Klebsiella Pneumonia Strains Research Articles

Virulence factors and antibiotic susceptibility patterns of Klebsiella pneumonia strains Histamine producing bacteria isolated from sputum

Virulence factors and antibiotic susceptibility patterns of Klebsiella pneumonia strains Histamine producing bacteria isolated from sputum

Prevalence of Carbapenemases among Klebsiella Pneumoniae Strains Isolated from Respiratory Tract Specimens

Background: The intensive use of carbapenems has resulted in the emergence of carbapenem-resistant isolates. Carbapenemase-producing Klebsiella pneumoniae has rapidly emerged as a major pathogen among carbapenemase-producing bacteria. Objectives: We aimed to characterize 28 Klebsiella pneumoniae strains isolated from respiratory specimens in Assiut University Hospitals, Egypt from May 2015 to August 2015. Methodology: We characterized the antimicrobial susceptibility profile of Klebsiella pneumoniae by disk diffusion method. Detection of carbapenemase genes (blaKPC-1, blaVIM-1, blaVIM-2, blaIMP-1, blaIMP-2, and bla-SPM-1) was performed by polymerase chain reaction. Results: Patients infected by Klebsiella pneumoniae experienced different types of respiratory infections. Carbapenemase genes were detected in 12 (43%) Klebsiella pneumoniae isolates. blaKPC-1 was found in 9 (32%) isolates, blaVIM-1 was detected in two (7%) isolates, and blaIMP-1 gene was expressed by two (7%) isolates. blaVIM-2, blaIMP-2, and blaSPM-1 genes were not expressed by any of the isolates. Carbapenemase-producing Klebsiella pneumoniae showed higher resistance rates to carbapenems and other antibiotics. Conclusion: The high resistance rates in our carbapenemase-producing strains impose limitations in the therapeutic options available. This should alert the medical authorities of our University to establish rigorous methods for more efficiently control the dissemination of antimicrobial resistance genes in the hospital environment.

Aminoglycoside and quinolone resistance in strains of Klebsiella pneumonia isolated from two units of intensive care unit of the University of the Andes Hospital, Merida, Venezuela between 2007 and 2009

Introducción: el incremento en la resistencia a aminoglucósidos y quinolonas es un grave problema para el tratamiento de las infecciones a nivel mundial. Sin duda uno de los factores que ha contribuido a este incremento, es la gran plasticidad que poseen para adquirir genes que le conieren resistencia a los antimicrobianos. Objetivo: determinar los patrones y genes de resistencia a aminoglucósidos y quinolonas en cepas de K. pneumoniae aisladas de dos unidades del Hospital Universitario de los Andes Mérida. Venezuela en 2007 y 2009. Materiales y Método: evaluaron 39 cepas de K. pneumoniae aisladas en la unidad de alto riesgo neonatal y unidad de cuidados intensivos de adultos. La sensibilidad antimicrobiana se determinó mediante la prueba de difusión del disco y por E-test. La detección de los genes aac(3)-IIa, aac(6)-Ib, arma, rmt, qnrA, qnrB y qnrS se realizó por PCR y posterior secuenciación. Resultados: el 100% de las cepas aisladas en 2007 portaban el gen aac(6)-Ib, mientras que el 57% de las cepas aisladas de la misma unidad y de la unidad de cuidados intensivos de adultos en el año 2009 portaban los genes de resistencia aac(3)-IIa, aac(6)-Ib. La resistencia a quinolonas se observó en el 88,8% de las cepas aisladas de la y portaban el gen qnrB. Conclusiones: la resistencia a los aminoglucósidos en las cepas aisladas en la unidad de alto riesgo neonatal estuvo mediada por los genes genes aac(3)-IIa y aac(6)-Ib. Mientras que la resistencia a quinolonas se presento en las cepas aisladas de la unidad de cuidados intensivos de adultos mediadas por el gen qnrB. MÉD.UIS. 2016;29(2):21-30.

Genotyping of Klebsiella Pneumonia Strains Isolated from Eldly Inpatients by Multiple-locus Variable-number Tandem-repeat Analysis.

Objective To investigate the genotype of klebsiella pneumonia strains isolated from eldly inpatients by multiple-locus variable-number tandem-repeat analysis. Methods Totally 184 klebsiella pneumonia strains,isolated from eldly inpatients,were collected,and their genome DNA were extracted. The polymorphism of 7 variable-number tandem-repeat locus in the DNA samples was analyzed by multiple primers polymerase chain reaction and capillary electrophoresis. The clustering analysis of genotyping was carried out with the BioNumerics 5.1 software. Results A total of 139 genotypes were identified in 184 klebsiella pneumonia clinical strains,showing obvious genetic polymorphisms. With clustering analysis of genotypes,all the strains were categorized into three gene clusters (genogroups 1,2,and 3). The genogroup 1 was the biggest cluster,containing 93.06% of the isolated strains. Conclusion There was a predominant cluster in the klebsiella pneumonia strains isolated from eldly inpatients in our center,and the major source of klebsiella pneumonia infection remained the nosocomial infection.

Klebsiella pneumoniae and Its Growing Concern in Healthcare Settings

The increasing clinical incidence of antibiotic-resistant bacteria is a major global health care issue. Among MDR pathogens, Klebsiella pneumoniae (KP) is one of the world's most dangerous superbugs; and becoming resistant to virtually every antibiotic available today. Published articles cited majorly from three sources were browsed using selected keywords. Screening technique was done based on article relevance, topic match and English language match. Duplication of findings was avoided. Prevalence of KP among isolates was determined in different study places and the most alarming figure was seen in study conducted in Nigeria (64.2%) followed by India (33.9%) and Denmark (17.4%). Based on our pooled data from a number of studies conducted at different part of the globe, antibiotic resistances among KP isolates were found to be 100% for Cephradin, 87.5% for Cefeclor, 84% for Tobramycin, 82.5% for Cefotaxime, and 80.4% for Norfloxacin. Whereas, K. pneumonia was found to be more sensitive to Impenem (92.5%), Meropenem (92.5%), Amoxicillin/Clavulanic acid (87.5%), Gatifloxacin (85%), Moxifloxacin (75%); and chloraphenicol (62.8%). Carbapenems have been regarded as the treatment of choice for serious infections caused by extended-spectrum βeta-lactamase (ESBL)-producers. The combination therapy of fosfomycin+colistin demonstrated synergistic and bactericidal effect against one metallobetalactamase producing KP strains that were resistant to fosfomycin. Some of the factors that are responsible for the decline in number of newly discovered antibiotic include reduced financial grant from funding agencies, closure of many major pharmaceutical and large biotech companies; and the lack of financial reward for large pharmaceutical companies to develop new ambitious projects. In conclusion, MDR bacteria are emerging worldwide causing many public health problems and challenges to healthcare. Based on the result from our pooled data, we can conclude that currently we have only few antibiotics that are effective to treat KP.

Construction of mutant strains of Klebsiella pneumoniae with ampG gene deletion

Objective To construct mutant strains of Klebsiella pneumoniae with ampG gene deletion by homologous recombination and to evaluate the role of ampG gene in inducing the expression of AmpC enzyme. Methods Polymerase chain reaction (PCR) was used to amplify the upstream and downstream fragments of ampG gene. The gene splicing by overlap extension PCR (SOE-PCR) technique was used to construct the fusion fragment, which was then ligated into the temperature sensitive suicide vector pKO3-km after enzyme digestion as pKO3-km-ΔampG. To achieve allelic exchange, the plasmid pKO3-km-ΔampG was introduced into Kp1 and Kp NTUH-K2044 strains by electroporation. The mutant strains of Klebsiella pneumoniae with ampG gene deletion were screened out. The plasmid pACYC184-ampCR was introduced into the Kp NTUH-K2044 wild-type strain and its mutant strain with ampG gene deletion to make them harbor the gene encoding AmpC enzyme. The disk diffusion method was used to evaluate the effects of ampG gene on the expression of AmpC enzyme in Klebsiella pneumoniae strains with cefoxitin as the inducer. Results The recombinant plasmid pKO3-km-ΔampG was constructed successfully. The mutant strains of Klebsiella pneumoniae with ampG gene deletion were constructed as verified by PCR and DNA sequencing. Compared with the Kp1 wild type strain, no AmpC enzyme was produced by the ampG gene knock-out Kp1 strain. The Kp NTUH-K2044 strain could produce AmpC enzyme, while the mutant strain of Kp NTUH-K2044 with ampG gene deletion could not after introduced the pACYC184-ampCR plasmid. Conclusion The mutant strain of Klebsiella pneumoniae with ampG gene deletion was successfully constructed. The Klebsiella pneumonia strain without the ampG gene could not produce the AmpC enzyme. Key words: Klebsiella pneumoniae; ampG gene; Homologous recombination; Gene knock-out; AmpC enzyme

Surgical site infection and distribution of pathogens of abdominal contaminated wound: a prospective study

Objective To investigate the characteristics of surgical site infection(SSI) and distribution of pathogens of abdominal contaminated wound. Methods The clinical data of 760 patients with digestive tract fistula who were prepared to undergo definitive operation at the Nanjing General Hospital of Nanjing Military Command between November 2011 and November 2013 were prospectively analyzed. Criteria for National Nosocomial Infection Surveillance (NNIS) of Centers for Disease Control and Prevention Definition (CDC) were used to determine SSI. A single-center and prospective observational study was performed in patients who were divided into SSI group and non-SSI group according to postoperative SSI. Demographic information, digestive tract fistula information, duration of hospital stay and SSI-related information were collected and analyzed. Measurement data were presented as M(Qn) and analyzed by the rank-sum test. Results Among 191 cases enrolled in the clinical trial, 51 patients developed SSI with overall incidence of 26.70%, including 36 cases of superficial incisional SSI, 8 cases of deep incisional SSI, and 7 cases of organic/lacunar SSI. SSI occured usually at postoperative week 1. Among the patients in the SSI group, bacteria culture was negative in 5 cases, and positive in 46 cases. There were 71 strains of pathogens separated from SSI group, including 22 strains of Escherichia coli, 14 strains of Enterococcus, 9 strains of Klebsiella pneumonia, 8 strains of Staphylococcus aureus, 7 strains of proteusbacillus vulgaris, 4 strains of Pseudomonas aeruginosa, 2 strains of Citrobacter, 2 strains of group D streptococcus, 1 strain of Morganella, 1 strain of Enterobacter and 1 strain of Aeromonas. A proportion of 72.7%(16/22) of Escherichia coli were ESBL (+ ). All the 8 strains of Staphylococcus aureus were β-lactamase (+ ), and 7 of them were MRSA (87.5%). The median duration of total hospital stay and postoperative hospital stay in the non-SSI group were 33.0 days (26.0 days, 46.0 days) and 16.5 days (13.0 days, 21.0 days), which were significantly shorter than 37.0 days (31.0 days, 64.0 days) and 23.0 days (17.0 days, 32.0 days) in the SSI group (Z=2 582.00, 1 757.00, P<0.05). Conclusions The incidence of SSI is high after definitive operation because digestive tract fistula is a kind of abdominal contaminated wound. The common pathogens are Escherichia coli, Enterococcus, Klebsiella pneumonia and Staphylococcus aureus, some of which are drug resistant. Registry This study was registered in Chinese Clinical Trial Registry with the registry number of ChiCTR-EOC-14005670. Key words: Abdominal contaminated wound; Surgical site infection; Distribution of pathogens

A non-pathogenic and optically high concentrated (R,R)-2,3-butanediol biosynthesizing Klebsiella strain

The objective of this work was to construct a non-pathogenic Klebsiella pneumonia strain that can produce optically high concentrated (R,R)-2,3-BDO. A K. pneumonia mutant lacking the pathogenic factor was used as the host strain. In order to construct a K. pneumonia strain that would biosynthesize high concentrated (R,R)-2,3-BDO, gene deletion and over-expression methods were combined; firstly, the 2,3-BDO dehydrogenase (budC) gene was deleted to re-direct utilization of the carbon source to (R,R)-2,3-BDO biosynthesis; secondly, the two glycerol dehydrogenase (GDH) enzymes in K. pneumonia (DhaD and GldA) were over-expressed to maximize (R,R)-2,3-BDO biosynthesis; and thirdly, the lactate dehydrogenase (ldhA) gene was deleted to minimize the accumulation of lactate. SGSB112, a non-pathogenic strain of K. pneumonia that can produce optically high concentrated (R,R)-2,3-BDO, was constructed as above. Approximately 36% of the carbon source was converted to (R,R)-2,3-BDO by SGSB112, achieving a production of 61gL−1 (R,R)-2,3-BDO in a fed-batch fermentation. On the other hand, meso-2,3-BDO was produced 1.4gL−1 and (S,S)-2,3-BDO was not detected. This study provides an insight into 2,3-BDO biosynthesis in K. pneumonia and demonstrates the achievement of high-yield production of optically high concentrated (R,R)-2,3-BDO through constructing a strain by genetic modification and metabolic engineering.

승용 씨암말의 생식기 유래 세균의 분포 및 항생제 감수성 양상

Abstract This study was carried out to investigate the genital tract bacterial flora of riding mare in Jangsu stud farm during March to September, 2014. The specimens were collected from vaginal and uterus using a swab from 104 riding mares. Colonies were selected on blood and MacConkey agar plates, and identi-fied as standard biochemical properties and Maldi-Tof MS. From this study, we isolated 148 strains includ-ing Escherichia ( E. ) coli (14.19%), Streptococcus ( S. ) equi subsp. zooepidemicus (2.7%), Streptococcus ( S. ) dysgalactiae subsp. equisimilis (2.03%), Klebsiella ( K. ) pneumonia (1.35%) and other strains from riding mares. In antimicrobial agents susceptibility test, it showed a high sensibility to the antibiotics of the most. E. coli and S. zooepidemicus were visible to have a high sensibility to almost antibiotics used in this study. However, K. pnemoniae showed a high antibiotic resistance patterns. These results may provide the basic information to establish strategies for the treatment and prevention of reproductive dis-eases in riding mares in Korea.

Isolation of a carbapenem-resistant K1 serotype Klebsiella pneumonia strain and the study of resistance mechanism

To study the virulence and mechanism of carbapenem resistance of a clinical isolate of carbapenem-resistant K1 serotype Klebsiella pneumonia strain. Identification of isolate was carried out with VITEK-2 compact system. Antimicrobial susceptibility was determined by E-test; Metallo β-lactamases and carbapenemases screening were conducted by imipenem-EDTA double disc synergy test and modified Hodge test, respectively.Specific polymerehse chain reaction (PCR) and DNA sequencing were preformed to detect the virulence genes including K1, K2, K5, K20, K54, K57, magA, rmpA, wcaG and a series of β-lactamase resistence genes. Conjunction experiment was also performed. The plasmids of transconjugants were submitted to PCR-based replicon typing (PBRT) method. Molecular typing was performed by multilocus sequence typing (MLST). Antimicrobial susceptibility testing revealed that the Klebsiella pneumonia strain was resistant to most of the antibiotics used in clinic. Phynotype confirmary rest revealed the production of carbapanemases, while Metallo β-lactamases were negative; PCR and DNA sequencing confirmed the isolate was positive for blaKPC-2, blaCTX-M-15, blaTEM-1, blaSHV-1 and virulence genes K1, magA, rmpA, wcaG simultaneously; blaKPC-2 was transferred from donor to Escherichia EC600 by conjunction experiment, while no virulence genes were found in the transconjugants. PBRT revealed that Frep plasmid was found in transconjugants. MLST analysis revealed that this strain belonged to ST23. K1 serotype Klebsiella pneumonia strain carries virulence genes and carbapenem resistance gene blaKPC-2, noteworthily the carbapenem resistance genes can be transferred through horizontal transmission on plasmids.

Rapid discrimination of klebsiella pneumoniae carbapenemase 2 – producing and non-producing klebsiella pneumoniae strains using near-infrared spectroscopy (NIRS) and multivariate analysis

Klebsiella pneumoniae Carbapenemase (KPC–2)-producing and non-producing Klebsiella pneumoniae (KP) have rapidly disseminated worldwide, challenging the diagnostics of Gram-negative infections. We evaluate the potential of a novel non-destructive and rapid method based on Near-Infrared Spectroscopic (NIRS) and multivariate analysis for distinguishing KPC-2 – producing and non-producing KP. Thirty-nine NIRS spectra (24 KPC-2-producing KP, 15 KPC-2 non-producing KP) were acquired; different pre-processing methods such as baseline correction, derivative and Savitzky–Golay smoothing were performed. A spectral region fingerprint was achieved after using genetic algorithm–linear discriminant analysis (GA–LDA) and successive projection algorithm (SPA–LDA) algorithms for variable selection. The variables selected were then used for discriminating the microorganisms.Accuracy test results including sensitivity and specificity were determined. Sensitivity in KPC-2 producing and non-producing KP categories was 66.7% and 75%, respectively, using a SPA-LDA model with 66 wavenumbers. The resulting GA-LDA model successfully classified both microorganisms with respect to their “fingerprints” using only 39 wavelengths. Sensitivity in KPC-2 producing category was moderate(≈66.7%) using a GA-LDA model. However, sensitivity in KPC-2 non-producing category using GA-LDA accurately predicted the correct class (with 100% accuracy). As100% accuracy was achieved, this novel approach identifies potential biochemical markers that may have a relation with microbial functional roles and means of rapid identification of KPC-2 producing and non-producing KP strains.

Sialic acid involved in hypermucoviscosity phenotype of Klebsiella pneumoniae and associated with resistance to neutrophil phagocytosis

Klebsiella pneumoniae (KP) with the hypermucoviscosity (HV) phenotype has abundant capsular polysaccharides (CPS) and usually causes an invasive syndrome. Sialic acid (Sia), a component of CPS in KP strains with the HV phenotype, may be anti-phagocytic. Sia-binding immunoglobulin-like lectin-9 (Siglec-9) act as an MHC class-I receptor on neutrophils that recognizes Sia and sends a signal to dampen inflammatory response. Three clinical KP strains with KP-M1 (HV-positive; capsular serotype K1), KP-14 (HV-negative; capsular serotype non-K1/K2), and DT-X (HV-negative; capsular serotype K1) were studied. We assessed total Sia in CPS extracts using enzymatic methods and phagocytosis by neutrophils of neuraminidase-treated bacteria using flow cytometry. Neutrophil killing was evaluated in the presence and absence of antibodies against Siglec-9. The concentration of Sia was significantly higher in the CPS extract of KP-M1 (56.75 ± 6.75 μmole/109 cfu) than in the CPS extract of KP-14 (0.02 ± 0.01 μmole/109 cfu) and DT-X (a negligible value). The KP-M1 (compared with the KP-14 and DT-X) was more resistant to neutrophil phagocytosis. Both the HV phenotype and resistance to phagocytosis of KP-M1 were significantly decreased after Sia removal with neuraminidase treatment. Fluorescence microscopy with an antibody against human Siglec-9 showed attachment of KP-M1 (but were absent of KP-14 and DT-X) to the surface of neutrophils and colocalization with human Siglec-9. Engagement of Siglec-9 via Sia enhanced neutrophils killing of KP-M1 by ex vivo human neutrophils bactericidal activity assay. The result showed that Sia might be a constituent of KP-M1 CPS responsible for HV, thereby contributing to anti-phagocytic activity of this pathogen.

OPPORTUNICTIC ENTEROBACTERIACAE AS THE CAUSE OF THE ACUTE DIARRHEA AND GUT DISBIOSIS

Abstract. Strains of Klebsiella pneumonia isolated from faces were studied to detect virulence factors of “classical” enteric pathogens causing acute diarrhea (Shigella, Salmonella, diarreagenic Escherichia coli). We haven’t detect in Klebsiella the genes encode different virulence factors: the abilities to adherence (sfa, afa, aaf/1, eae), invasion (ipaH, ial), production of heat-lable toxins (elt, LT II), heat-stable toxins (st1, st2) and Shiga toxins (stx1, stx2). Klebsiella spp. is well-known pathogen of the opportunistic infections of urinary tract, blood, wound, respiratory tract. But this bacteria hasn’t virulence factors of diarreagenic Enterobacteriaceae and can’t cause acute diarrhea and other gut pathology.

Phenolic content of Ruprechtia salicifolia leaf and its immunomodulatory, anti-inflammatory, anticancer and antibacterial activity

ObjectivesThis work aimed to isolate phenolics from leaves of Ruprechtia salicifolia and evaluate its immunomodulatory, anti-inflammatory, anticancer and antibacterial activity. Methods80% MeOH leaf extract was subjected to chromatographic separation, structures of the isolated compounds were established by different chromatographic and spectral techniques UV, MS, 1H and 13C NMR. Immunomodulatory was evaluated through RAW 264.7 macrophages proliferation by MTT assay. Anti-inflammatory was evaluated by inhibition of NO and TNF-α factor generation in LPS-stimulated cells through bicinchoninici acid assay and ELISA assay, respectively. Cytotoxicity estimated through Hep-G2, MCF-7 and HCT-116 cell lines measured by MTT assay. Antibacterial activity tested by agar diffusion method. ResultsEleven known phenolic compounds were isolated for the first time from this species including five flavonoid glycosides viz; Rutin 3, quercetin 3-O-arabinoglucoside 4, apigenin 7-O-β-d-glucoside 5, quercetin 3-O-α-l-arabinofuranoside 6 and isoquercetin 7 along with four aglycones viz; kaemferide 8, apigenin 9, quercetin 10 and naringenin 11 and two phenolic acids; caffeic 1 and gallic 2. Compounds 5 showed the most activity increasing macrophage proliferation implying immunomodulatory activity. 80% MeOH extract, 4, 5 and 11 inhibited nitrite oxide by 68.19%, 52.95%, 20.33% and 15.22%, respectively and TNF-α generation by 70.82%, 29.88%, 13.13% and 6.14%, respectively in LPS-stimulated cells implying anti-inflammatory activity. 80% MeOH leaf extract and the tested compounds 4 and 5 were safe possessing no cytotoxic activity against hepatocellular carcinoma (Hep-G2), breast adenocarcinoma (MCF-7) and colon carcinoma (HCT-116), while Compound 11 had cytotoxicity against only HCT-116 cells (IC50 = 27.67 μg/ml). Also 80% MeOH leaf extract showed antibacterial activity against both G +ve and G −ve bacteria, moreover it inhibits growth of Klebsiella pneumonia strain, which is resistant to Ciprofloxacin broad-spectrum antibiotic. ConclusionsR. salicifolia contain phenolics of immunomodulatory anti-inflammatory, cytotoxicity and antibacterial activity, giving R. salicifolia grate potential as a medicinal natural drug.

Draft Genome Sequences of Two Multidrug Resistant Klebsiella pneumoniae ST258 Isolates Resistant to Colistin

Sequence type 258 (ST258) is the most widespread multidrug resistant (MDR) Klebsiella pneumoniae strain worldwide. Here, we report the draft genome sequences of two colistin-resistant MDR K. pneumoniae ST258 clinical strains isolated from hospital patients in Italy. These strains are resistant to β-lactams, cephalosporins, fluoroquinolones, aminoglycosides, macrolides, tetracyclines, carbapenems, and colistin.

Prevalence of extended spectrum β- lactamases inKlebsiellapneumoniae in a tertiary care hospital.

Purpose: To know the prevalence of extended spectrum β- lactamases (ESBL) in multidrug resistant strains of Klebsiellapneumoniaefrom various clinical samples.Material and Methods: A total of 97 strains of Klebsiellapneumoniae were selected for the study, screened for ESBL and confirmed by phenotypic confirmatory disc diffusion test (PCDDT)Results: 92(94.84%) of isolates were resistant to one or more 3 rd Generation cephalosporins (3GC) and which were confirmed for ESBL production by using the PCDDTmethod.Conclusion: Our study shows high prevalence of ESBL production. PCDDT is a simple and cost effective test which can be done as a routine in our microbiology labs.

Novel fluorescent cephalosporins: Synthesis, antimicrobial activity and photodynamic inactivation of antibiotic resistant bacteria

Two novel fluorescent cephalosporins, TCA and TBCA, were synthesized and characterized by 1H NMR, 13C NMR, UV–vis, and fluorescence spectroscopies. Biological activity assays demonstrated that TCA inactivated a Klebsiella pneumonia strain that expressed extended-spectrum β-lactamases. Incubation of 6 μM TCA with K. pneumonia cultures resulted in cell death for 84% of the cells after 126 J/cm2 of light irradiation. In vitro, TCA exhibited a MIC = 0.5 μg/mL with Staphylococcus aureus. Kinetic evaluation revealed that TCA and TBCA were substrates for B1 and B3 subclass metallo-β-lactamases. TBCA exhibited stronger binding affinities to the Gram-positive bacterial strains MRSA1, MRSA2, and S. aureus with value of 2.95–6.59 μM per 108 cells/mL.

Mutation in fucose synthesis gene ofKlebsiella pneumoniaeaffects capsule composition and virulence in mice

The emerging pathogenicity of Klebsiella pneumoniae (KP) is evident by the increasing number of clinical cases of liver abscess (LA) due to KP infection. A unique property of KP is its thick mucoid capsule. The bacterial capsule has been found to contain fucose in KP strains causing LA but not in those causing urinary tract infections. The products of the gmd and wcaG genes are responsible for converting mannose to fucose in KP. A KP strain, KpL1, which is known to have a high death rate in infected mice, was mutated by inserting an apramycin-resistance gene into the gmd. The mutant expressed genes upstream and downstream of gmd, but not gmd itself, as determined by reverse transcriptase polymerase chain reaction. The DNA mapping confirmed the disruption of the gmd gene. This mutant decreased its ability to kill infected mice and showed decreased virulence in infected HepG2 cells. Compared with wild-type KpL1, the gmd mutant lost fucose in capsular polysaccharides, increased biofilm formation and interacted more readily with macrophages. The mutant displayed morphological changes with long filament forms and less uniform sizes. The mutation also converted the serotype from K1 of wild-type to K2 and weak K3. The results indicate that disruption of the fucose synthesis gene affected the pathophysiology of this bacterium and may be related to the virulence of this KpL1 strain.

Prevalence of fecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae among healthy adult people in Japan

In Japan, the prevalence of extended-spectrum β-lactamase (ESBL) producers in hospital settings has shown an increasing trend. In the present study, we investigated the prevalence of the fecal carriage of ESBL-producing Enterobacteriaceae among healthy adults. Stool samples were collected for the phenotypic and genotypic identification of ESBL-producing Enterobacteriaceae. We found the prevalence of ESBL producers to be 6.4% by phenotypic identification, and 92.9% of them possessed the bla(CTX-M) gene. Among the CTX-M ESBL-producing Enterobacteriaceae, we identified 11 Escherichia coli and 2 Klebsiella pneumonia strains. The findings suggest that the fecal carriage of CTX-M-type ESBL producers by healthy people is rapidly increasing in Japan. This may be one of the causes of the increased spread of ESBL-producing bacteria in hospitals.

Synthesis, Characterization, and Antimicrobial Evaluation of Sulfonamides Containing N-Acyl Moieties Catalyzed by Bismuth(III) Salts Under Both Solvent and Solvent-Free Conditions

Efficient N-acylation of sulfonamides with both readily available carboxylic acid chlorides and anhydrides has been carried out with catalysis by bismuth(III) salts including BiCl3 and Bi (OTf)3. The reactions proceed rapidly in both heterogeneous and solvent-free conditions and afforded the corresponding N-acylsulfonamides in good to excellent yields. The mild reaction conditions and low toxicity of bismuth salts make this procedure attractive and in close agreement with the goals of green chemistry. Some of the synthesized compounds were evaluated in vitro as antimicrobial agents against representative strains of Gram-positive (Staphylococcus aureus ATCC 25922, clinical strains of Staphylococcus aureus VISA and Enterococcus spp.) and Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, clinical strains of Klebsiella pneumonia and Escherichia coli) and as antifungal agents against Candida albicans (clinically isolated) by both disc diffusion and minimal inhibition concentration (MIC) methods. All these bacteria and fungi studied were screened against some antibiotics to compare with our chemicals' zone diameters.