What spreads faster than a petri dish of listeria?

Well, apparently, a news report that claims to out the anonymity of a humorist on Twitter. Who knew the bar was so low for what is essentially a parlor-game whodunit in the rarefied world of food?

The story, which began as a blog item from me posted Friday on StarTribune.com, had spread to online news outlets worldwide over the weekend, many of them picking up the Associated Press version headlined "Food world goes nuts."

And indeed it did.

Should you care? Unless you're on Twitter, probably not. But if you tweet and follow the parody of the anonymous Twitter handle @RuthBourdain, aka RuBo, then it's a different story. He/she is a mash-up of two rock stars of the food world: Ruth Reichl, former Gourmet editor and New York Times restaurant critic, and Anthony Bourdain, TV host of "No Reservations" and potty-mouthed author. The disturbing avatar of Ruth Bourdain, shown here, spews all sorts of snarky comments that have attracted more than 45,000 fans since the first tweet in March 2010.

A recent RuBo commentary fit for the newspaper: "Have you heard about the vegan strip club in Portland? This is so wrong. No woman deserves to be treated like a piece of tofu."

In May, the writings of Ruth Bourdain won the James Beard Foundation's award for humor and, not surprisingly, the humorist did not show up to claim the medallion.

Food celebrities often are delighted to find themselves to be subject of the zingers. "It is kind of genius. I love it. I'm a total addict. I'm hooked already and, frankly, flattered and disturbed in equal measure," Anthony Bourdain has said.

The envelope, please ...

So who is the masked writer? My bet's on Robert Sietsema, a Minnesota native who grew up in Edina and has been a restaurant critic at the Village Voice in New York City since 1993. He was with a roomful of writers in Charleston, S.C., at the annual conference of the Association of Food Journalists, during which time Ruth Bourdain began tweeting commentary on the meeting.

Yes, it's possible through technology for this to be directed from another location, but the continued tweeting struck me and others as out of the norm: Could Ruth Bourdain be in the room, playing with us? That began a slow process of evaluation and deduction, which initially cast a wide net that became smaller and smaller: Think of the method in the child's game of Clue. When the search was narrowed to only a few journalists, I headed to the computer to compare writing styles and word choices online in an attempt to find similar patterns of patter in a likely candidate.

Sietsema denies the connection, though his explanations have varied wildly as he responded to assorted reporters.

Still, he confided to me, "If I was Ruth Bourdain, I wouldn't tell you."

A new character in the Twittersphere has popped up in response: Ruth Sietsema, the supposed half-sibling of Ruth Bourdain. The small world of food is all atwitter.