Escherichia marmotae: a multidrug-resistant opportunistic human pathogen - first clinical isolation in the Czech Republic.

The genus Escherichia comprises seven species, including Escherichia marmotae, described in 2015 from the feces of healthy Himalayan marmots (Marmota himalayana). This species exhibits atypical biochemical properties, such as negative lactose fermentation and indole production. The pathogenic potential of E. marmotae is demonstrated by its ability to invade epithelial cells and the presence of virulence genes. The first human infections with E. marmotae were recorded in Norway in 2021. This article describes the case of a 64-year-old man undergoing chemotherapy for urinary tract cancer, who was hospitalized with febrile neutropenia. An infection caused by E. marmotae and K. pneumoniae was detected. Laboratory diagnostics revealed a multidrug-resistant strain of E. coli producing KPC-type carbapenemase, subsequently identified as E. marmotae by MALDI-TOF MS (Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry) and confirmed by 16S rRNA sequencing and whole genome sequencing. Biochemical tests indicated similarities to E. coli. Virulence analysis revealed the presence of genes typical of pathogenic strains of E. coli. This case report is the first documented instance of E. marmotae in the Czech Republic and highlights the difficulty of distinguishing this species from E. coli in routine diagnostics. Accurate identification requires advanced methods such as MALDI-TOF and sequencing analysis.