Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 22, Number 12—December 2016
Letter

Pathogenic Lineage of mcr-Negative Colistin-Resistant Escherichia coli, Japan, 2008–2015

Cite This Article

To the Editor: Colistin is a last-line drug for treatment of multidrug-resistant, gram-negative bacterial infections, including those caused by Escherichia coli. We report colistin-resistant E. coli isolates from Japan, including a global-spreading pathogenic lineage, serotype O25b:H4, sequence type (ST) 131, and subclone H30-R (O25b:H4-ST131-H30R).

We tested 514 E. coli isolates obtained from clinical specimens taken at Sapporo Clinical Laboratory Inc. (Sapporo, Japan) and Sapporo Medical University Hospital in Japan during 2008–2009 (1) and 2015, respectively. Samples were processed according to Clinical and Laboratory Standards Institute guidelines (2). Identification of O25b:H4-ST131, O25b, H4, and ST131 were determined as described previously (1). For identification of the H30Rx subclone of O25b:H4-ST131, H30 was determined by PCR using a specific primer set (3), R was determined according to ciprofloxacin MIC, and x was determined by detecting 2 single-nucleotide polymorphisms, as previously described (4).

Four E. coli isolates exceeded the colistin resistance breakpoint (>2 mg/mL) (Table). None of the patients from whom the E. coli isolates were derived had a history of colistin treatment. Three of the 4 colistin-resistant isolates belonged to a pandemic lineage, O25b:H4-ST131-H30R, which has been isolated from urinary tract and bloodstream infections (3,4). The frequency of colistin-resistant ST131 E. coli isolates among O25b:H4-ST131 was 2.2%. This lineage is fluoroquinolone resistant and is frequently resistant to β-lactams because it possesses CTX-M–type extended-spectrum β-lactamase genes (1,3,4).

The colistin-resistant isolates reported were resistant to fluoroquinolones, and 1 (SME296) was resistant to cephalosporins (due to expression of blaCTX-M-14). Another colistin-resistant E. coli isolate (SME222) belonged to O18-ST416, which is also known as an extraintestinal pathogenic E. coli (5), although this lineage has not previously been reported to exhibit colistin resistance.

The colistin-resistant E. coli isolates we identified were sensitive to carbapenems and aminoglycosides, including amikacin, whereas previously it was reported that some E. coli ST131 isolates exhibited resistance to carbapenems by possessing carbapenemases, such as NDM-1 and KPC-2; the NDM-1–possessing ST131 isolate also exhibited resistance to amikacin (6,7). Thus, these findings may affect future antimicrobial choices because of the clonal dominance, multidrug resistance, and pathogenicity of the isolates.

Recent studies reported a plasmid-mediated colistin resistance gene, mcr-1, in various countries (8). In addition, a novel plasmid-mediated colistin resistance gene, mcr-2 (76.7% nucleotide identity to mcr-1), was found in E. coli isolates in Belgium (9). These genes encode a phosphoethanolamine transferase family protein, which modifies the lipid A component of lipopolysaccharide (8,9). The colistin-resistant E. coli isolates we identified did not possess mcr-1or mcr-2, although the MICs for colistin were the same as or higher than that of the transconjugant of a mcr-1–harboring plasmid in an E. coli ST131 isolate (4 mg/L) reported by Liu et al. (8). Thus, these colistin-resistant isolates may have other colistin resistance mechanisms. For example, modification of lipid A with 4-amino-4-deoxy-l-arabinose or phosphoethanolamine, caused by chromosomal mutations in mgrB, phoPQ, and pmrAB genes, might occur and could be responsible for the resistance. This polymyxin-resistance mechanism is seen in Enterobacteriaceae; however, other novel mechanisms are also conceivable.

In conclusion, we report colistin resistance in a major global-spreading extraintestinal pathogenic E. coli strain, O25b:H4-ST131-H30R, in Japan. This strain acquired colistin resistance without carrying a plasmid bearing the mcr gene. Clarifying the colistin-resistance mechanisms in these isolates is necessary if we are to forestall the emergence of multidrug (including colistin)–resistant O25b:H4-ST131-H30R. The worst-case scenario is the global spread of this isolate, which has acquired resistance to the last-line antimicrobial drug, colistin.

Top

Acknowledgments

We thank Osamu Kuwahara for providing some of the E. coli clinical isolates.

This study was partly supported by grants from JSPS KAKENHI (grant nos. 15H06521 and 25861574) and the Yuasa Memorial Foundation.

Top

Toyotaka SatoComments to Author , Akira Fukuda, Yuuki Suzuki, Tsukasa Shiraishi, Hiroyuki Honda, Masaaki Shinagawa, Soh Yamamoto, Noriko Ogasawara, Masaru Usui, Hiroki Takahashi, Satoshi Takahashi, Yutaka Tamura, and Shin-ichi Yokota

Author affiliations: Sapporo Medical University School of Medicine, Sapporo, Japan (T. Sato, Y. Suzuki, T. Shiraishi, H. Honda, S. Yamamoto, N. Ogasawara, H. Takahashi, S. Takahashi, S. Yokota); Rakuno Gakuen University, Ebetsu, Japan (A. Fukuda, M. Usui, Y. Tamura); Sapporo Medical University Hospital, Sapporo (M. Shinagawa)

Top

References

  1. Yokota  S, Sato  T, Okubo  T, Ohkoshi  Y, Okabayashi  T, Kuwahara  O, et al. Prevalence of fluoroquinolone-resistant Escherichia coli O25:H4-ST131 (CTX-M-15-nonproducing) strains isolated in Japan. Chemotherapy. 2012;58:529.DOIPubMed
  2. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing (M100-S25). Wayne (PA): The Institute; 2015.
  3. Colpan  A, Johnston  B, Porter  S, Clabots  C, Anway  R, Thao  L, et al.; VICTORY (Veterans Influence of Clonal Types on Resistance: Year 2011) Investigators. Escherichia coli sequence type 131 (ST131) subclone H30 as an emergent multidrug-resistant pathogen among US veterans. Clin Infect Dis. 2013;57:125665.DOIPubMed
  4. Price  LB, Johnson  JR, Aziz  M, Clabots  C, Johnston  B, Tchesnokova  V, et al. The epidemic of extended-spectrum-β-lactamase-producing Escherichia coli ST131 is driven by a single highly pathogenic subclone, H30-Rx. MBio. 2013;4:e0037713.DOIPubMed
  5. Lau  SH, Reddy  S, Cheesbrough  J, Bolton  FJ, Willshaw  G, Cheasty  T, et al. Major uropathogenic Escherichia coli strain isolated in the northwest of England identified by multilocus sequence typing. J Clin Microbiol. 2008;46:107680.DOIPubMed
  6. Peirano  G, Schreckenberger  PC, Pitout  JD. Characteristics of NDM-1-producing Escherichia coli isolates that belong to the successful and virulent clone ST131. Antimicrob Agents Chemother. 2011;55:29868.DOIPubMed
  7. Morris  D, Boyle  F, Ludden  C, Condon  I, Hale  J, O’Connell  N, et al. Production of KPC-2 carbapenemase by an Escherichia coli clinical isolate belonging to the international ST131 clone. Antimicrob Agents Chemother. 2011;55:49356.DOIPubMed
  8. Liu  YY, Wang  Y, Walsh  TR, Yi  LX, Zhang  R, Spencer  J, et al. Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study. Lancet Infect Dis. 2016;16:1618.DOIPubMed
  9. Xavier  BB, Lammens  C, Ruhal  R, Kumar-Singh  S, Butaye  P, Goossens  H, et al. Identification of a novel plasmid-mediated colistin-resistance gene, mcr-2, in Escherichia coli, Belgium, 2016. Euro Surveill. 2016;21. DOI

Top

Table

Top

Cite This Article

DOI: 10.3201/eid2212.161117

Related Links

Top

Table of Contents – Volume 22, Number 12—December 2016

Comments

Please use the form below to submit correspondence to the authors or contact them at the following address:

Toyotaka Sato, Department of Microbiology, Sapporo Medical University School of Medicine, S1 W17, Chuo-ku, Sapporo, 060–8556, Japan

Send To

character(s) remaining.

Comment submitted successfully, thank you for your feedback.

Top

Page created: November 18, 2016
Page updated: November 18, 2016
Page reviewed: November 18, 2016
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external