Characterising the clonality and resistome of carbapenem-resistant Providencia stuartii

Providencia stuartii is an important hospital and community-acquired pathogen. It is intrinsically resistant to natural and semisynthetic penicillins and their combinations with inhibitors, and to first generation cephalosporins. Recently, the emergence of multidrug resistant isolates was reported due to production of extended-spectrum ß-lactamases (ESBL) and carbapenemases. Carbapenemase producing isolates pose a significant therapeutic challenge due to intrinsic resistance to polymixins, tigecyline and gentamicin. The aim of the project is to characterize the resistance traits of P. stuartii isolates and detect antimicrobial resistance genes. Moreover, the molecular epidemiology of isolates will be analyzed and hospital and community isolates from different geographic regions in Croatia will be compared in order to clarify the mechanisms and routes of spread. Representative isolates will be subjected to whole-genome sequencing in order to analyze the whole resistome and to create the phylogenetic tree. If the isolates are found to be clonal that would indicate vertical transmission of related isolates. Diverse genotypes possessing identical plasmid indicate horizontal transmission via mobile genetic elements. Genotyping is important for implementation of the measures to prevent spread of resistant isolates. If horizontal transmission is proved, it is necessary to limit the antibiotic consumption in order to reduce the selection pressure. Vertical transmission of genetically related isolates points out to lapses in hospital hygiene. Studies on molecular epidemiology of carbapenem-resistant P. stuartii isolates are scarce in the medical bibliography and there are none from Croatia.