Klebsiella pneumoniae
Pnuemonia, UTIs and bacteremia
Classic Case: K. pneumoniae Pneumonia
Middle aged patient, alcoholic, presents with fever/chills, productive cough, and difficulty breathing. Sputum has a thick, currant jelly-like consistency. Sputum samples show a Gram-negative, encapsulated, non-motile bacillus that ferments lactose.
Causative Agent of:
- Pneumonia
- UTIs
Physical Features
- Enterobacteriaceae members
- Gram-negative
- Rods
- Non-motile
- Has a thick polysaccharide capsule
- = Mucoid colonies
Epidemiology
- World-wide
- Second most-common cause of bacteremia post-UTI
- After E. coli
- Common hospital-acquired (nosocomial) infection
- Very commonly isolated in hospitals
Growth Features
- Facultative anaerobe
- Lactose fermenter
- Catalase-positive
- Antibiotic resistance
- β-lactamase (all are ampicillin-resistant)
- Carbapenem-resistance
- MDR (multi-drug-resistance) increasing
Reservoir
- Found in soil and water
- Also normal flora of human GI tract
- Sometimes the oropharynx as well
- As high as 40% of general population
Transmission and Risk Groups
Transmission:
- Person-person
- Typically in health-care settings
- Nosocomial (hospital-acquired) infection
- Pneumonia: Aspiration of bacteria into lung
- e.g. via ventilators
- UTI: Bacteria ascend urinary tract
- e.g. via catheters
Risk Groups:
- Hospitalized patients
- Immunocompromised
- Alcoholics (specific risk of pneumonia)
K. pneumoniae mucoid colonies
K. pneumoniae, electron micrograph
Klebsiella pneumoniae, Summary
Clinical
KlebsiellaSymptoms
- Pneumonia:
- Usually rapid onset, usually upper lobes
- Can cause necrotizing/hemorrhagic lesions
- Sputum: Often called “currant-jelly” (BW)
- Due to hemorrhaging/blood in sputum
- Urinary tract infections:
- Dysuria, abdominal pain
- Can lead to bacteremia
- Indistinguishable from other bacterial causes
Complications
- Bacteremia is greatest risk in UTI patients
- Meningitis, wound infections possible
VIrulence Factors
- Capsule: Blocks phagocytosis
- Adheres to pulmonary, urinary linings
- Causes mucoid colony appearance
- Antibiotic resistance:
- Ampicillin-resistant (chromosomal β-lactamase)
- Plasmids with β-lactamases, carbapenemases
- KPC: K. pneumoniae carbapenemase
- A serious threat: can spread drug-resistance
- = Carbapenem-resistant Enterobacteriaceae (CRE)
Diagnosis
- Pneumonia:
- Sputum analysis, microscopy and isolation
- UTI:
- Urine analysis, microscopy and isolation
Prevention
- Infection-control precautions in healthcare settings
- Good hygiene
Klebsiella pneumoniae, Gram stain
Treatment
- Multi-drug resistance (MDR) a major problem
- Especially with nosocomial isolates
- Tx depends on susceptibility
- Non-MDR? Cephalosporins, TMP-sulfamethoxazole
- Fluoroquinolones, aminoglycosides
- MDR? Carbapenems, 4th-gen cephalosporins
- Some KPC strains can be resistant to all drugs
Other Klebsiella spp. that cause disease:
K. oxytoca:
- Also causes nosocomial infections
K. granulomatis:
- Chronic genital ulcers (genitals, anus)
- Usually painless
- Can reach large sizes, cause lymphedema
References
- The CDC on Klebsiella.
- Carbapenemase-producing Klebsiella pneumoniae. 2014. F1000Prime Rep. 6:80.
- Clinical epidemiology of the global expansion of Klebsiella pneumoniae carbapenemases.2013. Lancet Infect Dis. 13:785.
- Limiting and controlling carbapenem-resistant Klebsiella pneumoniae. 2014. Infect. Drug Resist. 7:9.
- Carbapenemase-Producing Klebsiella pneumoniae, a Key Pathogen Set for Global Nosocomial Dominance. 2015. Antimicrob. Agents Chemother. 59:5873.
- Klebsiella: a long way to go towards understanding this enigmatic jet-setter. 2014. F1000Prime Rep. 6:64.
- Hypervirulent (hypermucoviscous) Klebsiella pneumoniae. 2013. Virulence. 4:107.
- Klebsiella spp. as Nosocomial Pathogens. 1998. Clin. Microbiol. Rev. 11:589.