TRENTON, N.J. ? Flesh-eating bacteria cases, fatal pneumonia and life-threatening heart infections suddenly are popping up around the country, striking healthy people and stunning their doctors.

The cause? Staph, a bacteria better known for causing skin boils easily treated with standard antibiotic pills.

No more, say infectious disease experts, who increasingly are seeing these “super bugs” — strains of Staphylococcus aureus unfazed by the entire penicillin family and other first-line drugs.

Until a few years ago, these drug-resistant infections were unheard of except in hospital patients, prison inmates and the chronically ill. Now, resistant strains are infecting healthy children, athletes and others with no connection to a hospital.

“This is a new bug,” said Dr. John Bartlett, chairman of the committee on antibiotic resistance at the Infectious Diseases Society of America. “It’s a different strain than in the hospital … more dangerous than other staph.

“Primary care physicians and ER doctors, they don’t all know (about this) and should,” he said.

The infections will be a hot topic at the society’s annual meeting this week in Boston. The group has been warning that drug companies aren’t developing enough new antibiotics to avert a crisis.

Among the case reports to be discussed:

• In Corpus Christi, Texas, doctors at Driscoll Children’s Hospital saw fewer than 10 cases a year of community-acquired resistant staph infections in the 1990s, then saw 459 in 2003, with 90 percent in healthy children. Half were admitted to the hospital to get intravenous antibiotics; a few developed life-threatening lung and heart infections or toxic shock syndrome.
• A Centers for Disease Control and Prevention study shows another new twist: The resistant staph strain caused pneumonia in 17 people, killing five, during last year’s flu season. Only one had any risk factors for the infection.

“Nobody dreamt when we were in medical school that this would ever enter the community,” said Dr. Rajendra Kapila of University of Medicine and Dentistry of New Jersey in Newark.

There are no national statistics on these infections, but health authorities are debating requiring doctors to report them.