Comparison of two sampling and culture systems for detection of Salmonella enterica in the environment of a large animal hospital.

The research compares two methods for detecting Salmonella enterica in large animal veterinary hospitals. The study indicates that electrostatic wipe sampling and culture method was more effective in detecting Salmonella than the sponge sampling and culture method.

Introduction

• The study revolves around nosocomial salmonellosis, a health issue faced in large veterinary hospitals treating animals such as horses, cows, and New World camelids.
• The nature of the problem necessitates effective and efficient detection of Salmonella enterica in the hospital environment to mitigate outbreaks and prevent healthcare-associated infections.

Methods

• The researchers conducted a comparison of two environmental sampling techniques already published.
• They collected 100 pairs of environmental samples from stalls housing large animals found with Salmonella via faecal culture. Special care was taken to cleanse and disinfect the stalls before sampling. The same areas in each stall were sampled for consistent results.
• Two methods of detection were examined. One method used sterile, premoistened sponges cultured with thioglycolate enrichment and then plated on XLT-4 agar. The second method utilized electrostatic wipes cultured using buffered peptone water, tetrathionate and Rappaport-Vassiliadis R10 broths then plated on the same agar.

Results

• The study found that the electrostatic wipe sampling method was able to recover Salmonella enterica from 14% of samples, whereas the sponge sampling method only managed to recover the bacteria from 4% of samples.
• The two methods showed agreement in 85 pairs of negative culture samples and 3 pairs of positive culture samples. However, disagreements were recorded in 12 pairs of culture samples, which indicated a significant differentiation between the two detection methods.

Conclusion

• The results indicate that even rigorous cleaning and disinfection in veterinary hospitals do not guarantee the complete eradication of Salmonella.
• Therefore, sensitive and effective methods of detection become crucial when combating Salmonella outbreaks in such environments.
• Out of the two methods tested, the electrostatic wipe method stood out as more sensitive in detecting Salmonella enterica than the sponge sampling method.