Detection of Airborne Acinetobacter baumannii Carbapenem-Resistant Strains in Hospital Settings

Despite its potential clinical relevance, research into air-bacteria contamination in hospital settings is still in its early stages. In this study, we present the results of a one-year investigation into Gram-negative airborne bacteria in a medical ward in a hospital in southern Italy. Data show that multidrug-resistant Acinetobacter baumannii strains, which were also resistant to carbapenems, were isolated over the course of the study. Strains were characterised by the Pulsed Field Gel Electrophoresis (PFGE) molecular typing method, and the identified PFGE profiles were clustered into three groups based on a genetic relatedness greater than 90%. These groups were termed A, B and C, with group A including the majority (71%) of isolates. Group A was further subdivided into three subgroups (A1, A2 and A3) based on the genetic relatedness of 97%, 99% and 94%, respectively. The presence of strains with distinct genetic relationships, as well as their detection in different rooms and at different sampling dates, suggests a possible dissemination of different clonal lineages. This study also highlights the importance of air monitoring as a key control measure, particularly for the detection of ESKAPE pathogens such as A. baumannii, which has proven desiccation-resistant properties and can therefore survive in the air and on inanimate surfaces.