A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants

The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (<0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 10 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status. [Abstract copyright: Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.

A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants

The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (&lt;0.1% to 38.3%), being positively correlated (p &lt; 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 103 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status

Stimulation of Slack K+ Channels Alters Mass at the Plasma Membrane by Triggering Dissociation of a Phosphatase-Regulatory Complex

Human mutations in the cytoplasmic C-terminal domain of Slack sodium-activated potassium (KNa) channels result in childhood epilepsy with severe intellectual disability. Slack currents can be increased by pharmacological activators or by phosphorylation of a Slack C-terminal residue by protein kinase C. Using an optical biosensor assay, we find that Slack channel stimulation in neurons or transfected cells produces loss of mass near the plasma membrane. Slack mutants associated with intellectual disability fail to trigger any change in mass. The loss of mass results from the dissociation of the protein phosphatase 1 (PP1) targeting protein, Phactr-1, from the channel. Phactr1 dissociation is specific to wild-type Slack channels and is not observed when related potassium channels are stimulated. Our findings suggest that Slack channels are coupled to cytoplasmic signaling pathways and that dysregulation of this coupling may trigger the aberrant intellectual development associated with specific childhood epilepsies

Kv3.3 Channels Bind Hax-1 and Arp2/3 to Assemble a Stable Local Actin Network that Regulates Channel Gating

Mutations in the Kv3.3 potassium channel (KCNC3) cause cerebellar neurodegeneration and impair auditory processing. The cytoplasmic C terminus of Kv3.3 contains a proline-rich domain conserved in proteins that activate actin nucleation through Arp2/3. We found that Kv3.3 recruits Arp2/3 to the plasma membrane, resulting in formation of a relatively stable cortical actin filament network resistant to cytochalasin D that inhibits fast barbed end actin assembly. These Kv3.3-associated actin structures are required to prevent very rapid N-type channel inactivation during short depolarizations of the plasma membrane. The effects of Kv3.3 on the actin cytoskeleton are mediated by the binding of the cytoplasmic C terminus of Kv3.3 to Hax-1, an anti-apoptotic protein that regulates actin nucleation through Arp2/3. A human Kv3.3 mutation within a conserved proline-rich domain produces channels that bind Hax-1 but are impaired in recruiting Arp2/3 to the plasma membrane, resulting in growth cones with deficient actin veils in stem cell-derived neurons