The purpose of this study was to examine
four urovirulence factors (UVFs) and their phylogenetic classes and compare
their levels of resistance to antimicrobial drug classes in 159 canine
uropathogenic E. coli (UPEC) isolates submitted to the Clinical bacteriology and
Mycology Laboratory of The University of Tennessee Veterinary Medical Center in
2007. Multiplex polymerase chain reaction was used to detect the following
UVFs: cytotoxic necrotizing factor (cnf),
hemolysin (hly), S-fimbrial adhesion
gene (sfa), and Pilus associated with
pyelonephritis gene G allele III (pap);
polymerase chain reaction was used to determine phylogenetic group. In vitro susceptibility to antimicrobial
classes was evaluated, and resistance was compared to UVF presence as well as
phylogenetic class. UVFs were presented in 48% of UPEC and were negatively correlated
with antimicrobial resistance. Of the 159 samples, the number of UVFs expressed
per isolate was 0 = 82 (52%), 1 = 24 (15%), 2 = 2 (1%), 3 = 18 (11%), and 4 =
33 (21%). The following UVFs were expressed: sfa (33%), hly (24%), cnf (25%), and pap (18%). Presence of all four UVFs, hly, cnf, and sfa together, and sfa alone, was associated with less resistance (P < 0.0001). Class B2 was the most
common phylogenetic class and contained the highest number of UVFs (P < 0.001). Mean antimicrobial
resistance was the highest in class A (P <
0.001) and the lowest in B2 (P <
0.001). Phylogenetic class A contained the lowest number of UVFs.