Development of selective medium for IMP-type carbapenemase-producing Enterobacteriaceae in stool specimens.
Identification of carbapenemase-producing Enterobacteriaceae (CPE) in faecal specimens is challenging. This fact is particularly critical because low-level carbapenem-resistant organisms such as IMP-producing CPE are most prevalent in Japan. We developed a modified selective medium more suitable for IMP-type CPE.



Fifteen reference CPE strains producing different types of β-lactamases were used to evaluate the commercially available CHROMagar KPC and chromID CARBA as well as the newly prepared MC-ECC medium (CHROMagar ECC supplemented with meropenem, cloxacillin, and ZnSO4) and M-ECC medium (CHROMagar ECC supplemented with meropenem and ZnSO4). A total of 1035 clinical samples were then examined to detect CPE using chromID CARBA and M-ECC medium.



All tested strains producing NDM-, KPC-, and OXA-48-carbapenemases were successfully cultured in the media employed. Although most of the IMP-positive strains did not grow in CHROMagar KPC, chromID CARBA, or MC-ECC, all tested strains grew on M-ECC. When faecal samples were applied to the media, M-ECC medium allowed the best growth of IMP-type CPE with a significantly higher sensitivity (99.3%) than that of chromID CARBA (13.9%).



M-ECC medium was determined as the most favourable selective medium for the detection of IMP-type CPE as well as other types of CPE.
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.|Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Norihisa
N
Yamamoto
Department of Bacteriology, Osaka Prefectural Institute of Public Health, Osaka, Japan.
Ryuji
R
Kawahara
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. akeda@biken.osaka-u.ac.jp.|Research Institute for Microbial Diseases, Osaka University, Osaka, Japan. akeda@biken.osaka-u.ac.jp.
Yukihiro
Y
Akeda
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.|Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Rathina Kumar
RK
Shanmugakani
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.|Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Hisao
H
Yoshida
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.|Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Hideharu
H
Hagiya
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Naohiro
N
Hara
Laboratory for Clinical Investigation, Osaka University Hospital, Osaka, Japan.
Isao
I
Nishi
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Satomi
S
Yukawa
Ibaraki Public Health Center, Osaka, Japan.
Rumiko
R
Asada
Clinical Laboratory Department Section 1, The Research Foundation for Microbial Diseases of Osaka University, Osaka, Japan.
Yumi
Y
Sasaki
Clinical Laboratory Department Section 1, The Research Foundation for Microbial Diseases of Osaka University, Osaka, Japan.
Kazuhiro
K
Maeda
Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Noriko
N
Sakamoto
Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
Shigeyuki
S
Hamada
Department of Infection Control and Prevention, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Kazunori
K
Tomono
D001426:Bacterial Proteins; D015373:Bacterial Typing Techniques / Q000379:methods*; D003470:Culture Media; D004755:Enterobacteriaceae / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism; D004756:Enterobacteriaceae Infections / Q000175:diagnosis / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D007291:Inosine Monophosphate / Q000378:metabolism*; D001618:beta-Lactamases
D001426:Bacterial Proteins; D003470:Culture Media; D007291:Inosine Monophosphate; D001618:beta-Lactamases; C063912:carbapenemase
Carbapenemase-producing Enterobacteriaceae; Faecal specimens; IMP; Selective culture medium