Three-year-old McKenzie Smith was taken to the hospital with a rare hereditary disease. She died, not from the disease she came in with but from an infection she got in the hospital, her distraught parents explained in the New York Post. The Post also reported that another little girl, Grace Murphy, treated on the same pediatric floor, died from the same infection a few months later.

Construction in hospitals is almost always to blame for the type of infection these little girls got – Aspergillus. It’s a fungus found in soil and old buildings, and when disturbed, its deadly spores can float through elevator shafts, windows, vents, and hallways into patients’ rooms. According to the grieving families, the little girls were treated within yards of the construction. The dust was so thick, McKenzie’s mother Michele told the Post, that she could run her finger through it on virtually every surface in her daughter’s room.

Hospitals undergoing construction are supposed to seal off the work site, move patients with weak immune systems as far away as possible, and monitor the environment for spores. Mrs. Smith was constantly wiping down her daughter’s room, struggling to remove the dust as it piled up. It makes you wonder whether hospitals are doing everything they can to protect their patients from deadly complications.

McKenzie died four years ago. Though Aspergillus is a rare infection that affects only a handful of people each year, her death is a sad indication of a vastly larger and underreported health crisis. Each year, 2 million people in our country contract infections in the hospital, and more than 100,000 die from them. All of us have heard of one of the most common infections, Staph, short for Staphylococcus aureus. It’s so widespread that it’s becoming a household name. Nearly all these infections have a common cause: poor hygiene.

Staph germs race through a hospital because of unclean hands, contaminated equipment, bacteria-laden uniforms, and inattention to proper procedures. Amazingly, doctors fail to clean their hands before treating patients 52% of the time according to research by infectious disease expert Didier Pittet, M.D. Equipment contaminated with bacteria – like stethoscopes – are used on one patient after another without being cleaned. Doctors and nurses carry bacteria from bedside to bedside on their own lab coats and uniforms, and some hospital workers even wear their scrub suits out on the street and then back to work.

Dealing with hospital construction is an unusual problem, but what is not unusual about Michele Smith’s plight is that she had to constantly clean her daughter’s room. All too commonly, family members are left to their own devices, scrubbing the bathroom floor or wiping up. When Lydia Dyroff’s mother went into a Florida hospital for bypass surgery, she did her best to clean her mother’s room, but it wasn’t quite enough.” It needed professional care. We complained to many, but nothing seemed to help” Lydia later recalled in an e-mail to the Committee to Reduce Infection Deaths. Her mother contracted a Staph infection that didn’t respond to medication. Her wounds didn’t heal, and she eventually died.

Staph infections are growing more dangerous because, increasingly, they cannot be cured with commonly used antibiotics. Patients who get MRSA, short for methicillin-resistant Staphylococcus aureus, often spend months in the hospital and go through several operations to cut out infected tissue. Sixty percent of Staph infections are now drug-resistant.

A new report (September 15) in the medical journal “Clinical Infectious Diseases” warns that another large group of infections, including Acinetobacter, Pseudonmonas, and Kliebsiella, to name a few, are rapidly becoming drug resistant. You’ve probably never head of these other “superbugs,” even if someone in your own family has suffered from them, because most hospitals say as little as possible when there’s an infection problem.

A few hospitals in Virginia, Pennsylvania, and Iowa have virtually eradicated the worst drug-resistant infections. How? Through rigorous hygiene, meticulous cleaning of equipment in between patients, testing incoming patients to identify those carrying dangerous bacteria, and strictly isolating them to prevent transmission to other patients. Unfortunately, most hospitals don’t make hygiene a top priority. It’s time they did.

Medical schools should also be teaching future doctors how to protect patients from infection. Some medical schools are stressing the importance of curbing the use of antibiotics. That’s good, because overuse of antibiotics wastes money and causes bacteria to morph into new, drug-resistant strains. But limiting the use of antibiotics won’t stop hospital infections. No hospital has ever eradicated infection merely by controlling the use of these drugs.

It’s hard to believe, but most medical schools devote virtually no time, not even one full class, to showing students how germs are transmitted from patient to patient on clothing, equipment, and hands, and what can be done to prevent it. It’s ironic. Medical schools have committees to ensure that bioterrorism is covered, but not hospital infection, a far more immediate threat to most of us. How could a hospital stop a covertly introduced contagion from racing through its patients if it cannot even stop a common infection from spreading? When medical students put on their white coats and swear the Hippocratic Oath, they should be taught how to do no harm. They should learn it before they go out on the hospital floors and touch their first patient.

Ms. McCaughey is a former lieutenant governor of New York State and chairman of the Committee to Reduce Infection Deaths (www.hospitalinfection.org).