Morfolojisi 
 Klebsiella pneumoniae hareketsiz, sporsuz, geniş kapsüllü, gram negatif  (-) basildir. Genellikle uç uca, ikişer ikişer kısa zincirler halinde ve tek tek bulunur. Bakteriyolojik boyalarla iyi boyanır.

Üreme Özellikleri 
Klebsiella pneumoniae, aerob ve fakültatif anaerobdur. Optimal üreme ısısı 37oC, optimal pH‟sı 7.4‟tür. Kuruluğa dirençli olup özellikle organik maddeler içinde kurutulurlarsa aylarca canlı kalır. Isıya dayanıksız olup nemli ısıda 55 oC‟de yarım saate ölür. Sıvı besiyerinde homojen bir bulanıklık, yüzeyde zar ve dipte mukoid bir çöküntü oluşturarak ürer. Katı besiyerinde mukuslu ve kapsüllü olduğu için öze ile alındığında sünen M tipi koloniler oluşturur; kanlı jelözde hemoliz oluşturmaz. İndol, H2S, Voges-Proskauer, metil kırmızısı testleri negatif, üre ve KCN testleri pozitif olan bakterilerdir.

Yaptığı Hastalıklar 
 Klebsiella pneumoniae; bulunduğu yerlerde uygun koşulların oluşması veya yer değiştirerek diğer organ ve sistemlere yerlemeleri halinde, başta pnömoni olmak üzere, anjin, sinüzit, otitis media, üst solunum yolu enfeksiyonu, gastroenterit, septesemi, menenjit, kolesistit ve üriner sistem hastalıklarına neden olur.

 Laboratuvar Teşhisi  
➨ İnceleme örnekleri: İdrar, balgam, kan, dışkı, boğaz sürüntüsü, cerahat. 
➨Teşhis yöntemleri 
➧ Mikrobiyolojik örneğin direkt mikroskobik incelemesi; santrifüj edilen idrardan hazırlanan preparatın incelenmesinde; bol lökosit ve ikişerli hareketsiz bakterilerin görülmesiyle ve hazırlanan preparatın gram boyasıyla boyanarak incelenmesiyle de teşhis edilir.
➧ Kültür; EMB AGAR, Endo, Mac-Conkey Agar besiyerine ekim yapılır.
➧ Biyokimyasal Testler; tipik mukoid kolonilerden çeşitli biyokimyasal testlerle teşhis edilir.
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The genus Klebsiella consists of non-motile, aerobic and facultatively anaerobic, Gram negative rods. At the time of writing, the genus Klebsiella comprises K. pneumoniae subsp. pneumoniae, K. pneumoniae subsp.ozaenae, K. pneumoniae subsp. rhinoscleromatis, K. oxytoca, K. ornithinolytica, K. planticola, and K. terrigena. However, comparison of the sequences of each species shows that the genus is heterogeneous, and may be more reasonably arranged in three clusters. Cluster 1 contains the three subspecies of  K. pneumoniae, cluster 3 contains K. oxytoca and cluster 2 contains the other species (which are notable for growth at 10° C and utilization of L-sorbose as a carbon source). It has been proposed that the genus Klebsiella be divided into two genera and one genogroup, with the name Raoultella being the genus name for those organisms in cluster 2.

For the purpose of conforming to current clinical usage, the clinically important species and subspecies will be referred to as K. pneumoniae, K. ozaenae, K. rhinoscleromatis and K. oxytoca in this chapter.

LABORATORY DIAGNOSIS

The members of the genus Klebsiella are Gram negative, nonmotile, facultative anaerobic rods ranging from 0.3 to 1.0 μm in width to 0.6-6.0 μm in length. Most strains grown readily on standard media, although occasionally cysteine requiring urinary isolates of K. pneumoniae are encountered. These strains will appear as pinpoint colonies on routine media, and require supplementation of media with cysteine for more adequate growth. The vast majority of Klebsiella spp. are encapsulated - contrary to popular belief it is probably not capsule which primarily contributes to the mucoid appearance that some Klebsiella strains exhibit.  The Klebsiella which has been linked to the invasive syndrome presenting as liver abscess have a mucoid appearance.

In practice, K. pneumoniae and K. oxytoca are distinguished by indole production by K. oxytoca but not K. pneumoniae. It should be noted however that K. ornitholytica is also an indole producer. The five clinically important species can be distinguished by tests for indole production, ornithine decarboxylase production, he Voges-Proskauer reaction, malonate utilization and o-nitrophenyl-β-D-galactopyranoside (ONPG) production.


Production of plasmid-mediated extended-spectrum beta-lactamases (ESBLs) by Klebsiella spp. has become a major problem. The nature and characteristics of ESBLs are described in greater detail below. Detection of ESBLs in clinical isolates of Klebsiella spp. is problematic since a significant proportion of ESBL producing isolates appear susceptible to third generation cephalosporins or aztreonam. Yet, poor clinical outcomes have been observed when these same antibiotics have been used to treat serious infections due to apparently susceptible ESBL producers. A single surrogate marker for ESBL production, such as ceftazidime resistance, is insufficient for the detection of ESBLs. Virtually all reliable laboratory tests used for detection of ESBLs rely on the change in in vitro activity of oxyimino containing beta-lactams in the presence of a beta-lactamase inhibitor such as clavulanic acid. Examples of ESBL detection methods include the double disk diffusion test, Etest strips containing ceftazidime or cefotaxime with and without clavulanic acid, the Vitek ESBL detection card and the Microscan ESBL plus detection system. Clinical and Laboratory Standards Institute (CLSI) has also developed screening and confirmatory tests for detection of ESBLs. It should be noted that these are standardized for K. pneumoniae and K. oxytoca only.


In some circumstances there is a need to detect ESBL producing Klebsiella spp. from stool or rectal swabs. Examples of such media include Drigalski agar supplemented with cefotaxime 0.5 mg/L , MacConkey agar supplemented with ceftazimide 4 mg/L and nutrient agar supplemented with ceftazimide 2 mg/L, vancomycin 5 mg/L and amphotericin B 1667 mg/L.

Quadrant 1:  Growth on the plate indicates the organism, Enterobacter aerogenes, is not inhibited by bile salts and crystal violet and is a gram-negative bacterium.  The pink color of the bacterial growth indicates E.aerogenes is able to ferment lactose.

Quadrant 2:  Growth on the plate indicates the organism, Escherichia coli, is not inhibited by bile salts and crystal violet and is a gram-negative bacterium.  The pink color of the bacterial growth indicates E.coli is able to ferment lactose.

Quadrant 3: Absence of growth indicates the organism, Staphylococcus epidermidis, is inhibited by bile salts and crystal violet and is a gram-positive bacterium.

Quadrant 4:  Growth on the plate indicates the organism, Salmonella typhimurium, is not inhibited by bile salts and crystal violet and is a gram-negative bacterium.  The absence of color in the bacterial growth indicates S. typhimurium  is unable to ferment lactose.



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