When we're sick, really sick, most of us will head for the hospital, but sometimes that stay can lead to another illness on top of that first medical issue. These hospital-acquired infections (also known as health care-associated infections or nosocomial infections) occur because a hospital puts a lot of people with infections in one place, many of them with compromised immune systems. Without strict procedures for maintaining sterile conditions, pathogens can spread.
One in 25 hospital patients contracted an HAI in 2011, according to a Centers for Disease Control and Prevention survey of U.S. hospital data. Overall, that worked out to an estimated 722,000 such infections that year, and 75,000 of those patients died, although not necessarily from the HAI) [source: CDC].
This article explains which infections are most common, how they're spread and what health care facilities are doing to prevent them.
Central Line Bloodstream Infection (CLABSI)
You may already know that a central line is an important medical tool. Health care professionals insert them into patients through a major vein in the neck, chest or groin. These lines allow doctors to administer fluids and precise doses of medication. Oppositely, they may allow pathogens to get directly into the bloodstream, causing a potentially serious widespread infection. Patients may develop chills and a fever, and the catheter site might become red and irritated [source: California Dept. of Public Health].
While these infections represent one of the most common hospital-acquired infections, with over 30,000 cases in 2011, the CDC reports a 44 percent decrease in such infections between 2008 and 2012 [sources: CDC, CDC]. That's excellent progress, accomplished mainly by ensuring hospital workers wash their hands before installing or handling a central line; keeping the line itself antiseptic through handy sterile items like gloves, gowns, caps, masks and sterile drapes; and leaving the line in only as long as necessary.
Catheter Urinary Tract Infection (UTI)
Sometimes patients can't urinate due to injury, surgery or other reasons. When that happens, a nurse or doctor may install a catheter that automatically drains urine from the person's bladder. One end of the tube goes through the skin and into the bladder; the other end attaches to a collection bag.
The problem is that the bladder and urinary tract are usually germ-free environments, and introducing an external tube can allow pathogens to get into the bladder and cause a UTI, the most common hospital-acquired infection.
These illnesses are often caused by common bacteria found in your intestines, on your skin, or in your mouth and nose. Escherichia coli and Klebsiella are potential culprits. When they get into the urinary tract, however, there are no other bacteria there to keep them in check, so they multiply quickly and cause an infection. Symptoms can include pain or difficulty urinating, excessively frequent urination (after the catheter is removed), fever, a painful lower abdomen or bloody urine [source: George Washington University Hospital].
The procedures for preventing catheter UTIs are similar to most hospital-acquired infections – thorough hand-washing by hospital workers, using soap and alcohol gel, plus carefully maintaining sterile conditions in the catheter itself, which should be removed as soon as possible. Other techniques include temporary catheters that are only in place while the bladder is being drained, as well as external catheters for male patients that don't introduce anything into the bladder or urinary tract [source: CDC].
Surgical Site Infection (SSI)
Whenever human skin is penetrated, microscopic invaders can bypass the body's natural defenses, leading to an infection. Surgical incisions give germs such a window to enter the body. According to Johns Hopkins Medicine, 2.8 percent of all surgical procedures in the U.S. result in a surgical site infection, with some facilities experiencing a rate as high as 11 percent [source: Johns Hopkins Medicine]. The effects can be as minor as redness and swelling at the surgical site or as major as sepsis, a body-wide reaction to infection that can lead to organ failure and death.
The CDC's Surgical Care Improvement Project is a set of procedures aimed at reducing the rate of SSIs in hospitals – as much as 17 percent of all hospital-acquired infections are SSIs, second only to UTIs [source: CDC]. An SSI can significantly increase a patient's chances of death following surgery, and sepsis can lead to long-term disabilities. There's a monetary cost, too, since a post-surgery infection prolongs hospital stays by about a week [source: Johns Hopkins Medicine].
Simply minimizing the number of people moving in and out of the room during surgery and stopping the use of razors to remove body hair before surgery can reduce the chances of an SSI. Dosing the patient with antibiotics before surgery also can prevent bacteria from thriving at the surgical site – specific dosage and timing are required for this to be effective.
Ventilator-associated Pneumonia (VAP)
Pneumonia is a broad term for an infection that causes lung inflammation. Much like urinary tract infections, pneumonia occurs when bacteria or viruses get into the lower respiratory system, which is usually sterile. Your body has built-in defenses against pathogens getting into the respiratory system, such as the chemicals in your saliva, the cough reflex and the mechanical barriers, like the cilia in your nose.
Unfortunately, many medical conditions and treatments can weaken or bypass these defenses. Feeding tubes, brain damage, lack of consciousness and prolonged periods spent lying down all can increase the risk of a patient getting pneumonia. Any pneumonia contracted in a hospital is known as a hospital-acquired pneumonia, or HAP [source: APIC].
Ventilator-associated pneumonia, or VAP, represents a specific type of pneumonia contracted through an intubation tube and ventilator. Someone on a ventilator is often subject to many of the factors that can lead to pneumonia, and if the ventilator apparatus itself is not kept sterile, it magnifies the problem. As with the other tubes we've mentioned, a breathing tube can act as a highway for bacteria to travel straight into the lungs, bypassing most of the body's defenses. Patients in intensive care trauma wards are at especially high risk.
Prevention requires several steps on the part of hospital workers, beginning with washing hands thoroughly and wearing protective gloves when touching the mouth and nose of a patient. Daily antibacterial agents like chlorhexidine can be used to rinse the mouth [source: Critical Care Nurse].
Beyond Pneumonia -- Other Respiratory Infections
Respiratory infections can be particularly insidious in a hospital, because they don't require any kind of incision or catheter to infect patients. Just as with pneumonia, lots of common scenarios in a hospital, such as being in a coma, using a breathing tube or lying prone for a long time, can make a patient more susceptible to respiratory infections.
The population of patients in a hospital might carry with them several different strains of respiratory infections, such a Legionella or influenza. These infections can be transmitted through the air and can spread through an entire building via air conditioning systems and other ducts. Legionella, for instance, is actually a waterborne bacterial infection, but contaminated water can spread the disease through air with the use of humidifiers and mist machines [source: Legionella.org]. Other illnesses, like tuberculosis, can be transmitted by air droplets produced when someone coughs or sneezes. These droplets can float in the air for a long time and be transported throughout a building.
To reduce transmission of these diseases, hospitals have to carefully consider their heating and ventilation systems. Proper filtering and cleaning of ducts is important, along with maintaining pressure differentials to control the direction of airflow within the building. For example, a patient undergoing surgery is very vulnerable to infection, so the surgical suite should have higher air pressure to keep potentially contaminated outside air from coming in [source: Pyrek].
Staphylococcus bacteria commonly reside on human skin and mucus membranes; they even live in soil. They're usually harmless. However, hospital patients, especially those with weakened immune systems, can be susceptible to skin infections from Staphylococcus. These staph infections can cause rashes, boils and other skin problems, and the infection can spread to the bloodstream [source: Mayo Clinic].
Staph infections are a serious concern, but the real problem comes from bacterial strains that are resistant to many antibiotics and thus extremely difficult to treat. Methicillin-resistant Staphylococcus aureus (MRSA) is the most infamous. It causes skin infections, but it also shows up under other categories on this list, like respiratory infections and surgical site infections. With few treatment options, MRSA can be life-threatening to someone with a compromised immune system.
Years of overuse and improper use of antibiotics are the major reasons these resistant strains have become so prevalent. That's why one of the CDC's big initiatives is something the agency calls "antimicrobial stewardship," an effort to ensure antibiotics are used properly and in a way that won't lead to more resistant strains of antibiotics [source: CDC].
When an infection moves into the gastrointestinal tract, the symptoms mirror food poisoning (food poisoning is just a gastrointestinal infection, also known as gastroenteritis, acquired by eating food contaminated with bacteria). Nausea, diarrhea, vomiting and dehydration are the result. It can be devastating to a healthy person, potentially fatal to someone who's already battling other health problems in a hospital.
According to the World Health Organization, gastroenteritis is the most common hospital-acquired infection in children, who are typically affected by rotavirus. Adults who contract gastroenteritis in a hospital are often infected by Clostridium difficile [source: WHO]. C. difficile is particularly dangerous since the bacterial strain has become resistant to many antibiotics.
Maintaining a sterile environment in the hospital remains the key to preventing these infections, but hospitals also have to consider the food they serve to patients, as well as the proper handling of any materials a patient might ingest.
Endometritis occurs when the inner lining of the uterus becomes inflamed due to infection. Like many of the other infections on this list, endometritis occurs when otherwise benign bacteria colonize a place where they aren't normally found, in this case, the uterus. Symptoms include fever and discharge.
Many of the procedures that accompany childbirth potentially allow passage of bacteria to the uterus. Sterile procedures, including thorough hand-washing and sterilization of all instruments used in exams are the primary line of defense. A cesarean section makes infection much more likely, so unnecessary c-sections are to be avoided. If one is necessary, or if labor is prolonged (which also increases risk of infection), using preventative antibiotics can hold off bacterial infection [source: Chongsomchai].
Bacteria cause many of the hospital-acquired infections we've discussed, but viruses pose worthy foes in hospitals, too. Whenever someone comes to a hospital infected with a virus, there's a chance that virus can spread to other patients. Many of the measures for preventing bacterial infections also work against viruses: hand-washing, sterile equipment and surfaces, and properly designed heat and ventilation systems.
Every virus has its own method of transmission though, which presents its own difficulties. For example, Ebola and HIV are spread through contact with bodily fluids, something hospital workers may encounter a lot. Meanwhile, hepatitis C spreads through contaminated blood. Ever flexible, hospitals have to develop and follow safety procedures for each possible virus, including the use of protective equipment, proper handling of needles, proper storage and handling of blood. They also have to limit the number of people who have contact with a patient to those necessary for care [source: CDC].
Fungal or Parasitic Infections
Fungal infections can enter the body and be spread through a hospital just like the other infections on this list. Catheters, surgical sites and examinations from hospital workers who haven't washed their hands loom as possible ways for fungal infections to occur. There are a few differences between fungal infections and viral or bacterial infections, however.
Fungi occur naturally in the environment. Patients with weak immune systems are most at risk, so if a doctor prescribes an antifungal medication, it's important to take it properly. Hospital cleanliness and ventilation are important, too [source: CDC]. But sometimes fungal infections can be transmitted in unexpected ways. An outbreak of a flesh-eating fungal infection, mucormycosis, at Children's Hospital in New Orleans was traced to improper handling of contaminated sheets and gowns. Ultimately, five patients died from the infection, and it was months before hospital officials determined the source of the outbreak [source: Urbina and Fink].
Parasites are less common in hospitals, but still a serious problem for people with vulnerable immune systems. Giardia, for example, spreads through the ingestion of cysts – contaminated food and improperly sterilized areas that have been in contact with patients' fecal matter are possible methods of transmission. Scabies could be one of the most unpleasant parasitic infections, caused by mites that spread by skin-to-skin contact. Patients with deficient immune systems can get crusted scabies, a highly contagious version in which the skin becomes crusted over with lesions that contain thousands of mites [source: CDC].
HowStuffWorks asks whether patients should ask doctors for reimbursement when they have to wait a long time to be seen.
Author's Note: 10 Common Hospital-acquired Infections
I've been fortunate to have avoided spending much time in hospitals in recent years, so this topic wasn't really on my radar. Antibiotic-resistant strains of bacteria are seriously scary, though. As a sci-fi fan, it's always tempting to look for apocalyptic worst-case scenarios, but fighting disease is a process – you really get a sense for the way procedures and methods are developed based on experience and research.
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- Augustyn, Beth. "Ventilator-Associated Pneumonia: Risk Factors and Prevention." Critical Care Nurse. August 2007. (Oct. 8, 2014) http://ccn.aacnjournals.org/content/27/4/32.full
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- Centers for Disease Control and Prevention. "Overview and Evidence to Support Stewardship." November 2010. (Oct. 8, 2014) http://www.cdc.gov/getsmart/healthcare/evidence.html
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- Urbina, Ian and Fink, Sheri. "A Deadly Fungus and Questions at a Hospital." The New York Times. April 28, 2014. (Oct. 8, 2014) http://www.nytimes.com/2014/04/29/us/a-deadly-fungus-and-questions-at-a-hospital.html
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