1620. Molecular epidemiology and antibiotic susceptibility of IMP-type metallo-?-lactamase-producing Enterobacter cloacae isolated in a tertiary medical center in Japan
Session: Poster Abstract Session: Multidrug-Resistant Gram Negative Rods
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C

Background : Reports of carbapenemase-producing E. cloacae have been increasing worldwide. However, information on the molecular epidemiology of IMP-type metallo-beta-lactamase (MBL)-producing E. cloacae (IMP-EC) is limited.

Methods : During the study period (10/2011 – 12/2012), clinical isolates of E. cloacae from National Center for Global Health and Medicine (NCGM) that were resistant to one or multiple agents in the extended-spectrum cephalosporin class and/or that demonstrated elevated MICs to imipenem and/or meropenem were tested for IMP-MBL production by immunochromatographic assay (ICGA). Isolates positive for MBL by ICGA were then analyzed by PCR, DNA sequencing and multilocus sequence typing. MICs were determined according to CLSI criteria (M100-S22).

Results : Of 18 E. cloacae positive for MBL by ICGA, 17 isolates from 15 patients were confirmed to be positive for blaIMP. Fourteen (82.4%) and 13 (76.5%) IMP-EC were found to be sensitive (MIC ≤1 µg/mL) to imipenem and meropenem, respectively, and 8 (47.1%) and 7 (41.2%) were sensitive to ciprofloxacin and aztreonam. All 17 isolates were sensitive to gentamicin, amikacin, and colistin (EUCAST criteria v3.1). IMP-EC isolates were frequently positive for other resistant determinants (Table). The phylogenetic tree (Figure) revealed close relatedness among IMP-EC samples isolated from NCGM during the study period, except for one (No. 15) isolated from a patient who had been transferred from another hospital.

Conclusion : Our data suggest the possible nosocomial spread of IMP-EC. It is difficult to identify IMP-EC based solely on susceptibility results. Further studies are warranted to identify the clinical significance of IMP-EC, appropriate treatment, and control measures.



Table. Resistance genes among IMP- E. cloacae

Figure. Phylogenetic tree of IMP- E. cloacae

No.

IMP-type (blaIMP)

aac(6')

aac/aad

gyrA

qnrS

blaTEM

1a

2a

 3b

4

1

IIc

5

11

aacA1

S83I

+

6

S83I

7

11

aacA1

S83I

+

+

8c

1

IIc

S83Y

9c

1

IIc

aadA1

S83Y

10

1

IIc

12

1

IIc

13

1

IIc

14

11

Ib

aacA4

+

15

1

IIc

16

1

IIc

17

1

IIc

S83Y

18

11

aacA1

S83Y

+

19

11

aacA1

S83Y

+

+

20

11

aacA1

S83Y

+

21

1

IIc

22

1

IIc

23

1

IIc

24

1

IIc

 25c

1

IIc

aDrug-susceptible, non-IMP-EC.

bPositive for IMP by ICGA, isolated in 2007 from NCGM.

cIMP-EC from other facilities in Japan.

Tohru Miyoshi-Akiyama1, Kayoko Hayakawa, M.D., PhD2, Maki Nagamatsu2, Kayo Shimada1, Kazuhisa Mesaki3, Shiho Kubota4, Emi Kuroda4, Yuko Sugiki4, Masayoshi Tojo2, Nozomi Takeshita2, Mugen Ujiie2, Satoshi Kutsuna, M.D., PhD2, Yohei Hamada2, Norio Ohmagari2 and Teruo Kirikae1, (1)Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan, (2)Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan, (3)Department of Clinical Laboratory, National Center for Global Health and Medicine, Tokyo, Japan, (4)Infection Control Department, National Center for Global Health and Medicine, Tokyo, Japan

Disclosures:

T. Miyoshi-Akiyama, None

K. Hayakawa, None

M. Nagamatsu, None

K. Shimada, None

K. Mesaki, None

S. Kubota, None

E. Kuroda, None

Y. Sugiki, None

M. Tojo, None

N. Takeshita, None

M. Ujiie, None

S. Kutsuna, None

Y. Hamada, None

N. Ohmagari, None

T. Kirikae, None

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