H Hahn's research while affiliated with Charité Universitätsmedizin Berlin and other places

Publications (171)

Article
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Oral viridans streptococci are a reservoir of resistance genes for pathogens. Through prolonged exposure, long-acting macrolides (e.g., azithromycin) may induce the resistance of the commensals to macrolides more frequently than macrolides with a shorter half-life (e.g., clarithromycin). In a prospective, randomized, evaluator-blinded trial in heal...
Article
This study investigated the seroprevalence of antibodies against Anaplasma phagocytophilum in Berlin/Brandenburg, north-eastern Germany. During 1994-2001, 422 sera from patients with proven tick-exposure (specimens with antibodies against Borrelia burgdorferi) were compared with 249 control sera. Using indirect fluorescent antibody testing, signifi...
Article
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Solid lipid nanoparticles (SLN) composed of two different lipid matrices were produced to assess their in vivo toxicity in mice. Matrix substances were (i) Compritol (glycerol behenate), a physiological lipid with GRAS status (generally recognized as safe [FDA]), and (ii) cetyl palmitate, a less physiological compound. Physicochemical data proved t...
Chapter
Enterokokken bilden eine Gattung grampositiver Kettenkokken in der Familie der Streptococcaceae (⊡ Tab. 27.1 ). Durch den Besitz des D-Polysaccharids in der Wand sind sie mit den D-Streptokokken nahe verwandt, verursachen aber keine β-Hämolyse. Die Gattung enthält die medizinisch relevanten Spezies Enterococcus (E.) faecalis und E. faecium (⊡ Tab....
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Nocardia paucivorans represents a new species of the genus Nocardia that has recently been isolated from bronchial secretions of a patient with chronic lung disease. Here, we report on the course of a disseminated infection caused by this species: i.e., cerebral and subsequent meningeal manifestations, isolation from the cerebrospinal fluid, and in...
Article
Solid lipid nanoparticles (SLN) interact with mononuclear cells following intravenous injection. Little is known about the interaction of SLN with these cells, including cytotoxic effects and a possible up-regulation of pro-inflammatory cytokines. Therefore, we investigated the influence of lipid matrix, concentration, and size of SLN on murine per...
Article
After intravenous (i.v.) injection, solid lipid nanoparticles (SLN) interact with mononuclear cells. Murine peritoneal macrophages were incubated with SLN formulations consisting of Dynasan 114 coated with different surfactants. The present study was performed to examine the impact of surfactants, which are important surface defining components of...
Chapter
Staphylokokken sind grampositive Kugelbakterien, die sich in Haufen, Tetraden oder in Paaren lagern und sich sowohl aerob als auch anaerob vermehren (Tabelle 1.1).
Chapter
Antimikrobielle Chemotherapie ist eine Heilmethode zur Behandlung von Infektionen. Die Erreger werden selektiv im Wirtsorganismus abgetötet oder an der Vermehrung gehindert, ohne daß die Zellen des Wirts durch die Chemotherapie geschädigt werden (Prinzip der selektiven Toxizität).
Chapter
Die Fähigkeit einer Spezies von Mikroorganismen, in einem Makroorganismus Krankheit zu erzeugen, heißt Pathogenität (Abb. 1.1).
Article
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A total of 212 clinical Streptococcus pyogenes isolates were tested for susceptibility to various antibiotics by agar dilution. The overall frequency of erythromycin resistance was 12.7%, being higher in isolates from children (18.9%) than in those from adult patients (10.7%). Similar results were found for clarithromycin, while 2.8% of the isolate...
Article
Because of the increasing resistance of Neisseria gonorrhoeae, we studied the actual resistance of isolates in Berlin. 85 Neisseria gonorrhoeae isolates were collected between 1995 and 1997. Susceptibility testing was performed for penicillin G, tetracycline, spectinomycin, ceftriaxone, ciprofloxacin and azithromycin by agar dilution. 18.8% isolate...
Article
Background and Objective. Because of the increasing resistance of Neisseria gonorrhoeae, we studied the actual resistance of isolats in Berlin. Patients/Methods. 85 Neisseria gonorrhoeae isolates were collected between 1995 and 1997. Susceptibility testing was performed for penicillin G, tetracycline, spectinomycin, ceftriaxon, ciprofloxycin and az...
Article
The purpose of this study was to investigate possible immunomodulatory and cytotoxic effects of solid lipid nanoparticles (SLN) on murine peritoneal macrophages. Immunomodulatory effects of SLN composed of either a lipid- (glycerol-behenate) or a wax (cetylpalmitate) matrix stabilized by the surfactant Poloxamer 188 were analysed by detection of pr...
Article
Clofazimine nanosuspensions were produced by high pressure homogenization and the formulation was optimized for lyophilization. Characterization of the product by photon correlation spectroscopy, laser diffraction and Coulter counter analysis showed that the clofazimine nanosuspensions were suitable for iv injection with a particle size permitting...
Article
More than half of the world's population is infected with Helicobacter (H.) pylori whereby the degree of infection is much lower in the industrial countries than in third-world countries for which social, economic and ethnic reasons are being suspected. Initially, direct methods (microbiological culture and histological examinations) are used for t...
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Bartonella henselae is an emerging pathogen causing cat scratch disease, bacillary angiomatosis, and peliosis hepatis. Progress in understanding the pathogenesis of and the immune response to these infections has been limited by the lack of an animal model. Following intraperitoneal infection of C57BL/6 mice with B. henselae, organs were cleared of...
Article
The minimum inhibitory concentrations of 39 Helicobacter pylori strains against antibiotics (ampicillin, tetracycline, metronidazole), colloidal bismuth subcitrate and proton pump inhibitors were assessed by the agar dilution method. 20.5% of the strains were metronidazole resistent. The comparison of the bactericidal action of omeprazole and lanso...
Article
Amikacin-loaded liposomes were produced and surface-modified by adsorption of PEG 4000, Tween 80, poloxamer 407 and gelatin. The organ distribution was studied in mice by analysing the amikacin content in liver, spleen, lung, kidneys and serum. Highest serum levels were obtained with the PEG- and Tween 80 modified liposomes (at 2 hours p.inj.). Mod...
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The potential of liposome-encapsulated antibiotics for prolonging drug application intervals was investigated by using a murine model of chronic lethal Mycobacterium avium infection. Liposomal encapsulation of amikacin, but not of ciprofloxacin, resulted in high and sustained drug levels in infected tissues, exceeding the minimal inhibitory concent...
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At present, the laboratory diagnosis of intestinal infections caused by microsporidia depends on the detection of the typical spores either with a modified trichrome stain (MTS) or by staining with fluorochromes. The purpose of the present study was (i) to compare staining with MTS (MTS method) and the staining with the fluorochrome Uvitex 2B (U2B...
Article
The detection of Cryptosporidium parvum oocysts in stool specimens by acid-fast (AF) stains or immunofluorescence assays (IFA) requires the presence of large numbers of oocysts. To determine whether new commercially available enzyme immunoassays (EIAs) are more sensitive alternatives, three EIAs, a direct IFA, and the modified cold Kinyoun AF stain...
Article
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The detection in stool specimens of Cryptosporidium parvum and microsporidia, the most frequent parasitic pathogens causing diarrhea in AIDS patients, until now has depended on two different staining methods. However, since double infections occur and minimization of laboratory costs is mandatory, development of a method for simultaneous detection...
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A total of 294 specimens collected from nonrespiratory sites of 268 patients were tested for direct detection of Mycobacterium tuberculosis complex by the Gen-Probe Amplified Mycobacterium tuberculosis Direct Test (AMTD). The specimens included ascitic, pleural, pericardial, and synovial fluids, abscess aspirates, and tissue and lymph node biopsy s...
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Streptococcal toxic shock syndrome (strepTSS) has been associated with various streptococcal soft-tissue infections including cellulitis, necrotizing fasciitis, and peritonitis in adults. We describe a 40-year-old patient with pharyngitis and strepTSS. Throat swab cultures yielded a strain of Streptococcus pyogenes that produced large amounts of er...
Article
A serum bactericidal test was established employing human sera of volunteers after intravenous administration of fosfomycin (CAS 23155-02-4) and teicoplanin (CAS 61036-62-2) against 40 staphylococcal strains (20 Staphylococcus aureus and 20 coagulase-negative staphylococci, 10 of each group being susceptible and 10 being resistant to oxacillin). Me...
Article
In up to 79% of cases, noninflamed and in­ flamed lesions in acne vulgaris are colonised with Gram-positive microorganisms.[1] Although these are apparently not responsible for the primary events of acne vulgaris, namely comedogenesis, they seem to be important in the initiation and maintenance of the inflammatory processes of acne. The principles...
Article
Seventy-one respiratory samples were analyzed in a new commercially available target rRNA amplification assay aimed at detecting Mycobacterium tuberculosis complex directly in patient specimens. The assay (Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test) correctly identified 26 of 27 samples positive for Mycobacterium tuberculosis and 43...
Article
Clostridium difficile toxin is frequently encountered in patients with antibiotic-associated diarrhea. A commercially available enzyme immunoassay (EIA) detecting toxins A and B was evaluated, screening 148 stool specimens specifically submitted for the detection of C. difficile. A sensitivity of 100% and a specificity of 97.5% were found compared...
Article
BCG(mycobacterium bovis)-modulated delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC) differs from that in nonmodulated mice with respect to kinetics of expression, cellular composition of inflammatory foci, and susceptibility to specific suppressor mechanisms. We investigated whether the differences between these two types of SRBC...
Article
Microbial hypercolonization with Propionibacterium acnes is one of the four factors in the pathogenesis of acne. Topical and systemic antibiotics play an important role in the treatment of inflammatory forms of acne. The purpose of the study was to investigate the clinical efficacy and tolerance of OPC-7251 compared with erythromycin by topical app...
Article
20 patients colonized by H. pylori (9 with duodenal ulcer, 11 with antral gastritis) were examined for the presence of a systemic cellular immune response to H. pylori using an in vitro lymphocyte transformation assay. Infiltration of the antral mucosa by myelomonocytic cells was assessed by immunohistology as a parameter of local cellular immune r...
Article
The prevalence of enteropathogenic bacteria over a three-year period was 3.1% in an urban population in Germany. Nontyphoidal Salmonella spp. (1.8% prevalence) represented 59.3% of all positive isolates, followed by Campylobacter spp., which constituted 22.1% of such isolates. Clostridium difficile toxin was detected in 5.6% of samples submitted sp...
Article
The anamnestic response to infection with Listeria monocytogenes is characterized by the rapid elimination of normally lethal doses of bacteria and accelerated granuloma formation. These phenomena are mediated by listeria-specific memory T cells within the first 24 h after reinfection. In order to elucidate the mechanisms operative during this deci...
Article
The antibacterial activity of the topical quinolone OPC-7251 against bacteria commonly found in acne vulgaris was tested in vitro by an agar dilution method. The MIC50 was 0.25 mg/l for Propionibacterium acnes, 0.125 mg/l for Propionibacterium granulosum, 0.03 mg/l for Staphylococcus aureus and 0.06 mg/l for coagulase-negative staphylococci. Compar...
Article
In a survey of 3004 clinical specimens from 1112 HIV-negative and 679 clinical specimens from 140 HIV-positive patients which were submitted to our mycobacterial laboratory, we have analysed the different diagnostic approaches concerning mycobacterial disease in these two populations. We have assessed specimen-type, culture result, microscopical di...
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Listeria-immune mice are able to express protective immunity in the absence of CD4+ T cells and an apparent granulomatous inflammation. Using a monoclonal antibody (5C6) able to inhibit the recruitment of myelomonocytic cells into inflammatory foci by binding to complement receptor type 3 (CR3/CD11b), we could show that protective immunity and gran...
Article
Much of our current understanding of cell-mediated immunity to facultative intracellular pathogens stems from studies of the immune response of mice to Listeria monocytogenes — a model first introduced by Mackaness in 1962 (1, for reviews see 2–4). The specific cellular immune response to this and other facultative intracellular bacteria results in...
Article
In the present study we attempted to analyze the possibility to induce in mice a T-cell response using killed Listeria monocytogenes in adjuvant. Clearly, nonviable antigen is capable of inducing protective and granuloma-forming T cells in C57BL/6 mice when emulsified in complete Freund's adjuvant. These T cells were cloned in vitro by using antige...
Chapter
The experimental infection of mice with facultative intracellular bacteria provides a model for the study of mechanisms underlying monocyte/macrophage dependent innate resistance and T cellmacrophage-interactions that result in the eradication of bacteria and granulomatous inflammation in infected tissues. The phenomenological re-evaluation of the...
Article
The combined activities of trospectomycin, a spectinomycin analogue, and colloidal bismuth subcitrate against Helicobacter pylori were investigated, the agar dilution method being employed. Forty-seven strains of H. pylori were examined. An additive effect was observed in 89%, and a synergistic interaction in 11% of the isolates. There was no antag...
Article
The role of phagocytes and the complement system as potential host defense mechanisms against bacterial infection were studied in mice with two isogenic strains of Yersinia enterocolitica serotype O8 differing in pathogenicity because of differences in plasmid content. Complement depletion in mice by intraperitoneal injection of cobra venom factor...
Chapter
Streptokokken bilden eine Gattung (Streptococcus) nichtbeweglicher, nichtsporenbildender, grampositiver Kokken, die sich in Ketten oder Paaren lagern (Abb. 2.1). Die meisten Streptokokken vermehren sich sowohl unter aeroben als auch unter anaeroben Bedingungen. Die Katalase- und die Oxidase-Reaktion fallen negativ aus. Nitrat wird nicht reduziert;...
Article
Cervical and vaginal carriage of group B streptococci (GBS) is normally associated with an appropriate immune response confining these organisms to a commensal state in this human habitat. A newly developed indirect enzyme-linked immunosorbent assay compares the antibody responses against two antigen preparations of GBS-serotypes Ia, Ib, II and III...
Article
Recent evidence indicates that ileal Peyer's patches represent the main infection route for Yersinia enterocolitica. In this study transmission and scanning electron microscopy have shown that only a small fraction of bacteria present in the lumen adhere to the follicle-associated murine epithelium with no discernible preference for either M or abs...
Article
Bordetella pertussis is the causative agent of whooping cough and little is known concerning the pathophysiology of the disease process. This is partially due to the fact that there is no suitable animal model for studying whooping cough. This microorganism produces a variety of toxins and biologically active extracellular products (10) including e...
Article
Gram negative obligately anaerobic bacteria constitute a major part of the normal indigenous bacterial flora of humans, however, they also have to be considered to be important opportunistic pathogens, e.g., infections with Bacteroidaceae may arise, when the function of the mucous membranes as anato­mic barrier for microorganisms is compromised and...
Article
Facultative intracellular bacteria induce specific T cell responses of both the CD4+ and the CD8+ subsets. The immunohistological study of the tissue responses to Listeria monocytogenes in T cell subset-depleted, Listeria-primed mice revealed that CD4+ cells not only represent the predominant lymphocyte population in granulomatous lesions but media...
Article
The invasion of intestinal tissue by Yersinia enterocolitica was studied after infection of mice with plasmid-bearing or with plasmidless strains of serotype 08 and 03. Within the first 15 h of infection each strain colonized the mouse ileum to the same extent, indicating that the initial binding and invasion are not plasmid dependent. This conclus...
Article
The experimental infection of mice with Yersinia enterocolitica serotype O8 was investigated in a quantitative and histological study. The course of bacterial penetration and spreading was precisely determined by immunohistochemical staining. After oral administration, the bacteria passed the epithelial barrier of the ileum and spread into the lami...
Article
The in vitro activity of enoxacin was tested in 14 German microbiological centers shortly after the introduction of the drug in Germany. 2748 unselected clinical isolates including 15 bacterial species were analysed using microtiter plates. The MIC90-values were as follows: Staphylococcus aureus 4 mg/l, Enterococcus faecalis 16 mg/l, Enterobacteria...
Article
The invasion of intestinal tissue by Yersinia enterocolitica was studied after infection of mice with plasmid-bearing or with plasmidless strains of serotype 08 and 03. Within the first 15 h of infection each strain colonized the mouse ileum to the same extent, indicating that the initial binding and invasion are not plasmid dependent. This conclus...
Article
The in vivo activity of ciprofloxacin against Pseudomonas aeruginosa was studied in a septicemia model in neutropenic mice and compared to that of other antibiotics with established activity against P. aeruginosa. When given as a single agent, ciprofloxacin proved to be as effective as imipenem/cilastatin, whereas azlocillin and tobramycin were rat...
Article
Thein vitro activity of enoxacin was tested in 14 German microbiological centers shortly after the introduction of the drug in Germany. 2748 unselected clinical isolates including 15 bacterial species were analysed using microtiter plates. The MIC90-values were as follows:Staphylococcus aureus 4 mg/l,Enterococcus faecalis 16 mg/l, Enterobacteriacea...
Article
Full-text available
Immunity to Listeria monocytogenes was studied in mice treated with rat monoclonal antibodies (MAbs) specific for the Thy-1.2, L3T4, and Lyt-2 T-cell markers. Three characteristic T-cell-mediated phenomena were investigated. Delayed-type hypersensitivity (DTH) to listerial antigen was totally abolished in mice treated with anti-Thy-1.2 or anti-L3T4...
Article
An enzyme-linked immunosorbent assay was used to quantify soluble interleukin 2 receptor (IL-2R) in the serum of patients with helminthic and protozoal infections. The results demonstrated that levels of IL-2R were normal in patients with helminthic infections limited to the intestinal tract (ascariasis, trichuriasis), but significantly elevated in...
Article
Various mouse strains and Lewis rats were either orally or intravenously infected with high inocula of Campylobacter pylori and bacterial counts in the liver, spleen, heart, kidneys, and the stomach were followed over time. The intravenously infected animals displayed transient bacteremia and colonization of their livers and spleens. A loglinear de...
Article
The therapeutic efficacy of ciprofloxacin, used alone and in combination with either ceftazidime or gentamicin, was evaluated in a model of experimental Klebsiella pneumoniae septicemia in neutropenic mice. Therapeutic results were compared to those achieved by treatment with ceftazidime or gentamicin alone, as well as their combination. Infections...