Risk factors for surgical site infection following laparotomy: Effect of season and perioperative variables and reporting of bacterial isolates in 287 horses.

This study explores the factors that influence the occurrence of surgical site infection (SSI) in horses that have undergone laparotomy. Using retrospective data from a 3-year period, it concludes that chances of infection increase with a horse’s bodyweight and packed cell volume, and whether small intestinal resection and postoperative colic occurred. The season, specifically winter and summer months, also influenced likelihood of infection. However, the time of surgery (whether or not it’s within working hours) had no significant impact. The most common bacterial isolates found in these infections were Escherichia coli and Enterococcus spp., with a high percentage proving resistant to antibiotics.

Understanding the Research

• The researchers launched this study to investigate the various factors that might influence the risk of surgical site infection (SSI) in horses following laparotomy, a surgical procedure that involves making a large incision through the abdominal wall to gain access into the abdominal cavity. The research was done through a retrospective cohort study, where past data was used.
• The data came from horses that had undergone an exploratory laparotomy in a UK hospital over a period of three years. Surgical site infection (SSI) was defined as any purulent (pus-filled) or serous (clear, yellowish fluid) discharge from the incision area that lasted for more than 24 hours during the horse’s hospitalisation.
• Various factors were examined for their impact on the probability of SSI. Such factors included the horse’s body weight, packed cell volume (proportion of blood volume that is occupied by red blood cells), whether small intestinal resection was performed, the occurrence of postoperative colic, and the season.
• Their conclusions revealed that horses that were heavier, had higher packed cell volumes on admission, had undergone small intestinal resection or exhibited postoperative colic were at a significantly higher risk of developing SSI. The risk also increased in winter and summer months. One remarkable finding was that a three-layer closure of the incision reduced the probability of SSI when compared to a two-layer closure.
• Interestingly, they found the timing of the surgery (inside or outside normal working hours) did not affect the probability of SSI occurring.

Bacterial Isolates in SSI

• Data on bacterial isolates was also produced through the research. The most common isolates found infecting the surgical site were the bacteria Escherichia coli, Enterococcus spp., and Staphylococcus spp.
• Most of the isolates were resistant to penicillin (92%), with a smaller proportion showing resistance to gentamicin (18%). This data provides valuable information for the development of targeted antibiotic therapies.
• This research contributes significantly to the understanding of risk factors for SSI in horses following laparotomy, which can aid in developing preventative strategies and understanding patterns of bacterial resistance in such scenarios. Greater focus on horses with these risk factors can increase the chances of preventing or addressing SSI more effectively, thus improving recovery outcomes and the overall health and wellbeing of the animal.