Escherichia coli ST131, an intriguing clonal group

Abstract

In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum β-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131.

FIG 1

Global dissemination of Escherichia coli ST131 clone (2013). Articles which mentioned for the first time the presence of clone ST131 in a given country or a given location are cited. Red stars indicate isolates producing ESBL enzymes, and blue stars indicate fluoroquinolone-resistant, non-ESBL-producing isolates. For Europe, references are for Belgium (58, 83), Croatia (220), the Czech Republic (206), Denmark (221), France (8), Germany (166, 170), Italia (222), Netherland (223), Norway (57), Portugal (8), Spain (8), Sweden (224), Switzerland (8), and the United Kingdom (67, 78, 108, 109). For Asia, references are for China (71, 95, 164, 225, 226), India (73, 227), Israel (228), Japan (25, 95, 171, 229), South Korea (8), Kuwait (8), Lebanon (8), Pakistan (23), Russia (192), Turkey (230), and United Arab Emirates (231). For the Americas, references are for Canada (8, 50, 84, 85, 140, 147), the United States (10, 42, 43, 46, 156, 232), Argentina (233), Brazil (234), Colombia (235), and Mexico (236). For Africa, references are for Cameroon (237), Central African Republic (125), Egypt (238), Kenya (177), Madagascar (239), Nigeria (240), South Africa (241), Tanzania (242) and Tunisia (243). For Oceania, references are for Australia (150, 172, 173, 244, 245) and New Zealand (246).

FIG 2

Dynamics of bacteremia ESBL-producing Escherichia coli isolates and proportion of ST131 E. coli isolates between 2000 and 2011 in Calgary (Canada) (84). The curve represents the percentage of ESBL-producing E. coli isolates and the histogram the proportion of E. coli ST131 among these isolates.