Antimicrobial resistance in pathogens isolated from blood cultures: A two-year multicenter hospital surveillance study in Italy

Background: Antimicrobial resistance (AMR) is one of the most concerning issues in medicine today. The objectives of this study were to investigate the AMR distribution of the blood-borne pathogens isolated over a two-year period in an Italian region. Methods: A retrospective electronic record review of laboratory-confirmed bloodstream infections (BSIs) was done, and data from three major diagnostic laboratories were used. Twelve invasive clinically important bacteria species were included in the sample. Results: During the study period, 1228 positive BSIs were collected. The most common pathogens were Coagulase-negative Staphylococcus (CoNS) (29.7%), Staphylococcus aureus (19.1%) and Escherichia coli (15.9%). With regard to the AMR pattern, 31.7% of CoNS and 28.1% of Staphylococcus aureus were oxacillin-resistant, and almost half of the Enterococci showed resistance to high-level gentamicin. Among Gram-negative species, 11.7% of Escherichia coli and 39.5% of Klebsiella pneumoniae were carbapenem-resistant. Among the non-fermentative Gram-negative bacteria, the most frequently combined AMR pattern was aminoglycosides and fluoro-quinolones (48.4% in A. baumannii and 14.6% in P. aeruginosa). Conclusion: The results display an alarming prevalence of AMR among hospital isolated pathogens, consistently higher than the European average. Information from surveillance systems to better characterize the trend in the incidence of AMR at local and national levels is needed.