The San Francisco bakery, which started in 1849, continues to use dough made from starter formulated during the Gold Rush.
Competitors, however, have begun to use the name sourdough for bread produced with a spray that gives the finished bread an acidic, sourdoughlike taste.
Andre-Boudin faces stiff competition from a half-dozen bakeries in the city, producing hand-crafted specialty sourdough as well as non-sourdough products.
Specialty breads, which sell in the range of $1.50 for a baguette, have become the latest affordable luxury, joining such products as cigars.
"It's a connoisseurship thing," said Nigel Carr, managing partner and general manager at Kirshenbaum West. "You can afford the best."
Boudin's, a Specialty Foods Corp. subsidiary, has more than 40 outlets in the Bay area and in southern California, Chicago and Dallas. In addition, its catalog sells specialty breads -- in the range of $20 for a sampler set -- as well as made-to-order breads.
Spending on the account, previously handled in-house, is expected to be the equivalent of about $2 million. Harry Groome, formerly principal of Odiorne Wilde Narraway & Partners, San Francisco, has joined Kirshenbaum to head up the account.
The win brings Kirshenbaum's San Francisco office billings to $16 million. The agency also handles Mother's Cake & Cookie Co., another Specialty Foods unit.