Virulence genotypes of feline urinary Escherichia coli isolates from New Zealand and Great Britain differ
Freitag, T., Squires, R.A., and Elliott, J. (2004) Virulence genotypes of feline urinary Escherichia coli isolates from New Zealand and Great Britain differ. Journal of Veterinary Internal Medicine, 18 (3). p. 387.
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Some of the strains of E. coli that cause urinary tract infection (UTI) in dogs and cats are reportedly indistinguishable from strains that cause serious extraintestinal infections in humans, despite the use of highly discriminating molecular tests including macrorestriction analysis and extended virulence factor genotyping. There is little incriminating evidence concerning feline urinary E. coli, but the potential for zoonotic transmission from pet cats to humans has nevertheless been suggested. One of several factors complicating this field of study is that human urinary E. coli isolates from different geographic regions have been shown to differ genetically. It is to be expected that feline urinary E. coli isolates will also differ according to geographic origin, but this has not been studied. Such information would assist future epidemiological investigations of this potential, unproven, zoonotic association. We retrospectively studied 36 cystocentesis-derived E. coli isolates from cats with UTI, 15 from New Zealand, and 21 from UK, by extended virulence factor (VF) genotyping using multiplex PCR to determine the presence or absence of 25 genes encoding fimbrial structures, toxins, siderophores, and protectins. We also carried out macrorestriction analysis of Xba1-digested bacterial DNA from each isolate using pulsed-field gel electrophoresis (PFGE). PFGE revealed 36 distinct band patterns, the closest DICE similarity between any two clones being 69%. According to UPGAMA cluster analysis of VF profiles, the 36 isolates segregated into 3 groups at a similarity level of approximately 60%, two of which contained exclusively UK isolates, the third being mixed. Cross-validated discriminant analysis based on the VF genotypes correctly categorized 15/15 NZ isolates and 17/21 UK isolates. Four P fimbrialencoding genes papA, papEF, papC, and papG III were present in all of the New Zealand isolates, but in a significantly smaller proportion, 43%, of UK isolates (Fisher’s exact test, p , 0.0005). Conversely, the protectins colicin (cvaC), serum survival factor (iss), and serum resistance factor (traT) were absent from all of the NZ isolates but present in 42%, 48%, and 67% of UK isolates, respectively (Fisher’s exact test, p # 0.005). This study has revealed substantial VF genotypic differences between feline urinary E. coli isolates from UK and New Zealand and calls into question the use of VF genotypes to study the zoonotic potential of feline urinary E. coli unless the source of isolates is carefully considered. In this retrospective study, clinical information concerning the NZ cats was incomplete, whereas all of the UK cats had been diagnosed with renal insufficiency or chronic renal failure. Therefore it cannot be ruled out that different disease states in the members of these two populations contributed to the genetic differences detected in the E. coli isolates derived from them.
|Item Type:||Article (Short Note)|
|Date Deposited:||23 Apr 2010 03:41|
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