Editors in Conversation

Discussing new guidelines on the use of vancomycin for severe Staphylocccus aureus infections.

The August issue of AAC includes interesting papers about mechanism of resistance to metronidazole in C. difficile, a variant of KPC resistant to ceftazidime-avibactam and description of a new "ultra-broad spectrum B-lactamase inhibitor" among others!

You can find the issue at https://aac.asm.org.

The state of the art treatment of COVID-19, understand the role of some medications currently used for COVID-19 and dissecting novel approaches and strategies for the treatment of COVID-19 likely to become available in the short term. Guests: Henry Masur MD and Adarsh Bhimraj MD.

Read the current issue of Antimicrobial Agents and Chemotherapy at https://aac.asm.org

A conversation with Lou Rice about his career and his experience of being the Editor of Chief for the AAC Journal for the past decade.

Visit aac.asm.org to read the current issue.

A discussion about laboratory testing for COVID-19 with two experts, Dr. Melissa Miller and Dr. Elitza Theel. Hosted by Journal of Clinical Microbiology Editor in Chief, Dr. Alexander McAdam.

Get the current issue of the Journal of Clinical Microbiology at https://jcm.asm.org/

Objectives: • Discuss the therapeutic options currently being used for COVID-19 • Evaluate some clinical data supporting the use of these drugs • Comment on clinical trials and enrollment

Participants: • Andre Kalil, Professor, University of Nebraska Medical Center, Omaha, NB, USA. Lead Investigator, NIH Clinical Trial for COVId-19 • Miguel A. Martinez, Editor AAC. Professor, AIDS Research Institute-IrsiCaixa, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain.

Visit https://aac.asm.org/ to browse issues and/or submit a manuscript.

Host: Jeff Fox with special guests, Julia Yeomans and Vikas Berry.

Julia Yeomans of Oxford University in the United Kingdom and chemical engineer
Vikas Berry of the University of Illinois, Chicago, talk with Jeff Fox about their separate, but in some ways similar, research efforts in which they use bacteria to perturb and probe the physical properties of simple machines, in one case, and unusual materials, in the other.

Yeomans and her collaborators are developing models of miniature windfarms in which 64 rotors are arrayed regularly within a symmetric lattice, to which actively swimming bacteria are added. Under appropriate constraints, the bacteria spontaneously organize in such a way that they induce neighboring rotors to spin in opposite directions. Single rotors would be "kicked around randomly," the researchers say, but the arrayed rotors form "a regular pattern." Yeomans says, "Nature is brilliant at creating tiny engines, and there is enormous potential if we can understand how to exploit similar designs."

Berry and his collaborators aligned rod-shaped gram-positive bacteria and then vacuum-shrunk a graphene sheet over them, thus forming nanoscale ripples into the otherwise smooth graphene surface. "The current across the graphene wrinkles is less than the current along them," says Berry. "We envision that with graphene one could make the smallest wavelength wrinkles in the world—about 2 nanometers. The structure is different, and the fundamental electronic properties are new."

This story was featured in the September 2016 issue of Microbe Magazine.

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Host: Jeff Fox with special guest, Emma Wilson.

Emma H. Wilson of the University of California, Riverside, talks with Jeff Fox about efforts, with her collaborators to determine more precisely how Toxoplasma gondii parasites disrupt the mammalian brain—in this case, the brains of mice. This same parasite infects about one-third of the human population, but is held in check by the immune system unless those host defense mechanisms become impaired.

Wilson and her collaborators find that these parasites interfere with the cycling of the neurotransmitter glutamate within the central nervous system, blocking its uptake by astrocytes, widely distributed cells within brains that are intertwine with and thus work very closely with neurons, which are the main cells for transmitting nerve impulses throughout the central nervous system. 

Some damaging effects of the parasites can be reversed by treating the mice with a drug—in this case, it happens to be an antibacterial drug but here acts by a separate mechanism-- that helps to restore the glutamate transport protein in astrocytes. In this way, it partly corrects that glutamate imbalance within the brain.

This story was featured in the August 2016 issue of Microbe Magazine.

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Host: Jeff Fox with special guests, Carolyn Shore and Ruben Tommasi.

Carolyn Shore of Pew Charitable Trusts in Washington, D.C., and Ruben Tommasi of Entasis Therapeutics in Waltham, Massachusetts, talk with Jeff Fox about what’s needed to identify and develop new antimicrobial agents to treat infections caused by bacterial pathogens, with an emphasis on gram-negative bacterial pathogens. 

According to that recent report from Pew Charitable Trust, which is based in Philadelphia, the challenges facing developers of such antibiotics fall into four main categories: developing a better understanding of the workings of gram-negative bacterial pathogens, a shortage of candidate drugs whose chemical design focuses on bacterial pathogens, an assessment of non-traditional efforts to control microbial infections, and an overview of what’s needed in terms of expertise and of sharing information among investigators in this field to meet these challenges.

This story was featured in the July 2016 issue of Microbe Magazine.

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Send your microbiology questions and comments (email or audio file) to [email protected]

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Host: Jeff Fox with special guests, Gemma Reguera and Geoffrey Gadd.

Gemma Reguera of Michigan State University in East Lansing and Geoffrey Gadd of the University of Dundee in Scotland talk with Jeff Fox about their efforts, to probe some of the electrical properties of materials produced naturally by specific microorganisms. Thus, Geobacter bacteria make protein filaments, called pili, that act as nanowires, transporting 1 billion electrons per second, according to Reguera and her collaborators. Analytic evidence suggests that the electrons move along these proteins by a thermally activated, multistep hopping mechanism, enabling these bacteria to draw electrons from the extracellular milieu.

Meanwhile, the fungus Neurospora crassa can transform manganese into a mineral composite with favorable electrochemical properties. The fungal cells produce filaments that take up manganese, which after heat treatment forms structures that have electrochemical properties that are suitable for use in supercapacitors or lithium-ion batteries. The carbonized fungal biomass-mineral composite has excellent cycling stability and retains more than 90% capacity after 200 cycles, according to Gadd and his collaborators.

This story was featured in the June 2016 issue of Microbe Magazine.

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Send your microbiology questions and comments (email or audio file) to [email protected]

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Host: Jeff Fox with special guests, Ron Milo and Shai Fuchs.

Ron Milo of Weizmann Institute of Science in Rehovot, Israel, and Shai Fuchs at the Hospital for Sick Children in Toronto, Canada, talk with Jeff Fox about their efforts, with Ron Sender at Weizmann, to redetermine the ratio of microbial to human cells. This ratio, widely cited as being 10 to 1, is closer to even, they find, while arguing that it may prove helpful in the long run to have a better and more rigorous grasp of how many cells there are in both the host and the microbiome.

Milo, Fuchs, and Sender update the widely-cited 10:1 ratio, “showing that the number of bacteria in our bodies” is instead “of the same order as the number of human cells. Indeed, the numbers are similar enough that each defecation event may flip the ratio to favor human cells over bacteria.”

Thus, the total number of bacteria in the ″reference man″ is about 3.9 x 1013 with an uncertainty of 25%, and a variation over the population of 52%. For human cells, they find that the hematopoietic lineage of cells plays a “dominant role, accounting for about 90% of all body cells. They also revise estimates to the a new total of 3.0 x 1013 human cells in a 70-kg ″reference man″ with a 2% uncertainty.

This story was featured in the May 2016 issue of Microbe Magazine.

Subscribe to MMP (free) on iTunes, Stitcher, Android, RSS, or by email. You can also listen on your mobile device with the Microbeworld app.

Send your microbiology questions and comments (email or audio file) to [email protected]

Tweet me your questions or just let me know you heard this episode!

Image: Colored transmission electron micrograph of methicillin-resistant Staphylococcus aureus (MRSA). MRSA are among the drugresistant pathogens that are drawing researchers to look at how such resistance moves through the environment (see p. 201). (Image © Credit: Biomedical Imaging Unit, Southhampton General Hospital/Science Source.)