Survival of extensively- and pandrug-resistant isolates of Acinetobacter baumannii in soils

The extensively- and pandrug-resistant isolates of Acinetobacter baumannii are a leading cause of hospital acquired infections. Aside from reports of A. baumannii in wastewaters influenced by hospital effluents, only two studies reported its detection in soils. The lack of data hinders the assessment of soil as the possible environmental reservoir of A. baumannii, prediction of the behaviour of this emergent pathogen in soils and their potential consequences. This study examined the survival of clinically relevant isolates of A. baumannii in the sterilized and fresh soils of different moisture and pH values. In the alkaline, weakly acid, and strongly acid soil A. baumannii survived for five months, up to 15 days, and up to one hour, respectively. Decrease of moisture below 16 wt% can help in the elimination, but the long-term maintenance of viable A. baumannii was detected in completely dry alkaline soil. Linear regression model confirmed that the pH value of soil is the most important environmental factor, which determines the survival of A. baumannii in soils. Acidification of soil seems a promising method in the remediation of soils contaminated with emerging human pathogen A. baumannii.