Diseases and Organisms in Healthcare Settings

The following organisms and diseases frequently occur in healthcare settings and can result in healthcare-associated infections (HAI).

Image of Staphylococcus aureus (from the Public Health Image Library- http://phil.cdc.gov).

The information provided below has been adapted from the CDC website:

http://www.cdc.gov/HAI/organisms/organisms.html (last updated Feb. 20, 2011)

Acinetobacter

Acinetobacter is a group of bacteria commonly found in soil and water. Outbreaks of Acinetobacter infections typically occur in intensive care units and healthcare settings housing very ill patients. While there are many types or “species” of Acinetobacter and all can cause human disease, Acinetobacter baumannii accounts for about 80% of reported infections. Acinetobacter infections rarely occur outside of healthcare settings.

Burkholderia cepacia

Burkholderia cepacia is the name for a group or "complex" of bacteria that can be found in soil and water. Burkholderia cepacia bacteria are often resistant to common antibiotics. Burkholderia cepacia poses little medical risk to healthy people; however, it is a known cause of infections in hospitalized patients. People with certain health conditions, like weakened immune systems or chronic lung diseases (particularly cystic fibrosis), may be more susceptible to infections with Burkholderia cepacia.

Clostridium difficile

Clostridium difficile is a bacterium that causes an inflammation of the colon; this condition is called colitis. Diarrhea and fever are the most common symptoms of Clostridium difficile infection. Overuse of antibiotics is the most important risk for getting Clostridium difficile infection. [Clostridium difficile is also called C. difficile, C. diff, and CDI (Clostridium difficile infection), CDAD(Clostridium difficile-associated disease)]

Clostridium sordellii

Clostridium sordellii is a rare bacterium that causes pneumonia, endocarditis, arthritis, peritonitis, and myonecrosis. Clostridium sordellii bacteremia and sepsis (bacteremia is when bacteria is present in the bloodstream; sepsis is when bacteremia or another infection triggers a serious bodywide response) occur rarely. Most cases of sepsis from Clostridium sordellii occur in patients with other health conditions. Severe toxic shock syndrome among previously healthy persons has been described in a small number of Clostridium sordellii cases, most often associated with gynecologic infections in women and infection of the umbilical stump in newborns.

Enterobacteriaceae

Enterobacteriaceae are a normal part of human flora and are an important cause of healthcare associated infections. Some strains have extensive antimicrobial resistance and referred to as carbapenem-resistant Enterobacteriaceae (CRE). CRE are an important public health problem, regardless of their mechanism of resistance or their country of origin. Carbapenem-resistance in Enterobacteriaceae can occur by many mechanisms, including the production of a metallo-beta-lactamase or a carbapenemase (such as Klebsiella pneumoniae carbapenemase, KPC).

Hepatitis

The word hepatitis means inflammation of the liver and also refers to a group of viral infections that affect the liver. The most common types are hepatitis A, hepatitis B, and hepatitis C.

The delivery of healthcare has the potential to transmit hepatitis to both healthcare workers and patients. Outbreaks have occurred in outpatient settings, hemodialysis units, long-term care facilities, and hospitals, primarily as a result of unsafe injection practices; reuse of needles, fingerstick devices, and syringes; and other lapses in infection control.

Human Immunodeficiency Virus (HIV/AIDS)

Human immunodeficiency virus (HIV) is the virus that can lead to acquired immune deficiency syndrome (AIDS). HIV destroys blood cells called CD4+ T cells, which are crucial to helping the body fight disease. This results in a weakened immune system, making persons with HIV or AIDS at risk for many different types of infections. Transmission of HIV to patients while in healthcare settings is rare. Most exposures do not result in infection.

Influenza

Influenza is primarily a community-based infection that is transmitted in households and community settings. Each year, 5% to 20% of U.S. residents acquire an influenza virus infection, and many will seek medical care in ambulatory healthcare settings (e.g., pediatricians’ offices, urgent-care clinics). In addition, more than 200,000 persons, on average, are hospitalized each year for influenza-related complications. Healthcare-associated influenza infections can occur in any healthcare setting and are most common when influenza is also circulating in the community.

Therefore,influenza-related complications should be implemented in all healthcare settings. Supplemental measures may need to be implemented during influenza season if outbreaks of healthcare-associated influenza occur within certain facilities, such as long-term care facilities and hospitals.

Klebsiella

Klebsiella is a type of Gram-negative bacteria that can cause healthcare-associated infections including pneumonia, bloodstream infections, wound or surgical site infections, and meningitis. Increasingly, Klebsiella bacteria have developed antimicrobial resistance, most recently to the class of antibiotics known as carbapenems. Klebsiella bacteria are normally found in the human intestines (where they do not cause disease). They are also found in human stool (feces). In healthcare settings, Klebsiella infections commonly occur among sick patients who are receiving treatment for other conditions. Patients who have devices like ventilators (breathing machines) or intravenous (vein) catheters, and patients who are taking long courses of certain antibiotics are most at risk for Klebsiella infections. Healthy people usually do not get Klebsiella infections.

Methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) is a type of staph bacteria that is resistant to certain antibiotics called beta-lactams. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin. In the community, most MRSA infections are skin infections. More severe or potentially life-threatening MRSA infections occur most frequently among patients in healthcare settings.

Mycobacterium abscessus

Mycobacterium abscessus is a bacterium distantly related to the ones that cause tuberculosis and leprosy. It is found in water, soil, and dust. It has been known to contaminate medications and products, including medical devices. Healthcare-associated Mycobacterium abscessus can cause a variety of infections that require medical attention. Infections due to this bacterium are usually of the skin and the soft tissues under the skin. It can also cause lung infections in persons with various chronic lung diseases.

Norovirus

Noroviruses are a group of viruses that cause gastroenteritis in people. Gastroenteritis is an inflammation of the lining of the stomach and intestines, causing an acute onset of severe vomiting and diarrhea. Norovirus illness is usually brief in people who are otherwise healthy. Young children, the elderly, and people with other medical illnesses are most at risk for more severe or prolonged infection. Like all viral infections, noroviruses are not affected by treatment with antibiotics.

Staphylococcus aureus

Staphylococcus aureus (staph), is a bacterium commonly found on the skin and in the nose of about 30% of individuals. Most of the time, staph does not cause any harm. These infections can look like pimples, boils, or other skin conditions and most are able to be treated.

Tuberculosis (TB)

Tuberculosis is caused by a bacterium called Mycobacteriumtuberculosis. Transmission of Mycobacterium tuberculosis is a recognized risk to patients and healthcare personnel in healthcare facilities. Transmission is most likely to occur from patients who have unrecognized pulmonary tuberculosis or tuberculosis related to their larynx, are not on effective anti-tuberculosis therapy, and have not been placed in tuberculosis isolation. Transmission of Mycobacterium tuberculosis in healthcare settings has been associated with close contact with persons who have infectious tuberculosis, particularly during the performance of cough-inducing procedures such as bronchoscopy and sputum induction. Mycobacterium Tuberculosis is spread through air and can travel long distances. Cases of multidrug-resistant tuberculosis (MDR-TB, which includes extensively drug-resistant tuberculosis [XDR-TB]), have been recognized and are more difficult to treat.

Vancomycin-intermediate Staphylococcus aureus (VISA) and Vancomycin-resistant Staphylococcus aureus (VRSA)

Vancomycin-intermediate Staphylococcus aureus (also called S. aureus) and vancomycin-resistant Staphylococcus aureus are specific staph bacteria that have developed resistance to the antimicrobial agent vancomycin. Persons who develop this type of staph infection may have underlying health conditions (such as diabetes and kidney disease), devices going into their bodies (such as catheters), previous infections with methicillin-resistant Staphylococcus aureus, and recent exposure to vancomycin and other antimicrobial agents.

Vancomycin-resistant Enterococci (VRE)

Vancomycin-resistant Enterococci are specific types of antimicrobial-resistant bacteria that are resistant to vancomycin, the drug often used to treat infections caused by enterococci. Enteroccocci are bacteria that are normally present in the human intestines and in the female genital tract and are often found in the environment. These bacteria can sometimes cause infections. Most vancomycin-resistant Enterococci infections occur in hospitals.