Snapshot of Phenotypic and Molecular Virulence and Resistance Profiles in Multidrug-Resistant Strains Isolated in a Tertiary Hospital in Romania

A current major healthcare problem is represented by antibiotic resistance, mainly due to multidrug resistant (MDR) Gram negative bacilli (GNB), because of their extended spread both in hospital facilities and in the community's environment. The aim of this study was to investigate the virulence traits of , and MDR, XDR, and PDR strains isolated from various hospitalized patients. These GNB strains were investigated for the presence of soluble virulence factors (VF), such as hemolysins, lecithinase, amylase, lipase, caseinase, gelatinase, and esculin hydrolysis, as well as for the presence of virulence genes encoding for VF involved in adherence ( , , and ), biofilm formation ( , , , , , and ), tissue destruction ( and ), and in toxin production ( , , , and complex). All strains produced hemolysins; 90% produced lecithinase; and 80% harbored and genes. The esculin hydrolysis was detected in 96.1% of the strains, whereas 86% of them were positive for the gene. All of the strains produced lecithinase and 80% presented the gene. A significant association was found between the number of VF and the XDR strains, regardless of the isolation sources. This study opens new research perspectives related to bacterial fitness and pathogenicity, and it provides new insights regarding the connection between biofilm formation, other virulence factors, and antibiotic resistance.