Antimicrobial resistance genes are enriched in aerosols near impacted urban surface waters in La Paz, Bolivia

Olivia Ginn, Dennis Nichols, Lucas Rocha-Melogno, Aaron Bivins, David Berendes, Freddy Soria, Marcos Andrade, Marc A. Deshusses, Mike Bergin, Joe Brown

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Antibiotic resistance poses a major global health threat. Understanding emergence and dissemination of antibiotic resistance in environmental media is critical to the design of control strategies. Because antibiotic resistance genes (ARGs) may be aerosolized from contaminated point sources and disseminated more widely in localized environments, we assessed ARGs in aerosols in urban La Paz, Bolivia, where wastewater flows in engineered surface water channels through the densely populated urban core. We quantified key ARGs and a mobile integron (MI) via ddPCR and E. coli spp. as a fecal indicator by culture over two years during both the rainy and dry seasons in sites near wastewater flows. ARG targets represented major antibiotic groups—tetracyclines (tetA), fluoroquinolines (qnrB), and beta-lactams (blaTEM)—and an MI (intI1) represented the potential for mobility of genetic material. Most air samples (82%) had detectable targets above the experimentally determined LOD: most commonly blaTEM and intI1 (68% and 47% respectively) followed by tetA and qnrB (17% and 11% respectively). ARG and MI densities in positive air samples ranged from 1.3 × 101 to 6.6 × 104 gene copies/m3 air. Additionally, we detected culturable E. coli in the air (52% of samples <1 km from impacted surface waters) with an average density of 11 CFU/m3 in positive samples. We observed decreasing density of blaTEM with increasing distance up to 150 m from impacted surface waters. To our knowledge this is the first study conducting absolute quantification and a spatial analysis of ARGs and MIs in ambient urban air of a city with contaminated surface waters. Environments in close proximity to urban wastewater flows in this setting may experience locally elevated concentrations of ARGs, a possible concern for the emergence and dissemination of antimicrobial resistance in cities with poor sanitation.

Original languageEnglish
Article number110730
JournalEnvironmental Research
Volume194
DOIs
StatePublished - Mar 2021

Bibliographical note

Funding Information:
This material is based upon work supported by the National Science Foundation under grant number 1653226 . The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. We are thankful for undergraduate and graduate students who helped with sampling and data collection in Bolivia.

Funding Information:
This material is based upon work supported by the National Science Foundation under grant number 1653226. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. We are thankful for undergraduate and graduate students who helped with sampling and data collection in Bolivia.

Publisher Copyright:
© 2021 Elsevier Inc.

Keywords

  • Antibiotic resistance
  • Bioaerosol
  • Dissemination
  • E. coli
  • Mobile integron
  • Wastewater

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