Change in the antimicrobial resistance profile of Pseudomonas aeruginosa from soil after exposure to herbicides

Abstract

The extensive use of pesticides represents a risk to human health and to the environment. This study aimed to investigate if the exposure to atrazine and diuron, two herbicides widely used in Brazil, could induce changes in the susceptibility profile to aztreonam, colistin and polymyxin B antimicrobials in isolates of P. aeruginosa obtained from soil samples by using the determination of minimum inhibitory concentration (MIC) test. Three isolates had an increase of MIC to aztreonam after exposure to both herbicides and one isolate did not show any MIC change. The MexAB-OprM efflux pump has already been upregulated in these isolates and the herbicides atrazine and diuron did not increase MexAB-OprM overexpression. Therefore, the decrease in aztreonam susceptibility was not directly related to this pump, suggesting that probably other mechanisms should be involved.

Keywords:

• Pseudomonas aeruginosa
• herbicides
• aztreonam
• antimicrobial resistance

Acknowledgments

We thank John Carpenter (Ribeirão Preto, SP, Brazil) for the English language revision.

Additional information

Funding

This work was supported by the São Paulo Research Foundation - FAPESP [grant number 2015/18990-2]. Ana Flavia Tonelli Fernandes was supported by the São Paulo Research Foundation - FAPESP [grant number 2014/02806-5]. Vânia Santos Braz was supported by the National Postdoctoral Program of CAPES, Brazil [grant number 1570964 PNPD/CAPES].