- Aim: The transmission dynamics of Acinetobacter baumannii in endemic settings, and the relation between microbial properties and patients' clinical outcomes, are yet obscure and hampered by insufficient metadata. Methods & Results: Of 20 consecutive patients with A. baumannii bloodstream infection that were thoroughly analyzed at a single center, at least one transmission opportunity was evident for 85% of patients. This implies that patient-to- patient transmission is the major mode of A. baumannii acquisitions in health facilities. Moreover, all patients who died immediately (< 24 h of admission) were infected with a single clone (ST457; relative risk= 1.6; p= 0.05). Conclusion: This preliminary analysis should prompt further investigation by mapping genomic virulence determinants among A. baumannii ST457 lineage compared with other strains.