Investigation and control of an outbreak of salmonellosis caused by multidrug-resistant Salmonella typhimurium in a population of hospitalized horses.

The research describes an outbreak of an infection caused by a multidrug-resistant strain of bacteria, Salmonella typhimurium, in hospitalized horses that led to the closure of a teaching hospital. The study provides details about the process of identifying the infection and the measures taken to control it.

Investigation of the Outbreak

• The outbreak of salmonellosis, an infection caused by the bacteria Salmonella, affected a group of horses that were being cared for in a teaching hospital. The serious nature of the outbreak resulted in the closure of the hospital for an extended period of 10 weeks.
• The researchers began their investigation by collecting fecal samples from the horses that were suspected to be infected. These samples were cultured to isolate any Salmonella bacteria present.
• The isolated Salmonella samples were then tested using various techniques. These included antimicrobial susceptibility testing to determine the level of resistance the bacteria had to different drugs, pulsed-field gel electrophoresis (PFGE) to examine the bacterial DNA, and phage typing to identify the specific type of Salmonella bacteria.
• It was found that 33 cases of the outbreak were caused by a strain of Salmonella typhimurium that was resistant to multiple drugs. The original case was identified in late August 1999.

Origin and Spread of the Outbreak

• The majority, about 45% of the cases, occurred between April and June 2000. This highlights the severity and rapid spread of the outbreak.
• The PFGE test results suggested that the multidrug-resistant strain of S. typhimurium may have been introduced into the hospital by a foal, a young horse, that was showing symptoms of diarrhea.

Outbreak Control Measures

• The hospital was shut down on June 13 and an intensive cleaning process was carried out. This included disinfection of the entire environment to get rid of any remaining bacteria.
• The researchers emphasized the importance of enforcing disease control protocols in hospital settings. This includes maintaining close surveillance of the patients and the environment to detect any signs of an outbreak and implementing strict infection prevention measures.

Conclusion

• The study highlights the challenges faced in controlling an outbreak caused by multidrug-resistant pathogens. It emphasizes the importance of rigorous sanitation and infection control practices, especially in veterinary hospitals.