Antibiotic-resistant bacteria, and more specifically, carbapenem-producing Enterobacterales (CPE) strains, are increasing worldwide. Despite their growing prevalence, in most high-income countries, the detection of CPE is still considered a low-frequency event. Sporadically, patients co-colonized with distinct CPE strains and/or different carbapenemase enzymes are detected. In this paper, we present three cases that illustrate the underlying mechanisms of co-colonization, focusing on horizontal gene transfer (HGT) and patient-to-patient transmission. We also demonstrate the diversity of CPE species and discuss the potential consequences of co-colonization.
Keywords: CPE; CRE; HGT; co-colonization.