Phylogroup and virulence gene association with clinical characteristics of Escherichia coli urinary tract infections from dogs and cats

Escherichia coli isolates from infections outside the gastrointestinal tract are termed extra-intestinal pathogenic E. coli (ExPEC) and can be divided into different subpathotypes; one of these is uropathogenic E. coli (UPEC). The frequency with which UPEC strains cause urinary tract infections in dogs and cats is not well documented. We used an oligonucleotide microarray to characterize 60 E. coli isolates associated with the urinary tract of dogs (n = 45) and cats (n = 15), collected from 2004 to 2007, into ExPEC and UPEC and to correlate results with patient clinical characteristics. Microarray analysis was performed, and phylogroup was determined by a quadruplex PCR assay. Isolates that were missing 1 or 2 of the gene determinants representative of a function (capsule, iron uptake related genes, or specific adhesins) were designated as "non-classifiable" by microarray. Phylogroup B2 was positively associated with the UPEC subpathotype (p < 0.0005) and negatively associated with "non-classifiable" isolates (p < 0.0005). Phylogroup D was positively associated with ExPEC pathotype (p = 0.025) and negatively associated with UPEC subpathotype (p = 0.014). The ExPEC pathotype was positively associated with hospitalization for one or more days (p = 0.031). The UPEC subpathotype was negatively associated with previous antimicrobial therapy (p = 0.045) and previous hospitalization within the 3 mo prior to the positive culture (p = 0.041). The UPEC subpathotype was positively associated with prostatitis (p = 0.073) and negatively associated with current immunosuppressive therapy (p = 0.090). Our results indicate that the case history observations may be critically important during the interpretation of laboratory results to encourage judicious use of antimicrobials.