Detection of Salmonella spp. in pooled environmental samples from an equine veterinary hospital using a novel point-of-care PCR assay.

Overview

• This study assessed the effectiveness of a novel point-of-care (POC) PCR assay for detecting Salmonella species in pooled environmental samples from an equine veterinary hospital.
• The POC PCR assay was compared to traditional quantitative PCR (qPCR) testing to evaluate agreement, speed, and feasibility of Salmonella monitoring in high-risk areas.

Study Background and Goals

• Context: Salmonella spp. are important pathogens that can cause infections in horses and pose contamination risks in veterinary clinics, especially in critical areas like ICUs and isolation stalls.
• Goal: To evaluate if pooling environmental samples and using a novel POC PCR assay allows rapid, accurate detection of Salmonella spp., potentially enabling faster infection control responses.

Methods

• Sample Collection:
  • 945 environmental samples collected from high-risk and high-traffic locations within the equine hospital (including ICU, isolation stalls, treatment rooms, surgical suites).
  • Samples collected using drag swabs placed into selenite broth, incubated at 35 °C for 20 hours.
• Sample Pooling:
  • Up to 10 individual samples were pooled into one combined sample for initial testing to maximize efficiency.
  • 135 pools were created, each containing 6 to 10 samples.
• Testing Procedure:
  • Nucleic acid purification followed by qPCR analysis was performed on each pool.
  • Direct testing of pools was also conducted with the POC PCR assay simultaneously.
  • Testing was masked so that the results of qPCR and POC PCR were unknown during processing to avoid bias.
  • Individual samples from pools that tested positive were subsequently tested individually by both methods to confirm presence of Salmonella spp.

Results

• Agreement Between Tests:
  • 100% concordance between qPCR and POC PCR results in pooled samples: out of 135 pools, 118 tested negative and 17 tested positive by both methods.
• Individual Sample Confirmation:
  • In the 17 positive pools, individual testing of samples confirmed the same samples as positive by both qPCR and POC PCR.
• Efficiency and Improvement:
  • Pooling strategy effectively reduced the number of total tests while still identifying contaminated environmental sites.
  • The POC PCR assay matched qPCR accuracy but reduced turnaround time to 24 hours from sample collection to results.

Conclusions and Implications

• Pooling environmental samples is a practical approach for routine monitoring of Salmonella spp. contamination in high-risk areas of equine hospitals.
• The novel POC PCR assay provides rapid, reliable detection comparable to traditional qPCR methods.
• Faster results can improve infection control responses by enabling quicker identification and intervention to prevent spread.
• The study supports the integration of POC PCR testing into environmental surveillance protocols to enhance compliance and reduce laboratory turnaround times.