General overview
Klebsiella spp are usually opportunistic pathogens. They cause nosocomial infections such as pneumonia and urinary tract infections.
Furthermore, Klebsiella pneumoniae causes respiratory tract infections outside hospitals as well.
They cause chest infections and occasionally severe bronchopneumonia with lung abscesses.
As these organisms are opportunistic pathogens, infections can be highly seen among the patients with existing chest diseases, diabetes mellitus, or in malnutrition.
Klebsiella spp also cause soft tissue infections, endocarditis, and infections in central nervous system and in many cases, they cause bacteraemia.
In those infections mortality rate is high. Polysaccharide capsule is the major virulent factor of Klebsiella spp.
Klebsiella spp is more related to the Enterobacter spp. Klebsiella also divided in to some species.
They are K. pneumoniae, K. aerogenes, K. ozaenae, and K. rhinoscleromatis.
Specimens such as urine, pus, blood, sputum and infected tissues are used for culture. It depends on the site of infection.
They are non-motile and capsulated organisms. On Gram-stained smears they can be seen as Gram negative bacilli. They are about 1–2 µm long.
They are aerobes and facultative anaerobes.
They may survive in room temperature without drying for many weeks and they may not destroy in dry conditions.
Blood agar
This organism produces large, mucoid colonies. They are gray white in colour.
MacConkey agar
Produce lactose fermenting pink colour colonies on MacConkey agar.
They are mucoid colonies.
CLED agar
Produce yellow colour mucoid colonies on CLED agar medium.
EMB agar also can be used as a differential medium. They produce pink colour, large, mucoid colonies. However, Klebsiella do not give metallic green sheen on EMB agar.
Biochemical Investigations
- Klebsiella are indole negative
- Ornithine decarboxylase negative
- Do not produce H2S
To differentiate Klebsiella upto species level, there are some other biochemical tests.
| Urease | Citrate | Malonate utilization | Lysine decarboxylase | Voges-Proskauer (VP) | Lactose fermentation |
K. pneumoniae | + | + | + | + | – | + |
K. aerogenes | + | + | + | + | + | + |
K. ozaenae | – | +/- | – | +/- | – | +/- |
K. rhinoscleromatis | – | – | + | – | – | – |
Treatment
They often produce beta-lactamases and are show multiple antibiotic drugs resistance.
Always they are highly resistant to penicillins and many cephalosporins.
Many strains also show resistant to chloramphenicol, tetracyclines and streptomycin.
However, many strains sensitive to fluoroquinolones, co-trimoxazole and carbapenems.
The choice of drug for the treatment depends on the formal antibiotic sensitivity test results.
When in hospital acquired infections, organisms show multiple drug resistance.
Prevention
By changing the site of intravenous catheters, removing or changing of urinary catheters without keeping them long time, proper management of respiratory therapy devices may be helpful to prevent some hospital-acquired infections.
There is no vaccine to prevent the disease.
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