Objective—To evaluate the in vitro efficacy of an ophthalmic drug combination against common corneal pathogens of horses.
Sample Population—Representative isolates of 3 bacterial and 2 fungal corneal pathogens of horses.
Procedures—Pathogens were subjected to minimum inhibitory concentration (MIC) testing of a drug combination that consisted of equal volumes of natamycin 3.33%, tobramycin 0.3%, cefazolin 5.5%, and equine serum. Proteinase inhibitory activity of the drug combination was assessed by use of a fluorescence microplate assay with gelatin and collagen I as substrates. The MICs of the drug combination were compared with those for each of the component medications and antiproteinase activity of the drug combination was compared with that of serum by use of paired t tests and a 2-way ANOVA, respectively.
Results—The drug combination was at least as effective as each medication separately for inhibiting microbial growth of all pathogens tested and was significantly more effective against B-hemolytic Streptococcus spp, Aspergillus spp, and Fusarium spp than the relevant medications separately. Serum and the drug combination both had significant antigelatinase activity, and serum had significant anticollagenase activity. Antiproteinase activity of serum was a concentration-dependent event, which enabled serum to achieve significantly greater activity than the drug combination after 3.5 and 4 hours of intubation for the gelatin and collagen I assays, respectively.
Conclusions and Clinical Relevance—Drug combinations have the attractive potential of minimizing the time, stress, and fatigue associated with topical treatment regimens consisting of multiple drugs used separately for horses with keratitis.
Objective—To examine the relationship between abdominal surgery and nosocomial Salmonella infections and the relationship between high caseload in combination with abdominal surgery and nosocomial Salmonella infections in hospitalized horses with signs of gastrointestinal tract disease.
Procedures—To accomplish the first objective, 1 to 4 control horses were matched with each nosocomial case horse on the basis of admission date of a primary case horse. The frequency of abdominal surgery and other investigated exposure factors were compared between nosocomial case horses and control horses. For the second objective, 4 control horses were matched with each nosocomial case horse on the basis of year of admission. The frequency of high caseload (≥ 26 inpatients), abdominal surgery, and other factors was compared between nosocomial case horses and control horses.
Results—The odds of nosocomial Salmonella infection were 8 times as high (odds ratio = 8.2; 95% confidence interval = 1.11, 60.24) in horses that underwent abdominal surgery, compared with the odds for horses that did not undergo surgery. High caseload alone or in combination with abdominal surgery was not associated with increased risk of nosocomial Salmonella infection.
Conclusions and Clinical Relevance—Abdominal surgery was identified as a risk factor for nosocomial Salmonella infections in horses. Horses that undergo abdominal surgery require enhanced infection control and preventative care. Risk of nosocomial Salmonella infections may be reduced by implementation of biosecurity measures (such as the use of plastic boots, gloves, and footbaths) immediately after surgery.