engleski

Defining the possible natural habitat of Acinetobacter baumannii outside hospitals

Background: Due to the development of resistance to last resort antibiotics, bacterium Acinetobacter baumannii is nowadays a leading cause of nosocomial outbreaks. Clinically relevant A. baumannii were reported outside hospital settings, including natural waters and soils influenced by human waste. Viable A. baumannii in nature represent a public-health risk for humans and animals that are exposed to it. Objective: The aim of this study was to investigate the survival of A. baumannii in natural substrates to define its possible natural habitat outside hospitals. Methods: Clinical and environmental but clinically relevant isolates of A. baumannii, resistant to carbapenems, fluoroquinolones and even colistin, were inoculated into different types of waters and soils. The pH and nutrient availability was determined in media employed. Numbers of A. baumannii were monitored using CHROMagar Acinetobacter plates with carbapenem-selective supplement CR102 after incubation at 42 °C/48 h. Results: In the treated urban wastewater and river water A. baumannii multiplied and survived during 50 days, while no multiplication occurred in the seawater. In the slight alkaline red palaeosol and technosol A. baumannii multiplied and survived up to 5 months, but did not multiply in weakly acid Terra Rossa. The multiplication dependent on the nutrient availability was confirmed in the nutrient broth, but was absent in the spring water. Conclusion: Natural waters and soils of near neutral pH rich in nutrients support the multiplication of A. baumannii, and are possible natural habitat of this emergent pathogen outside hospitals.

Acinetobacter baumannii, environment, soil, water

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