromised individuals, or people who have traveled to enteric fever–endemic areas 1.
- In some cases, healthcare providers might use rapid diagnostic tests that detect Salmonella antigens in stool samples, though these are generally less reliable than cultures.
- Multiple stool samples collected over several days may be necessary since Salmonella is shed intermittently in the stool.
- For accurate results, it's essential to collect samples before starting antibiotics, as medication can interfere with bacterial growth in culture.
Patient Evaluation
Patients experiencing symptoms like diarrhea, fever, and abdominal cramps should seek medical attention promptly for proper testing, especially if symptoms are severe or persistent, or if they have recently traveled internationally. The guidelines also emphasize the importance of considering the clinical manifestations of infectious diarrhea, including acute, persistent, and chronic diarrhea, and evaluating people with infectious diarrhea based on their symptoms, epidemiologic risk factors, and host factors 1. In addition, the 2009 guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents recommend obtaining blood cultures from any patient with diarrhea and fever, particularly in patients with advanced disease, due to the high rate of bacteremia associated with Salmonella gastroenteritis in HIV-infected patients 1.
From the Research
Testing for Salmonella
- The recommended method for testing for salmonella infection is still a topic of discussion, with different studies suggesting various approaches 2, 3, 4.
- According to a study published in the Journal of Medical Microbiology, enrichment culture is significantly more sensitive than PCR using the BD MAX Enteric Bacterial Panel for detecting salmonella in stool 2.
- The study suggests that where PCR testing is used for the detection of enteric pathogens, enrichment culture for salmonella should be continued in parallel, unless the PCR method is shown to be at least as sensitive as culture 2.
- Another study published in Animals: an open access journal from MDPI, emphasizes the importance of a comprehensive approach to prevent salmonellosis, including proper handling of food, avoiding cross-contamination, and thorough cooking 3.
- A review published in Antibiotics (Basel, Switzerland) highlights the need for effective infection management and the development of antibiotic alternatives due to the emergence of antibiotic resistance and the rise of multidrug-resistant (MDR) Salmonella strains 4.
- A systematic review published in IJID regions found that azithromycin and ceftriaxone were more effective in treating Salmonella infections, and azithromycin was found to be the physicians' preferred choice of medication due to its less resistance development 5.
- However, a study published in The Journal of Antimicrobial Chemotherapy found that azithromycin resistance is emerging in typhoidal Salmonella, and there were discordances in results using MIC gradient strips, highlighting the need for accurate susceptibility testing 6.