Phenotypic and molecular characterization of IMP-producing Enterobacterales in Spain: Predominance of IMP-8 in Klebsiella pneumoniae and IMP-22 in Enterobacter roggenkampii

Abstract

ObjectivesLittle is known about IMP-producing Enterobacterales (IMP-Ent) in Europe. We analyzed at genomic and phenotypic level IMP-Ent isolates circulating in Spain in a 9-year period.Materials and methodsIMP-Ent isolates submitted to our reference laboratory were included. Antibiotic susceptibility was performed using microdilution method (EUCAST), and IMP-carbapenemase activity was measured with carbapenemase inhibitors, the β-CARBA method, the modified Hodge test (MHT), and the modified carbapenemase inhibition method (mCIM). All isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis.ResultsFifty IMP-Ent isolates, collected from 19 hospitals in 13 Spanish provinces, were detected: Klebsiella pneumoniae (IMP-Kpn) (24; 48%), Enterobacter roggenkampii (13; 26%), Enterobacter hormaechei (8, 16%), Klebsiella oxytoca (two; 4%), Enterobacter asburiae (one, 2%), Serratia marcescens (one; 2%) and Escherichia coli (one; 2%). All isolates were positive by the MHT and β-CARBA tests; 48 (96%) were mCIM positive; 12 (24%) and 26 (52%) displayed positive inhibition with dipicolinic (meropenem) and EDTA (ertapenem), respectively. Five IMP-carbapenemase types were identified: IMP-8 (22; 44%), IMP-22 (17; 34%), IMP-13 (7; 14%), IMP-28 (two; 4%), and IMP-15 (two; 4%), predominating IMP-8 in K. pneumoniae and IMP-22 in E. roggenkampii. IMP-28 was exclusively identified in K. oxytoca and IMP-15 in E. hormaechei. Predominant STs were ST405 (29.2%), ST15 (25%) and ST464 (20.8%) in IMP-Kpn; ST96 (100%) in E. roggenkampii and ST182 (62.5%) in E. hormachei. Colistin and amikacin were the most active non-carbapenem antibiotics against IMP-Ent.ConclusionIMP-Ent isolates remain infrequent in Spain, although in recent years have been circulating causing nosocomial outbreaks, being IMP-8-producing K. pneumoniae and IMP-22-producing E. roggenkampii the most frequently detected in this study. Inhibition with EDTA or dipicolinic acid presented false negative results in some IMP-producing strains. Active microbiological and molecular surveillance is essential for a better comprehension and control of IMP-Ent dissemination.

Genomic and clinical characteristics of carbapenem-resistant Enterobacter cloacae complex isolates collected in a Chinese tertiary hospital during 2013–2021

“…Similarly, a study conducted in the Chinese cities Shenzhen and Dongguan indicated that ST418, which produces NDM-1 carbapenemase, is the main epidemic CREC strain (Jin et al, 2018), highlighting the necessity of active surveillance. To date, E. hormaechei ST182 was the main host for blaIMP-15 Canada-Garcia et al, 2022); E. hormaechei ST50, ST66 and ST145 have been found to be VIM-producer in France (Emeraud et al, 2022); E. hormaechei ST90 isolates carrying the blaOXA-436 gene were suspected to be the source of the outbreak in Denmark (Raun-Petersen et al, 2022); And co-occurrence of E. hormaechei ST177 carrying blaNDM-1 and blaKPC-2 has been reported in China (Yang et al, 2018). In Northeast USA, CREC ST171 carried blaKPC-3 on the IncFIA plasmid (Gomez-Simmonds et al, 2018), and stable uptake of the IncFIA plasmid helped ST171 to proliferate successfully throughout this area, as isolates lacking this plasmid were rare (Annavajhala et al, 2019).…”

Comparison of carbapenem-susceptible and carbapenem-resistant Enterobacterales at nine sites in the USA, 2013–2016: a resource for antimicrobial resistance investigators

“…This could be an instance of a minor AST error (labelling an isolate as intermediate when it is resistant) as broth microdilution MIC testing is only accurate to within ±1 doubling dilution [ 68 ]. Another possible explanation is that bla IMP-8 is a weak carbapenemase and isolates with this gene frequently test susceptible to carbapenems [ 69 ]. In addition to the CR phenotypes, many other genotype–phenotype associations can be examined as there are data on aminoglycosides, fluoroquinolones and many other drugs.…”