KENNETT SQUARE, Pennsylvania (AP) -- Marguerite Harris and her staff of eight provide prenatal care and child immunizations, write prescriptions, and diagnose and treat ailments from diabetes to the sniffles.
Though it may sound like a typical doctor's office, no one on staff at Project Salud is a doctor. The medical center is run by nurse practitioners -- registered nurses with specialized training and advanced degrees -- whose numbers in the United States have risen from 30,000 in 1990 to 115,000 today.
Increasingly, U.S. patients are being treated by nurse practitioners. Nurse-managed primary care centers such as Project Salud have increased to about 250 nationwide today, from a small handful 15 years ago.
"We've come a long way since the early days, the knockdown drag-outs with doctors who thought we were overstepping our roles," said Harris, a nurse practitioner at the Philadelphia-area medical center since 1974.
The change is attributed to factors that include a drop in the number of doctors choosing primary care as their specialty, a falloff expected to continue.
According to the American College of Physicians, U.S. medical school surveys showed that from 1998 to 2005, the percentage of third-year residents intending to pursue careers in general internal medicine dropped from 54 percent to 20 percent. Many new doctors, saddled with high student loans, are choosing more lucrative specialties.
The supply of general practice physicians is falling just as the American baby boomer population is aging and in greater need of medical care, and nurse-run medical centers are helping to bridge the gap.
Nurse practitioners first appeared about 40 years ago in pediatrics, and quickly expanded into obstetrics and gynecology, family medicine, and adult primary care.
They can perform many of the duties of primary care doctors such as performing physical exams, diagnosing and treating common health problems, prescribing medications, ordering and interpreting X-rays, and providing family planning services.
However, some physicians' groups are concerned about the trend.
The American Medical Association is against giving full autonomy to nurse practitioners, stating as its official policy position that a physician should be supervising nurse practitioners at all times and in all settings. An AMA spokeswoman said the association would not provide additional comment on its position.
"There is an element within the physician community that gets a little antsy. ... They think it's going to take away revenue and business from them," said Dr. Jan Towers, director of health policy for the American Academy of Nurse Practitioners. "Really, there's more than enough for everybody."
A 2000 study in the Journal of the American Medical Association concluded that patients who receive primary care from nurse practitioners fare just as well as those treated by doctors and report similar levels of satisfaction with their care.
Nurse practitioners also have steadily been gaining greater acceptance by insurers and in most states. In about half of America's states, nurse practitioners -- who frequently have lower fees for office visits than doctors -- are now recognized by insurance carriers as primary care physicians.
"One of the statistics that stands out is that we (nurse practitioners) see our patients twice as often as similar practices of physicians," said Tine Hansen-Turton, executive director of the National Nursing Centers Consortium, a Philadelphia-based industry group. "Doing primary care well is the foundation for saving health care dollars -- working on improving health early instead of, for example, paying for coronary surgery and bypasses later."