Microbiology · Enterobacterales
Klebsiella pneumoniae !
- Bacterium
- Gram-negative
- Contact
- Exam priority: medium
A gut bacterium with a thick capsule. It causes pneumonia, urinary infection and sepsis in hospitals; many strains resist key antibiotics.
Updated 2026-11-01
At a glance
- Gram
- Gram-negative
- Shape
- Rod
- Oxygen
- Facultative anaerobe
- Family
- Enterobacteriaceae
- Stain
- Gram: red encapsulated rods
Morphology
- Non-motile Gram-negative rod with a large polysaccharide capsule
- Lactose fermenter: pink, very mucoid colonies on MacConkey
- Urease-positive, oxidase-negative
Transmission
- Person-to-person contact, mainly through contaminated hands in hospital
- Contaminated equipment: ventilators, IV catheters and urinary catheters
- Not airborne
- Contact (on top of standard) for carbapenem-resistant strains
Reservoir: Human gut; Hospital environment, water and soil
Isolation precautions
What the care team adds to standard precautions.
- Contact
- Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.
Virulence factors
- Capsule: blocks phagocytosis; hypermucoviscous strains are more aggressive
- LPS: sepsis
- Intrinsic ampicillin resistance (SHV-1 beta-lactamase)
- Plasmids carrying ESBL and carbapenemases (KPC, NDM) that pass to other bacteria
Diseases it causes
- Pneumonia, classic in people with alcohol use disorder or diabetes, and ventilator-associated pneumonia Community-acquired pneumonia →
- Urinary infection, especially catheter-associated Urinary tract infection (acute cystitis) →
- Bacteremia and sepsis; also liver abscess and surgical wound infection Sepsis and septic shock →
Clinical picture
- Pneumonia with thick bloody sputum ("currant jelly"), often upper lobe and cavitating
Diagnosis
- Culture of sputum, urine or blood: pink mucoid colonies
- Susceptibility testing with screening for ESBL and carbapenemases (phenotypic tests and PCR for KPC, NDM and others)
Treatment
Guided by the antibiogram. Susceptible strains: third-generation cephalosporins; ESBL producers: carbapenems; KPC producers: newer beta-lactamase inhibitor combinations such as ceftazidime-avibactam, or combination regimens chosen with infectious diseases.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Hand hygiene and contact precautions for resistant strains
- Early removal of catheters and ventilators
- Careful antibiotic use (stewardship programs)
- Carrier screening during outbreaks
Test yourself
Think of the answer, then tap the question to see it.
What do Klebsiella pneumoniae colonies look like, and why?
Pink and very mucoid, from its large polysaccharide capsule and lactose fermentation.
Which classic pneumonia is described in patients with alcohol use disorder?
Klebsiella pneumonia, with thick bloody "currant jelly" sputum and cavitation.
What is KPC?
A plasmid-encoded carbapenemase of Klebsiella pneumoniae that destroys almost all beta-lactams, carbapenems included.
Which isolation precaution is used for carbapenem-resistant Enterobacterales?
Contact precautions, on top of standard.
Related
Related conditions
← Back to the group: Enterobacterales
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: About Klebsiella (CDC, 2025); First Detection of the Plasmid-Mediated Class A Carbapenemase KPC-2 in Clinical Isolates of Klebsiella pneumoniae from South America (Antimicrobial Agents and Chemotherapy (PMC), 2006); Epidemiological Alert: Emergence and increase of new combinations of carbapenemases in Enterobacterales in Latin America and the Caribbean - 22 October 2021 (PAHO, 2021); Antimicrobial resistance (WHO, 2026).
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Representative model, for educational purposes only.