Microbiologic evaluation of canine urine: direct microscopic examination and preservation of specimen quality for culture

Abstract

Urine specimens were obtained from 115 dogs. Each specimen was divided into 2 aliquots; one aliquot was placed into a sterile container (non-preserved), and the other was preserved in a boric acid-glycerol-sodium formate at 4 C. Both aliquots were then transported to a laboratory, and specimens of each aliquot were bacteriologically cultured immediately upon arrival at the laboratory. Specimens of the preserved aliquot also were cultured after 24, 48, and 72 hours of preservation. In 47 specimens containing greater than or equal to 1 X 10(4) colony-forming units (CFU)/ml, the results of quantitative bacteriologic culturing of preserved urine at 0, 24, 48, and 72 hours were the same as the result of the immediate quantitative bacteriologic culture of non-preserved urine. In 2 of 5 specimens containing greater than or equal to 1 X 10(3) CFU/ml but less than 1 X 10(4) CFU/ml, the results of quantitative bacteriologic culture of preserved urine differed from the corresponding immediate culture of nonpreserved urine. Bacteria were not isolated from 63 specimens (less than 1 X 10(3) CFU/ml). Bacteriologic cultures of preserved urine were also negative for bacterial growth at 0, 24, 48, and 72 hours. Bacteriuria was detected by direct microscopic examination of gram-stained smears of uncentrifuged urine in 50 of 52 urine specimens from dogs with urinary tract infection. Bacteria were observed in 1 of 63 specimens that did not have bacterial growth when cultured.