Acinetobacter baumannii is a major hospital-acquired pathogen in Thailand that has a negative effect on patient survival. The nature of its transmission is poorly understood.

To investigate the genotypic and spatiotemporal pattern of A. baumannii infection at a hospital in Thailand.

The medical records of patients infected with A. baumannii at an 800-bed tertiary care hospital in southern Thailand between January 2010 and December 2011 were reviewed retrospectively. A. baumannii was identified at the genomospecies level. Carbapenemase genes were identified among carbapenem-resistant isolates associated with A. baumannii infection. A spatiotemporal analysis was performed by admission ward, time of infection and pulsed-field gel electrophoresis (PFGE) groups of A. baumannii.

Nine PFGE groups were identified among the 197 A. baumannii infections. All A. baumannii isolates were assigned to International Clonal Lineage II. bla_OXA-23 was the most prevalent carbapenemase gene. Outbreaks were observed mainly in respiratory and intensive care units. The association between PFGE group and hospital unit was significant. Spatiotemporal analysis identified 20 clusters of single PFGE group infections. Approximately half of the clusters involved multiple hospital units simultaneously.

A. baumannii transmitted both within and between hospital wards. Better understanding and control of the transmission of A. baumannii are needed.