Genome Sequences of Two Klebsiella pneumoniae Isolates from Different Geographical Regions, Argentina (Strain JHCK1) and the United States (Strain VA360)

We report the sequences of two Klebsiella pneumoniae clinical isolates, strains JHCK1 and VA360, from a newborn with meningitis in Buenos Aires, Argentina, and from a tertiary care medical center in Cleveland, OH, respectively. Both isolates contain one chromosome and at least five plasmids; isolate VA360 contains the Klebsiella pneumoniae carbapenemase (KPC) gene

Emergence of Klebsiella pneumoniae co-producing NDM-1, OXA-48, CTX-M-15, CMY-16, QnrA and ArmA in Switzerland

Extensively drug-resistant (XDR) Klebsiella pneumoniae isolates usually carry a single carbapenemase (e.g. KPC, NDM, OXA-48-like). Here we describe an XDR K. pneumoniae of sequence type 101 that was detected in the screening rectal swab of a patient transferred from the intensive care unit of a hospital located in Belgrade (Serbia) to Bern University Hospital (Switzerland). The isolate was resistant to all antibiotics with the exception of colistin [minimum inhibitory concentration] (MIC≤0.125μg/mL), tigecycline (MIC=0.5μg/mL) and fosfomycin (MIC=2μg/mL). The isolate co-possessed class B (NDM-1) and class D (OXA-48) carbapenemases, class A extended-spectrum β-lactamase (CTX-M-15), class C cephalosporinase (CMY-16), ArmA 16S rRNA methyltransferase, substitutions in GyrA and ParC, loss of OmpK35 porin, as well as other genes conferring resistance to quinolones (qnrA), tetracyclines [tet(A)], sulfonamides (sul1, sul2), trimethoprim (dfrA12, dfrA14), rifampicin (arr-1), chloramphenicol (cmlA1, floR) and streptomycin (aadA1). The patient was placed under contact isolation precautions preventing the spread of this nearly untreatable pathogen.

Third-Generation-Cephalosporin-Resistant Klebsiella pneumoniae Isolates from Humans and Companion Animals in Switzerland: Spread of a DHA-Producing Sequence Type 11 Clone in a Veterinary Setting.

Characterization of third-generation-cephalosporin-resistant Klebsiella pneumoniae isolates originating mainly from one human hospital (n = 22) and one companion animal hospital (n = 25) in Bern (Switzerland) revealed the absence of epidemiological links between human and animal isolates. Human infections were not associated with the spread of any specific clone, while the majority of animal infections were due to K. pneumoniae sequence type 11 isolates producing plasmidic DHA AmpC. This clonal dissemination within the veterinary hospital emphasizes the need for effective infection control practices.

First report of a multidrug-resistant Klebsiella pneumoniae of sequence type 11 causing sepsis in a free-ranging beaver (Castor fiber).

Klebsiella pneumoniae of sequence type (ST) 11 is a hyper-epidemic nosocomial clone spreading worldwide among humans and also emerging in pets. In this report, we describe a clinical case of fatal sepsis due to this multidrug-resistant (MDR) pathogen in a Eurasian beaver. The isolate showed resistance to six different classes of antimicrobials including third generation cephalosporins and fluoroquinolones. This is the first report describing the detection of a MDR K. pneumoniae ST11 in a free-ranging animal. Our finding highlights the potential for environmental dissemination of hyper-epidemic clones of K. pneumoniae and possible spread in wildlife and cause epizootics.

Double Copies of bla(KPC-3)::Tn4401a on an IncX3 Plasmid in Klebsiella pneumoniae Successful Clone ST512 from Italy.

A carbapenem-resistant sequence type 512 (ST512) Klebsiella pneumoniae carbapenemase 3 (KPC-3)-producing K. pneumoniae strain showing a novel variant plasmid content was isolated in Palermo, Italy, in 2014. ST512 is a worldwide successful clone associated with the spread of bla(KPC) genes located on the IncFIIk pKpQIL plasmid. In our ST512 strain, the bla(KPC-3) gene was unusually located on an IncX3 plasmid, whose complete sequence was determined. Two copies of bla(KPC-3)::Tn4401a caused by intramolecular transposition events were detected in the plasmid.

Complete Genome Sequence of KPC-3- and CTX-M-15-Producing Klebsiella pneumoniae Sequence Type 307.

Klebsiella pneumoniaesequence type (ST) 307, carryingblaKPC-3,blaCTX-M-15,blaOXA-1,aac(6')-Ib-cr, andqnrB1 genes, is replacing the predominant hyperepidemic ST258 clone in Italy. Whole-genome and complete plasmid sequencing of one ST307 strain was performed and new features were identified.

Klebsiella pneumoniae multirresistente: un problema de salud pública. Estudio de su presencia en el Hospital General Universitario de Alicante

Enterobacterias como Klebsiella pneumoniae y E.coli, junto con otros microorganismos no fermentadores como P. aeruginosa o A. baumanii son de gran importancia a nivel clínico, debido a la reciente aparición de cepas productoras de BLEE y carbapenemasas. Klebsiella es una bacteria Gram negativa capaz de provocar infecciones en el ser humano, de echo aparece en pacientes que estén en estado de cuidados intensivos con mayor frecuencia que en pacientes sanos. La producción de BLEE por parte de muchas cepas de Klebsiella ha provocado que éstas sean mucho más resistentes a gran cantidad de antibióticos y sean más difíciles de eliminar en el paciente. Klebsiella pneumoniae tiene mecanismos de resistencia naturales y resistencias adquiridas, éstas últimas dependen de la cepa de Klebsiella. Un ejemplo de resistencia adquirida es la producción de BLEE que se encargan de romper el anillo betalactámico de gran cantidad de antibióticos inactivándolos, como por ejemplo penicilinas, cefalosporinas y monobactámicos.

The crystal structures of Klebsiella pneumoniae acetolactate synthase with enzyme-bound cofactor and with an unusual intermediate

Acetohydroxyacid synthase (AHAS) and acetolactate synthase (ALS) are thiamine diphosphate (ThDP)-dependent enzymes that catalyze the decarboxylation of pyruvate to give a cofactor-bound hydroxyethyl group, which is transferred to a second molecule of pyruvate to give 2-acetolactate. AHAS is found in plants, fungi, and bacteria, is involved in the biosynthesis of the branched-chain amino acids, and contains non-catalytic FAD. ALS is found only in some bacteria, is a catabolic enzyme required for the butanediol fermentation, and does not contain FAD. Here we report the 2.3-Angstrom crystal structure of Klebsiella pneumoniae ALS. The overall structure is similar to AHAS except for a groove that accommodates FAD in AHAS, which is filled with amino acid side chains in ALS. The ThDP cofactor has an unusual conformation that is unprecedented among the 26 known three-dimensional structures of nine ThDP-dependent enzymes, including AHAS. This conformation suggests a novel mechanism for ALS. A second structure, at 2.0 Angstrom, is described in which the enzyme is trapped halfway through the catalytic cycle so that it contains the hydroxyethyl intermediate bound to ThDP. The cofactor has a tricyclic structure that has not been observed previously in any ThDP-dependent enzyme, although similar structures are well known for free thiamine. This structure is consistent with our proposed mechanism and probably results from an intramolecular proton transfer within a tricyclic carbanion that is the true reaction intermediate. Modeling of the second molecule of pyruvate into the active site of the enzyme with the bound intermediate is consistent with the stereochemistry and specificity of ALS.

Antibiotic therapy for Klebsiella pneumoniae bacteremia: Implications of production of extended-spectrum beta-lactamases

The prevalence of extended-spectrum beta-lactamase (ESBL) production by Klebsiella pneumonia approaches 50% in some countries, with particularly high rates in eastern Europe and Latin America. No randomized trials have ever been performed on treatment of bacteremia due to ESBL-producing organisms; existing data comes only from retrospective, single-institution studies. In a prospective study of 455 consecutive episodes of Klebsiella pneumoniae bacteremia in 12 hospitals in 7 countries, 85 episodes were due to an ESBL-producing organism. Failure to use an antibiotic active against ESBL-producing K. pneumoniae was associated with extremely high mortality. Use of a carbapenem ( primarily imipenem) was associated with a significantly lower 14-day mortality than was use of other antibiotics active in vitro. Multivariate analysis including other predictors of mortality showed that use of a carbapenem during the 5-day period after onset of bacteremia due to an ESBL-producing organism was independently associated with lower mortality. Antibiotic choice is particularly important in seriously ill patients with infections due to ESBL-producing K. pneumoniae.

Capsule and fimbria interaction in Klebsiella pneumoniae

The capsular polysaccharide and type I fimbriae are two of the major surface-located virulence properties associated with the pathogenesis of Klebsiella pneumoniae. The capsule is an elaborate polysaccharide matrix that encases the entire cell surface and provides resistance against many host defense mechanisms. In contrast, type 1 fimbriae are thin adhesive thread-like surface organelles that can extend beyond the capsular matrix and mediate D-mannose-sensitive adhesion to host epithelial cells. These fimbriae are archetypical and consist of a major building block protein (FimA) that comprises the bulk of the organelle and a tip-located adhesin (FimH). It is assumed that the extended major-subunit protein structure permits the FimH adhesin to function independently of the presence of a capsule. In this study, we have employed a defined set of K. pneumoniae capsulated and noncapsulated strains to show that the function of type I fimbriae is actually impeded by the concomitant expression of a polysaccharide capsule. Capsule expression had significant effects on two parameters commonly used to define FimH function, namely, yeast cell agglutination and biofilm formation. Our data suggest that this effect is not due to transcriptional/translational changes in fimbrial gene/protein expression but rather the result of direct physical interference. This was further demonstrated by the fact that we could restore fimbrial function by inhibiting capsule synthesis. It remains to be determined whether the expression of these very different surface components occurs simply via random events of phase variation or in a coordinated manner in response to specific environmental cues.

Mechanism of uptake of the catecholic (7)-α-formamido cephalosporin BRL 41897A by klebsiella pneumoniae

The catecholic cephalosporin BRL 41897 A is resistant to β-lactamases and is taken up by bacteria via the iron transport system. The uptake of this antibiotic in E.coli uses the Fiu and Cir outer membrane proteins, whereas in P. aerugtnosa it enters via the pyochelin transport system. In this thesis mutants of K. pneumoniae resistant to BRL 41897A were isolated using TnphoA mutagenesis and used to study the mechanism of uptake of BRL 41897A by K. pneumoniae. The activity of BRL 41897A towards the parent strain (M10) was increased in iron depleted media, whereas no significant differences in the resistant (KSL) mutants were observed. Three mutants (KSL19, KSL38and KSL59) produced decreased amounts of certain iron-regulated outer membrane proteins. The uptake of 55Fe-BRL 41897A by M10 in iron-deficient medium was higher than in iron-rich medium. This result indicated the involvement of an iron transport system in the uptake of BRL 41897A by K. pneumoniae. Uptake by the KSL mutants in iron-deficient culture was higher than that by M10. This result, supported by analysis of outer membrane and periplasmic proteins of the KSL mutants, indicates that loss of one outer membrane protein can be compensated by over expression of other outer membrane and/or periplasmic proteins. However, the increased uptake of BRL 41897A by the KSL mutants did not reflect increased activity towards these strains, indicating that there are defects in the transport of BRL 41897A resulting in failure to reach the penicillin binding protein target sites in the cytoplasmic membrane. Southern blotting of chromosomal digests and sequencing in one mutant (KSL19) showed that only one copy of TnphoA was inserted into its chromosome. A putative TnphoA inserted gene in KSL19, designated kslA, carrying a signal sequence was identified. Transformation of a fragment containing the kslA gene into KSL19 cells restored the sensitivity to BRL 41897A to that of the parent strain. Data base peptide sequence searches revealed that the kslA gene in the KSL19 has some amino acid homology with the E. coli ExbD protein, which is involved in stabilisation of the TonB protein.