Science: Doing antibiotic chemistry in ants

Yes, ants like these

An assistant professor of bugs (entymology) at Auburn U, and his colleagues, found that ants naturally make and carry a slew of antibiotics in their bodies. That makes the little critters resistant to lots of fungi, gram positive bacteria and gram negative bacteria. The team or researchers looked at six ant species common in the southeastern US to see just what's there. They were amazed and happy to find a slew of antibiotics, including ones that kill off the human superbug Candida auris. Superbugs are human pathogens have evolved to be resistant to nearly all known antibiotic drugs used in humans, hence the 'superbug' label. 

The researchers write in the abstract of their research paper: 

The evolution of sociality provides many benefits but also increases the risk of disease transmission. In response, social insects have evolved social immune defenses, including the production of antimicrobial compounds. The development of exocrine glands that secrete these antimicrobials is linked to the origins of sociality. However, it remains unclear how social insects prevent pathogens from evolving resistance to these compounds. We tested whether ants use chemically diverse and pathogen-specific antimicrobial compounds, both of which may combat antimicrobial resistance. Using solvents of varying polarity, we extracted compounds from six ant species and tested their inhibitory effects on Gram-positive bacteria, Gram-negative bacteria, and a fungal pathogen. Our results show that ants exhibit antimicrobial activity in both polar and non-polar extracts, consistent with the presence of compounds that differ in chemical properties. Inhibition also varied across microbial groups, with some species showing stronger effects against particular classes of microbes. Notably, five of the six ant species tested inhibited Candida auris, an emerging fungal pathogen of critical concern in human medicine due to its multidrug resistance. These findings suggest that social immunity in ants may be supported by both chemically diverse and microbe specific antimicrobials, which may combat antimicrobial resistance.

Context: The first description of ants making antibiotics was published in 1999, when researchers found that leaf-cutter and other fungus-farming ants maintain symbiotic relationships with antibiotic-producing Pseudonocardia bacteria that live on specialized parts of the ants' bodies. This paper presents a new methodological framework for trying to understand why ant antimicrobials have remained effective for millions of years, which is something that human antibiotics have failed to achieve in less than a century. 

What they found in this paper is that ants produce both polar and non-polar antibiotics, which is evidence that ants are producing chemically diverse antimicrobials with different molecular structures​. If activity is specific to certain pathogen types (gram-positive bacteria vs. gram-negative bacteria vs. fungi), this indicates that ants make targeted rather than broad-spectrum antibiotics. This study asks a systems-level evolutionary question: What strategies do ants use to avoid the resistance problem now seriously plaguing human medicine?

By Germaine: Concerned about the rise of superbugs and public health generally -- not an anti-vaccine crackpot

Not Germaine