Adding friendly bac­te­ria to skin lo­tion wards off bad germs

The Hamilton Spectator - - HEALTH - LAU­RAN NEER­GAARD

WASH­ING­TON — Bac­te­ria live on ev­ery­one’s skin, and new re­search shows some friendly germs pro­duce nat­u­ral an­tibi­otics that ward off their dis­ease-caus­ing cousins. Now sci­en­tists are mix­ing the good bugs into lo­tions in hopes of spread­ing pro­tec­tion.

In one early test, those cus­tom­ized creams guarded five pa­tients with a kind of itchy eczema against risky bac­te­ria that were gath­er­ing on their cracked skin, re­searchers re­ported Wed­nes­day.

“It’s boost­ing the body’s over­all im­mune de­fences,” said Dr. Richard Gallo, der­ma­tol­ogy chair at the Univer­sity of Cal­i­for­nia, San Diego, who is lead­ing the work.

We share our bod­ies with tril­lions of mi­crobes that live on our skin, in our noses, in the gut. This com­mu­nity — what sci­en­tists call the mi­cro­biome — plays crit­i­cal roles in whether we stay healthy or be­come more vul­ner­a­ble to var­i­ous dis­eases. Learn­ing what makes a healthy mi­cro­biome is a huge field of re­search, and al­ready sci­en­tists are al­ter­ing gut bac­te­ria to fight di­ar­rhea-caus­ing in­fec­tions.

Wed­nes­day’s re­search sheds new light on the skin’s mi­cro­biome — sug­gest­ing that one day it may be pos­si­ble to re­store the right bal­ance of good bugs to treat skin dis­or­ders, too.

“It’s a re­ally im­por­tant pa­per,” said Dr. Emma Guttman-Yassky of the Ic­ahn School of Medicine at Mount Si­nai Hospi­tal in New York, who wasn’t in­volved with the new re­search. “It does open a win­dow for a po­ten­tial new treat­ment.”

Healthy skin har­bours a dif­fer­ent mix of bac­te­ria than skin dam­aged by dis­or­ders such as atopic der­mati­tis, the most com­mon form of eczema. Those patches of dry, red, itchy skin are at in­creased risk of in­fec­tions, par­tic­u­larly from a wor­ri­some germ known as Sta­phy­lo­coc­cus au­reus.

Gallo’s team took a closer look at how mi­crobes in healthy skin might be keep­ing that bad staph in check.

They dis­cov­ered cer­tain strains of some pro­tec­tive bac­te­ria se­crete two “an­timi­cro­bial pep­tides,” a type of nat­u­ral an­tibi­otic. In lab tests and on the sur­face of an­i­mal skin, those sub­stances could se­lec­tively kill Staph au­reus, and even a drug-re­sis­tant strain known as MRSA, with­out killing neigh­bour­ing bac­te­ria like reg­u­lar an­tibi­otics do, the team re­ported in the jour­nal Science Trans­la­tional Medicine.

But those good bugs are rare in the skin of peo­ple with atopic der­mati­tis, Gallo said.

“Peo­ple with this type of eczema, for some rea­son that’s not quite known yet, have a lot of bac­te­ria on the skin but it’s the wrong type of bac­te­ria. They’re not pro­duc­ing the an­timi­cro­bials they need,” he ex­plained.

Would re­plen­ish­ing the good bugs help? “They’re nor­mal skin bac­te­ria, so we knew they would be safe,” Gallo noted.

His team tested five vol­un­teers with atopic der­mati­tis who had Staph au­reus grow­ing on their skin’s sur­face — what’s called col­o­niza­tion — but didn’t have an in­fec­tion. Re­searchers culled some of the rare pro­tec­tive bac­te­ria from the vol­un­teers’ skin, grew a larger sup­ply and mixed a dose into an over­the-counter mois­tur­izer. Vol­un­teers had the doc­tored lo­tion slathered onto one arm and reg­u­lar mois­tur­izer on the other.

A day later, much of the staph on the treated arms was killed — and in two cases, it was wiped out — com­pared to the un­treated arms.

“We’re en­cour­aged that we see the Staph au­reus, which we know makes the dis­ease worse, go away,” he said.

The study couldn’t ad­dress the big­ger ques­tion of whether ex­po­sure to the right mix of pro­tec­tive bac­te­ria might im­prove atopic der­mati­tis it­self, cau­tioned Mount Si­nai’s Guttman-Yassky.

Next-step clin­i­cal tri­als are un­der­way to start test­ing the ef­fects of longer-term use.

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