New, growing threat: Resistance to Cipro antibiotic

By Dan Vergano, USA TODAY

Overuse of Cipro, spawned by anthrax fears, threatens to neuter the drug and make people more vulnerable to common illnesses, infectious-disease experts warn.

On the biological battleground between man and microbe, people taking unneeded antibiotics means aiding the enemy, says Carol Baker, head of the Infectious Disease Society of America.

Antibiotics kill bacteria — not only anthrax, but also bugs that cause urinary tract ailments, gonorrhea and infections in trauma patients. But with use of drugs, especially in cases where patients fail to take them long enough to fully eliminate the infection, bacteria develop resistance to antibiotics.

"The New Jersey area already may have antibiotic resistance," says Baker, citing reported runs on Cipro among people there. Such resistance occurs two ways:

Mutations. Random changes in bacteria's genes may allow them to evade a drug's effects. Descendants of bacteria out-compete their weak peers and spread widely.

Trades. On the microbial level, bugs swap genetic information much as kids swap baseball cards. Transfers between unrelated bacteria can give new diseases resistance.

In a "closed environment" such as a hospital floor, resistance can spread among bacteria in as little as 24 hours, says Stuart Levy of Tufts University School of Medicine in Boston.

Nationwide, resistant bacteria appeared in about 77% of the 90,000 infection-related deaths last year in hospitals, Levy says. Auto accident victims, the elderly and people with impaired immune systems, HIV or transplant patients face the biggest threat.

Infections that accompany pneumonia will quickly acquire resistance to fluoroquinolones, the class of antibiotics to which Cipro belongs, says medical microbiologist Tony Hart of Britain's University of Liverpool. Most notably, Streptococcus pneumoniae bacteria will gain resistance, he says.

Each year, Streptococcus hospitalizes more than 100,000 pneumonia patients, causes about 6 million ear infections and kills 8,400 people, according to the U.S. Centers for Disease Control and Prevention. Up to 40% of cases already show some drug resistance.

Development of new antibiotics has been stymied in recent years by reluctance among drug firms to invest in the drugs, Levy says. Despite Cipro's popularity, antibiotics are generally not seen as blockbuster drugs in terms of profits.

"We're asking people not to take antibiotics unless they've been told to by their physician," Baker says. Taking antibiotics without any need means "you're likely to spread resistance to the people you live with," she says.