Association of the genus Acinetobacter with the decomposition of a swine carcass and the isolation and characterization of a novel strain of Acinetobacter sp. P4.

Using fluorescence in situ hybridization (FISH) and a selective and differential medium, Acinetobacter numbers were enumerated over the time course of decomposition, from fresh to putrid/dry, of a swine carcass. In addition, Acinetobacter diversity and succession were also characterized. Acinetobacter bacterial counts were observed to be the lowest before exposure (undetectable) and increased to their highest during active decay then decreased and leveled during advanced decay through putrid/dry. FISH analysis revealed Acinetobacter cells were mostly clustered together, which is consistent with growth in a non-mixed environment, such as soil. The abundance of Acinetobacter cells decreased from active decomposition to putrid/dry. BLAST analysis using the 16S rRNA-gene sequence identified the isolates as one of the following Acinetobacter spp: A. baumannii, A. haemolyticus, A. junii, A. johnsonii, and A. gerneri. Phenotypic description of the identified isolates closely matched those of known genomic species. One isolate, P4, was observed to be unique in its phenotypic and phylogenetic characteristics and was more closely related to A. sp E10. The isolates from this study displayed multi-antibiotic resistance. The results from the study revealed the association of Acinetobacter spp. with that of carrion which adds to our knowledge of the ecology of this genus along with the potential implications of infection for this opportunistic pathogen.