Effect of oxygen on antimicrobial resistance genes from a one health perspective
Science of the total environment publish this investigation article
April 25th, 2025
Bacteria must face and adapt to a variety of physicochemical conditions in the environment and during infection. A key condition is the concentration of dissolved oxygen, proportional to the partial pressure of oxygen (PO2), which is extremely variable among environmental biogeographical areas and also compartments of the human and animal body. Here, we sought to understand if the phenotype of resistance determinants commonly found in Enterobacterales can be influenced by oxygen pressure. To do so, we have compared the MIC in aerobic and anaerobic conditions of isogenic Escherichia coli strains containing 136 different resistance genes against 8 antibiotic families. Our results show a complex landscape of changes in the performance of resistance genes in anaerobiosis. Certain changes are especially relevant for their intensity and the importance of the antibiotic family, like the large decreases in resistance observed against ertapenem and fosfomycin among blaVIM ?-lactamases and certain fos genes, respectively; however, the blaOXA-48 ?-lactamase from the clinically relevant pOXA-48 plasmid conferred 4-fold higher ertapenem resistance in anaerobiosis. Strong changes in resistance patterns in anaerobiosis were also conserved in Klebsiella pneumoniae. Our results suggest that anaerobiosis is a relevant aspect that can affect the action and selective power of antibiotics for specific AMRs in different environments
Ortiz-Miravalles L., Prieto A., Kieffer N., Vergara E., Canton R., San Millan A., Baquero F., Hipolito A. and Escudero JA..
 | Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM). |
| Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM). |
 | Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS). Hospital Universitario Ramón y Cajal. Salud Madrid. Comunidad de Madrid. |
 | Centro de Investigación de Enfermedades Infecciosas (CIBERINFEC). Instituto de Salud Carlos III (ISCIII). |
 | Centro Nacional de Biotecnología (CNB). Consejo Superior de Investigaciones Científicas (CSIC). |
| Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP). Instituto de Salud Carlos III (ISCIII). |
