New Yorkers are used to trekking to New Jersey to avoid high sales taxes. Now they may have to cross the Hudson to avoid deadly hospital infections too.

On Thursday, August 2, the governor of New Jersey, Jon Corzine, signed a law requiring that hospital patients in intensive care, neonatal intensive care, and other units where the most vulnerable patients are treated be routinely tested for a super-bug called methicillin-resistant Staphyloccus aureus, or MRSA, a type of bacteria that causes serious hospital infections.

The test is noninvasive, a simple skin or nasal swab. Research shows that it’s essential to stopping MRSA infections that are raging through hospitals. In 2003, a committee of the Society for Healthcare Epidemiology of America urged hospitals to initiate screening programs. Hospitals such as Brigham & Women’s in Boston, Johns Hopkins in Baltimore, Evanston Northwestern in Illinois, University of Pittsburgh in Pennsylvania, and Veterans’ Administration medical centers are leading the way. But most hospitals in New York have been slow to act, and New York lawmakers have been even slower.

Why is MRSA testing needed? Because MRSA is transmitted easily from patient to patient on clothing, medical equipment, hands, and gloves. Research shows that you cannot prevent MRSA infections until you identify which patients bring these bacteria into the hospital.

Patients who unknowingly carry MRSA shed it in tiny particles on bedrails, wheelchairs, blood pressure cuffs, stethoscopes, and the floor under their beds. They don’t realize they have it, because the germ doesn’t make you sick unless it gets inside your body via a catheter, a surgical incision or other open wound, or a ventilator.

MRSA can live for many hours on surfaces and fabrics. Doctors and other caregivers who lean over an MRSA-positive patient to change a dressing or do an examination often pick up the germ on their lab coats and transmit it to their next patient.

When a nurse wraps an inflatable blood pressure cuff around your bare arm, the cuff frequently contains live bacteria, including MRSA, left behind by a previous patient. Being placed in a room previously occupied by a patient unknowingly carrying MRSA, or even asked to sit in a wheelchair previously used by an MRSA positive patient, puts you at risk.

Holland, Denmark, and Finland once faced soaring rates of MRSA hospital infections, and nearly eradicated them. How? By identifying patients silently carrying MRSA and taking precautions to prevent the germ from spreading to other patients on hands, equipment, and clothing. The Dutch called their method “search and destroy.” These precautions work in America too. The University of Pittsburgh-Presbyterian Medical Center reduced MRSA infections by 90% using screening and the same follow-up precautions.

Can hospitals afford to screen for MRSA? They can’t afford not to. When a patient develops an infection and has to spend many additional weeks hospitalized, the hospital isn’t paid for most of that additional care.

Preventing MRSA infections costs far less than treating them. For example, in a medical intensive care unit at the University of Pittsburgh, screening tests, gowns, and other precautions cost $35,000 a year and yielded over $800,000 a year in avoided infection costs. No capital outlay was required. “Virtually all published analyses” reach similar conclusions, according to the medical journal, Lancet, in its September 2006 issue. Screening patients for MRSA makes hospitals more profitable. Most importantly, it saves lives.

That’s why hospitals in New York should routinely screen patients for MRSA. Research proves that you cannot prevent the spread of this deadly bacteria if you don’t know the source. Screening also protects patients who have MRSA, because once you know that you carry it on your skin, added precautions can be taken before and during your surgery to prevent the bacteria from getting inside your body.

The financial and medical reasons for screening are so compelling that legislation should not be necessary. Hospitals in New York City, where more patients are treated and more health care workers are employed than in any other metropolitan area, should be leading the nation in MRSA screening.

“It’s a sorry state of affairs,” Maureen Daly of Brooklyn said, when she heard about New Jersey’s new screening law. Ms. Daly lost her 64-year-old mother, Johanna, to an infection contracted in a hospital in New York City. “I can’t believe it’s going to be safer to go to New Jersey for medical care, because hospitals here won’t do the right thing.”

Ms. McCaughey, the former lieutenant governor of New York State, is the founder and chairman of the Committee to Reduce Infection Deaths, hospitalinfection.org, a nonprofit campaign to improve hospital hygiene and procedures.