JOURNAL OF CLINICAL MICROBIOLOGY, OCt. 1976, p. 326-329 Copyright © 1976 American Society for Microbiology
Vol. 4, No. 4 Printed in U.S.A.
Quantitative and Bacteriological Studies of Urine Specimens from Canine and Feline Urinary Tract Infections R. E. WOOLEY* AND J. L. BLUE Department of Medical Microbiology, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602 Received for publication 4 June 1976
The most prevalent microorganisms isolated from urine specimens of dogs (385) and cats (132) with clinical signs of urinary tract infections were Escherichia coli, Proteus spp., and Staphylococcus aureus. The results of quantitative urine-culturing methods showed 48.6% of the canine and 12.1% of the feline specimens had more than 105 organisms per ml of urine. The bacteria isolated appear to have a greater resistance to antibacterial agents than previously reported.
Veterinarians commonly encounter dogs and tained from the animals. Standardized bacterial incats with what are assumed to be urinary tract oculation loops calibrated to deliver 0.01 and 0.001 infections. To conserve time, therapy is fre- ml of urine were used to determine the number of in each milliliter of urine (9, 13). Specimens quently initiated without bacterial cultures or bacteria were streaked onto 5% bovine blood agar plates and antibiotic sensitivities. Changes in susceptibil- inoculated into thioglycolate broth. Media were inity of bacteria to antibacterial agents (10) have cubated aerobically at 37°C for 24 to 72 h. Bacterial occurred in the past decade. This has made colonies were counted on the blood agar plates, and effective antibiotic therapy more difficult in the quantitative counts were determined. Isolation urinary tract infections. In veterinary (8, 9) and of anaerobic and aerobic bacteria (2) was attempted human (4, 7) diagnostic procedures, it has be- from the thioglycolate broth when no growth apcome convention that microorganisms isolated peared on the inoculated blood agar plates. After 7 from urine samples in excess of 105 organisms days of incubation, all cultures with no growth were Isolates of microorganisms were identiper ml of urine are considered significant and discarded. fied standard procedures (1, 2). Sensitivities to by indicate the presence of urinary tract infec- antibacterial agents were on isolated coltions. The purpose of this report is to present a onies by the disk method performed (2). compilation of microorganisms isolated, quanRESULTS titation of their numbers, and description of their sensitivities to antibacterial agents from In the study of 385 dogs diagnosed as having 517 urine specimens from dogs (385) and cats urinary tract infections, 186 (48.3%) were males (132) diagnosed as having urinary tract infec- and 199 (51.7%) were females. In the canine tions. population, negative bacteriological cultures were obtained from 144 (37.4%) of the cases. AND METHODS MATERIALS Bacteriological quantitation of the microorgaUrine specimens from dogs and cats diagnosed as nisms present in the urine samples resulted in having urinary tract infections were submitted to 187 (48.6%) cases having more than 105 microorthe Clinical Microbiology Laboratory, College of Veterinary Medicine, University of Georgia, Ath- ganisms per ml of urine. Fifty-four (14.0%) of ens, in sterile containers collected by midstream the cases had fewer than 105 microorganisms flow, sterile catheterization, or transabdominal per ml of urine (Table 1). In the study of 132 cats diagnosed as having puncture. For specimens obtained by midstream flow and catheterization, the external genitals and urinary tract infections, 94 (71.2%) were males adjacent area of each animal were cleansed with an and 38 (28.8%) were females. In the feline popuantiseptic surgical soap and rinsed with sterile wa- lation, negative cultures resulted from 79 ter before collecting midstream specimens or insert- (59.9%) cases. Bacteriological quantitation of ing a sterile catheter into the bladder. Urines col- the microorganisms present in the urine specilected by transabdominal puncture were obtained by clipping the hair, surgically preparing a 25-cm2 area mens resulted in 16 (12.1%) cases having more in the suprapubic area, and inserting a 22-gauge than 105 per ml of urine. Thirty-seven (25.3%) needle into the bladder. Urine specimens were bac- of the cases had fewer than 105 microorganisms teriologically processed within 15 min of being ob- per ml of urine (Table 1). 326
lates were sensitive to bacitracin, neomycin, gentamicin, nitrofurantoin, chloramphenical, tetracycline, and erythromycin. Isolates of Streptococcus spp. were sensitive to penicillin and nitrofurantoin. Table 5 lists the percentage of cases with polymicrobic bacteriuria. The prevalence and sensitivities to antibacterial agents of bacteria isolated from urine specimens in numbers less than 105 per ml of urine were not significantly different from those in Tables 2, 3, and 4. DISCUSSION Quantitative bacteriological analysis and the use of antibacterial sensitivity tests are of value in diagnosing urinary tract infections and choosing appropriate therapeutic agents. It is well documented in veterinary and human medicine that bacteria in excess of 105 organisms per ml of urine indicate the presence of a urinary tract infection (4, 7-9).
The most prevalent bacteria isolated (Table 2) from urine specimens from dogs and cats having more than 105 organisms per ml of urine were Escherichia coli, Proteus spp., Staphylococcus aureus, and Streptococcus spp. Smaller numbers of Enterobacter spp., Klebsiella spp., and Pseudomonas aeruginosa were also isolated. No anaerobic bacteria were isolated from the urine specimens. Of the 18 streptococci isolates, 12 were alpha-hemolytic, 5 were betahemolytic, and 1 was gamma-hemolytic. The sensitivities of bacteria (isolated in excess of 105 per ml of urine) to antibacterial agents are listed in Tables 3 and 4. Analysis of the antibiograms of bacterial isolates from canine and feline urine specimens showed no significant differences; therefore, Tables 3 and 4 are a composite of data from both species. E. coli isolates were very susceptible (>90%) to gentamicin and nitrofurantoin, but highly resistant to other antibacterial agents. Proteus spp. isolates also were highly sensitive to gentamicin. Eighty percent of the S. aureus iso-
TABLE 2. Microorganisms isolated from canine and feline urine specimens in excess of 105/ml of urine
TABx 1. Results of quantitative bacteriological cultures of urine specimens from dogs and cats diagnosed with urinary tract infectionsa Feline Canine No. of microorganisms/ml of urine
URINARY TRACT INFECTIONS OF DOGS AND CATS
VOL. 4, 1976
Escherichia coli .... Proteus spp ........ Staphylococcus aureus ............. Streptococcus ....... Enterobacter spp. ... Klebsiella spp. ..... Pseudomonas aeruginosa ........... Staphylococcus epidermidis ......... Pasteurella multocida
16 48.6 187 >105 4 4.2 16