Comparison of Escherichia coli ST131 Pulsotypes, by Epidemiologic Traits, 1967–2009 - Vol. 18 No. 4 - April 2012 - Emerging Infectious Disease journal - CDC
Table of Contents
Volume 18, Number 4–April 2012
Volume 18, Number 4—April 2012
Comparison of Escherichia coli ST131 Pulsotypes, by Epidemiologic Traits, 1967–2009
AbstractEscherichia coli sequence type 131 (ST131), an emerging disseminated public health threat, causes multidrug-resistant extraintestinal infections. Among 579 diverse E. coli ST131 isolates from 1967–2009, we compared pulsotypes (>94% similar XbaI pulsed-field gel electrophoresis profiles) by collection year, geographic origin, source, and antimicrobial drug–resistance traits. Of 170 pulsotypes, 65 had >2 isolates and accounted for 85% of isolates. Although extensively dispersed geographically, pulsotypes were significantly source specific (e.g., had little commonality between humans vs. foods and food animals). The most prevalent pulsotypes were associated with recent isolation, humans, and antimicrobial drug resistance. Predominant pulsotype 968 was associated specifically with fluoroquinolone resistance but not with extended-spectrum β-lactamase production or blaCTX-M-15. Thus, several highly successful antimicrobial drug–resistant lineages within E. coli ST131 have recently emerged and diffused extensively among locales while maintaining a comparatively restricted host/source range. Identification of factors contributing to this behavior of ST131 could help protect public health.
By definition, ST131 is homogeneous with respect to housekeeping gene sequence across the 7 MLST loci; however, within-lineage genetic variation has been noted since ST131 was first described (3–5). Specifically, diversity of pulsed-field gel electrophoresis (PFGE) profiles has provided insights into the ecology of ST131. For example, the presence of ST131 isolates with similar PFGE profiles in widely dispersed locales and of isolates with quite different profiles in the same locale has suggested rapid and ongoing global dissemination of ST131 (3,8). Likewise, recovery of ST131 isolates with similar PFGE profiles from multiple household members (9–12) and from food animals (or retail meats) and humans (13) has suggested host-to-host or foodborne transmission, respectively, as potential mechanisms for dissemination of ST131.
However, relevant studies to date have included relatively few isolates, locales, and sources and limited time periods (2,6). In addition, the idiosyncratic nature of PFGE analysis precludes across-study comparisons. Thus, we analyzed 579 ST131 isolates from diverse sources according to a standardized PFGE protocol and then compared PFGE profiles with other characteristics, including geographic origin, time of collection, ecologic source, and antimicrobial drug–resistance traits.