The importance of meropenem resistance, rather than imipenem resistance, in defining carbapenem-resistant Enterobacterales for public health surveillance: an analysis of national population-based surveillance

Table 4 IPM-criteria-only group and MEPM-criteria group: Comparison among the isolates satisfying Japanese CRE criteria at national central laboratory (N = 315)

N (%)	IPMcriteria-only group N = 169	MEPM criteria group N = 146	P-value
IPM criteria fulfilled	169 (100%)	104 (71.2%)	–
Klebsiella aerogenes	109 (64.5%)	13 (8.9%)	< 0.0001
Enterobacter cloacae complex	55 (32.5%)	40 (27.4%)	0.328
Klebsiella pneumoniae	0 (0%)	40 (27.4%)	< 0.0001
Escherichia coli	1 (0.6%)	44 (30.1%)	< 0.0001
Serratia marcescens	4 (2.4%)	9 (6.2%)	0.153
CgPE	0 (0%)	99 (67.8%)	< 0.0001
Multidrug resistance	2 (1.2%)	96 (65.8%)	< 0.0001
7-day-mortality	3 (1.8%)	10 (6.9%)	0.0428
US-CDC CRE reporting criteria^a fulfilled	46 (27.2%)	146 (100%)	< 0.0001
Meropenem MIC≥4	0 (0%)	128 (87.7%)	< 0.0001
Imipenem MIC≥4	41 (24.3%)	85 (58.2%)	< 0.0001
Ertapenem MIC≥2	10 (5.9%)	146 (100%)	< 0.0001

IPMcriteria-only group = Isolates meeting the criteria only for imipenem MIC≥2 and cefmetazole MIC≥64
MEPM criteria group = Isolates meeting the criteria for meropenem MIC≥2, irrespective of imipenem resistance
^a US CDC-CRE criteria definition: (a) Resistant to any carbapenem antimicrobial (i.e., minimum inhibitory concentrations of ≥4 mcg/ml for doripenem, meropenem, or imipenem OR ≥ 2 mcg/ml for ertapenem); (b) In addition: (i) For bacteria that have intrinsic imipenem nonsusceptibility (i.e., Morganella morganii, Proteus spp., Providencia spp.), resistance to carbapenems other than imipenem is required, OR (ii) Documented to produce carbapenemase

ISSN: 1471-2334