L P Andersen

Statens Serum Institut, København, Capital Region, Denmark

Are you L P Andersen?

Claim your profile

Publications (119)454.28 Total impact

  • Source
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Reducing adhesion of Helicobacter pylori to gastric epithelial cells could be a new way to counteract infections with this organism. We here present a novel method for quantification of Helicobacter pylori adhesion to cells. Helicobacter pylori is allowed to adhere to AGS or MKN45g cells in a 96-well microtiter plate. Then wells are added saponin, which lyses the cells without affecting the bacteria. After addition of alamarBlue(®) (resazurin) and 1- to 2-hour incubation, fluorescence measurements can be used to quantify the number of adherent bacteria. By use of the method, we demonstrate that adhesion of both a sabA and babA deletion mutant of H. pylori is significantly reduced compared to the wild type. The method offers a number of applications and may be used to compare the adherence potential of different strains of H. pylori to either cells or different materials or to screen for potential anti-adhesive compounds. The results presented here suggest that this easy and reproducible assay is well suited for quantitative investigation of H. pylori adhesion. © 2015 John Wiley & Sons Ltd.
    Helicobacter 01/2015; DOI:10.1111/hel.12191 · 2.99 Impact Factor
  • Source
  • Source
    06/2013; 2(1). DOI:10.1186/2047-2994-2-S1-P372
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective Resistance to antibiotics is the major cause of treatment failure of Helicobacter pylori infection. A study was conducted to assess prospectively the antibacterial resistance rates of H pylori in Europe and to study the link between outpatient antibiotic use and resistance levels in different countries. Design Primary antibiotic resistance rates of H pylori were determined from April 2008 to June 2009 in 18 European countries. Data on yearly and cumulative use over several years of systemic antibacterial agents in ambulatory care for the period 2001-8 were expressed in Defined Daily Doses (DDD) per 1000 inhabitants per day. The fit of models and the degree of ecological association between antibiotic use and resistance data were assessed using generalised linear mixed models. Results Of 2204 patients included, H pylori resistance rates for adults were 17.5% for clarithromycin, 14.1% for levofloxacin and 34.9% for metronidazole, and were significantly higher for clarithromycin and levofloxacin in Western/Central and Southern Europe (>20%) than in Northern European countries (<10%). Model fit improved for each additional year of antibiotic use accumulated, but the best fit was obtained for 2005. A significant association was found between outpatient quinolone use and the proportion of levofloxacin resistance (p = 0.0013) and between the use of long-acting macrolides only and clarithromycin resistance (p = 0.036). Conclusion In many countries the high rate of clarithromycin resistance no longer allows its empirical use in standard anti-H pylori regimens. The knowledge of outpatient antibiotic consumption may provide a simple tool to predict the susceptibility of H pylori to quinolones and to macrolides and to adapt the treatment strategies.
    Gut 01/2013; 62(1-1):34-42. DOI:10.1136/gutjnl-2012-302254 · 13.32 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: Resistance to antibiotics is the major cause of treatment failure of Helicobacter pylori infection. A study was conducted to assess prospectively the antibacterial resistance rates of H pylori in Europe and to study the link between outpatient antibiotic use and resistance levels in different countries. DESIGN: Primary antibiotic resistance rates of H pylori were determined from April 2008 to June 2009 in 18 European countries. Data on yearly and cumulative use over several years of systemic antibacterial agents in ambulatory care for the period 2001-8 were expressed in Defined Daily Doses (DDD) per 1000 inhabitants per day. The fit of models and the degree of ecological association between antibiotic use and resistance data were assessed using generalised linear mixed models. RESULTS: Of 2204 patients included, H pylori resistance rates for adults were 17.5% for clarithromycin, 14.1% for levofloxacin and 34.9% for metronidazole, and were significantly higher for clarithromycin and levofloxacin in Western/Central and Southern Europe (>20%) than in Northern European countries (<10%). Model fit improved for each additional year of antibiotic use accumulated, but the best fit was obtained for 2005. A significant association was found between outpatient quinolone use and the proportion of levofloxacin resistance (p=0.0013) and between the use of long-acting macrolides only and clarithromycin resistance (p=0.036). CONCLUSION: In many countries the high rate of clarithromycin resistance no longer allows its empirical use in standard anti-H pylori regimens. The knowledge of outpatient antibiotic consumption may provide a simple tool to predict the susceptibility of H pylori to quinolones and to macrolides and to adapt the treatment strategies.
    Gut 01/2013; 62(1):34-42. · 13.32 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The study evaluated the changes in the prevalence of Helicobacter pylori strains with primary resistance to antibiotics during the last 10 years in Lithuania. H. pylori susceptibilities to antibiotics were tested in 89 patients in 1998, in 81 patients in 2001 and in 90 patients in 2007/2008. Susceptibility to metronidazole, clarithromycin, amoxicillin and tetracycline was tested using E-test or agar dilution method. Susceptibility to ciprofloxacin was only tested in 2007/2008. Data about utilization of all authorized and available on market macrolides and clindamycin in Lithuania during 2003-2007 were evaluated using WHO ATC/DDD methodology. A total of 260 H. pylori strains cultured from untreated adult patients were investigated. Primary resistance rates (1998, 2001 and 2007/2008) for metronidazole were 24.7%, 33.3%, and 35.6%, for clarithromycin 1.1%, 3.7%, and 3.3% and for tetracycline 0%, 2.5% and 0% respectively. No cases of amoxicillin resistance have been detected. The resistance rate for ciprofloxacin was 5.6% in 2007/2008. Data of total macrolides and clarithromycin utilization in Lithuania revealed that despite an increase of consumption of these drugs in Lithuania during 2003-2007 in 1.5 times, the total macrolide consumption remains one of the lowest in Europe. We have not observed any significant changes in the susceptibility of H. pylori to the most widely used antibiotics during the recent 10-year period. The low resistance rate to clarithromycin might be related to the policy to avoid use of macrolides as first-line treatment for pulmonary and other infections.
    Apmis 10/2012; DOI:10.1111/apm.12012 · 1.92 Impact Factor
  • Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)61257-2 · 13.93 Impact Factor
  • Lone Rasmussen, Leif Percival Andersen
    [Show abstract] [Hide abstract]
    ABSTRACT: Helicobacter pylori is a Gram-negative, microaerophilic curved rod, that possesses an unipolar bundle of two to six flagella which enables it to move to a specific target with high concentration of chemoattractants, such as urea. H. pylori is a pathogenic bacterium, which is present in more than half of the population worldwide with a range from 20 to 30% in developed countries to 60–80% in developing countries.
    10/2010: pages 161-166;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Enterococcus species are common in nosocomial bloodstream infections and their incidence is rising. Although well recognized in several serious bacterial infections, the influence of appropriate antimicrobial therapy in enterococcal bacteraemia has not been fully settled. The aim of the study was to determine whether administration of inappropriate antibiotics in enterococcal bacteraemia is an independent risk factor for mortality, among other known and suspected risk factors. We conducted a cohort study of E. faecalis/faecium bacteraemia during a 3-year period at a single tertiary care hospital in Denmark. Patients with growth of non-enterococcus co-pathogens apart from the enterococcal bacteraemia were also included, as were patients with repeated enterococcal bacteraemia. Time to appropriate antimicrobial therapy was counted from the first episode. Appropriate antibiotic therapy was defined as any therapy with documented clinical effect, in vitro activity and a minimum treatment length of 6 days. Multivariate regression models were built to determine the independent risk factors for mortality. We included 196 patients with enterococcal bacteraemia. Appropriate antibiotics for at least 6 days were administered in 146 of these (74%). Thirty-day mortality was 26%. Multivariate logistic regression identified independent predictors of 30-day all-cause mortality: appropriate antimicrobial therapy for ≥ 6 days (odds ratio for mortality 0.33, 0.14-0.79), ICU admission (4.2, 1.7-10), thrombocytopenia (3.9, 1.6-9.3), chronic liver failure (3.3, 1.1-10) and age ≥ 60 years (2.2, 0.99-5.0). Antibiotics not appropriately covering enterococci are frequently administered empirically in suspected bloodstream infections. Inappropriate antibiotic therapy was an independent risk factor for mortality in enterococcal bacteraemia.
    Clinical Microbiology and Infection 10/2010; 17(7):1078-83. DOI:10.1111/j.1469-0691.2010.03394.x · 5.20 Impact Factor
  • L P Andersen, P Lange, M Tvede
    European Journal of Clinical Microbiology 07/2010; 29(7):891-2. DOI:10.1007/s10096-010-0925-z · 2.54 Impact Factor
  • Jalal Alimoradi, Lone Rasmussen, Leif Percival Andersen
    [Show abstract] [Hide abstract]
    ABSTRACT: Helicobacter pylori (H. pylori) is recognized as the causative of several gastroduodenal disorders. The discovery of H. pylori revolutionized the treatment for ulcus pepticum. Antibiotics combined with proton pump inhibitors or bismuth have been effective in the treatment of H. pylori infections, but there is an emerging problem with H. pylori resistance against the most frequently used antibiotics, which substantially impairs the treatment of H. pylori-associated disorders. In this article the focus is on the prevalence of H. pylori resistance, its clinical implications and the molecular mechanisms behind resistance development.
    Ugeskrift for laeger 05/2010; 172(20):1516-21.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Heat-stable antigens from Helicobacter pylori were investigated for the detection of serum IgG, IgA and IgM antibodies against H. pylori by an ELISA technique. Antibody titers against H. pylori were measured in 167 dyspeptic patients, of whom 96 were H. pylori positive confirmed by culture or microscopy, and in 482 controls (0–98 years). Increased IgG antibody titers were found significantly more often in dyspeptic patients with active chronic gastritis than in patients with normal morphology, as well as in H. pylori-positive patients as compared to H. pylori-negative patients, independent of the endoscopic findings. The heat-stable antigens were compared with acid glycine-extracted antigens and a high degree of concordance was found in the results obtained with the two antigen preparations. The differences in the IgA antibody titers against H. pylori between H. pylori-positive and H. pylori-negative dyspeptic patients were significant and may be useful to confirm a borderline IgG result. No differences were found in IgM antibody titer between H. pylori-positive and -negative patients. The greatest age-dependent increase in IgG and IgA antibody titers was found in children, and if a lower cut-off level is used for children than for adults, as has been proposed, the proportion of people with increased antibody titers against H. pylori would be almost constant from the age of between five and 10 years until the time between 61 and 80 years. Comparison of H. pylori IgG antibodies with IgG antibodies against Campylobacter jejuni and total antibodies against cytomegalovirus (CMV) showed a greater similarity between H. pylori and C. jejuni (R = 0.51) than between H. pylori and CMV (R = 0.22). This may possibly be caused by cross-reactions between H. pylori and C. jejuni. The H. pylori heat-stabile antigen seems not to be very different from other crude H. pylori antigens like acid glycine-extracted antigens, but purification and characterization of the antigens are needed to improve antibody assays.
    Apmis 08/2009; 100(7‐12):779 - 789. DOI:10.1111/j.1699-0463.1992.tb04000.x · 1.92 Impact Factor
  • Source
    Leif Percival Andersen, Lone Rasmussen
    [Show abstract] [Hide abstract]
    ABSTRACT: Electron microscopic studies have shown that Helicobacter pylori occurs in three stages: spiral forms, coccoid forms and degenerative forms. The spiral forms are viable, culturable, virulent and can colonize experimental animals and induce inflammation. The coccoid forms may also be viable but are nonculturable, less virulent and are less likely to colonize and induce inflammation in experimental animals than the spiral forms. The degenerative forms are pyknotic, nonculturable, coccoid forms of dead H. pylori. These forms cannot be cultured and the cell membrane has disintegrated but gene material can be detected by PCR in water supplies. There is no substantial evidence for viable H. pylori persisting in water supplies. Epidemiological studies suggest that environmental water is a risk factor for H. pylori infection when compared with tap water, and formation of H. pylori biofilm cannot be excluded. Helicobacter pylori does not seem to take part in biofilm formation in the oral cavity even though the bacterium may be detected.
    FEMS Immunology & Medical Microbiology 05/2009; 56(2):112-5. DOI:10.1111/j.1574-695X.2009.00556.x · 2.55 Impact Factor
  • Source
    Rune Aabenhus, Unne Stenram, Leif Percival Andersen, Henrik Permin, Asa Ljungh
    [Show abstract] [Hide abstract]
    ABSTRACT: To infect mice with atypical Campylobacter concisus (C. concisus) for the first time. Three separate experiments were conducted in order to screen the ability of five clinical C. concisus isolates of intestinal origin and the ATCC 33237 type strain of oral origin to colonize and produce infection in immunocompetent BALB/cA mice. The majority of the BALB/cA mice were treated with cyclophosphamide prior to C. concisus inoculation to suppress immune functions. Inoculation of C. concisus was performed by the gastric route. C. concisus was isolated from the liver, ileum and jejunum of cyclophosphamide-treated mice in the first experiment. No C. concisus strains were isolated in the two subsequent experiments. Mice infected with C. concisus showed a significant loss of body weight from day two through to day five of infection but this decreased at the end of the first week. Histopathological examination did not consistently find signs of inflammation in the gut, but occasionally microabscesses were found in the liver of infected animals. Transient colonization with C. concisus was observed in mice with loss of body weight. Future studies should concentrate on the first few days after inoculation and in other strains of mice.
    World Journal of Gastroenterology 01/2009; 14(45):6954-9. · 2.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The impact of environmental contamination on nosocomial cross-transmission is mostly unresolved and in Danish hospitals assessment of cleaning is based on visible criteria only. The use of premoistened microfibre cloths and the 16-side method have been introduced into Danish hospitals because of economic and ergonomic advantages but they have not been evaluated for applicability in hospital cleaning. Our hypothesis was that this method may spread bacteria. A surface was contaminated with bacteria (4 cfu/bacteria/cm(2)), and cleaned with a premoistened microfibre cloth folded to 16-side use. Each of 15 sterile surfaces was cleaned with a new side of the microfibre cloth; imprints were made and the experiment repeated 12 times. After cleaning, the contaminated surface imprints of microfibre cloths showed a median of 45.5 cfu/plate for E. faecalis and 2.5 cfu/plate for B. cereus. Median values from imprints from cloth sides 2-16 were between 1 and 12 cfu/plate for E. faecalis and 0 cfu/plate for B. cereus. Imprints of the contaminated surfaces were a median of 45.5 cfu/plate for E. faecalis, giving a reduction of 5.6-fold. For B. cereus the median value was 0 cfu/plate. The surface numbers 2-16 had median values between 0.5 and 7.5 for E. faecalis, which was spread to 11-15 of the 15 sterile surfaces (P<0.01). B. cereus was found in six out of 180 imprints on surfaces 2-16, all with 1 cfu/plate (non-significant). The implication is that although there was an overall reduction in bacterial counts on the contaminated surface, bacteria were spread to subsequently cleaned surfaces.
    Journal of Hospital Infection 12/2008; 71(2):132-7. DOI:10.1016/j.jhin.2008.10.025 · 2.78 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to evaluate the efficacy of the natural antioxidant astaxanthin in functional dyspepsia in different doses and compared with placebo. The study was a controlled, prospective, randomized, and double blind trial. Patients with functional dyspepsia, divided into three groups with 44 individuals in each group (placebo, 16mg, or 40mg astaxanthin, respectively). Participants were asked to accept gastroscopy before treatment, together with questionnaires: GSRS and SF-36. Urea breath test (UBT) was done before the treatment. The primary objective was to test the hypothesis that the antioxidant astaxanthin at two doses regimens compared to placebo should ameliorate gastrointestinal discomfort measured as GSRS in patients with functional dyspepsia, who were either positive or negative for Helicobacter pylori, after 4 weeks of treatment. At the end of therapy (week 4) no difference between the three treatment groups was observed regarding mean Gastrointestinal Symptom Rating Scale (GSRS) scores of abdominal pain, indigestion and reflux syndromes. The same results were observed at the end of follow-up. However reduction of reflux syndrome before treatment to week 4 was significantly pronounced in the higher (40mg) dose compared to the other treatment groups (16mg and placebo, p=0.04). In general, no curative effect of astaxanthin was found in functional dyspepsia patients. Significantly greater reduction of reflux symptoms were detected in patients treated with the highest dose of the natural antioxidant astaxanthin. The response was more pronounced in H. pylori-infected patients.
    Phytomedicine: international journal of phytotherapy and phytopharmacology 07/2008; 15(6-7):391-9. DOI:10.1016/j.phymed.2008.04.004 · 2.88 Impact Factor
  • Leif Percival Andersen
    [Show abstract] [Hide abstract]
    ABSTRACT: When Helicobacter pylori arrives in the human stomach, it may penetrate the mucin layer and adhere to the gastric epithelial cells or it may pass through the stomach without colonizing the mucosa. In this paper, the colonization process and the ensuing immunological response will be briefly described. Urease production is necessary for H. pylori to establish a pH-neutral microenvironment around the bacteria. The flagella enable the bacteria to move and the shape of H. pylori makes it possible to penetrate the mucin layer where it comes into contact with the gastric epithelial cells. H. pylori contains several adhesins that enable it to adhere to the epithelial cells. This adherence activates IL-8 which, together with bacterial antigens, attracts polymorphs and monocytes and causes acute gastritis. Antigen-presenting cells activate lymphocytes and other mononuclear cells that are attracted to the inflamed mucosa, causing chronic superficial gastritis and initiating a cytotoxic or an antigen-producing Th response. The infection is established within a few weeks after the primary exposure to H. pylori. After this initial colonization, many chemical, biochemical, and immunologic reactions take place that are of importance in the progress of the infection and the development of disease.
    Helicobacter 12/2007; 12 Suppl 2:12-5. DOI:10.1111/j.1523-5378.2007.00574.x · 2.99 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Helicobacter pylori is an important pathogen in major gastroduodenal diseases, including inflammation with ulceration and gastric malignancies. Alterations in H. pylori associated cell turnover in gastric epithelial cells are examined in relation to inflammatory activity, bacteria load and cytokines which may improve knowledge concerning the outcome of gastric diseases caused by H. pylori. Antral biopsies from 42 dyspeptic patients including 27 H. pylori-positive and 15 H. pylori-negative patients were tested for apoptotic activity by the TUNEL assay, and immuno-histochemically for p53 and the proliferative marker Ki-67. H. pylori infection, bacteria load and inflammatory activity were associated with increased cell turnover as judged by enhanced activities of TUNEL, p53 and Ki-67. Only p53 was significantly correlated to IFN-gamma, IL-8 and IL-10. The H. pylori-positive state was furthermore accompanied by varying degrees of altered distribution pattern of the markers studied, with occasional presence of apoptosis in the deeper pit zones, upward extension of Ki-67 and to a lesser degree of p53. Given a similar pattern of change in proliferation and apoptosis in some neoplastic lesions in other parts of the gastrointestinal tract, such studies in cell turnover may provide insights valuable in the investigations of potential precursors of gastric malignancies.
    FEMS Immunology & Medical Microbiology 08/2007; 50(2):206-12. DOI:10.1111/j.1574-695X.2007.00254.x · 2.55 Impact Factor

Publication Stats

3k Citations
454.28 Total Impact Points

Institutions

  • 2015
    • Statens Serum Institut
      • Department of Microbiology and Infection Control
      København, Capital Region, Denmark
  • 1995–2013
    • Copenhagen University Hospital
      København, Capital Region, Denmark
  • 1996–2010
    • Glostrup Hospital
      • Department of Internal Medicine
      Glostrup, Capital Region, Denmark
  • 1992–2009
    • IT University of Copenhagen
      København, Capital Region, Denmark
  • 2005
    • Erasmus MC
      • Department of Gastroenterology and Hepatology
      Rotterdam, South Holland, Netherlands
  • 2003
    • Pasteur Institute of Iran (IPI)
      Teheran, Tehrān, Iran
  • 2002
    • Lund University
      Lund, Skåne, Sweden
  • 1999–2001
    • Rigshospitalet
      • Department of Clinical Microbiology
      København, Capital Region, Denmark
  • 1997–2001
    • Bispebjerg Hospital, Copenhagen University
      København, Capital Region, Denmark
  • 1996–2001
    • National University (California)
      San Diego, California, United States
  • 1999–2000
    • Aalborg University Hospital
      • Department of Clinical Immunology
      Aalborg, Region North Jutland, Denmark
  • 1998
    • Næstved Hospital
      • Department of Medicine
      Нествед, Zealand, Denmark
  • 1989–1995
    • Hillerød Hospital
      Hillerød, Capital Region, Denmark