Klebsiella, Enterobacter, and Serratia are closely related gram-negative bacteria that occasionally infect the urinary tract or respiratory tract of people in hospitals or in long-term care facilities.
These bacteria may infect the urinary or respiratory tract, intravenous catheters used to give medications or fluids, burns, wounds made during surgery, or the bloodstream.
Identifying the bacteria in a sample taken from blood or from infected tissue confirms the diagnosis.
Infections caused by all 3 bacteria are treated with antibiotics given by vein (intravenously).
(See also Overview of Bacteria.)
Klebsiella, Enterobacter, and Serratia bacteria reside in the intestine of many healthy people and rarely cause infection in them. Infections with these bacteria are often acquired in hospitals and long-term care facilities. They usually occur in people whose resistance to infection is weakened and/or who have a medical device (such as catheters, drains, and airway tubes) in their body.
These bacteria may infect different places in the body:
Urinary or respiratory tract (causing pneumonia, bladder infections, or kidney infections)
Catheters inserted into a vein (intravenous catheter), used to administer medications or fluids
Wounds made during surgery
Bloodstream (causing bacteremia or sepsis)
Rarely, Klebsiella bacteria cause pneumonia in people who live outside a health care facility (in the community), usually in people with an alcohol use disorder, older adults, people with diabetes, or people with a weakened immune system. Typically, this severe infection causes cough, bringing up a sticky, dark brown or dark red sputum, and collections of pus (abscesses) in the lungs or in the membrane between the lungs and chest wall (empyema).
One species of Klebsiella produces a toxin that can cause inflammation of the colon and bleeding (hemorrhagic colitis) after antibiotics are taken. This disorder is called antibiotic-associated colitis. The antibiotics kill bacteria that normally reside in the intestine. Then Klebsiella bacteria are able to multiply and produce the toxin. However, antibiotic-associated colitis usually results from toxins produced by Clostridioides difficile.
Diagnosis of Klebsiella, Enterobacter, and Serratia Infections
Examination and culture of a sample of infected tissue
Doctors suspect one of these infections in people at high risk of getting one, such as people who live in a long-term care facility or in a place when there is or was an outbreak.
To confirm the diagnosis, doctors take a sample of sputum, lung secretions (obtained through a bronchoscope), blood, urine, or infected tissue. The sample is stained with Gram stain, cultured, and examined under a microscope. These bacteria can be readily identified.
Other tests depend on the type of infection. They may include imaging tests, such as ultrasound studies, x-rays, and computed tomography (CT) scans.
Bacteria identified in samples are tested to determine which antibiotics are likely to be effective (a process called susceptibility testing).
Treatment of Klebsiella, Enterobacter, and Serratia Infections
Antibiotics given by vein (intravenously)
Infections caused by any of these 3 bacteria are treated with antibiotics given intravenously.
If an infection with any of these 3 bacteria is acquired in a health care facility, the infection can be difficult to treat because bacteria acquired in such facilities are usually resistant to many antibiotics.
