Bill Gates connects climate change to meat consumption

In an interview with MIT Technology Review, Bill Gates discusses highlights from his new book on climate change and connects climate change with meat consumption. Concerned about greenhouse gas emissions resulting from raising livestock, Bill Gates suggests that consumers in high-income countries could make the switch from farm-grown meats to synthetic products. Though Gates does not see this approach scaling up for low-resource contexts, he sees remarkable returns from investing in livestock, saying to the Sunday Times, “Livestock is magical. You can sell the output, and that’s money for school fees. You can keep the output, and that’s diet diversification.” He also suggested that breeding a cow that has greater productivity as well as survivability in higher-temperature climates, as in Africa, would offer both dividends in terms of economic returns as well as health impact. Along these lines, he has invested $40 million in Global Alliance for Livestock Veterinary Medicines (GALVmed), a public-private partnership based in Edinburgh that develops livestock diagnostics, medicines and vaccines and makes them available to smallholder farmers in South Asia and Africa. Such efforts could bring co-benefits for tackling antimicrobial resistance if animal husbandry practices became less reliant as well on the use of antimicrobials with, for example, the use of new livestock vaccines.

Nonnutritive sweeteners as drivers of antibiotic resistance

While the transfer of antibiotic resistant genes is generally known to be attributable to an overuse of antibiotics, recent research also indicates that nonnutritive sweeteners such as saccharine, sucralose, and aspartame have been associated with microbiome shifts similar to those caused by an overuse of antibiotics. In the single-cell model examined, these nonnutritive sweeteners were found to promote plasmid-mediated conjugative transfer of antibiotic resistant genes. In E. coli, for example, plasmids with multiple clinically relevant resistance genes were found to undertake more gene transfers in the presence of saccharine, sucralose, aspartame, and acesulfame potassium than without. Moreover, these nonnutritive sweeteners were found to increase cell membrane permeability of both donor and recipient cells, further promoting conjugative transfer of antibiotic resistance genes. In addition to the clinical setting, however, researchers found that nonnutritive sweeteners were metabolically resistant to tested bacterial strains and that antibiotic resistant genes in the presence of these sweeteners could cause a cascading spread of such genes in wastewater treatment plans and the environment. While these findings are yet to be replicated in live models, they could be important, as nonnutritive sweeteners are often permitted as safe food additives. Indeed, nearly 120,000 metric tons of nonnutritive sweeteners are consumed every year and these products are also excreted directly into the environment.

Medical effluent found to result in selection for antibiotic resistant bacteria

Researchers in Sweden examined the role of hospital effluent in driving antibiotic resistance and found that wastewater from hospitals were associated with a strong selection for multidrug-resistant bacteria. Based on one hospital’s effluent, 24 different antibiotics were detected, along with both antibacterial biocides and non-antibiotic pharmaceuticals. The highest concentrations were those of cefadroxil, norfloxacin, and ofloxacin, which were present in 92, 67, and 76 times higher concentrations (respectively) compared to control wastewater treatment plants. When artificial E. coli samples were exposed to the hospital effluent, multidrug resistant bacteria were observed to quickly predominate in the wastewater. Based on resistance patterns, researchers concluded that beta-lactams and ciprofloxacin might contribute the most towards this bacterial selection process; however, additional research would be needed to definitively demonstrate these relationships. In addition to hospital effluent driving multidrug resistance, municipal wastewater treatment facilities were also found to have potentially selective effects, resulting in the selection of beta-lactam-resistant strains. As a result, researchers write that further evaluations at both the wastewater treatment and hospital levels must be carried out, in an effort to better implement antibiotic resistance mitigation strategies.