Epidemiologic analysis of nosocomial Salmonella infections in hospitalized horses.

This research investigated how abdominal surgery and the number of inpatients affected the occurrence of hospital-acquired Salmonella infections in horses. It found that horses undergoing abdominal surgery were eight times more likely to contract Salmonella, however, high patient volume did not result in a higher risk. The authors concluded that better infection control after surgery could reduce this risk.

Methodology

• The study used cases and controls, a common epidemiological method. For the first part of the study looking at the link between abdominal surgery and hospital-acquired Salmonella, each infected horse was matched with 1 to 4 horses who were admitted on the same date but did not get infected.
• The frequency of abdominal surgery and other potential risk factors were compared between the infected horses and the matched controls.
• For the second part of the study which involved looking at the combined effect of high caseload and abdominal surgery, each infected horse was matched with 4 uninfected horses admitted in the same year.
• The frequency of high caseload (26 or more inpatient horses), abdominal surgery, and other factors were compared between infected horses and matched controls.

Findings

• The odds of hospital-acquired Salmonella infection were 8 times higher in horses that underwent abdominal surgery, as compared with horses that did not. This was statistically significant with an odds ratio of 8.2 within a 95% confidence interval of 1.11 and 60.24.
• High caseload, either on its own or combined with abdominal surgery, did not increase the risk of infection. This contradicts assumptions that higher patient volumes could put greater strain on infection control measures.

Implications

• The results suggest that abdominal surgery is a risk factor for hospital-acquired Salmonella infections in horses. This indicates that infection control and preventive measures need to be enhanced in these cases.
• While high caseloads didn’t increase infection risk, the authors suggested that reducing the risk of these nosocomial infections could still be achieved through stricter biosecurity measures after surgery such as the use of plastic boots, gloves, and footbaths.