Klebsiella

Klebsiella is a genus of bacteria that is usually acquired in healthcare settings such as hospitals, nursing homes, and other long-term care facilities. Species of Klebsiella can cause a variety of infections, including pneumonia, urinary tract infections, blood infections, meningitis, and infections of wounds or surgical incisions. They present specific problems for healthcare providers because they often attack people who are already weakened by illness or injury, and because they are increasingly resistant to antibiotics.

Overview

Klebsiella bacteria are named for the German biologist who discovered them in the late nineteenth century, Edwin Klebs (1834-1913). They occur naturally in the human intestines, where they are not dangerous, and in human feces. The bacteria are non-motile, or incapable of moving on their own, and completely covered in a capsule made of carbohydrate molecules known as polysaccharides. This capsule helps to protect the bacterium from attacks by the body's immune system.

Several species of the genus Klebsiella affect humans; for example, Klebsiella pneumoniae, Klebsiella oxytoca, and Klebsiella rhinoscleromatis. They are spread by person-to-person contact (i.e., through contact with contaminated hands, surfaces, or medical equipment). The bacteria can also easily enter the body through medical devices such as catheters or ventilators. While otherwise healthy people can contract a Klebsiella infection, they are more common in people whose immune systems are already weakened and by those in an inpatient medical setting.

The type of symptoms that will be exhibited depends on what part of the body is affected by the bacteria and will be the same as an infection in that location from any other cause. For instance, a person who contracts pneumonia from a Klebsiella bacterium will have the same symptoms of fever, chills, chest pain, and breathing issues as a person whose pneumonia has another cause. This is why it is very important for the medical team to order tests to determine the cause and identify the presence of Klebsiella as soon as possible.

Klebsiella bacteria are opportunistic organisms, which means they take advantage of various forms of weakness to enter and infect the body. In addition to the risk from being immunocompromised or a hospital or surgical patient, older adults are also more likely to be affected. In some parts of the world, such as Asia, senior citizens account for the majority of those who fall victim to a Klebsiella-related infection. In the United States, alcohol use disorder is a risk factor among patients diagnosed with Klebsiella infections. While Klebsiella infections can be severe, mortality is higher in patients with underlying conditions, including alcohol use disorder.

Klebsiella infections are diagnosed by gathering a specimen for testing in the laboratory. Klebsiella has developed resistance to many antibiotics. This includes carbapenems, which are antibiotics that were developed to treat resistant organisms. The Centers for Disease Control and Prevention (CDC) classified carbapenem-resistant Klebsiella as part of an urgent public health threat due to its resistance to multiple antibiotics. Treatment depends on antibiotic susceptibility testing, but the antibiotics used commonly include third-generation cephalosporins such as ceftriaxone, aminoglycosides such as gentamicin, and quinolones. Clinical guidelines recommend β-lactam/β-lactamase inhibitor combinations for treating multidrug-resistant Klebsiella infections, and a combination product, ceftazidime/avibactam, was approved for use in the United States for the types of infections caused by Klebsiella bacteria in 2015. From the early 2000s, Klebsiella began to develop resistance to many antibiotics. Hence, antibiotics such as meropenem-vaborbactam and imipenem-cilastatin-relebactam are recommended for drug-resistant Klebsiella infections.

Bibliography

“About Klebsiella.” Centers for Disease Control, 12 June 2025, www.cdc.gov/klebsiella/about/index.html. Accessed 28 Mar. 2026.

Centers for Disease Control and Prevention. “Antibiotic Resistance Threats in the United States, 2019.” U.S. Department of Health and Human Services, 2019, www.cdc.gov/antimicrobial-resistance/media/pdfs/2019-ar-threats-report-508.pdf. Accessed 28 Mar. 2026.

“Klebsiella Species: Guidance, Data and Analysis.” Gov.UK, 12 July 2018, www.gov.uk/guidance/klebsiella-species. Accessed 28 Mar. 2026.

Park, Sung-Yeon, et al. “Guidelines for Antibacterial Treatment of Carbapenem-Resistant Enterobacterales Infections.” Infectious Chemotherapy, vol. 56, no. 3, 2024, pp. 308-328, doi: 10.3947/ic.2024.0038. Accessed 28 Mar. 2026.

Qureshi, Shahab. “Klebsiella Infections.” Medscape, 16 Oct. 2024, emedicine.medscape.com/article/219907-overview. Accessed 28 Mar. 2026.

Shaw, Gina. “Breaking News: Deadly Klebsiella Pneumoniae Strain Resistant to Carbapenems.” Emergency Medicine News, Mar. 2013, journals.lww.com/em-news/fulltext/2013/03000/breaking_news__deadly__klebsiella_pneumoniae_.3.aspx.3.aspx. Accessed 28 Mar. 2026.

Srivastava, Roli. “Drug Resistant Bug Klebsiella Causes Worry.” The Hindu, 16 Nov. 2021, www.thehindu.com/sci-tech/health/medicine-and-research/drugresistant-bug-klebsiella-causes-worry/article7928014.ece. Accessed 28 Mar. 2026.