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 18, Number 8—August 2012
Letter

blaNDM-1–positive Klebsiella pneumoniae from Environment, Vietnam

Cite This Article

To the Editor: The blaNDM-1 gene, which produces the New Delhi metallo-β-lactamase (NDM-1) enzyme, confers resistance to the carbapenem class of antimicrobial drugs and can be transferred among different types of bacteria. NDM-1 was identified in 2008 in Sweden from a patient from India who had been hospitalized in New Delhi (1). Since that report, blaNDM-1–positive bacteria have been identified from patients in several countries; most of these patients had a direct link with the Indian subcontinent (2). The spread of blaNDM-1 among bacterial pathogens is of concern not only because of resistance to carbapenems but also because such pathogens typically are resistant to multiple antimicrobial drug classes, which leaves few treatment choices available (35). In 2011, spread of blaNDM-1–positive bacteria in an environmental setting in New Delhi was reported (6).

The possible appearance of bacteria harboring blaNDM-1 in Vietnam is of concern because cultural and economic links between Vietnam and India are strongly established, including extensive person-to-person exchanges that could enable easy exchange of pathogens. In addition, Vietnam faces a serious problem of antimicrobial drug resistance because drugs are freely available and used in an indiscriminate fashion. Thus, once blaNDM-1–positive bacteria colonize persons in Vietnam, they would be able to spread easily and pose a serious public health threat.

During September 2011, we collected paired swab samples (1 for PCR, 1 for culture) of seepage water from 20 sites (rivers, lakes, and water pools in streets) within a 10-km radius of central Hanoi, Vietnam. Samples were transported in Transystem (COPAN Italia S.p.A, Brescia, Italy) to preserve bacteria and DNA. The 20 PCR swab specimens were squeezed out into 0.5-mL volumes of sterile water and centrifuged at 3,000 × g for 30 seconds; 1 μL of the resulting suspension was then used as PCR template to detect blaNDM-1 as described (7). Two samples were positive for blaNDM-1; these 2 samples were collected from the same river (Kim Nguu River) but at sites 3 km apart.

To isolate and identify the phenotype and genotype of blaNDM-1–positive bacteria, we repeatedly spread the 20 culture swab specimens onto Muller-Hinton agar (Nissui, Tokyo, Japan) containing 100 mg/L vancomycin (Nakalai, Kyoto, Japan) plus 0.5 mg/L meropenem (LKT Laboratories, St. Paul, MN, USA) until single colonies were obtained. Each colony was then subcultured by plating onto MacConkey agar (Nihon Seiyaku, Tokyo, Japan) containing 0.5 mg/L meropenem to ensure culture purity; colonies were identified by using API 20E strips (bioMérieux, Basingstoke, UK). MICs of these isolates for 13 antimicrobial drugs were calculated by using Etest (bioMérieux), and susceptibility data were interpreted by using Clinical and Laboratory Standards Institute guidelines (www.clsi.org).

We harvested several species of bacteria from the 2 seepage samples positive for blaNDM-1: Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, P. fluorescens/putida, and P. luteola. These isolates were placed onto media containing 0.5 mg/L meropenem, and bacterial DNA was extracted and used for the template for PCR analysis to detect blaNDM-1 as described (7). blaNDM-1 was detected in 3 K. pneumoniae isolates from each of the 2 positive samples (6 isolates total); this result was confirmed by sequencing. All 6 isolates were highly resistant to all β-lactam antimicrobial drugs, including carbapenems (Table). To detect another β-lactamase, multiplex PCRs were carried out as described (8); genetic variants blaTEM, blaSHV, blaOXA, blaCTX-M, blaIMP, blaVIM, and blaKPC were not detected in any of the isolates other than K. pneumoniae. All 6 K. pneumoniae isolates were positive for blaTEM and blaCTX-M variants by PCR; these variants were confirmed as blaTEM-1 and blaCTX-M-3 by sequencing.

Aminoglycosides are often used in the management of severe infectious diseases caused by gram-negative pathogens. 16S rRNA methylases were found to confer high levels of resistance to aminoglycosides such as amikacin, tobramycin, and gentamicin. The 6 K. pneumoniae isolates we found were highly resistant to gentamicin (MIC >1,024 mg/L) and tobramycin (MIC 256–>1,024 mg/L) (Table). Therefore, we screened genetic elements of 16S rRNA methylases (rmtB, rmtC, and armA) by PCR and detected rmtB in all 6 isolates (9). Multilocus sequence typing was applied for these 6 isolates; all were identified as K. pneumoniae sequence type 283 (10), which had not been reported as harboring blaNDM-1. The azide-resistant Escherichia coli strain J53 has been used as recipient for conjugation assay, which had been reported previously (6), but we found no transconjugant strain with blaNDM-1 on MacConkey agar containing 100 mg/L sodium azide and 0.5 mg/L meropenem.

Our results show that blaNDM-1–positive K. pneumoniae sequence type 283 is present in the Kim Nguu River, which flows through the central part of Hanoi at 2 sites. The isolates we obtained were also positive for 2 other β-lactamases, blaTEM-1 and blaCTX-M-3, were highly resistant to aminoglycosides related to rmtB, and showed mild elevation of MIC against ciprofloxacin up to 1.5 mg/L. Wide-scale surveillance of environmental and clinical samples in Vietnam and establishment of a strategy to prevent further spread of blaNDM-1 are urgently needed.

Top

Rie IsozumiComments to Author , Kumiko Yoshimatsu, Tetsu Yamashiro, Futoshi Hasebe, Binh Minh Nguyen, Tuan Cuong Ngo, Shumpei P. Yasuda, Takaaki Koma, Kenta Shimizu, and Jiro Arikawa
Author affiliations: Hokkaido University, Sapporo, Japan (R. Isozumi, K. Yoshimatsu, S.P. Yasuda, T. Koma, K. Shimizu, J. Arikawa); Nagasaki University, Nagasaki, Japan (T. Yamashiro, F. Hasebe); and National Institute of Hygiene and Epidemiology, Hanoi, Vietnam (B.M.. Nguyen, T.C. Ngo)

Top

References

  1. Yong  D, Toleman  MA, Giske  CG, Cho  HS, Sundman  K, Lee  K, Characterization of a new metallo-beta-lactamase gene, bla (NDM-1), and a novel erythromycin esterase gene carried on a unique genetic structure in Klebsiella pneumoniae sequence type 14 from India. Antimicrob Agents Chemother. 2009;53:504654. DOIGoogle Scholar
  2. Nordmann  P, Nass  T, Poirel  L. Global spread of carbapenem-producing Enterobacteriaceae. Emerg Infect Dis. 2011;17:17918.
  3. Kumarasamy  KK, Toleman  MA, Walsh  TR, Bagaria  J, Butt  F, Balakrishnan  R, Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study. Lancet Infect Dis. 2010;10:597602. DOIGoogle Scholar
  4. Walsh  TR. Emerging carbapenemases: a global perspective. Int J Antimicrob Agents. 2010;36:S814. DOIGoogle Scholar
  5. Moellering  RC Jr. NDM-1—a cause for worldwide concern. N Engl J Med. 2010;363:23779. DOIGoogle Scholar
  6. Walsh  TR, Weeks  J, Livermore  DM, Toleman  MA. Dissemination of NDM-1 positive bacteria in the New Delhi environment and its implications for human health: an environmental point prevalence study. Lancet Infect Dis. 2011;11:35562. DOIGoogle Scholar
  7. Pfeifer  Y, Wilharm  G, Zander  E, Wichelhaus  TA, Gottig  S, Hunfeld  KP, Molecular characterization of blaNDM-1 in an Acinetobacter baumannii strain isolated in Germany in 2007. J Antimicrob Chemother. 2011;66:19982001. DOIGoogle Scholar
  8. Dallenne  C, Da Costa  A, Decre  D, Favier  C, Arlet  G. Development of a set of multiplex PCR assays for the detection of genes encoding important beta-lactamases in Enterobacteriaceae. J Antimicrob Chemother. 2010;65:4905. DOIGoogle Scholar
  9. Doi  Y, Arakawa  Y. 16S ribosomal RNA methylation: emerging resistance mechanism against aminoglycosides. Clin Infect Dis. 2007;45:8894. DOIGoogle Scholar
  10. Diancourt  L, Passet  V, Verhoef  J, Grimont  PA, Brisse  S. Multilocus sequence typing of Klebsiella pneumoniae nosocomial isolates. J Clin Microbiol. 2005;43:417882. DOIGoogle Scholar

Top

Table

Top

Cite This Article

DOI: 10.3201/eid1808.111816

Related Links

Top

Table of Contents – Volume 18, Number 8—August 2012

EID Search Options
presentation_01 Advanced Article Search – Search articles by author and/or keyword.
presentation_01 Articles by Country Search – Search articles by the topic country.
presentation_01 Article Type Search – Search articles by article type and issue.

Top

Comments

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

Rie Isozumi, Hokkaido University, Kita15, Nishi7, Kita-ku, Sapporo, Hokkaido, 060-8638, Japan

Send To

10000 character(s) remaining.

Top

Page created: July 18, 2012
Page updated: July 18, 2012
Page reviewed: July 18, 2012
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