Veiled La­tency

SLOW Magazine - - Contents - Text: Gary Muir Im­age © is­tock­photo.com

For­get the cat­a­clysmic weather event, the nu­clear apoc­a­lypse, the alien takeover, or the zom­bie in­va­sion – what re­searchers are in­creas­ingly com­ing to be­lieve will bring down the hu­man race is mi­cro­scopic: bac­te­ria. The over-pre­scrip­tion and over-use of an­tibi­otics in re­cent decades has led bac­te­ria to de­velop tol­er­ances to the drugs that are cur­rently on the mar­ket. And, as bac­te­ria in­creas­ingly evolves its re­sis­tance to an­tibi­otics, we could be cast back into the dark ages of medicine, sci­en­tists say. An­tibi­otics are our last line of de­fence in many cases where they stop the spread of in­fec­tion. With­out them, we are all in big trou­ble. Re­ports sug­gest that if left unchecked, “su­per­bugs” could be re­spon­si­ble for up to 10 mil­lion deaths an­nu­ally by 2050. To put that num­ber into per­spec­tive, con­sider that there are cur­rently 56 mil­lion peo­ple in South Africa, or 53 mil­lion in Eng­land. So we are talk­ing about roughly 20 % of those pop­u­la­tions each year.

The dilemma gets even more dis­mal be­cause not only is bac­te­ria in­creas­ingly be­com­ing re­sis­tant to an­tibi­otics, some bugs have man­aged to turn the drugs into a food source. Yes, the bugs are eat­ing our an­tibi­otics. The very thing that is meant to end them is in­stead sus­tain­ing them.

Re­search be­ing un­der­taken by the Wash­ing­ton Univer­sity School of Medicine in St Louis is look­ing into how bac­te­ria is able to do this. Ac­cord­ing to Gau­tam Dan­tas, se­nior au­thor of the study, when it was first dis­cov­ered 10 years ago that bac­te­ria could eat an­tibi­otics, ev­ery­one was shocked by it. How­ever, it is now be­gin­ning to make sense, he says. “It’s just car­bon, and wher­ever there’s car­bon, some­body will fig­ure out how to eat it. Now that we un­der­stand how these bac­te­ria do it, we can start think­ing of ways to use this abil­ity to get rid of an­tibi­otics where they are caus­ing harm.”

Luck­ily, we have not lost the bat­tle against su­per­bugs yet. Bac­te­ria have strong cell walls that pro­tect it against drugs, viruses and other dan­gers, mak­ing it pretty tough to kill. Ex­cept that re­searchers at Har­vard Med­i­cal School think they have found an Achilles heel, a struc­tural weak­ness that is seem­ingly built into a range of bac­te­rial species.

The Har­vard study fo­cused on a pro­tein called Roda, which builds the pro­tec­tive cell walls of bac­te­ria out of sugar mol­e­cules and amino acids. Roda be­longs to a fam­ily of pro­teins that is com­mon to al­most all bac­te­ria, mak­ing it the ideal tar­get for a broad­spec­trum an­tibi­otic. Fur­ther study re­vealed a vul­ner­a­ble-look­ing cav­ity on the outer sur­face of the pro­tein which, when al­tered, caused the pro­tein to mal­func­tion, lead­ing the bac­te­ria to first bloat and then burst, ul­ti­mately killing it. Ac­cord­ing to sci­en­tists work­ing on the study, this sug­gests that a drug de­signed to prompt the same re­ac­tion would be an ef­fec­tive an­tibi­otic in the fu­ture.

While they work to find so­lu­tions to the loom­ing su­per­bug cri­sis, sci­en­tists have also looked to na­ture for al­ter­na­tives to an­tibi­otics. Po­ten­tial has been found thus far in fairly in­nocu­ous foods like berries, honey, maple syrup, and fungi, but also stranger sources such as frog skin, rat­tlesnake venom and platy­pus milk.

A new study in­volv­ing re­searchers from Aus­tralia’s Univer­sity of Queens­land and Spain’s Pom­peu Fabra Univer­sity is test­ing a new an­tibi­otic con­tender, the pep­tide Cro­tal­i­cidin (Ctn), found in the venom gland of South Amer­i­can rat­tlesnakes. Prior re­search re­vealed that this par­tic­u­lar pep­tide pos­sesses an­timi­cro­bial prop­er­ties and was not only highly ef­fec­tive at killing bac­te­ria, but also less toxic to healthy cells.

Só­nia Troeira Henriques, co-au­thor of the study, has called this “an ex­am­ple of tak­ing what na­ture has given us and try­ing to un­der­stand how it works, so we can mod­ify it to be more po­tent, more sta­ble or more drug-like, to use as an al­ter­na­tive to what we have in our phar­ma­cies now”.

Platy­pus milk is also un­der the mi­cro­scope – quite lit­er­ally – as a team of Aus­tralian re­searchers dis­cov­ered sev­eral years ago that it con­tains in­no­va­tive an­timi­cro­bial prop­er­ties likely due to a unique pro­tein found in the milk. Platy­puses, part of the monotreme fam­ily, are fas­ci­nat­ing crea­tures – they lay eggs like rep­tiles but feed their ba­bies milk, like mam­mals. Ex­cept that they have no teats, so milk is ex­pressed through pores on the mother’s belly. The milk pools in grooves from which the ba­bies then lap it up. It is this process which sci­en­tists be­lieve ex­poses the milk to bac­te­ria in the en­vi­ron­ment.

This un­usual pro­tein – only found in the milk of monotremes – has since been suc­cess­fully repli­cated in a lab, where it was found to have a novel ringlet-like for­ma­tion, lead­ing it to be nick­named the “Shirley Tem­ple” pro­tein. Sci­en­tists work­ing on the study have said that the dis­cov­ery in­creases the scope of knowl­edge of pro­tein struc­tures in gen­eral, and will go on to in­form other drug dis­cov­ery work cur­rently be­ing done.

There is no doubt that we are in trou­ble. Our over-de­pen­dence on and over-use of an­tibi­otics hav­ing cre­ated a som­bre and sober­ing sit­u­a­tion which, if not given im­me­di­ate and ad­e­quate at­ten­tion, may well be the cat­a­strophic event that takes man out of the equa­tion en­tirely.

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