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Year : 2015  |  Volume : 33  |  Issue : 4  |  Page : 615--617

New Delhi metallo-β-lactamase-1-producing acinetobacter lwoffii of companion animal origin in China

Y Sun1, X Ji1, Y Liu2, Q Liu3, X Guo1, J Liu1, L Xu3, L Zhu1, W Zhou1, S Feng1,  
1 Institute of Military Veterinary, AMMS, Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Changchun, China
2 The Affiliated Hospital, Changchun University of Chinese Medicine, Changchun, China
3 Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China

Correspondence Address:
S Feng
Institute of Military Veterinary, AMMS, Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Changchun

How to cite this article:
Sun Y, Ji X, Liu Y, Liu Q, Guo X, Liu J, Xu L, Zhu L, Zhou W, Feng S. New Delhi metallo-β-lactamase-1-producing acinetobacter lwoffii of companion animal origin in China.Indian J Med Microbiol 2015;33:615-617

How to cite this URL:
Sun Y, Ji X, Liu Y, Liu Q, Guo X, Liu J, Xu L, Zhu L, Zhou W, Feng S. New Delhi metallo-β-lactamase-1-producing acinetobacter lwoffii of companion animal origin in China. Indian J Med Microbiol [serial online] 2015 [cited 2020 Aug 12 ];33:615-617
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Dear Editor,

The emergence of New Delhi metallo-β-lactamase(NDM)-1-producing bacteria is a significant public health concern. blaNDM-1 is present worldwide in diverse pathogens, including Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterobacter cloacae. To date, two groups have reported the identification of blaNDM-1-carrying strains of livestock origin in China,[1],[2] which imply a potential zoonotic transmission of blaNDM-1 gene.

In order to investigate the epidemiology of drug-resistant bacteria in companion animals, a total of 57 Gram-negative imipenem-resistant strains [minimum inhibitory concentration (MIC) ≥ 8 mg/L], in which carbapenemase genes were detected by polymerase chain reaction (PCR) assay, has been isolated from 258 rectal swab samples from house pets by our group since 2012. Among these, one NDM-1-producing Acinetobacter lwoffii was characterized and identified from a cat. An 8-year-old male pet cat was sent to a pet clinic in Changchun, Jilin Province, China, in December 2012 because it had symptoms of listlessness and loss of appetite. The cat was diagnosed with diabetes. A rectal swab was collected for drug-resistant bacteria screening, and an imipenem-resistant strain was isolated. The isolate was named after Iz4b.

The isolate was identified as Acinetobacter lwoffii/junii by using the Merieux Vitek32 (panel GNI +). Further identification showed that the strain could hydrolyze arginine, utilize citrate, but could not grow at 41°C. The results suggested that the Iz4b isolate was a strain of A. lwoffii. 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis (GenBank: KJ531441) showed that A. lwoffii Iz4b had the highest homology with Acinetobacter sp. LI BR 12345 (GenBank: JQ247327) from Brazil and Acinetobacter guillouiae ATCC11171 (GenBank: HE651924) from Australia (99.9% for both). Drug susceptibility testing demonstrated that A. lwoffii Iz4b was resistant to all tested β-lactam antibiotics, including imipenem, meropenem, ertapenem, cefazolin, ceftazidime, cefotaxime, cefepime, aztreonam, ampicillin and piperacillin. It was also resistant to gentamicin, trimethoprim–sulfamethoxazole, ciprofloxacin, levofloxacin and moxiflocacin, but remained susceptible to amikacin, chloramphenicol, tetracycline and colistin [Table 1].{Table 1}

The presence of genes encoding carbapenemases (blaNDM-1, blaIMP-1, blaIMP-2, blaVIM-1, blaV1M-2, blaSPM-1, blaTEM, blaCTX-M, blaSHV and blaKPC) was investigated by polymerase chain reaction (PCR), and only blaNDM-1 gene was detected in A. lwoffii Iz4b. Further analysis revealed that the blaNDM-1 gene was located on a plasmid, which was designated pNDM-Iz4b. Plasmid DNA was extracted using a Qiagen Large-Construct Kit (Hilden, Germany) according to the manufacturer's instructions. The complete plasmid sequence was obtained using the Illumina HiSeq 2000 method. Gaps of plasmid sequences were bridged by PCR and confirmed by capillary sequencing. Sequences were submitted to Genbank (KJ547696). The plasmid had a length of 46570 bp with an average GC content of 40.91%. Most predicted coding sequences were identical to genes found on pNDM-BJ01 from A. lwoffii[3] and blaNDM-1-carrying plasmid from Acinetobacter strain XM1570[4] of human origin in China. Sequence comparisons revealed one region that distinguished pNDM-Iz4b from pNDM-BJ01. A deletion was found in a region for conjugative transfer. The 705-bp deletion contained a gene encoding an antirestrict superfamily protein and a 206-bp direct repeat sequence in pNDM-BJ01 (nucleotides 43860–44359) and another blaNDM-1-carrying plasmid pNDM-AB from A. baumannii of food animal origin.[2] The other distinctions between pNDM-Iz4b and pNDM-AB were located on a resistance gene region near blaNDM-1 [Figure 1]. All of them represent a novel incompatibility group. Filter mating conjugation using E. coli DH5α:pBR322 as the recipient strain was performed as described previously,[5] with modifications. Susceptibility tests revealed that the transconjugant presented resistance to all tested carbapenems as compared with the recipient strain [Table 1], indicating that the resistance gene is transferable. The minimum bacteriostatic concentration of meropenem was 0.0625 mg/L for DH5α:pBR322 and 64 mg/L for the transconjugant.{Figure 1}

In summary, we have isolated and identified a blaNDM-1-carrying bacterial strain of companion animal origin for the first time in China. This finding suggests a diversity of NDM-1 drug-resistance transmission in bacteria, and the companion animal may be a host for dissemination of resistance. Thus, it deserves more attention to prevent the blaNDM-1 to be horizontally transmitted to other intestinal bacterial flora in companion animals. Carbapenems are not licensed for treatment of companion animals in China, therefore, the carbapenem-resistance genes in cats might be derived from humans or the environment. Considering the closer contact between companion animals and humans, the potential for transmission of NDM-1 is a major public health concern. Therefore, further epidemiological studies of NDM-1-producing organisms in companion animals are necessary for preventing the transmission of NDM-1-producing bacteria.


This work was supported by National Science and Technology Major Project of China (No. 2013ZX10004-217-002), National 863 Project of China (No. 2012AA022006) and Jilin Province science and technology development project (No. 20140101032JC, 20150101110JC).

Financial support and sponsorship


Conflicts of interest.

There are no conflicts of interest.


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