Aug. 4 (Bloomberg) -- Jack Welch, the retired General Electric Co. chief undergoing treatment for a spinal infection called discitis, said he is recovering steadily after a month of hospitalization.

“I’m on a six-week protocol to clean out the infection,” Welch, 73, said in a telephone interview Aug. 3 from New York- Presbyterian Hospital. “We’ve gone through four weeks. I’m up and walking around the hospital. And doing better every day.”

The Welches have been updating his condition on their Twitter accounts since his admission to the hospital July 5. Jack Welch led GE for two decades before retiring in 2001.

“He will fully recover,” Suzy Welch said. “It’s rare, but it’s fully treatable, and it’s treatable with antibiotics. It’s all good news, but it’s long-haul.”

Discitis is an infection of a disc, one of 23 pads of tissue that bind and cushion the bones of the human spine, said Daniel Sexton, director of the Infection Control Outreach Network at Duke University School of Medicine in Durham, North Carolina. The infection often occurs when harmful bacteria, such as Staphylococcus aureus, or staph, travel to the spinal area and settle in the discs and spinal bones, he said in an Aug. 3 telephone interview.

Infections can be serious if allowed to spread, and patients often need a long course of antibiotics, usually six weeks or more, Sexton said. In cases where patients don’t respond to drugs, or the health of the spine is at risk, doctors may recommend surgery to remove infected tissue, he said.

Most Common Cause

The most common cause of discitis is staph, said Sexton, who has never treated Welch and doesn’t know the details of his condition. While one study found the condition in just one in 450,000 patients, specialists believe it is becoming more common as the population ages and more people use syringes and implanted devices that can increase risk, Sexton said.

Discitis can be difficult to spot because many patients assume the pain is from muscle strain, said Sexton, who co-wrote a chapter on the condition for Uptodate, an informational service for doctors.

The Welches plan to resume a Business Week column they write together once Jack Welch recovers, Suzy Welch wrote on a Twitter post on Aug. 3.

Welch oversaw the growth of Fairfield, Connecticut-based GE from a $15 billion company to one with a market value of more than $400 billion that generated an average annual return of 24 percent for investors, fueled in part by the economic boom of the past decade. He handpicked current GE Chief Executive Officer Jeffrey Immelt.

Welch’s Proteges

Welch also trained executives who went on to run some of the world’s biggest companies, including Boeing Co. and Honeywell International Inc., implementing many of the same cost-cutting and market-share initiatives he embraced.

After leaving GE in September 2001, Welch went to Clayton Dubilier & Rice, where he helped the leveraged buyout firm assess new investments and expand overseas. He also served on the board of Fiat SpA. Welch was named “Manager of the Century” by Fortune magazine in 1999.

He recently announced the Jack Welch Management Institute, with classes offered online and at the Cleveland-based Chancellor University campus.

His 2005 book “Winning,” was co-written by Suzy Welch, whom Jack Welch met while she was Harvard Business Review Editor. He described the book as “a handbook for people in the trenches, turning their companies and the economy around.”

Bestseller Lists

Suzy Welch is currently promoting her own book, released earlier this year, called “10-10-10.” It describes a decision- making tactic in which users consider consequences of their decision making in 10 minutes, 10 months and 10 years. Like “Winning,” it has been on the New York Times bestseller list.

During his tenure, Welch generated criticism as well as admiration, earning the nickname “Neutron Jack” after cutting more than 100,000 jobs at GE in the 1980s. Welch also presided over the failed $46 billion takeover of Honeywell, which was blocked by European Union antitrust regulators in his last year.

Jack Welch’s Twitter posts, every two to three days since July 18, also comment on the Boston Red Sox baseball team, of which the Salem, Massachusetts, native is a lifelong fan. In the interview, he noted the Sox had won four straight games, sweeping the Baltimore Orioles in the last three-game series.

To contact the reporters on this story: Rachel Layne in Boston at rlayne@bloomberg.net; John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: August 4, 2009 00:01 EDT