01860-A: Rapid and Accurate Diagnosis of Bacterial Peritonitis
Grant Status: Closed
Project SummaryBacterial peritonitis (infection in the abdominal cavity) is a life-threatening condition in dogs having a high mortality rate (up to 30% in some reports). It usually results from a perforation of the gastrointestinal tract. Such a perforation commonly occurs secondary to things like a tumor in the intestines, a foreign body, an ulcer in the stomach, etc. Clinical signs associated with this condition are variable, ranging from vague signs such as lethargy and anorexia to more specific signs such as vomiting or abdominal pain. However, at best only half of dogs with bacterial peritonitis show abdominal pain and only � of affected dogs exhibit signs of vomiting. The fact that clinical signs are so variable can make diagnosis of bacterial peritonitis a challenge for veterinarians. Cases of bacterial peritonitis will eventually produce free abdominal fluid that can be seen on radiographs (X-rays) or abdominal ultrasound and can be sampled. However, since peritonitis is not the only reason dogs can have free abdominal fluid, the fluid needs to be further analyzed to prove that it is consistent with bacterial peritonitis. In many cases, primary care veterinarians are unable to perform such fluid analysis in-house. In veterinary medicine, it is widely accepted that bacterial peritonitis is present when there are bacteria-filled inflammatory cells in the fluid. This is seen on a slide made from the abdominal fluid. Alternatively, a positive bacterial culture of the abdominal fluid can prove peritonitis. For many primary care veterinarians, neither of these tests can be done at the time the fluid is sampled. Cultures can take up to 5-7 days to return from the laboratory during which time the dog's condition can decline to the point of death, especially if untreated. Similarly, fluid analysis including a cytologic examination is usually performed at a reference laboratory due to discomfort with or lack of access to an in-house microscopic exam. This means that there is a minimum of a 12-24 hour turn-around time for a practitioner to get results from the fluid analysis. This time delay can lead to significant worsening of the dog's condition and, in some cases, death. There is a need for all primary care and first line emergency clinicians to have access to a bed-side diagnostic test that can aid in the challenging diagnosis of bacterial peritonitis. In human medicine, there are multiple publications describing use of the Multistix 8 SG Reagent Strip (a commonly used dipstick strip for urine analyses) to diagnose spontaneous bacterial peritonitis. Specifically, the leukocyte esterase test pad on the reagent strip is designed to determine the degree of activity of granulocyte esterase. Granulocyte esterase is an enzyme produced by activated neutrophils (inflammatory cells). In the presence of granulocyte esterase, the leukocyte esterase test pad on the reagent strip will have a colorimetric reaction (ie. change color) with the degree of color change indicating the amount of the enzyme that is present in the sample. Therefore, a positive reaction on the reagent strip in a patient with abdominal effusion is consistent with a patient with bacterial peritonitis. We collected samples of free abdominal fluid from 60 dogs presenting to the Purdue University Veterinary Teaching Hospital from June 2012-July 2013. Each sample was tested via the reagent strip, analyzed microscopically at the clinical pathology laboratory, and cultured. We compared the results from the reagent strip (color change or not) to the microscopic and culture findings to determine the accuracy of the reagent strip to diagnose peritonitis or not. We determined that the results of the dipstick had a 91.7% specificity. Therefore, if the dipstick results are negative, 91.7% of the time the patient does not have bacterial peritonitis. This finding is very similar to what was determined in human medicine. Based on these findings,
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