The threat of carbapenem-resistant bacteria in the environment: Evidence of widespread contamination of reservoirs at a global scale.

Environmental reservoirs of antibiotic resistance (AR) are a growing concern that are gathering more attention as potential sources for human infection. Carbapenem-resistant Enterobacteriaceae (CRE) are extremely dangerous, as carbapenems are often drugs of last resort that are used to treat multi-drug resistant infections. Among the genes capable of conferring carbapenem resistance to bacteria, the most transferrable are those that produce carbapenemase, an enzyme that hydrolyzes carbapenems and other β-lactam antibiotics. The goal of this review was to comprehensively identify global environmental reservoirs of carbapenemase-producing genes, as well as identify potential routes of transmission to humans. The genes of interest were Klebsiella pneumoniae carbapenemase (KPC), New Delhi Metallo-β-lactamase (NDM), Oxacillinase-48-type carbapenemases (OXA-48), and Verona Integron-Mediated Metallo-β-lactamase (VIM). Carbapenemase genes have been reported in the environment on almost every continent. Hospital and municipal wastewater, drinking water, natural waterways, sediments, recreational waters, companion animals, wildlife, agricultural environments, food animals, and retail food products were identified as current reservoirs of carbapenemase-producing bacteria and genes. Humans have been recorded as carrying CRE, without recent admittance to a hospital or long-term care facility in France, Egypt, and China. CRE infections from the environment have been reported in patients in Montpellier, France and Cairo, Egypt. This review demonstrates the need for 1) comprehensive monitoring of AR not only in waterways, but also other types of environmental matrices, such as aerosol, dusts, periphyton, and surfaces in indoor environments; and 2) action to reduce the prevalence and mitigate the effects of these potentially deadly resistance genes. In order to develop an accurate quantitative model for environmental dimensions of AR, longitudinal sampling and quantification of AR genes and bacteria are needed, using a One Health approach.