Survival in lake water of Klebsiella pneumoniae discharged by a paper mill.

We investigated survival of Klebsiella pneumoniae in freshwater, by determining bacterial densities at eight temperatures between 0 and 20 degrees C at various distances from the discharge area in a lake receiving bacteria mainly from a paper mill. An mFC-inositol-carbenicillin-agar medium was used for Klebsiella enumeration by the membrane filter method. About 90% of the bacteria forming typical colonies on this medium were identified as Klebsiella species. About 10% of the bacteria were false positive, and, an equal percentage were false negative. Semilogarithmic plots of bacterial densities as a function of distance were found to be linear, with slopes depending on water temperature. The average velocity of the flow was estimated from the travel-of-bacterial-density minima caused by production stops. Regression equations were calculated for the dependence of death rate on temperature alone and on both temperature and discharge. The temperature coefficient (Q10) of the death rate was estimated to be 2.1 +/- 0.4. The decimal reduction time (T90) of K. pneumoniae at 0 degrees C was calculated to be about 24 days, and that at 20 degrees C was slightly over 5 days. The regression model was verified by independent observations. Factors affecting the reliability of the estimates were evaluated.     

Klebsiella pneumoniae in orange juice concentrate.

Fecal coliform-positive, capsule-forming Klebsiella pneumoniae cells were observed in high densities (10(4) to 10(8) CFU/100 ml) in two commercial batches of frozen orange juice concentrate at a cannery in Puerto Rico. Contamination of both lots was gross and included off colors and odors. Isolates of K. pneumoniae from these concentrates revealed growth at 4, 25, and 34 degrees C with generation times from 0.39 to 1.84 h.     

肺炎克雷伯菌研究进展

近年来由于各种抗菌药物的广泛使用,导致肺炎克雷伯菌多重耐药现象普遍存在,给临床治疗带来极大的困扰,造成医院获得性肺炎感染严重的现状。着重论述了肺炎克雷伯菌流行现状、耐药机制、致病因子及防治措施。     

Pathway of galactitol catabolism in Klebsiella pneumoniae.

Cell extracts of galactitol-grown Klebsiella pneumoniae phosphorylate galactitol by means of a phosphoenolpyruvate:galactitol phosphotransferase system. Both the product and authentic L-galactitol-l-P are oxidized with NAD⁺ by a dehydrogenase to yield D-tagatose-6-P, which is phosphorylated with ATP by a kinase to form D-tagatose-1,6-P₂. This ketohexose diphosphate is cleaved by an aldolase to yield dihydroxyacetone-P and D-glyceraldehyde-3-P. Mutants deficient in either the dehydrogenase, kinase, or aldolase failed to grow on galactitol, indicating that the described pathway is of physiological significance in this organism.     

Purification and characterization of Klebsiella pneumoniae cytotoxins.

Isolation, purification and characterization of 3 new cytotoxins of a K. pneumoniae strain isolated from ready to eat pork sausage are reported. Purification process involved extraction of cytotoxins with polymyxin B sulphate, salt precipitation, gel filtration and anion exchange chromatography. Klebsiella cytotoxin (KCT) I, a glycoprotein of about 65 kDa was verocytotoxic, enterotoxic and dermonerotic. KCT II was erythemogenic, verocytotoxic and enterotoxic protein of co 55 kDa, while KCT III was about double in MW (110 kDa) hadverocytotoxicity but neither enterotoxicity nor dermatotoxicity. KCT I and II caused granulation, conglomeration, shrinkage, detachment and lysis of MDBK and Vero cells, while KCT III induced enlargement, vacuolation, granulation, multinucleolation and syncytia formation in exposed cells. All the three cytotoxins induced specific neutralizing antibodies and cytotoxins were detectable in nanogram quantities with enzyme-linked immunosorbant assay using homologous antibodies. None of the anticytotoxin cross-reacted with either heterologous Klebsiella cytotoxins or with verocytotoxic preparations of Shigella dysenteriae.     

Homocitrate cures the NifV- phenotype in Klebsiella pneumoniae.

Dinitrogenase was isolated from a culture of a Klebsiella pneumoniae NifV- strain derepressed for nitrogenase in the presence of homocitrate. The enzyme isolated from this culture was identical to the wild-type dinitrogenase. These data provide in vivo evidence that the absence of homocitrate is responsible for the NifV- phenotype.     

Hemolytic activity of Klebsiella pneumoniae and Klebsiella oxytoca

We demonstrated that Klebsiella pneumoniae and Klebsiella oxytoca possess a selective haemolytic activity on rabbit erythrocytes. Thirty one Klebsiella strains (18 strains of K. pneumoniae and 13 strains of K. oxytoca) were isolated from hospitalized patients. The liquid (Trypcase-soy broth--TSB) and solid (Trypcase-soy agar--TSA) medium, containing the red cells were used for the tests. All the screened strains showed a haemolytic effect on rabbit erythrocytes, provided that the supernatants of the cultures were preincubated with beta-mercaptoethanol or calcium chloride. There was no human and sheep erythrocyte lysis.     

Nitrogenase of Klebsiella pneumoniae nifV mutants.

The MoFe protein of nitrogenase from Klebsiella pneumoniae nifV mutants, NifV- Kp1 protein, in combination with the Fe protein from wild-type cells, catalysed CO-sensitive H2 evolution, in contrast with the CO-insensitive reaction catalysed by the wild-type enzyme. The decrease in H2 production was accompanied by a stoicheiometric decrease in dithionite (reductant) utilization, implying that CO was not reduced. However, CO did not affect the rate of phosphate release from ATP. Therefore the ATP/2e ratio increased, indicating futile cycling of electrons between the Fe protein and the MoFe protein. The inhibition of H2 evolution by CO was partial; it increased from 40% at pH6.3 to 82% at pH 8.6. Inhibition at pH7.4 (maximum 73%) was half-maximal at 3.1 Pa (0.031 matm) CO. The pH optimum of the mutant enzyme was lower in the presence of CO. Steady-state kinetic analysis of acetylene reduction indicated that CO was a linear, intersecting, non-competitive inhibitor of acetylene reduction with Kii = 2.5 Pa and Kis = 9.5 Pa. This may indicate that a single high-affinity CO-binding site in the NifV- Kp1 protein can cause both partial inhibition of H2 evolution and total elimination of acetylene reduction. Various models to explain the data are discussed.     

The capsular network of Klebsiella pneumoniae.

Attempts at improving chemical fixation for electron-microscopic observation of the capsule of Klebsiella pneumoniae were made. The capsule was preserved by using alcian blue - lanthanum and tris-(1-aziridinyl) phosphine oxide (TAPO) - aldehyde - osmium procedures. Despite the different retention of the overall capsular material and minor variations in morphological details, in both cases the interpretation of ultrastructural patterns suggested that the capsule be composed of a meshed network of thin polysaccharide fibrils radiating from the cell wall. This organization is in keeping with all recognized chemical properties of bacterial polysaccharide capsules or, at least, does not contradict them. Moreover, an effective preservation of bacterial structures other than capsule has been obtained, mostly in specimens fixed by the TAPO-aldehyde-osmium method, a fact which gives further reliability to the technical approach used for capsule visualization.     

Metabolism of benzonitrile and butyronitrile by Klebsiella pneumoniae.

A strain of Klebsiella pneumoniae that used aliphatic nitriles as the sole source of nitrogen was adapted to benzonitrile as the sole source of carbon and nitrogen. Gas chromatographic and mass spectral analyses of culture filtrates indicated that K. pneumoniae metabolized 8.4 mM benzonitrile to 4.0 mM benzoic acid and 2.7 mM ammonia. In addition, butyronitrile was metabolized to butyramide and ammonia. The isolate also degraded mixtures of benzonitrile and aliphatic nitriles. Cell extracts contained nitrile hydratase and amidase activities. The enzyme activities were higher with butyronitrile and butyramide than with benzonitrile and benzamide, and amidase activities were twofold higher than nitrile hydratase activities. K. pneumoniae appears promising for the bioremediation of sites contaminated with aliphatic and aromatic nitriles.     

Acquisitive evolution of ribitol dehydrogenase in Klebsiella pneumoniae.

Selection in continuous culture of Klebsiella pneumoniae mutants that have gained the ability to utilize xylitol while also retaining regulatory control over ribitol utilization was achieved with a dual-substrate regime. Initial steady-state cultures of wild-type organisms were maintained with 0.005% (0.329 mM) ribitol. Mutants of various types proliferated when the composition of the limiting medium was changed to 0.005% ribitol plus 0.250% (16.43 mM) xylitol.     

Metabolism of benzonitrile and butyronitrile by Klebsiella pneumoniae.

A strain of Klebsiella pneumoniae that used aliphatic nitriles as the sole source of nitrogen was adapted to benzonitrile as the sole source of carbon and nitrogen. Gas chromatographic and mass spectral analyses of culture filtrates indicated that K. pneumoniae metabolized 8.4 mM benzonitrile to 4.0 mM benzoic acid and 2.7 mM ammonia. In addition, butyronitrile was metabolized to butyramide and ammonia. The isolate also degraded mixtures of benzonitrile and aliphatic nitriles. Cell extracts contained nitrile hydratase and amidase activities. The enzyme activities were higher with butyronitrile and butyramide than with benzonitrile and benzamide, and amidase activities were twofold higher than nitrile hydratase activities. K. pneumoniae appears promising for the bioremediation of sites contaminated with aliphatic and aromatic nitriles.     

Fimbrial hemagglutinins in Klebsiella pneumoniae

Eleven Klebsiella pneumoniae strains were isolated from urine specimens which were examined for their ability to produce hemagglutinins (HAs). Bacteria were grown under various culture conditions. Suspension of bacteria grown in broth or on Phosphate-buffered nutrient agar (PBA) were tested for agglutination in the presence and absence of 2% (w/v) D-mannose, on rockedtiles at 4 degrees C and ambient temperature with mangroup-O(M), fowl(F), ox(O), guinea-pig(G), horse (H), rabbit (R) and sheep (S) erythrocytes and tannic acid treated, but not fresh oxen erythrocytes. Each of the 11 strains was hemagglutinating. Ten strains (99%) producing two or three hemagglutinins (HAs), were multiple hemagglutinating. One strain produced only mannose-resistant, Klebsiella, the "Tanned ox hemagglutinin" (MR/K-HA). Solely mannose-sensitive hemagglutinin (MS/HA) was not produced by any of the strains. No mannose-sensitive hemagglutinating strains acted on sheep erythrocytes. Three main kinds of hemagglutinin (HA) were detected. These were: (a) a mannose-sensitive hemagglutinin (MS-HA); (b) a mannose resistant, Klebsiella, the "tanned ox hemagglutinin (MR/K-HA); (c) mannose-resistant, Proteus hemagglutinin (MR/P-HA). All strains (100%) produced MR/K-HA, 45% of MR/K-HA+ strains produced MR/P-HA at 37 degrees C and 99% of all strains produced MS/HA, MR/P-HA activity was never dependent on MR/K-HA: Electronmicroscopic examination of bacteria showed that all strains were fimbriate.     

Genotoxic Klebsiella pneumoniae in Taiwan

Background

Colibactin is a nonribosomal peptide-polyketide synthesized by multi-enzyme complexes encoded by the pks gene cluster. Colibactin-producing Escherichia coli have been demonstrated to induce host DNA damage and promote colorectal cancer (CRC) development. In Taiwan, the occurrence of pyogenic liver abscess (PLA) has been suggested to correlate with an increasing risk of CRC, and Klebsiella pneumoniae is the predominant PLA pathogen in Taiwan

Methodology/Principal Findings

At the asn tRNA loci of the newly sequenced K. pneumoniae 1084 genome, we identified a 208-kb genomic island, KPHPI208, of which a module identical to the E. coli pks colibactin gene cluster was recognized. KPHPI208 consists of eight modules, including the colibactin module and the modules predicted to be involved in integration, conjugation, yersiniabactin production, microcin production, and unknown functions. Transient infection of BALB/c normal liver cells with K. pneumoniae 1084 increased the phosphorylation of histone H2AX, indicating the induction of host DNA damage. Colibactin was required for the genotoxicity of K. pneumoniae 1084, as it was diminished by deletion of clbA gene and restored to the wild type level by trans-complementation with a clbA coding plasmid. Besides, BALB/c mice infected with K. pneumoniae 1084 exhibited enhanced DNA damage in the liver parenchymal cells when compared to the isogenic clbA deletion mutant. By PCR detection, the prevalence of pks-positive K. pneumoniae in Taiwan is 25.6%, which is higher than that reported in Europe (3.5%), and is significantly correlated with K1 type, which predominantly accounted for PLA in Taiwan.

Conclusions

Our knowledge regarding how bacteria contribute to carcinogenesis has just begun. The identification of genotoxic K. pneumoniae and its genetic components will facilitate future studies to elucidate the molecular basis underlying the link between K. pneumoniae, PLA, and CRC.     

Transport of 4-hydroxyphenylacetic acid in Klebsiella pneumoniae.

Klebsiella pneumoniae M5a1 has been shown to possess an inducible transport system for 4-hydroxyphenylacetate (4-HPA). This transport system has a Kt of 16.3 microM and a maximal velocity of 31.2 nmol/min (milligrams dry weight). The transport system has been inhibited by inhibitors of energy metabolism with a concomitant decrease in cellular ATP concentrations, and the 4-HPA binding activity has been detected in the crude shock extracts. All these observations indicate that 4-HPA uptake is an active transport which involves a periplasmic binding protein and it seems to be energized by phosphate bond energy.     

Order of genes near nif in Klebsiella pneumoniae.

Analysis of strains with deletions of all or part of nif have ordered the Klebsiella pneumoniae genetic loci as thi rbt dal udk gnd rfb has nif shiA. The his-nif plasmids pRD1 and pTM4010 contain the genes gnd rfb his nif shiA.