Emergence and spread of O16-ST131 and O25b-ST131 clones among faecal CTX-M-producing Escherichia coli in healthy individuals in Hunan Province, China

Abstract

ObjectivesThe objectives of this study were to determine CTX-M-producing Escherichia coli ST131 strain prevalence in stool specimens from healthy subjects in central China and to molecularly characterize clonal groups.MethodsFrom November 2013 to January 2014, stool specimens from healthy individuals in Hunan Province were screened for ESBL-producing E. coli using chromogenic medium and CTX-M genotypes and phylogenetic groups were determined. ST131 clonal groups were detected by PCR and characterized for antibiotic resistance, fimH, gyrA and parC alleles, plasmid-mediated quinolone resistance determinants, virulence genotypes and PFGE patterns.ResultsAmong 563 subjects, 287 (51.0%) exhibited the presence of faecal ESBL-producing E. coli, all of which produced CTX-M enzymes. The most common CTX-M genotypes were CTX-M-14 (48.4%), CTX-M-15 (27.5%) and CTX-M-27 (15.0%). Of the 287 CTX-M-producing isolates, 32 (11.1%) belonged to the ST131 clone. O16-ST131 isolates were dominant (75%) and contained the fimH41 allele. The remaining eight (25%) ST131 isolates were of the O25b subgroup and contained fimH30 or fimH41. Ciprofloxacin resistance was found in 100% of the O25b-ST131 isolates, whereas only 8% of the O16-ST131 isolates were resistant. All of the O25b-ST131 isolates except one showed gyrA1AB and parC1aAB mutations; most of the O16-ST131 isolates had gyrA1A and parC1b mutations. The virulence genotypes of O16-ST131 resembled those of the O25b-ST131 isolates. The 32 ST131 isolates formed one large group at the 64% similarity level. They comprised 15 PFGE groups (defined at ≥85% similarity).ConclusionsO16-ST131 isolates have emerged as the predominant type of ST131 isolate in faecal CTX-M-producing E. coli in healthy individuals in China.

GlobalEscherichia coliSequence Type 131 Clade withblaCTX-M-27Gene

“…ST131 with bla CTXM-15 is rare among animal and environmental E. coli isolates ( 26 ). Our analysis of IEH71520, an E. coli isolate from vacuum cleaner dust in the United States ( 15 ), showed that this ST131 isolate belong to the C1-M27 clade. The C1-M27 clade is likely to be present among animal and environmental ST131, and such isolates might act as a hidden reservoir for the introduction of ST131 containing bla CTX-M-27 into human medicine.…”

“…ST131 containing bla CTX-M-27 responsible for human infections has been reported from various continents ( 2 ) and is especially common among ESBL-producing ExPEC in certain countries, such as Israel, the Czech Republic, and Switzerland ( 2 , 13 , 14 ). CTX-M-27–producing ST131 also is present among nonclinical and nonhuman E. coli isolates, including fecal specimens of healthy children attending day care centers in France; fecal specimens of healthy adults in China, Portugal, and the Netherlands; samples from sick dogs and cats in Japan; samples from water birds from central Europe and Swiss rivers and lakes; and samples of well water from China ( 2 , 10 , 11 , 15 , 23 – 25 ). The most common ESBL among E. coli ST131 in nonhuman samples is CTX-M-27 ( 2 , 23 – 25 ).…”

“…CTX-M-27–producing ST131 that belongs to the H 41 lineage previously had been described from Japan ( 6 ) and China ( 15 ). The characterization of the Japanese ST131 H 41 isolates showed different genetic structures flanking the bla CTX-M-27 from those structures present in E. coli ST131 H 30R ( 6 ).…”

“…ST131 with CTX-M-27 had previously been reported from other countries, such as Korea (isolation year 2008), China (2013–2014), Australia (2009–2010), Nepal (2013–2014), Cambodia (2004–2005), Israel (2008–2009), Czech Republic (2008–2011), Switzerland (2011), Spain (2012), France (2012), Portugal (2013–2014), Netherlands (2011), Canada (2005), and United States (2013) ( 2 , 5 – 15 ). Because of the rapid increase of CTX-M-27–producing ST131 in Japan since 2010 ( 6 ), we designed a study to characterize these isolates using WGS techniques.…”

Genomic epidemiology of globalKlebsiella pneumoniaecarbapenemase (KPC)-producingEscherichia coli

“…Notably, the H30R/C1 clade (fluoroquinolone-resistant) and H30Rx/C2 clade (fluoroquinolone and extended-spectrum cephalosporin-resistant) sub-lineages of this strain have previously expanded globally in association with particular drug resistance mechanisms, including the extended-spectrum beta-lactamase (ESBL) gene, bla CTX-M-15 (clade C2) 21,22 . Given the high rates of community and healthcareassociated infections attributable to ST131 23 , and its capacity to be harbored asymptomatically in the gastrointestinal tract 24 , a stable association of ST131 with bla KPC could have dramatic consequences for the management of E. coli infections 12 .…”