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K. Pneumoniae (k + pneumoniae)
Selected AbstractsThe characterization of functions involved in the establishment and maturation of Klebsiella pneumoniae in vitro biofilm reveals dual roles for surface exopolysaccharidesENVIRONMENTAL MICROBIOLOGY, Issue 3 2008Damien Balestrino Summary The ability to form biofilm is seen as an increasingly important colonization strategy among both pathogenic and environmental Klebsiella pneumoniae strains. The aim of the present study was to identify abiotic surface colonization factors of K. pneumoniae using different models at different phases of biofilm development. A 2200 K. pneumoniae mutant library previously obtained by signature-tagged mutagenesis was screened in static and dynamic culture models to detect clones impaired at early and/or mature stages of biofilm formation. A total of 28 mutants were affected during late phases of biofilm formation, whereas 16 mutants displayed early adhesion defect. These mutants corresponded to genes involved in potential cellular and DNA metabolism pathways and to membrane transport functions. Eight mutants were deficient in capsule or LPS production. Gene disruption and microscopic analyses showed that LPS is involved in initial adhesion on both glass and polyvinyl-chloride and the capsule required for the appropriate initial coverage of substratum and the construction of mature biofilm architecture. These results give new insight into the bacterial factors sequentially associated with the ability to colonize an abiotic surface and reveal the dual roles played by surface exopolysaccharides during K. pneumoniae biofilm formation. [source] Deep neck infection: Analysis of 185 casesHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 10 2004Tung-Tsun Huang MD Abstract Purpose. This study reviews our experience with deep neck infections and tries to identify the predisposing factors of life-threatening complications. Methods. A retrospective review was conducted of patients who were diagnosed as having deep neck infections in the Department of Otolaryngology at National Taiwan University Hospital from 1997 to 2002. Their demographics etiology, associated systemic diseases, bacteriology, radiology, treatment, duration of hospitalization, complications, and outcomes were reviewed. The attributing factors to deep neck infections, such as the age and systemic diseases of patients, were also analyzed. Results. One hundred eighty-five charts were recorded; 109 (58.9%) were men, and 76 (41.1%) were women, with a mean age of 49.5 ± 20.5 years. Ninety-seven (52.4%) of the patients were older than 50 years old. There were 63 patients (34.1%) who had associated systemic diseases, with 88.9% (56/63) of those having diabetes mellitus (DM). The parapharyngeal space (38.4%) was the most commonly involved space. Odontogenic infections and upper airway infections were the two most common causes of deep neck infections (53.2% and 30.5% of the known causes). Streptococcus viridans and Klebsiella pneumoniae were the most common organisms (33.9%, 33.9%) identified through pus cultures. K. pneumoniae was also the most common infective organism (56.1%) in patients with DM. Of the abscess group (142 patients), 103 patients (72.5%) underwent surgical drainages. Thirty patients (16.2%) had major complications during admission, and among them, 18 patients received tracheostomies. Those patients with underlying systemic diseases or complications or who received tracheostomy tended to have a longer hospital stay and were older. There were three deaths (mortality rate, 1.6%). All had an underlying systemic disease and were older than 72 years of age. Conclusions. When dealing with deep neck infections in a high-risk group (older patients with DM or other underlying systemic diseases) in the clinic, more attention should be paid to the prevention of complications and even the possibility of death. Early surgical drainage remains the main method of treating deep neck abscesses. Therapeutic needle aspiration and conservative medical treatment are effective in selective cases such as those with minimal abscess formation. © 2004 Wiley Periodicals, Inc. Head Neck26: 854,860, 2004 [source] Over-expression of glycerol dehydrogenase and 1,3-propanediol oxidoreductase in Klebsiella pneumoniae and their effects on conversion of glycerol into 1,3-propanediol in resting cell systemJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2009Li Zhao Abstract BACKGROUND: Glycerol dehydrogenase [EC.1.1.1.6] and 1,3-propanediol oxidoreductase [EC.1.1.1.202] were proved to be two of the key enzymes for glycerol conversion to 1,3-propanediol in Klebsiella pneumoniae under anaerobic conditions. For insight into their significance on 1,3-propanediol production under micro-aerobic conditions, these two enzymes were over-expressed in K. pneumoniae individually, and their effects on conversion of glycerol into 1,3-propanediol in a resting cell system under micro-aerobic conditions were investigated. RESULTS: In the resting cell system, over-expression of 1,3-propanediol oxidoreductase led to faster glycerol conversion and 1,3-propanediol production. After a 12 h conversion process, it improved the yield of 1,3-propanediol by 20.4% (222.1 mmol L,1 versus 184.4 mmol L,1) and enhanced the conversion ratio of glycerol into 1,3-propanediol from 50.8% to 59.8% (mol mol,1). Over-expression of glycerol dehydrogenase in K. pneumoniae had no significant influence both on 1,3-propanediol yield and on the conversion ratio of glycerol into 1,3-propanediol in the resting cell system. CONCLUSION: The results were important for an understanding of the significance of glycerol dehydrogenase and 1,3-propanediol oxidoreductase in 1,3-proanediol production under micro-aerobic conditions, and for developing better strategies to improve 1,3-propanediol yield. Copyright © 2008 Society of Chemical Industry [source] SIDEROPHORE PRODUCTION, SERUM RESISTANCE, HEMOLYTIC ACTIVITY AND EXTENDED-SPECTRUM ,-LACTAMASE-PRODUCING KLEBSIELLA SPECIES ISOLATED FROM MILK AND MILK PRODUCTSJOURNAL OF FOOD SAFETY, Issue 3 2007HAN GUNDOGAN ABSTRACT This study aimed at the isolation and identification of Klebsiella spp. from dairy product to establish their public health significance by determining their virulence factors, antibiotic resistance and extended-spectrum ,-lactamase (ESBL). Klebsiella pneumoniae, Klebsiella oxytoca and Klebsiella rhinoscleromatis were identified in 25 (58%), 11 (26%) and 7 (16%) isolates, respectively. A high prevalence of Klebsiella isolates had virulence factors such as siderophore production (63%), serum resistance (32.5%) and hemolytic activity (58%). ESBL - producing Klebsiella spp. was detected in 35% of the isolates. Resistance to the antimicrobial agents tested was found to be much higher in the ESBL-producing Klebsiella spp. than in non-ESBL-producing isolates. All ESBL-producing Klebsiella spp. showed high-level resistance to cephalosporins and monobactams. The majority of the serum resistant, siderophore, hemolysin and ESBL producers were K. pneumoniae. [source] Invasiveness and Intracellular Growth of Multidrug-Resistant Salmonella and Other Pathogens in Caco-2 CellsJOURNAL OF FOOD SCIENCE, Issue 2 2007S.-H. Kim ABSTRACT:, The increase of multidrug-resistant pathogens of human and animal origins is a major public health concern. For a better understanding of the health consequences of multidrug-resistant bacteria transmitted from animal products to humans, the host interaction of zoonotic Salmonella isolates along with other pathogenic and commensal bacteria was evaluated using a human intestinal Caco-2 cell system. Multidrug-resistant S. Agona, S. Heidelberg, and S. Typhimurium possessed plasmid-mediated class 1 integrons. The S. Typhimurium DT104 isolate from ground beef showed the well-known genotypic and phenotypic resistance characteristics of the species, and contained the chromosomally located class 1 integron. Among the multidrug-resistant Salmonella isolates, the S. Heidelberg 219 had the highest invasion number at 1.0 × 104 CFU/mL, followed by the S. Typhimurium DT104 isolate at 7.7 × 103 CFU/mL. Listeria monocytogenes was the best performer among the tested species in invading the Caco-2 cell. Multidrug-resistant opportunistic pathogens Klebsiella pneumoniae and Pseudomonas aeruginosa were also able to invade the cells. The invasion of S. Heidelberg 219, S. Typhimurium DT104, L. monocytogenes, K. pneumoniae, and P. aeruginosa into the Caco-2 cells was not affected even in the presence of commensal E. coli. During the intracellular growth of S. Heidelberg 219, S. Typhimurium DT104, and L. monocytogenes, the bacterial counts increased 2 log cycles in 9 h in the Caco-2 cells. Therefore, these strains could rapidly proliferate after their invasion into the cells. [source] Restoration of antibacterial activity of ,-lactams by epigallocatechin gallate against ,-lactamase-producing species depending on location of ,-lactamaseJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2003Wei-Hua Zhao The combined effects of (,)-epigallocatechin gallate (EGCg) and ,-lactams were investigated against various ,-lactamase-producing clinical isolates, including 21 Staphylococcus aureus, 6 Escherichia coli, 3 Klebsiella pneumoniae and 8 Serratia marcescens strains. Penicillin in combination with EGCg at 12.5,g mL,1 showed the most potent synergy against 100% penicillinase-producing S. aureus. However, cefotaxime or imipenem in combination with higher concentration of EGCg (100 ,g mL,1) only showed slight synergy against 2 of 17 Gram-negative rods. Similar to the effect on the penicillinase from S. aureus, however, EGCg also directly inhibited the extracted ,-lactamases from the Gram-negative rods, thereby protecting ,-lactams from inactivation. The different effects of the combinations on different ,-lactamase-producing species were confirmed to be related to the cellular locations of ,-lactamases. In contrast to a 32.7% extracellular fraction of total ,-lactamase activity in a penicillinase-producing S. aureus, the fractions were 0.6%, 0.6% and 1.2% in a TEM-derived extended-spectrum ,-lactamase-producing E. coli, an inhibitor-resistant ,-lactamase-producing K. pneumoniae and an IMP-producing S. marcescens, respectively. In conclusion, the combination of penicillin with EGCg showed potent synergy against penicillinase-producing S. aureus in-vitro. The combinations of ,-lactams and EGCg against ,-lactamase-producing Gram-negative rods do indicate a limitation owing to the cellular location of ,-lactamases. [source] Effects of Ethanol on Cytokine Production After Surgery in a Murine Model of Gram-Negative PneumoniaALCOHOLISM, Issue 2 2008Claudia D. Spies Background:, Both alcohol abuse and surgery have been shown to impair immune function. The frequency of postoperative infectious complications is 2- to 5-fold increased in long-term alcoholic patients, leading to prolonged hospital stay. Following surgery, an increase in interleukin (IL)-6 has been shown to be associated with increased tissue injury and interleukin 1-(IL-10) is known to represent an anti-inflammatory signal. The purpose of this study was to test the hypothesis that several days of excess alcohol consumption results in more pronounced immunosuppression. We assume that alcoholic animals show increased levels of IL-10 in response to infection and increased IL-6 due to a more pronounced lung pathology. Methods:, Thirty-two female Balb/c mice were pretreated with ethanol (EtOH) at a dose of (3.8 mg/g body weight) or saline (NaCl) for 8 days. At day 8 of the experiment all mice underwent a median laparotomy. Two days postsurgery mice were either applicated 104 CFU Klebsiella pneumoniae or received sham-infection with saline. A total number of 4 groups (EtOH/K. pneumoniae; NaCl/K. pneumoniae; EtOH/Sham-infection, NaCl/Sham-infection) was investigated and a clinical score evaluated. Twenty-four hours later mice were killed; lung, spleen, and liver were excised for protein isolation and histological assessment. IL-6 and IL-10 levels were detected by ELISA. Results:, Alcohol-exposed mice exhibited a worsened clinical appearance. The histological assessment demonstrated a distinct deterioration of the pulmonary structure in alcohol-treated animals. In the lung, IL-6 and IL-10 was significantly increased in alcohol-exposed infected mice compared to saline-treated infected mice. The clinical score correlated significantly with IL-6 (r = 0.71; p < 0.01) and IL-10 levels (r = 0.64; p < 0.01) in the lung. Conclusions:, Ethanol treatment in this surgical model led to a more severe pulmonary infection with K. pneumoniae which was associated with more tissue destruction and increased levels of IL-6 and IL-10 and a worsened clinical score. [source] Acute Alcohol Intoxication During Hemorrhagic Shock: Impact on Host Defense From InfectionALCOHOLISM, Issue 4 2004K. L. Zambell Abstract: Background: Acute alcohol intoxication is a frequent underlying condition associated with traumatic injury. Our studies have demonstrated that acute alcohol intoxication significantly impairs the immediate hemodynamic, metabolic, and inflammatory responses to hemorrhagic shock. This study investigated whether acute alcohol intoxication during hemorrhagic shock would alter the outcome from an infectious challenge during the initial 24 hr recovery period. Methods: Chronically catheterized male Sprague Dawley® rats were randomized to acute alcohol intoxication (EtOH; 1.75 g/kg bolus followed by a constant 15 hr infusion at 250,300 mg/kg/hr) or isocaloric isovolemic dextrose infusion (dex; 3 ml + 0.375 ml/hr). EtOH and dex were assigned to either fixed-volume (50%) hemorrhagic shock followed by fluid resuscitation with Ringer's lactate (EtOH/hem, dex/hem) or sham hemorrhagic shock (EtOH/sham, dex/sham). Indexes of circulating neutrophil function (apoptosis, phagocytosis, oxidative burst) were obtained at baseline, at completion of hemorrhagic shock, and at the end of fluid resuscitation. Bacterial clearance, lung cytokine expression, and myeloperoxidase activity were determined at 6 and 18 hr after an intratracheal challenge with Klebsiella pneumoniae (107 colony-forming units). Results: Mean arterial blood pressure was significantly lower in acute alcohol intoxication-hemorrhagic shock animals throughout the hemorrhagic shock. In sham animals, acute alcohol intoxication alone did not produce significant changes in neutrophil apoptosis or phagocytic activity but significantly suppressed phorbol myristic acid (PMA)-stimulated oxidative burst. Hemorrhagic shock produced a modest increase in neutrophil apoptosis and suppression of neutrophil phagocytic capacity but significantly suppressed PMA-stimulated oxidative burst. Acute alcohol intoxication exacerbated the hemorrhagic shock-induced neutrophil apoptosis and the hemorrhagic shock-induced suppression of phagocytosis without further affecting PMA-stimulated oxidative burst. Fluid resuscitation did not restore neutrophil phagocytosis or oxidative burst. Acute alcohol intoxication decreased (,40%) 3-day survival from K. pneumoniae in hemorrhagic shock animals, impaired bacterial clearance during the first 18 hr postinfection, and prolonged lung proinflammatory cytokine expression. Conclusions: These results demonstrate that the early alterations in metabolic and inflammatory responses to hemorrhagic shock produced by acute alcohol intoxication are associated with neutrophil dysfunction and impaired host response to a secondary infectious challenge leading to increased morbidity and mortality. [source] Detection of extended-spectrum ,-lactamase-producing Klebsiella pneumoniae in effluents and sludge of a hospital sewage treatment plantLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2008T. Prado Abstract Aims:, To detect ESBL (extended-spectrum ,-lactamase)-producing Klebsiella pneumoniae present in the effluents and sludge of a hospital sewage treatment plant, evaluating the treatment plant's potential to remove these micro-organisms. Methods and Results:, Twenty samples (crude sewage, UASB reactor effluent, filtered effluent and sludge) were collected in the period from May to December 2006, in order to analyse antimicrobial susceptibility and to check ESBL production, the disc-diffusion and the combined disc methods were used. Total and faecal coliform concentrations were also determined. ESBL-producing K. pneumoniae were detected in all samples analysed, representing 46·5% of the total strains isolated. Among the non-ESBL-producing strains, 26% were multiresistant and one strain resistant to eight of the nine antimicrobials tested was detected in the treated effluent. Conclusions:, The hospital wastewater treatment plant did not show a satisfactory efficacy in removing pathogenic micro-organisms, allowing for the dissemination of multiresistant bacteria into the environment. Significance and Impact of the Study:, The inefficacy of hospital wastewater treatment plants can result in routes of dissemination of multiresistant bacteria and their genes of resistance into the environment, thus contaminating water resources, and having serious negative impact on public health. [source] Sputum bacteriology in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease in Taiwan with an emphasis on Klebsiella pneumoniae and Pseudomonas aeruginosaRESPIROLOGY, Issue 1 2007Sheng-Hsiang LIN Background and objective: Bacterial infection is one of the major causes of acute exacerbation of COPD (AECOPD). This study was undertaken to investigate the microbiology of AECOPD. Methods: Medical records from 494 episodes of AECOPD in patients admitted to the National Taiwan University Hospital from January 2000 to June 2004 were reviewed. Severity of COPD was classified according to the 2003 Global Initiative for Chronic Obstructive Lung Disease guideline. Results: Potential pathogenic microorganisms were isolated from patients in 328 (66.4%) episodes of AECOPD. The predominant bacteria were Klebsiella pneumoniae (19.6%), Pseudomonas aeruginosa (16.8%) and Haemophilus influenzae (7.5%), followed by Acinetobacter baumannii (6.9%), Enterobacter species (6.1%) and Staphylococcus aureus (6.1%). The incidence of Streptococcus pneumoniae was 2.4%. Spirometry results obtained within 1 year of the exacerbation were available in 186 cases. K. pneumoniae was more frequently isolated in stage I COPD (39.1%) than stage II (16.6%), III (13.8%) and IV (9.4%). No glucose non-fermentative Gram-negative bacilli were isolated in stage I patients. Multivariate logistic regression analysis revealed that P. aeruginosa (odds ratio (OR) 3.19; 95% confidence interval (CI): 1.21,8.38), intubation (OR 14.81; 95% CI: 5.08,43.12) and age (OR 1.1; 95% CI: 1.03,1.17) were independent risk factors for mortality. Conclusions: Klebsiella pneumoniae and P. aeruginosa are the most common sputum pathogens in hospitalized patients with AECOPD in Taiwan, with the former being more commonly isolated from mild COPD and the latter associated with poor clinical outcome. These results should be considered when deciding which antibiotics should initially be used to treat patients with AECOPD. [source] Bacteriologic Comparison of Tonsil Core in Recurrent Tonsillitis and Tonsillar Hypertrophy,THE LARYNGOSCOPE, Issue 12 2007Jin Hyeok Jeong MD Abstract Objectives: Although many bacteriology studies on tonsillar diseases have been completed, all have been confined to children and were characterized by a paucity of cases. The purpose of this study was to analyze the underlying bacterial pathogens in tonsillar disease. Methods: A retrospective study was performed on 824 patients who underwent elective tonsillectomy with or without adenoidectomy. We analyzed the differences between the bacterial pathogens in recurrent tonsillitis and tonsillar hypertrophy with regard to age, season, and antibiotic sensitivity. Results: Among 824 cases, 966 bacterial strains from the tonsil core were isolated. In recurrent tonsillitis, Staphylococcus aureus was the most common pathogen (30.3%), followed by Haemophilus influenzae (15.5%) and group A ,-hemolytic Streptococcus (Streptococcus pyogenes, 14.4%). In patients over 14 years of age, quite differently from other age groups, Klebsiella pneumoniae was isolated at a significantly higher percentage. In tonsillar hypertrophy, H. influenzae was isolated most commonly (31.4%) regardless of age, followed by S. pyogenes (24.2%), S. aureus (22.9%), and Streptococcus pneumoniae (12.6%). Furthermore, mixed infection was common because of its high resistance to penicillin. In both groups, S. pneumoniae was more common in younger patients, whereas K. pneumoniae was relatively common in adults. We found no differences in the detection rate by season; however, H. influenzae was frequently isolated in the tonsillar hypertrophy group regardless of seasonal variations. We also found no difference in the antibiotic sensitivity between the two groups; however, strains resistant to penicillin were relatively prevalent and showed a high sensitivity to third-generation cephalosporin. Conclusions: We observed some differences in the types of bacteria in the tonsillar core between the recurrent tonsillitis and tonsillar hypertrophy groups. Our study indicates that essential bacteria have been changing and, thus, we need to change our choice of antibiotics. [source] Prevalence and resistance patterns of extended-spectrum and AmpC ,-lactamase in Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Salmonella serovar Stanley in a Korean tertiary hospitalAPMIS, Issue 10 2010SOON DEOK PARK Park SD, Uh Y, Lee G, Lim K, Kim JB, Jeong SH. Prevalence and resistance patterns of extended-spectrum and AmpC ,-lactamase in Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Salmonella serovar Stanley in a Korean tertiary hospital. APMIS 2010; 118: 801,8. A total of 100 clinical isolates of Escherichia coli (n = 35), Klebsiella pneumoniae (n = 63), Proteus mirabilis (n = 1), and Salmonella serovar Stanley (n = 1), showing resistance to cefoxitin, or returning positive in extended-spectrum ,-lactamase (ESBL) by Clinical and Laboratory Standards Institute (CLSI) ESBL confirmatory method, were studied. The isolates were examined by the boronic acid (BA) disk test, polymerase chain reaction, and pulsed-field gel electrophoresis (PFGE) to investigate genetic similarities. The concurrence rates for ESBLs by the CLSI and the BA disk test were 97% for E. coli and 96.7% for K. pneumoniae. A total of 41 isolates showing cefoxitin resistance yielded all positive by the BA disk test. All the 33 K. pneumoniae isolates, which showed positive by the BA disk test, were carrying AmpC genes. The TEM and CTX-M types were predominant in E. coli and the SHV and the CIT and/or DHA types were predominant in K. pneumoniae. PFGE analysis showed almost 75% of genetic similarities among K. pneumoniae isolates producing ESBLs and/or AmpC ,-lactamases (AmpCs) as each K. pneumoniae carried variable genes and showed variable antibiotic patterns. Clearly, the BA disk test was a useful method for the detection of ESBLs and AmpCs. In particular, cefoxitin resistance and BA-positive trait of K. pneumoniae do reflect the presence of AmpC genes in the organism. [source] The first major extended-spectrum ,-lactamase outbreak in Scandinavia was caused by clonal spread of a multiresistant Klebsiella pneumoniae producing CTX-M-15,APMIS, Issue 4 2008BIRGITTA LYTSY Between May and December 2005, 64 multidrug-resistant isolates of Klebsiella pneumoniae were detected from patients admitted to Uppsala University Hospital. This represented a dramatic increase in ESBL-producing K. pneumoniae compared to previous years. To investigate the epidemiology and to characterize the resistance mechanisms of the isolates, a study was initiated. Antibiotic susceptibility was determined by means of the Etest and the disc diffusion method. Extended-spectrum beta-lactamase (ESBL) production was identified by clavulanic acid synergy test and confirmed with PCR amplification followed by DNA sequencing. DNA profiles of the isolates were examined with pulsed-field gel electrophoresis (PFGE). All isolates were resistant or exhibited reduced susceptibility to cefadroxil, cefuroxime, cefotaxime, ceftazidime, aztreonam, piperacillin/tazobactam, ciprofloxacin, tobramycin, and trimethoprim-sulfamethoxazole. They produced ESBL of the CTX-M-15 type, and the involvement of a single K. pneumoniae clone was shown. This is the first major clonal outbreak of multiresistant ESBL-producing K. pneumoniae in Scandinavia. The outbreak demonstrates the epidemic potential of enterobacteria containing ESBLs of the CTX-M type, even in a country with a relatively low selective pressure and a low prevalence of multiresistant bacteria. [source] Heterologous expression and characterization of recombinant glycerol dehydratase from Klebsiella pneumoniae in Escherichia coliBIOTECHNOLOGY JOURNAL, Issue 6 2007Fenghuan Wang Abstract Glycerol dehydratase (EC 4.2.1.30), as one of the key enzymes in converting glycerol to the valuable intermediate 1,3-propanediol, is important for biochemical industry. The dhaB genes encoding coenzyme B12 -dependent glycerol dehydratase in Klebsiella pneumoniae were cloned and expressed in Escherichia coli. An effective co-expression system of multiple subunits protein was constructed. Heterologous expression vectors were constructed using the splicing by overlap extension-PCR technique to co-express the three subunits of the glycerol dehydratase. After induction by isopropyl-,- D -thiogalactopyranoside, SDS-PAGE analysis revealed that: (i) only the , subunit of glycerol dehydratase was expressed in direct expression system, (ii) the three subunits of glycerol dehydratase with predicted molecular massess of 64 (agr;), 22 (,), and 16 kDa (,) were expressed simultaneously in co-expression system, and (iii) the fusion expression system expressed the fusion protein of 99 kDa. Enzyme assay showed that the activities of three heterologous expression products were 27.4, 2.3, and 0.2 U/mg. The highest enzyme activity was almost 17 times of that in K. pneumoniae. The recombinant enzyme was purified and biochemically characterized. The apparent Km values of the enzyme for coenzyme B12 and 1, 2-propanediol were 8.5 nM and 1.2 mM, respectively. The enzyme showed maximum activity at pH 8.5 and 37°C. [source] Improving 1,3-Propanediol Production from Glycerol in a Metabolically Engineered Escherichia coliby Reducing Accumulation of sn -Glycerol-3-phosphateBIOTECHNOLOGY PROGRESS, Issue 4 2002Marie M. Zhu High levels of glycerol significantly inhibit cell growth and 1,3-propanediol (1,3-PD) production in anaerobic glycerol fermentation by genetically engineered Escherichia coli( E. coli) strains expressing genes from the Klebsiella pneumoniae dha( K.pneumoniae) regulon. We have previously demonstrated that 1,3-PD production by the engineered E. colican be improved by reducing the accumulation of methylglyoxal. This study focuses on investigation of another lesser-known metabolite in the pathways related to 1,3-PD production-glycerol-3-phosphate (G3P). When grown anaerobically on glycerol in the absence of an exogenous acceptor, the engineered E.colistrains have intracellular G3P levels that are significantly higher than those in K. pneumoniae, a natural 1,3-PD producer. Furthermore, in the engineered E. colistrains, the G3P levels increase with increasing glycerol concentrations, whereas, in K. pneumoniae, the concentrations of G3P remain relatively constant. Addition of fumarate, which can stimulate activity of anaerobic G3P dehydrogenase, into the fermentation medium led to a greater than 30-fold increase in the specific activity of anaerobic G3P dehydrogenase and a significant decrease in concentrations of intracellular G3P and resulted in better cell growth and an improved production of 1,3-PD. This indicates that the low activity of G3P dehydrogenase in the absence of an exogenous electron acceptor is one of the reasons for G3P accumulation. In addition, spent media from E. coliLin61, a glycerol kinase (responsible for conversion of glycerol to G3P) mutant, contains greatly decreased concentrations of G3P and shows improved production of 1,3-PD (by 2.5-fold), when compared to media from its parent strain E. coliK10. This further suggests that G3P accumulation is one of the reasons for the inhibition of 1,3-PD production during anaerobic fermentation. [source] Impaired host defense to Klebsiella pneumoniae infection in mice treated with the PDE4 inhibitor rolipramBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2003A C Soares The increase in levels of cAMP in leukocytes by selective inhibitors of PDE4 may result in reduction of inflammation, and may be useful in the treatment of pulmonary inflammatory disorders in humans. Here, we have assessed whether oral treatment with the prototype PDE4 inhibitor, rolipram, interfered with the antibacterial host response following pulmonary infection of mice with Klebsiella pneumoniae. K. pneumoniae infection induced a marked increase in the recruitment of neutrophils to the lungs and the production of proinflammatory cytokines and chemokines, including tumor necrosis factor- , (TNF- ,) and keratinocyte-derived chemokine (KC), in bronchoalveolar (BAL) fluid and lung tissue. There were also detectable amounts of interleukin-10 (IL-10) and significant lethality. Treatment with rolipram (3,30 mg kg,1) was associated with earlier lethality and significant inhibition of the TNF- , production. This was associated with enhanced production of IL-10 in lung tissue of rolipram-treated animals. Rolipram treatment did not affect KC expression and the recruitment of neutrophils in the lung tissue. Over 70% of neutrophils that migrated into the BAL fluid following K. pneumoniae infection ingested bacteria. Treatment with rolipram inhibited the percentage of neutrophils undergoing phagocytosis of K. pneumoniae in a dose-dependent manner. Maximal inhibition (62%) occurred at doses equal to or greater than 10 mg kg,1. Thus, treatment of mice with the PDE4 inhibitor rolipram is accompanied by earlier lethality, enhanced bacterial load and decreased capacity of the responding host to produce TNF- , and of neutrophils to phagocytose bacteria. It will be important to investigate whether the shown ability of PDE4 inhibitors to inhibit neutrophil phagocytosis and control experimental bacterial infection will translate into an inhibition of the ability of neutrophils to deal with infectious microorganisms in the clinical setting. British Journal of Pharmacology (2003) 140, 855,862. doi:10.1038/sj.bjp.0705517 [source] Decreased incidence of ventilator-associated pneumonia caused by Pseudomonas aeruginosa over 3 yearsBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2000M. Fiore Background Ventilator-associated pneumonia (VAP) is a frequently occurring infection among critically ill patients. Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli are the most common micro-organisms causing VAP. The aim of this study was to ascertain the incidence of VAP diagnosed with bronchoalveolar lavage (BAL) by these possible pathogenic micro-organisms (PPMOs). Because VAP is often preceded by colonization of the oropharynx with the causative pathogen, sputum cultures were compared with the BAL cultures. Methods Over a 3-year period, all ventilated patients in two intensive care units (n = 1136) were reviewed for pneumonia. A VAP was present when the bacterial count of the BAL was more than 104 colony-forming units ml,1. The microbial results of all patients with a VAP (polymicrobial or monomicrobial) were recorded. Results The mean incidence of VAP was 8 per cent (n = 92), decreasing only slightly during the period (P > 0·05). The most frequent aetiological agents were P. aeruginosa (n = 34), S. aureus (n = 22), E. coli (n = 16) and K. pneumoniae (n = 10). The percentage of VAPs due to P. aeruginosa has declined progressively from 53 to 31 per cent. Concurrently, the incidence of Pseudomonas colonizing the sputum culture has declined (from 54 to 44 per cent). On the other hand, the incidence of VAP due to E. coli has increased from 13 (n = 2) to 36 per cent (n = 6). Colonization of the sputum with E. coli has similarly increased (from 13 to 27 per cent). Conclusion The incidence of VAP in the intensive care unit is in accordance with the literature, when diagnosed with strict criteria. No significant change in the incidence of VAP was noted during the 3-year period. Neither the decrease in incidence of VAP caused by P. aeruginosa nor the increase in E. coli pneumonia can be explained by a change in antibiotic regimens in the period studied. Hypothetically, cross-colonization of PPMOs by healthcare personnel can be influenced by hand-washing and wearing gloves. This can especially influence colonization by P. aeruginosa, thus explaining the decrease. © 2000 British Journal of Surgery Society Ltd [source] Emergence of CTX-M-15 extended-spectrum ,-lactamase-producing Klebsiella pneumoniae isolates in Bosnia and HerzegovinaCLINICAL MICROBIOLOGY AND INFECTION, Issue 2 2010A. Dedeic-Ljubovic Clin Microbiol Infect 2010; 16: 152,156 Abstract Fifty-seven nosocomial Klebsiella pneumoniae isolates producing extended-spectrum ,-lactamases (ESBLs) were collected between February 2007 and November 2007 in different wards of the Sarajevo (Bosnia-Herzegovina) reference hospital. These isolates comprise two major epidemic pulsed-field electrophoresis-defined clones plus two minor clones. In addition to the ESBL-mediated resistance, all strains uniformly showed resistance to ciprofloxacin, gentamicin and tobramycin. The ,-lactamases involved in this resistance phenotype were TEM-1, SHV-1, and CTX-M-15, as demonstrated by isoelectric focusing, PCR amplification, and sequencing. TEM-1 and CTX-M-15 ,-lactamases, as well as the aminoglycoside resistance determinants, were encoded in plasmids that could be transferred to Escherichia coli by conjugation. In three of the infected patients with the predominant clone, cefoxitin resistance development (MICs >128 mg/L) was documented. The analysis of the outer membrane proteins of the cefoxitin-susceptible and cefoxitin-resistant isolates revealed that the former expressed only one of the two major porins, OmpK36, whereas in the latter, the expression of Ompk36 was altered or abolished. This is the first report of CTX-M-15-producing K. pneumoniae in Bosnia-Herzegovina. Furthermore, we document and characterize for the first time cefoxitin resistance development in CTX-M-15-producing K. pneumoniae. [source] Activity of ciprofloxacin and levofloxacin in experimental pneumonia caused by Klebsiella pneumoniae deficient in porins, expressing active efflux and producing QnrA1CLINICAL MICROBIOLOGY AND INFECTION, Issue 7 2008J. M. Rodríguez-Martínez Abstract The objective of this study was to evaluate the activities of ciprofloxacin and levofloxacin in a murine model of pneumonia caused by Klebsiella pneumoniae C2 (with altered GyrA, deficient in porins and expressing active efflux of quinolones) and the transconjugant C2pMG252 derived from it and expressing the qnrA1 determinant. MICs and MBCs of the two quinolones were determined according to CLSI guidelines. Time-kill curves (at 1× and 4× MIC) were also performed to assess bactericidal activity. An experimental model of pneumonia in mice was evaluated. Groups of 15 mice were infected with either strain and treated with ciprofloxacin (80 mg/kg/day) or levofloxacin (100 mg/kg/day). Control non-treated animals were also evaluated. In the case of strain C2, log10 CFU/g of lung in non-treated animals was 9.16 ± 2.16. This value was reduced to 3.53 ± 1.04 (p <0.001) and 3.38 ± 0.46 (p <0.001) in animals treated with ciprofloxacin or levofloxacin, respectively. Percentages of surviving mice were 26.7% (control group) and 100% (both ciprofloxacin and levofloxacin; p <0.001 vs. controls). Bacterial counts (log10 CFU/g) in lungs of animals infected with strain C2pMG252 were 9.65 ± 2.49 in non-treated animals and 7.74 ± 2.67 and 7.57 ± 3.84 for those treated with ciprofloxacin or levofloxacin, respectively (p >0.05 vs. control group). Of non-treated animals infected with strain C2pMG252, 14.3% survived. Ciprofloxacin and levofloxacin improved the survival in these mice (53.3% for both antimicrobials, p 0.03). In conclusion, the expression of qnrA1 in K. pneumoniae with additional mechanisms of resistance causes decreased efficacy of fluoroquinolones in a pneumonia model in mice. [source] | ||||||||||||||||