Klebsiella pneumoniae - MegaMicro

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Klebsiella pneumoniae

Micro > Bacteriology > Gram-negative bacteria > Gram-negative bacilli > Enterobacteriaceae > Klebsiella
1. Structure
a. K. pneumoniae is a gram negative, non-motile, bacilli part of the Enterobacteriaceae family.
b. They have a cell wall with LPS, and express both O and K surface antigens. They are encapusulated.
2. Pathobiology:
a. They are facultative anaerobes. They participate in lactose fermentation.
b. They have endotoxin activity via the lipid A component of the LPS. They have a capsule which will protect against phagocytosis, phase variation of antigens, type 3 secretion system, and may sequester growth factors. Additionally, they have factors that prevent complement binding and express adhesins to better attach to hosts.
3. Epidemiology
a. Ubiquitous but normally found in normal flora of mouth, skin, and intestines.
b. Growing involvement in nosocomial infections.
c. Oropharyngeal carriage has been associated with endotracheal intubation, impaired host defenses, and antimicrobial use.
d. Higher risk for those with alcoholism (more common among older and middle-aged men).
4. Laboratory diagnosis
a. Obtain cultures from possible sites of infection or sputum sample
b. Gram stain: Bacteria appear as short, plump, gram negative bacilli surrounded by a clear capsular space.
c. Growth on MacConkey agar: mucoid colonies, lactose-fermenting
d. Can be isolated from blood, urine, pleural fluid, and wounds.
5. Disease manifestations
a. Diagnosed using culture.
b. Supported with lab studies, need to look at chest x-rays for presence of swelling in lobes (bulging fissure sign) or unilateral necrotizing pneumonia.
c. More prone to pleural effusion, empyema, abscess formation, and pleura adhesions.
d. Commonly manifests as pneumonia, UTI, nosocomial infection.
6. Therapy
a. Often resistant to multiple antibiotics.
b. Usually use third generation cephalosporins, carbapenems, aminoglycosides, and quinolones.
c. Often resistant to ampicillin, amoxicillin, and ticarcillin.
7. Prevention and control
a. Following hospital protocol and limiting spread of nosocomial infection is key. This includes proper hand washing and using single-use devices, removing medical devices when no longer needed, adjusting position of intubated patients, etc.

Related concepts

Key Words
Enterobacteriaceae
community-acquired pneumonia
nosocomial

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