Recently, we isolated a multidrug-resistant
We isolated an antibiotic-resistant E. coli strain KBN10P04689, which caused bacteremia from the bloodstream of an acute myeloid leukemia patient. Antibiotics susceptibility testing with VITEK2 (bioMérieux) showed that the strain was resistant to carbapenem, non-extended spectrum cephalosporin, extended-spectrum cephalosporin, cephamycin, fluoroquinolones, folate pathway inhibitors, monobactams, and penicillins.
To investigate the genomic potential of the drug-resistant E. coli strain KBN10P04689 extensively, the strain was cultured at 37°C on blood agar. Then, genomic DNA was extracted using the i-genomic BYF Mini Kit (iNtRON Biotechnology). Genome sequencing was performed using PacBio RS II single-molecule real-time (SMRT) sequencing technology (Pacific Biosciences). A standard PacBio library with an average of 20-kb inserts were prepared and sequenced, yielding an average genome coverage of >179.2X. De novo assembly of the 101,776 reads with an average of 15,304 nucleotides (total 1,557,581,797 bp) was conducted using the hierarchical genome-assembly process (HGAP) pipeline of SMRT Analysis v2.3.0 (Chin et al., 2013).
The genome consists of one circular chromosome (4,840,855 bp with 50.57% G + C content) and three circular plasmids, pKBN10P04689A (107,229 bp with 51.69% G + C content), pKBN10P04689B (104,701 bp with 46.96% G + C content) and pKBN10P04689C (51,479 bp with 46.37% G + C content) (Table 1).
Different types of antibiotic-resistant genes encoding enzymes for structure-altering or inactivating antibiotics and modifying target sites, and encoding the enzymes resistant to inhibitors of a metabolic pathway (trimethoprim-sulfamethoxazole) were found in the chromosome, pKBN10P04689A and pKBN10P04689C. The chromosome harbors two antibiotic-resistant genes, blaCMY-2 (YKEC1_2769) and arnA (YKEC1_1480). In the plasmid pKBN10P04689A, the genes related to gentamicin resistance (aac(3)-IIb/YKEC1_4558), penicillin and cefazolin resistance (blaTEM-1/YKEC1_4537 and YKEC1_4562), extended-spectrum cephalosporin resistance (blaCTX-M-15/YKEC1_4533) and folate pathway inhibitor resistance (dfrA12/ YKEC1_4578, sul1/ YKEC1_4570 and YKEC1_4581, sul2 /YKEC1_4546) were identified. In addition, the plasmid contains blaNDM-5 (YKEC1_4575), which has been reported to confer resistance against piperacillin-tazobactam and carbapenem, extended-spectrum cephalosporins, and blaNDM-5 or its variant, which has recently spread to a large extent (Hawkey and Jones, 2009). Besides, the genes involved in erythromycin, chloramphenicol and tetracycline resistance (mphA/YKEC1_4553, catB3/YKEC1_4533, and tetB/YKEC1_4586) were detected. The plasmid pKBN10P04689C harbors genes that confer resistance to amoxicillin-clavulanic acid (blaOXA-181/YKEC1_4795) and resistance to fluoroquinolones, including ciprofloxacin (qnrS1/YKEC1_4788). Although the aac(6’)-Ib-cr gene (YKEC1_4527), which encodes a bifunctional protein to catalyze the acetylation of fluoroquinolones as well as aminoglycosides such as amikacin and gentamicin, was detected in pKBN10P04869A, the strain shows susceptibility against amikacin, as observed after an antimicrobial test (Table 2).
The complete genome sequence of the E. coli strain KBN10P04869 has been deposited at DDBJ/EMBL/GenBank under the accession numbers CP026473 (chromosome), CP026474 (pKBN10P04869A), CP026475 (pKBN10P04869B), and CP026476 (pKBN10P04869C). This strain is available from the Kyungpook National University Hospital Culture Collection for Pathogens.
저자들은 최근 급성골수성백혈병 환자로부터 다제내성대장균 균주 KBN10P04869를 분리했다. 균주는 4,457개의 단백질 코딩 유전자, 88개의 운반 RNA, 22개의 리보솜 RNA를 포함하는 5,104,264 염기쌍으로 구성되고, blaCMY-2, blaTEM-1, blaCTX-M-15, blaNDM-5, blaOXA-18를 포함한 다제내성유전자를 가지고 있다. 저자들은 이 균주의 총유전체를 보고하는 바이다.
No potential conflicts of interest relevant to this article are reported.
This research was supported by Kyungpook National University Research Fund, 2017.