Genus Klebsiella Research Articles

Variations of hydrogen production and microbial community with heavy metals during fermentative hydrogen production

The effects of heavy metals on fermentative hydrogen production were examined based on metal type and concentration. Hydrogen production was stimulated by low concentrations of Cd and Zn but decreased at concentrations of 40 and 1 mg/L, respectively. Hydrogen production was inhibited for the entire range of Cu tested. The order of toxic density was Cu > Zn > Cd at concentrations below 2 mg/L but was Zn > Cu > Cd at higher concentrations. The depression rates of hydrogen production were calculated to be 225.8 mL-H 2/mg-Zn, 67.37 mL-H 2/mg-Cu, and 13.39 mL-H 2/mg-Cd. The presence of heavy metals caused a shift in microbial community. The presence of Clostridium genus bacteria, identified as Clostridium magum, Clostridium diolis, and Clostridium sp., resulted in active hydrogen production. Klebsiella genus bacteria were the most abundant of the class Gammaproteobacteria and also stimulated hydrogen production at relatively low concentrations of heavy metal. When Rhodocista pekingensis, Erwinia chrysanthemi strain 1015-1, Delftia sp. YF 31, or uncultured Klebsiella sp. clone F1 apr.32 were present, hydrogen production was seriously decreased.

Multidrug resistance in hydrocarbon-tolerant Gram-positive and Gram-negative bacteria

New Gram-positive and Gram-negative bacteria were isolated from Poeni oily sludge, using enrichment procedures. The six Gram-positive strains belong to Bacillus, Lysinibacillus and Rhodococcus genera. The eight Gram-negative strains belong to Shewanella, Aeromonas, Pseudomonas and Klebsiella genera. Isolated bacterial strains were tolerant to saturated (i.e., n-hexane, n-heptane, n-decane, n-pentadecane, n-hexadecane, cyclohexane), monoaromatic (i.e., benzene, toluene, styrene, xylene isomers, ethylbenzene, propylbenzene) and polyaromatic (i.e., naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons, and also resistant to different antimicrobial agents (i.e., ampicillin, kanamycin, rhodamine 6G, crystal violet, malachite green, sodium dodecyl sulfate). The presence of hydrophilic antibiotics like ampicillin or kanamycin in liquid LB-Mg medium has no effects on Gram-positive and Gram-negative bacteria resistance to toxic compounds. The results indicated that Gram-negative bacteria are less sensitive to toxic compounds than Gram-positive bacteria, except one bacteria belonging to Lysinibacillus genus. There were observed cellular and molecular modifications induced by ampicillin or kanamycin to isolated bacterial strains. Gram-negative bacteria possessed between two and four catabolic genes (alkB, alkM, alkB/alkB1, todC1, xylM, PAH dioxygenase, catechol 2,3-dioxygenase), compared with Gram-positive bacteria (except one bacteria belonging to Bacillus genus) which possessed one catabolic gene (alkB/alkB1). Transporter genes (HAE1, acrAB) were detected only in Gram-negative bacteria.

LES ENTÉROBACTÉRIES BLSE DES INFECTIONS URINAIRES : ÉPIDÉMIOLOGIE ET RÉSISTANCE

Introduction : The enterobacteria secreting beta-lactamases extended spectrum (ESBL) isolated from various infections are a public health problem in hospitals. The aim of this study was to determine the epidemiology and the resistance to gentamicin and fluoroquinolones of this enterobacteria that was isolated of urinary infection. Materials and methods : This is a retrospective study including the results of urine exam and their corresponding antibiograms. a study that concerne all enterobacteria isolated during a period of seven months from march 2010 to september 2010. Results : From 6350 exam of urines, five hundred fifty-eight strains of enterobacteria was positif. The prevalence of ESLB enterobacteria represents 13.8%. The genus Klebsiella present 59.7% of ESBL isolates and is also the most secreting of the ESBL with 25% of Klebsiella strains. The resistance of enterobacteria to trimethoprim-sulfamethoxazole is generally high. The co-resistance of strains secreting ESBL to fluoroquinolones was 75%; that associated with gentamicin was 86%. Similarly; co-resistance to both gentamicin and fluoroquinolones was 72%. Discussion : Analysis of the results shows a gradual increase in the frequency of ESBL-E isolated from urine in both middles hospital and community. So therapeutic alternatives available for these multiresistant bacilli are particularly limited for patients living in fragile situation. Conclusion : Improving hospital hygiene and good clinical practice in using antibiotics are fundamental to fight against the spread of multi-drug resistant bacteria.

Predation of human pathogens by the predatory bacteria Micavibrio aeruginosavorus and Bdellovibrio bacteriovorus

The focus of this study was to evaluate the potential use of the predatory bacteria Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to control the pathogens associated with human infection. By coculturing B. bacteriovorus 109J and M. aeruginosavorus ARL-13 with selected pathogens, we have demonstrated that predatory bacteria are able to attack bacteria from the genus Acinetobacter, Aeromonas, Bordetella, Burkholderia, Citrobacter, Enterobacter, Escherichia, Klebsiella, Listonella, Morganella, Proteus, Pseudomonas, Salmonella, Serratia, Shigella, Vibrio and Yersinia. Predation was measured in single and multispecies microbial cultures as well as on monolayer and multilayer preformed biofilms. Additional experiments aimed at assessing the optimal predation characteristics of M. aeruginosavorus demonstrated that the predator is able to prey at temperatures of 25-37°C but is unable to prey under oxygen-limiting conditions. In addition, an increase in M. aeruginosavorus ARL-13 prey range was also observed. Bdellovibrio bacteriovorus and M. aeruginosavorus have an ability to prey and reduce many of the multidrug-resistant pathogens associated with human infection. Infectious complications caused by micro-organisms that have become resistant to drug therapy are an increasing problem in medicine, with more infections becoming difficult to treat using traditional antimicrobial agents. The work presented here highlights the potential use of predatory bacteria as a biological-based agent for eradicating multidrug-resistant bacteria, with the hope of paving the way for future studies in animal models.

Bacterial community associated with the trunk latex of Hancornia speciosa Gomes (Apocynaceae) grown in the northeast of Brazil

Prevention or cure of different illnesses through the use of plant latex is a worldwide known concept. The antifungal activity of Hancornia speciosa latex has been observed against Candida albicans. However, H. speciosa latex is not a sterile plant exudate and secondary metabolites produced by bacteria could be involved in fungal inhibition. In the present study, the bacterial communities of the latex from three H. speciosa trees were characterized using traditional plating and molecular methods. Twelve strains isolated from the latex samples were clustered into four groups by amplified ribosomal DNA restriction analysis (ARDRA). One representative of each group was sequenced and they were identified as belonging to the genera Bacillus, Klebsiella, Enterobacter and Escherichia. None of the 12 isolates showed antifungal activity against C. albicans. A lack of a microbial origin for the antifungal properties of latex was noted. DGGE profiles generated from each of the three latex samples showed unique patterns. Sequencing of the DGGE bands demonstrated the affiliation with the genera Klebsiella, Pantoea, Enterobacter and Burkholderia. In addition, clone libraries were generated and the phylogenetic distribution of the 50 analyzed clones was similar to that obtained using DGGE. The presence of some potential pathogens should be considered before using H. speciosa latex in folk medicine.

Antiserum against Raoultella terrigena ATCC 33257 identifies a large number of Raoultella and Klebsiella clinical isolates as serotype O12

Raoultella terrigena ATCC 33257, recently reclassified from the genus Klebsiella, is a drinking water isolate and belongs to a large group of non-typeable Klebsiella and Raoultella strains. Using an O-antiserum against a capsule-deficient mutant of this strain, we could show a high prevalence (10.5%) of the R. terrigena O-serotype among non-typeable, clinical Klebsiella and Raoultella isolates. We observed a strong serological cross-reaction with the K. pneumoniae O12 reference strain, indicating that a large percentage of these non-typeable strains may belong to the O12 serotype, although these are currently not detectable by the K. pneumoniae O12 reference antiserum in use. Therefore, we analyzed the O-polysaccharide (O-PS) structure and genetic organization of the wb gene cluster of R. terrigena ATCC 33257, and both confirmed a close relation of R. terrigena and K. pneumoniae O12. The two strains possess an identical O-PS, lipopolysaccharide core structure, and genetic organization of the wb gene cluster. Heterologous expression of the R. terrigena wb gene cluster in Escherichia coli K-12 resulted in the WecA-dependent synthesis of an O-PS reactive with the K. pneumoniae O12 antiserum. The serological data presented here suggest a higher prevalence of the O12-serotype among Klebsiella and Raoultella isolates than generally assumed.

Klebsiella alba sp. nov., a novel pesticide-tolerant bacterium from a heavily polluted environment

A novel Gram-negative, aerobic, rod-shaped and pesticide (chlorpyrifos and atrazine) tolerant strain, designated CW-D 3(T), was isolated from a heavily polluted soil sample in Jiangsu Province, China. The strain could tolerate about 800 microg.ml(-1) atrazine or chlorpyrifos when added in TYB medium. A polyphasic taxonomy including phylogenetic and phenotypic analysis was performed on the new isolate. Phylogenetic analysis and chemotaxonomic characteristics revealed that strain CW-D 3(T) belongs to the genus Klebsiella. Its closest phylogenetic neighbors were K. singaporensis (strain LX3(T)), three subspecies of K. pneumoniae (strains ATCC 13883(T), ATCC 13884(T) and ATCC 11296(T)) and K. granulomatis, according to 16S rRNA and rpoB gene analysis. The 16S rRNA gene sequence similarity was about 94.8-97.6% and the rpoB gene sequence similarity was about 96.8-98.6% to its phylogenetic neighbors. Strain CW-D 3(T) also showed low DNA-DNA reassociation values (less than 21%) with respect to the three subspecies of K. pneumoniae and Klebsiella singaporensis. Its major fatty acids were C14:0, C16:0, c-C17:0 and c-C19:0 omega8c. The G+C content of the DNA was 58.3 mol%. Phylogenetic and phenotypic results supported the assignment of CW-D 3(T) as a novel species of the genus Klebsiella, for which the name Klebsiella alba sp. nov. is proposed. The type strain is CW-D 3(T) (=LMG 24441(T)=KCTC 12878(T) =CCTCC AB 206144(T)).

Klebsiella and Gastrointestinal Syndromes with Particular Emphasis on Klebsiella oxytoca Antibiotic-Associated Colitis

The genus Klebsiella (family Enterobacteriaceae), of which K. pneumoniae and K. oxytoca are the two most commonly isolated members, consists of gram-negative, non-motile, encapsulated rods. As opportunistic pathogens, Klebsiella spp. can cause a variety of illnesses including pneumonia, urinary tract infections, septicemia, soft tissue, intravenous, meningitis, liver abscess, and gastrointestinal disease, in the immunocompromised or those with underlying conditions. Current studies strongly suggest that klebsiellae, and in particular K. oxytoca, may also be associated with a variety of gastrointestinal syndromes that include antibiotic-associated hemorrhagic colitis.

Phylogenetic and characteristic analysis of 16S rDNA and rpoB gene sequence of Klebsiella

Objective To compare and analyze the phylogenetic tree and sequence variant characteristics of Klebsiella species between 16S rDNA and rpoB. Methods Eighteen isolates identified as genus Klebsiella (with 15 of K. Pneumoniae and 3 of K. Oxytoca) by automated biochemical tests were selected. DNA were extracted, 16S rDNA and rpoB genes were amplified and sequenced with Klebsiella 16S rDNA and rpoB primers. Together with already published 8 species of Klebsiella and 9 species of Enterobacteriaceae 16S rDNA and rpoB sequences from GenBank, totally 35 sequences of 16S rDNA and rpoB respectively, phylogenetic trees were constructed with MEGA 4.0 to the analysis of groups. DNAStar/MegAlign was used for comparison of variable regions of 16S rDNA and rpoB, with analysis of degree of divergent at the same time. Results As for all 35 sequences, both 16S rDNA and rpoB phylogenetic trees divided Klebsiella species into three groups, 15 of K. Pneumoniae in this study and 6 of K. Pneumoniae from GenBank (except for K. Oxytoca and K. Mobilis) cluster to group Ⅰ, K. Oxytoca and K. Mobilis were cluster to group Ⅱ and Ⅲ, respectively. In rpoB phylogenetic tree, no matter group Ⅰ and group Ⅱ, or subgroup within group Ⅰ, the bootstrap values in each node of rpoB phylogenetic tree is obviously higher than that of 16S rDNA. Moreover, as for cluster to K. Oxytoca, rpoB is better than 16S rDNA. Analysis nucleic acid sequences of Klebsiella species, with 41 variable regions and 4 most significant regions were found within the Klebsiella 16S rDNA, while rpoB with 63 variable regions, and 1 most significant region. The similarity of 16S rDNA and rpoB within Klebsiella were 95.9%-100% and 90.2%-100% respectively. Further analysis divergent degree of 16S rDNA and rpoB within Klebsiella, the divergent value of rpoB (0-10.6) is higher than that of the 16S rDNA(0-4.0). Conclusion As for molecular classification and identification within KlebsieUa species, rpoB has more advantages than 16S rDNA. Key words: Klebsiella; 16S rDNA; rpoB; Phylogenetic development; Sequence characteristic

Characterization of a methane-utilizing strain and its application for monitoring methane

To explore new resources of methane-utilizing micro-organism and develop a microbial biosensing system for monitoring methane released from natural and semi-natural ecosystems. A methane (CH(4))-utilizing bacterial strain was isolated from paddy soil using CH(4) as the sole carbon source and identified as Klebsiella sp. ME17 by phenotyping and 16S rDNA sequence analysis. The efficiency of CH(4) utilization of strain ME17 was 83.2% by gas chromatography analysis. A microbial biosensing system for CH(4) detection was developed by combining immobilized cells of strain ME17 with a dissolved oxygen sensor. It was found that response time of the system to CH(4) was <90s. The dissolved O(2) consumption increased with increasing CH(4) from 0% to 16.0% (v/v) demonstrating a positive linear relationship with a low detection limit of 0.2% (v/v). The relative standard deviation is 3.48%. Klebsiella sp. ME17 isolate is capable of utilizing CH(4). The microbial biosensing system of strain ME17 has been successfully applied to measure standard CH(4) sample with satisfactory results. This study suggests that certain strains of Klebsiella genus are capable of utilizing CH(4). Our proposed method appears very attractive for CH(4) measurement in coal mine.

Diversity of hydrocarbon-degradingKlebsiellastrains isolated from hydrocarbon-contaminated estuaries

To investigate the diversity and the catabolic capacity of oil-degrading Klebsiella strains isolated from hydrocarbon-contaminated sediments in Santos-São Vicente estuary systems in Brazil. Klebsiella strains obtained from the estuary were characterized using 16S rRNA gene sequencing and BOX-PCR patterns, testing their catabolic capacity to degrade toluene, xylene, naphthalene and nonane, and identifying the catabolic genes present in the oil-degrading strains. Results show that Klebsiella strains were widespread in the estuary. Twenty-one isolates from the Klebsiella genus were obtained; 14 had unique BOX patterns and were further investigated. Among four distinct catabolic genes tested (todC1, ndoB, xylE and alkB1), only the todC1 gene could be amplified in two Klebsiella strains. The biodegradation assay showed that most of the strains had the ability to degrade all of the tested hydrocarbons; however, the strains displayed different efficiencies. The oil-degrading Klebsiella isolates obtained from the estuary were closely related to Klebsiella pneumoniae and Klebsiella ornithinolytica. The isolates demonstrated a substantial degree of catabolic plasticity for hydrocarbon degradation. The results of this study show that several strains from the Klebsiella genus are able to degrade diverse hydrocarbon compounds. These findings indicate that Klebsiella spp. can be an important part of the oil-degrading microbial community in estuarine areas exposed to sewage.

Spreading and mechanisms of antimicrobial resistance in microorganisms, producing beta-lactamases. Molecular mechanisms of resistance to beta-lactam antibiotics of Klebsiella spp. strains, isolated in cases of nosocomial infections

Antibiotic sensivity of nosocomial Klebsiella spp. strains (n = 212), isolated from patients treated in 30 medical centers of 15 various regions of Russia was investigated. The Klebsiella genus was represented by the following species: Klebsiella pneumoniae ss. pneumoniae--182 (85.8%), Klebsiella pneumoniae ss. ozaenae--1 (0.5%), Klebsiella oxytoca--29 (13.7%) isolates. The most active antibacterial agents against the investigated strains were carbapenems (imipenem and meropenem). Among 3rd generation cephalosporine the lowest MICs were observed for ceftazidime/clavulanic acid (MIC50--0.25 microg/ml, MIC90--64 microg/ml) and cefoperazone/sulbactam (MIC50--16 microg/ml, MIC90--64 microg/ml). Beta-lactamase genes (TEM, SHV, CTX) were detected in 42 Klebsiella pneumoniae ss. pneumoniae strains by PCR. Alone or in various combinations TEM type beta-lactamases have been found in 16 (38.1%) isolates, SHV--in 29 (69%), and CTX--in 27 (64.3%). Combinations of 2 different determinants were detected in 23.8% of the isolates, 3--in 26.2%. There were not isolates producing MBL class B among resistant to carbapenems nosocomial Klebsiella spp. strains.

Fluorescent in situ hybridization and flow cytometry as tools to evaluate the treatments for the control of slime-forming enterobacteria in paper mills

Slime formation is a serious problem nowadays in the paper industry. Some enterobacteria are associated with the formation of slime deposits in paper and board mills. Detection and characterization of slime forming bacteria, belonging to the genus Enterobacter, Raoultella, and Klebsiella have been achieved by fluorescence in situ hybridization (FISH), using one probe based on the enterobacterial repetitive intergenic consensus sequence and other two rRNA targeted oligonucleotide probes. The effects of three kinds of antimicrobiological products (biocides, dispersants, and enzymes) on these enterobacterial cells were analyzed by flow cytometry (FC). Biocides B: utrol 1009 and 1072 were the most effective microbiocides against all enterobacterial cells analyzed, reaching 90% of dead bacteria after 24 h. However, the enzymatic treatment (Buzyme) was not equally efficient on enterobacteria and its microbiocide capacity varied depending on the type of microorganism. FISH and FC were effective tools to detect important slime forming enterobacteria and to select specific treatments to control microbial problems in the paper industry.

O496 Multiresistant Klebsiella pneumoniae from NYC hospitals contain β-lactamase KPC-2 or KPC-3 and porin changes

Bacteria of the genus Klebsiella are opportunistic pathogens responsible for an increasing number of multiresistant infections in hospitals. The two clinically and epidemiologically most important species, Klebsiella pneumoniae and K. oxytoca, have recently been shown to be subdivided into three and two phylogenetic groups, respectively. The aim of this study was an in depth evaluation of the amplified fragment length polymorphism (AFLP) genetic characterization method for epidemiological and phylogenic analyzes of Klebsiella isolates. First, we investigated the variability of AFLP patterns for Klebsiella strains within and between different outbreaks. Second, by use of carefully characterized phylogenetically representative strains, we examined whether different Klebsiella species and phylogenetic groups can be discriminated using AFLP. Twenty-four strains originating from seven presumed outbreaks and 31 non-associated strains were investigated. The AFLP fingerprints of all epidemiologically associated strains showed three or fewer fragment differences, whereas unrelated strains differed by at least four fragments. Cluster analysis of the AFLP data revealed a very high concordance with the phylogenetic assignation of strains based on the gyrA sequence and ribotyping data. The species K. pneumoniae, K. oxytoca, K. terrigena and the possibly synonymous pair K. planticola/K. ornithinolytica each formed a separate cluster. Similarly, strains of the phylogenetic groups of K. pneumoniae and K. oxytoca fell into their corresponding clusters, with only two exceptions. This study provides a preliminary cut-off value for distinguishing epidemiologically non-related Klebsiella isolates based on AFLP data; it confirms the sharp delineation of the recently identified phylogenetic groups, and demonstrates that AFLP is suitable for identification of Klebsiella species and phylogenetic groups.

New Bacterial Species Isolated from Malaysian Sea Cucumbers with Optimized Secreted Antibacterial Activity

In this study, several Malaysian sea cucumber species that have traditional medicine value were selected and from them, the native bacterial population was isolated. Optimization of growth was designed and all bacterial secretions were tested for antibacterial properties. 30 bacterial types were isolated and 7 types recorded moderate antibacterial activity against K. pneumoniae, S. marscens, P. aeruginosa and E. feacalis. Antibacterial plate screening was done, with various testing parameters. Turbidometry revealed a single dose of the 10x concentrated crude antibacterial extracts were effective in preventing pathogenic growth for up to 4 hrs. PCR and subsequent sequencing of the 16S rDNA showed that the bacterial species were from the halopholic Bacillus and Klebsiella genera.

Effects of a Campylobacter jejuni Infection on the Development of the Intestinal Microflora of Broiler Chickens

The effect of a Campylobacter jejuni colonization on the development of the microflora of the cecum and the ileum of broiler chickens was studied using molecular methods. The infection did affect the development and complexity of the microbial communities of the ceca, but we found no permanent effect of a C. jejuni infection on the ileal microflora of the broilers. In addition, denaturant gradient gel electrophoresis (DGGE) profiles generated from cecal and ileal contents revealed several DGGE bands that were present in the control chickens, but not in the chickens colonized with C. jejuni. Some of these DGGE bands could be affiliated with Lactobacillus reuteri, Clostridium perfringens, and the genus Klebsiella.

Major structural proteins of type 1 and type 3 Klebsiella fimbriae are effective protein carriers and immunogens in conjugates as revealed from their immunochemical characterization

Fimbriae are filamentous structures present on the cell surface of many bacteria, including genus Klebsiella. The use of fimbriae as protein carriers in conjugates may allow to formulate effective multivalent vaccines and suitable diagnostics. However, the evidences have been reported that fimbriae may enhance the inflammatory response. This prompted us to examine the degree of cytokine induction by the type 1 and type 3 Klebsiella fimbriae and their conjugates. Fimbriae were assessed as carrier proteins for Escherichia coli K12 endotoxin core oligosaccharide. MALDI-MS revealed the molecular mass of fimbrial monomer major protein, which was 15,847 Da for type 1 and 18,574 Da for type 3 fimbriae of Klebsiella. These two types of fimbriae were moderate inductors of IL-6 and interferon and almost inactive with regard to the stimulation of TNF when tested in human whole blood assay. Coupling of fimbriae with E. coli K12 core oligosaccharide gave immunogenic conjugates with respect to a saccharide ligand and protein carrier, although only 10% of the pilin monomers possessed the attached oligosaccharide. Rabbit antiserum reacted with a broad spectrum of lipopolysaccharides, as measured by ELISA and immunoblotting assays. The antibodies against glycoconjugates were bactericidal for the wild, S-type bacteria of some species. Regarding the induction of cytokines by conjugates only the TNF level was noticeably elevated. These results prompt for the practical use of fimbriae, as effective protein carriers for conjugates to obtain broad-spectrum antisera for diagnostic applications.

Microbial flora of Clarias Gariepinus in the early stages of Development

A study was carried out to establish the microbial flora in farmed Clarias gariepinus hatchery systems. Enumeration of total aerobic heterotrophic bacteria and fungi, total coliforms, Salmonella spp. Vibrio spp. and Aeromonas hydrophila from eggs (fertilized and unfertilized), larvae, fry, fry feed and tank water showed that these microorganisms occurred more in advanced fry than in other early stages of fish development. The highest aerobic heterotrophic bacteria and fungi and total coliforms were encountered in fry feed while tank water gave the lowest counts of all microbial groups. A total of 136 bacterial and 13 fungal isolates were identified. The bacteria isolated from the samples were predominantly Gram negative except in fry feed where Gram positive bacteria predominated. Bacteria of the genera Bacillus, Staphylococcus, Micrococcus, Streptococcus, Acinetobacter, Alcaligenes, Flavobacterium, Pseudomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, Salmonella, Aeromonas, Vibrio and Chromobacterium were isolated from the samples at different frequencies with Staphylococcus, Acinetobacter and Flavobacterium predominating. Fungi of the genera Aspergillus, Mucor, Fusarium, Penicillium, Cladosporium, Phoma, Phialophora, Exophila, Candida, Saccharomyces and Cryptococcus were isolated from the samples with Aspergillus and Saccharomyces predominating and contaminating all the samples. The microbial generic diversity increased with fish development. Key Words: Clarias eggs, larvae, fry, fry feed, hatchery systems, microbial flora Tropical Freshwater Biology 11 (2002) 91-100

First Isolation of bla VIM-2 in Klebsiella oxytoca Clinical Isolates from Portugal

VIM-type carbapenemases were originally detected in Europe (2, 4, 7) and have been essentially found in Pseudomonas aeruginosa, as well as in Enterobacteriaceae (2, 6, 8). The blaVIM genes are often carried by mobile gene cassettes inserted into class 1 integrons (7, 11). The Klebsiella genus is responsible for the most frequent human nosocomial infections of the respiratory and urinary tracts. Four Klebsiella oxytoca clinical isolates were recovered by blood culture from neonatal patients at a pediatric hospital. The clinical isolates showed resistance to amoxicillin and ticarcillin, which was restored by clavulanate, aminoglycosides, and fluoroquinolones, and intermediate susceptibility to imipenem (MIC, 4 μg/ml) and broad-spectrum cephalosporins and aztreonam (MICs, 8 and 16 μg/ml) and were susceptible to meropenem (MIC, 0.075 μg/ml). A deformation of ellipses between the two gradient sections with E-test MBL (metallo-β-lactamase) strips was indicative of MBL production (10).

Klebsiella singaporensis sp. nov., a novel isomaltulose-producing bacterium

Cells of strain LX3(T), isolated from soil, were Gram-negative, facultatively anaerobic, non-motile, capsulated and non-endospore-forming straight rods, able to grow at 10 degrees C, unable to produce gas from lactose at 45 degrees C and unable to produce indole. The isolate converted sucrose to isomaltulose and did not produce detectable glucose by-products. The G+C content of the DNA was 56.4 mol%. Furthermore, comparison of 16S rRNA and rpoB gene sequences showed that the isolate clearly belongs to the genus Klebsiella. The closest phylogenetic relative was Klebsiella pneumoniae, there being 99.3 and 97.5 % similarity in 16S rRNA and rpoB gene sequences, respectively. DNA-DNA hybridization analysis demonstrated a very low level of relatedness to other members of the genus Klebsiella, indicating that the isolated strain and other species in the genus Klebsiella were not related at the species level. The isolate could be differentiated from other previously described members of the genus Klebsiella on the basis of phenotypic differences and 16S rRNA and rpoB gene sequence divergence, together with DNA-DNA reassociation data. Therefore, it is proposed that strain LX3(T) (=DSM 16265(T)=JCM 12419(T)) should be classified as the type strain of a novel species of genus Klebsiella, Klebsiella singaporensis sp. nov.