A 14-year-old baseball player from Alief, unconscious and on a breathing machine in the Texas Children's Hospital intensive care unit since Oct. 22, is the latest in an alarming series of hospitalizations triggered by antibiotic-resistant bacteria known as MRSA.

MRSA is the acronym for methicillin-resistant Staphylococcus aureus, a bacterium once seen only in hospitals but now widespread in communities across the country -- and causing severe, sometimes fatal, disease in Houston youngsters. In the past four months, Texas Children's has seen at least three deaths among patients with overwhelming staph infections and a dozen more children requiring ICU treatment.

"Something is going on. I know the intensive care people are very upset about this because of the deaths and the severity (of illness)," said Dr. Sheldon Kaplan, a Baylor College of Medicine professor and chief of infectious disease at Texas Children's, one of the country's largest children's hospitals. "I think we have a problem."

Typically, staph causes nothing more than impetigo, or small boils on the skin. But in its most ferocious form, staph can invade the heart or cause bone infections, pneumonia and blood infections. Scientists understand very little about why the microbe, which commonly resides harmlessly on the skin or inside the nose, sometimes turns deadly. Antibiotic overuse has been blamed for creating mutant strains that are increasingly difficult to control.

"Some of these common strains contain certain genes which make them more virulent, so (MRSA patients) get sicker than you might expect another staph to be," said Dr. Ed Septimus, an infectious disease expert with the Memorial Hermann Healthcare System.

Because of heightened concern about life-threatening MRSA, Kaplan, president of the Pediatric Infectious Disease Society, is giving weekly talks about MRSA to local pediatricians and at national scientific meetings. Letters have gone out to the Texas Children's medical staff recommending specific antibiotics against the infection.

At Memorial Hermann Children's Hospital, which has reported no MRSA deaths, new cases are considered antibiotic-resistant until shown otherwise and patients are placed in isolation. "MRSA has increased markedly," said Dr. Gloria Heresi, an associate professor of pediatrics at University of Texas Medical School at Houston. "It's concerning."

Pediatricians are seeing some of the most severe infections not in small or medically fragile children, but in strapping, healthy adolescents. No one knows why. Dr. Regina Okhyusen-Cawley, a pediatric critical care specialist at Texas Children's, said the infection may originate in a minor sports injury, but in many cases there's no apparent cause.

"It's very scary from the medical standpoint to take care of these kids," said Okhyusen-Cawley.

Severe, life-threatening staph infections are the most frightening manifestation of a growing public health concern, the surge in MRSA cases both lethal and mild. Health experts are worried because the bacterium, once easily beaten by penicillin-related drugs, is undeterred by many conventional antibiotics. Doctors must now resort to vancomycin, given intravenously, or a battery of lesser antibiotics that take longer to work.

In recent months, MRSA -- transmitted by skin-to-skin contact, sharing towels or unwashed athletic equipment -- has made headlines because it is plaguing sports teams, at all levels, with clusters of skin infections.

Last November, 29 athletes at Pasadena's Sam Rayburn High School suffered staph infections. In August, the Centers for Disease Control and Prevention reported MRSA infections among fencers, wrestlers and football players at high schools and colleges in four states. Cases are cropping up among professional athletes, including the Houston Texans, which has had five lab-confirmed cases since July. In addition, correctional facilities in Texas and elsewhere are reporting MRSA outbreaks.

Risk factors and the prevalence of community-onset MRSA -- MRSA infection not associated with hospitalization -- are difficult to assess because there has been no large-scale tracking by state or federal epidemiologists. Once confined to nursing home and hospital populations, severe, community-acquired MRSA only recently mushroomed into a widely recognized concern. CDC is beginning a national program of surveillance for infections with MRSA.

In Houston, infectious disease experts say the prevalence of antibiotic-resistant staph has soared, particularly among children. UT Medical School researchers say they can pinpoint a risk factor for contracting MRSA in about half of pediatric cases. Those risk factors include being in child care, having a family member who is hospitalized or having taken many antibiotics. However, in the other half of children, there are no identifiable risk factors for MRSA infections, Heresi said.

Of the staph isolated from patients at Texas Children's with community-acquired infections, 70 percent are MRSA, up from 33 percent in February 2000. The number of invasive cases -- infections of the bones, bloodstream or lungs -- jumped 30 percent between 2001 and 2003.

"That's a very big deal," Kaplan said. "This is not just Houston, Texas. This is being seen throughout the state of Texas. This is becoming a major issue."

Seven-year-old Zacharias Nunley was admitted to Memorial Hermann Children's Hospital in August with a mysterious, excruciating pain in his leg. He had no scrapes, insect bites or injuries anyone knew of. A surgeon found fluid in Zacharias' hip teeming with MRSA and a blood clot caused by the infection that could have killed him.

The second-grader spent three weeks in the hospital on IV antibiotics. Now back at school, he has his blood drawn and tested every week and will be on oral antibiotics until March, said his mother, Charla Rigsby.

"I said, `How did he get it? Do I need to throw away my furniture? Was it the food?'," Rigsby recalled. " They said, `No ma'am, the bacteria is everywhere. There's no telling where he got it.' That's what really, really truly bothered me."

MRSA's origins are unclear. For years, it has been a serious problem in hospitals and nursing homes, evolving among severely ill patients on antibiotics. The birth of community-acquired or community-onset MRSA -- genetically distinct from the hospital-acquired type -- remains a mystery. Overuse and improper use of antibiotics are considered one culprit.

Okhyusen-Cawley said children with fever, pain in a specific joint or bone, or respiratory distress "need to be evaluated in an ER and most likely admitted for IV antibiotics."

"The kids have a history of two or three days of not really being themselves, and then they get really sick very suddenly," Okhyusen-Cawley said. "It's just nasty, nasty, nasty."

Copyright 2003 Houston Chronicle Medical Writer