Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
College of Veterinary Medicine
Non Technical Summary
Outbreaks of nosocomial Salmonella infections in veterinary hospitals are of major concern because of public health, animal health, and economic consequences. In university hospitals, the academic and economic impact of outbreaks of nosocomial Salmonella infections can be significant. In the outbreak of equine salmonellosis at the University of Pennsylvania in 2004, students had to go out-of-state for clinical training. Estimated losses were over $ 2 million in lost revenue, hospital renovations, cleaning and disinfection procedures, and a reduced caseload for 10 months after re-opening. Outbreaks of salmonellosis in private equine hospitals have not been documented, and quality of infection control infrastructure and standard operating procedures are not known. In a recent epidemiologic study of nosocomial Salmonella infections at the University of Florida Large Animal Hospital, horses that underwent abdominal surgery were identified at high risk of nosocomial Salmonella infection. In that study, all horses that underwent abdominal surgery were treated with antimicrobial drugs. While previous studies failed to identify abdominal surgery as a risk factor for nosocomial Salmonella infections, the association between exposure to antimicrobial drugs and nosocomial infection has been well established; antimicrobial drugs can eliminate intestinal flora that are antagonistic to Salmonella organisms. Our research will examine the effect of surgical stress on the immune system of horses that undergo abdominal surgery. Knowledge of the effect of surgical stress on the immune system in horses that undergo abdominal surgery is essential to further develop infection control strategies designed to reduce the risk of nosocomial Salmonella infections in hospitalized horses. In addition, because bacteriologic culture methods for diagnosis of Salmonella in horses are not standardized, we will compare the sensitivity (ability of laboratory test to identify infected horses) of fecal culture procedures for diagnosis of Salmonella in horses when using 1, 10, and 25g fecal sample weights. Finally, we will conduct a survey to characterize the quality of surveillance and infection control programs in place at university and private equine hospitals in SE and NE United States.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
OBJECTIVE 1: Examine the effect of sedatives and anesthetics on plasma TNF-alpha (TNF-a), IL-10, and LPB activity, the release of TNF-a and IL-10 in response to LPS, and the expression of TLR-4 and mCD14 in horses with lameness that undergo magnetic resonance imaging (MRI). Enrollment will occur from July 2009 - July 2010. EXPECTED RESULTS: Exposure to sedatives and anesthetics is not expected to have an effect on immune response. However, exposure to ketamine is expected to suppress LPS-induced TNF-a. It is expected that the magnitude of suppression observed in this group of horses will be less, compared to that in healthy horses that will go abdominal surgery and horses with signs of gastro-intestinal tract (GI) disease that undergo abdominal surgery. OBJECTIVE 2: Examine the effect of surgical stress on immune response measured in healthy horses that will undergo abdominal surgery. Enrollment will occur from July 2009 -July 2010. EXPECTED RESULTS: Surgical stress is expected to suppress the immune response. It is expected that the magnitude of suppression observed in this group of horses will be higher, compared to that in horses with lameness. OBJECTIVE 3: Examine the effect of surgical stress on immune response measured in hospitalized horses with signs of GI disease that undergo abdominal surgery. Enrollment will occur from July 2010 - July 2011. EXPECTED RESULTS: Surgical stress is expected to suppress the immune response in horses with signs of GI disease that undergo abdominal surgery. It is expected that the magnitude of suppression observed in this group of horses will be higher, compared to that in horses with lameness. In horses that test positively to Salmonella shedding, we expect that the combined effect of exposure to Salmonella spp and surgical stress will result in lower overall immune response. OBJECTIVE 4: Compare the sensitivity of bacteriological culture of Salmonella spp when using different fecal sample weight (1, 10, and 25g) in horses that present with signs of GI disease. Enrollment will occur from July 2010 - July 2011. EXPECTED RESULTS: The proportion of horses that test positively to Salmonella will be higher when using fecal samples of greater weight. OBJECTIVE 5: Characterize the infection control infrastructure and SOP used to reduce risk of nosocomial Salmonella infections in equine hospitals in SE and NE United States. Surveys will be sent out September 1, 2009, with expected responses 4 weeks later. EXPECTED RESULTS: Survey results will reveal differences in surveillance and infection control, education, and communication with clients between university and private hospitals, between regions, between main types of horses hospitalized, and between low and high caseload. EXPECTED OUTPUT: We expect to publish 5 scientific articles in AJVR or JAVMA, one for each objective.
Project Methods
OBJECTIVE 1: A sample of 14 horses presenting for MRI will be enrolled. A standardized anesthetic and analgesic regimen will be used. MRI will be used to evaluate horses with lameness. For each horse, 50 ml of blood will be collected at 20 minutes before sedation, 10 minutes after sedation, as well as 30 and 90 minutes after induction. Assays for TNF-a, IL-10, LPB, TLR-4, and mCD14 will be performed. Data will be analyzed using repeated measures ANOVA. The potential confounding effects of known, prior exposure to NSAIDs on the immune responses will be examined. OBJECTIVES 2 and 3: A sample of 13 healthy horses will be enrolled in Objective 2, and 30 horses with GI disease in Objective 3. A standardized anesthetic and analgesic regimen will be used. Following induction of general anesthesia, horses in Objective 2 will undergo a celiotomy. Horses in Objective 3 will undergo abdominal surgery as directed. For each horse, 50 ml of blood will be collected 20 minutes before sedation, 10 minutes after sedation, pre-incision (30 minutes after induction), and 1, 4, 24, and 48 hours after incision. For each horse, a fecal sample will be collected before abdominal surgery and submitted for bacteriological culture of Salmonella spp. Four additional fecal samples will be collected after abdominal surgery. Assays for TNF-a, IL-10, LPB, TLR-4, and mCD14 will be performed. Data will be analyzed using repeated measures ANOVA. The potential confounding effects that exposure to NSAIDs, diagnosis, Salmonella shedding status, endotoxin concentrations, and duration of surgery may have on the immune responses will be examined. OBJECTIVE 4: A sample size of 400 horses will be enrolled and tested for Salmonella by using a real-time PCR. Fecal samples will be collected from each horse. Among horses classified as positive (40), additional samples will be collected. Real-time PCR will be conducted on the first fecal sample only. Bacterial culture for detection of Salmonella organisms will be performed on the additional fecal samples using different weights (1, 10, and 25g). McNemar's chi-square test will be used for statistical analysis. OBJECTIVE 5: A structured questionnaire requesting information on infrastructure, surveillance, infection control procedures, education, and communication with clients will be administered to 12 university hospitals and 64 private equine hospitals. The questionnaire will be mailed to each study hospital on 09/1/09. Four weeks after the questionnaires are mailed (10/1/09), hospital managers who fail to return the questionnaire will be contacted via phone call for an interview to complete the questionnaire. Investigated variables will be compared between type of hospitals, regions, and main type of horses admitted for hospitalization by using a chi-square test.