Emergence and spread of O16-ST131 and O25b-ST131 clones among faecal CTX-M-producing Escherichia coli in healthy individuals in Hunan Province, China. (9th May 2015)

• Record Type: Journal Article
• Authors: Zhong, Yi-Ming; Liu, Wen-En; Liang, Xiang-Hui; Li, Yan-Ming; Jian, Zi-Juan; Hawkey, Peter M.
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 70:Number 8(2015:Aug.)
• Page Start: 2223
• Page End: 2227
• Publication Date: 2015-05-09
• Subjects: E. coli -- faecal carriage -- ESBLs -- genotypes; Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dkv114
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Objectives: The 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. Methods: From 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. Results: Among 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 fimH 41 allele. The remaining eight (25%) ST131 isolates were of the O25b subgroup and contained fimH 30 or fimH 41. 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 gyrA 1AB and parC 1aAB mutations; most of the O16-ST131 isolates had gyrA 1A and parC 1b 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). Conclusions: O16-ST131 isolates have emerged as the predominant type of ST131 isolate in faecal CTX-M-producing E. coli in healthy individuals in China.