BACKGROUND: Acinetobacter baumannii is ubiquitous, facultative intracellular, and opportunistic bacterial pathogen. Its unique abilities allow it to survive in a diverse range of environments, including health care settings, leading to nosocomial infections. And its exceptional ability to develop resistance to multiple antibiotics leaves few drug options for treatment. It has been recognized as a leading cause of nosocomial pneumonia and bacteremia over the world.
METHODS: In this case, a 73-year-old woman presented with a Neer Group VI proximal humeral fracture. Six hours after a successfully performed hemiarthroplasty, she developed continuous fever. Clinical examination revealed that the vitals were regular. Laboratory and radiographic examinations revealed only elevated procalcitonin levels. Blood culture revealed no bacterial or fungal growth. Cooling treatment and empirical broad-spectrum antibiotic therapy showed no apparent effect.
CONCLUSIONS: We report a postoperative infection caused by Acinetobacter baumannii. The infectious pathogen was identified via molecular DNA sequencing and was initially misidentified as a free-living amoeba species upon microscopic examinations. The patient was mistreated with antiamebic combination therapy. Her symptoms persisted for over 4 months and were eventually followed by her death.

Acanthamoeba culbertsoni trophozoites, previously isolated from a human keratitis case with severe intraocular damage, were maintained in axenic culture. Co-incubation of amoebae with MDCK cell monolayers demonstrated an apparent preference of the amoebae to introduce themselves between the cells. The trophozoites appeared to cross the cell monolayer through the tight junctions, which resulted in decreased trans-epithelial resistance (TER) measurements. Unexpectedly, after co-incubation of amoebae with hamster corneas, we observed that the trophozoites were able to cross the different cell layers and reach the corneal stroma after only 12 h of interaction, in contrast to other Acanthamoeba species. These observations suggest that this A. culbertsoni isolate is particularly pathogenic. Further research with diverse methodologies needs to be performed to explain the unique behavior of this Acanthamoeba strain.