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What Is a Nosocomial Infection?

Hospital Acquired Exogenous, Endogenous, Iatrogenic & Superinfection

© Tami Port

Jan 31, 2009
Clostridium difficile Colonies on Blood Agar, CDC Centers for Disease Control
Whether you are a patient or a health care worker, nosocomial infections are a type of illness that you should be concerned about. Read on and help protect yourself.

People visit the doctor to get well, right? But many unwittingly go to the doctor’s office or hospital to get sick. How’s this possible?

Nosocomial infections are infections acquired in a health care environment (also called hospital-acquired or healthcare-associated infections), and both patients and health care workers are at risk. Current estimates by the CDC (Centers for Disease Control) indicate that more than two million people (10% of US patients) fall victim to a nosocomial infection each year, and 90,000 afflicted die.

Transmission of Nosocomial Infections

  • In a health care environment, anyone can easily become exposed to pathogens from ill patients. And many of these microbes are especially tough; resistant to antibiotics and other antimicrobial agents frequently used in health care establishments.

  • The weakened immune system of patients who are ill is also a factor. In other words, if your immune system is busy fighting off an infection, it has fewer resources available to battle new invaders.

  • Transmission of pathogenic (disease causing) microbes can easily occur between sick patients and health care workers moving from room to room, patient to patient.

This may seem like a bizarre concept, after all, people who are sick seek out medical care in order to get better. But think about it. When you enter a health care establishment, be it a doctor’s office or hospital, who do you find there? A bunch of sick people. Yet you really need to go to the doctor when you are sick. So how do you protect yourself? It helps to understand the different types, or categories of nosocomial infections.

Exogenous Nosocomial Infections

Exogenous infections are from pathogens acquired in the health care environment, where there is a high concentration of sick people carrying pathogenic microbes, and where health care workers come in contact with multiple patients, potentially spreading those infections.

Endogenous Nosocomial Infections

Endogenous infections are those acquired from normal microbiota (the usually harmless microbes that normally live on our bodies) which have ‘gone rogue’ in the health care environment, where people often have compromised immune systems and are more vulnerable to opportunistic infections (infections resulting from microbes that are normally harmless, but always ready to take advantage and cause infection if the opportunity presents itself).

Iatrogenic Nosocomial Infections

Iatrogenic literally means ‘doctor induced’. These are a type of nosocomial infection that results from modern medicine itself—catheters, surgery and other invasive medical procedures can introduce bacterial into axenic (sterile) areas of the body.

Superinfections

Certain infections can actually result from the use of antibiotics (drugs designed to combat bacterial infections). Since our bodies are covered with normal microbiota (microbes that normally live in and on our bodies without causing us harm). These normal microbiota aren’t typically harmful. They even help protect us from infection from other microbes that can cause disease (pathogens). At the very least, normal microbiota take up space and resources on our body, and if ‘good-guy’ microbes are taking up space, ‘bad guy’ microbes have a more difficult time establishing themselves and causing infection.

When we take broad spectrum antibiotics, which indiscriminately wipe out good and bad microbes, we inadvertently remove the competition—providing pathogens with a competition-free environment in which to thrive, and selecting for antibiotic resistant bacteria. Clostidium diffucile (C. diff) infections are an excellent example of this is phenomenon. Normal microbiota prevent C. diff from persisting and thriving in the colon. A painful condition called pseudomembranous colitis can result when antibiotic resistant C. diff are allowed to flourish in the aftermath of antibiotic treatment.

Sources

Bauman, R. (2007). Microbiology with Diseases by Taxonomy. Pearson Benjamin Cummings.

Bauman, R. (2004). Microbiology. Pearson Benjamin Cummings.


The copyright of the article What Is a Nosocomial Infection? in Human Infections is owned by Tami Port. Permission to republish What Is a Nosocomial Infection? in print or online must be granted by the author in writing.


Clostridium difficile Colonies on Blood Agar, CDC Centers for Disease Control
        


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Comments
Mar 23, 2009 12:21 AM
Guest :
We must warn all healthcare workers about the danger of using devices & instruments in hospitals and clinics. Today its stethoscope, tomorrow it will be autoscore and next the ophthalmoscope. We must go back thirty years and see how we managed patients without these instrument. Healthcare professionals have forgotten why these instruments are used and how to use them. They have become the status symbol more than necessary.

My teachers (student of the great clinician Chamberlain) educated me to diagnose children with heart disease without using a stethoscope. “The most important part of a stethoscope in not the diaphragm nor the make, but the part between the two ear pieces”. This I have cherished and practiced for more than twenty five years and still came out triumphant when others failed to diagnose a simple clinical symptom or disease.

I feel sad to see doctors and nurses take out their stethoscope from their bug-filled handbags and place them on the chest. They seem to think they can diagnose what is wrong with the patient, when they could just check the pulse and probably tell more about the clinical condition. The past twenty years, most clinicians have dangled the stethoscope and made this synonymous with the word “Doctor”, patients demand using a stethascope.

It looks as if we have forgotten the important steps like observation, palpation and percussion and then the auscultation. Based on present evidence of MRSA colonized in medical instruments, we will soon be fighting legal battles due to claims brought in by patients accusing us of using unsterile stethoscope or an otoscope. I do not know how it will be when they start sexual assault charges because you placed your hands on the breast of a young female patient to avoid using a stethoscope.

I am in the process of writing an article "To or Not To Clinically Examine", please contribute to this debate or email me a note.
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