Detection of Salmonella enteritidis in equine feces using the polymerase chain reaction and genus-specific oligonucleotide primers.

This research identified Salmonella in horse feces using a method called the polymerase chain reaction (PCR) along with genus-specific primers. The study demonstrated the method’s sensitivity using samples inoculated with known amounts of Salmonella.

Experimental Procedure

• The researchers conducted the experiment using fecal samples from healthy horses which were confirmed to be negative for Salmonella both through culture and PCR methods.
• These fecal samples were then purposely inoculated, or treated, with known quantities of colony-forming units (CFUs) of a specific Salmonella strain, S. enteritidis.
• In order to create the most favorable conditions for bacteria growth and detection, the inoculated fecal samples were enriched in tetrathionate broth overnight.

DNA Extraction and Amplification

• Following enrichment, DNA was extracted from the samples and then amplified using the PCR technique along with primers specific to the Salmonella genus.
• The sensitivity of the PCR assay was determined to be able to detect as few as 10 CFUs of Salmonella enteritidis per gram of feces.
• The researchers found the sensitivity of microbiological culture with enrichment to likewise extend to 10 CFUs of Salmonella enteritidis per gram of feces.

Testing Efficacy and Efficiency

• PCR proved that it could quickly and accurately identify fecal samples not inoculated with S. enteritidis as negative.
• PCR allowed for the detection of Salmonella in feces within 24 hours from the time the samples were submitted, showcasing the method’s efficiency.

Additional Benefits

• Due to the initial enrichment of samples in the tetrathionate broth, isolates of the Salmonella bacteria were readily available for further testing and study, such as antibiogram determination and serologic grouping or typing.

In conclusion, the study presents Polymerase Chain Reaction (PCR) as a sensitive and efficient method in detecting Salmonella enteritidis in equine feces that, combined with the use of enrichment broths, could facilitate more in-depth bacteriological studies.