Molecular epidemiological analysis and risk factors for acquisition of carbapenemase-producing Enterobacter cloacae complex in a Japanese university hospital

Nobuyuki Tetsuka,
Aki Hirabayashi,
Akane Matsumoto,
Keisuke Oka,
Yuki Hara,
Hiroshi Morioka,
Mitsutaka Iguchi,
Yuka Tomita,
Masato Suzuki,
Keigo Shibayama and
Tetsuya YagiEmail author View ORCID ID profile

Antimicrobial Resistance & Infection Control20198:126

https://doi.org/10.1186/s13756-019-0578-3

Received: 17 April 2019
Accepted: 15 July 2019
Published: 24 July 2019

Abstract

Background

To clarify the molecular epidemiology of carbapenem-resistant Enterobacter cloacaecomplex (CREC) and the risk factors for acquisition of carbapenemase-producing E. cloacae complex (CPEC).

Methods

Using clinical CREC isolates detected in a Japanese university hospital over 4 years, carbapenemase production was screened with phenotypic methods. Carbapenemase genes were analysed by PCR and sequencing. Molecular epidemiological analyses were conducted with repetitive extragenic palindromic (REP)-PCR and multilocus sequence typing (MLST). CRECs were identified to the subspecies level by hsp60sequencing. Whole-genome sequencing of plasmids was conducted. A case-control study was performed to identify risk factors for acquisition of CPEC among patients with CREC.

Results

Thirty-nine CRECs including 20 CPECs carrying blaIMP-1 were identified. Patients with CPEC had longer hospital stay before detection (26.5 days vs. 12 days, p = 0.008), a urinary catheter (odds ratio [OR], 5.36; 95% confidence interval [CI], 1.14–30.9; p = 0.023), or intubation (OR, 7.53; 95% CI, 1.47–53.8; p = 0.008) compared to patients without CPEC. Four genetically closely related CPEC clusters were observed, which showed that three of four CPEC clusters corresponded to E. asburiae (ST 53), E. hormaechei subsp. steigerwaltii (ST 113 and ST 1047) and E. cloacae subsp. cloacae (ST 513) by MLST and hsp60 sequencing. Seven representative plasmids shared structures with class I integron containing blaIMP-1and IncHI2A replicon type.

Conclusions

A longer hospital stay, presence of a urinary catheter, and intubation are risk factors for CPEC acquisition. In addition to horizontal transmission of genetically indistinguishable CPECs, IncHI2A plasmid carrying blaIMP-1 appeared to be transferred among genetically different ECs.