Effects of Tigecycline, Linezolid and Vancomycin on Biofilms of Viridans Streptococci Isolates from Patients with Endocarditis

Background

Endocarditis, and prosthetic valve endocarditis in particular, is a serious disease with high morbidity and mortality. We investigate the effects of tigecycline, linezolid and vancomycin on biofilms of viridans group streptococci (VGS) isolated from patients with definite native or prosthetic valve endocarditis.

Methods and Results

Ten of 20 VGS blood stream isolates from patients with endocarditis formed biofilms in the microtiter plate biofilm model. The minimal inhibitory concentrations (MIC) for tigecycline, linezolid and vancomycin were determined using the microdilution broth method. Biofilms were grown for 24 hours and were incubated with tigecycline, linezolid and vancomycin at increasing concentrations from 1-128x MIC of the isolate being tested. Biofilm thickness was quantified by measuring the optical density (OD) after dyeing it with crystal violet. The incubation of the biofilms with tigecycline, linezolid or vancomycin resulted in a significant reduction of OD compared to the control biofilm without antibiotic (p<0.05). The optical density ratio (Odr) decreased significantly at 2x MIC for tigecycline, and at 8x MIC for linezolid and vancomycin (p<0.05). Although biofilms persisted even at the highest antibiotic concentrations of 128x MIC, bacterial growth was eradicated starting at concentrations of 16x MIC for vancomycin and of 32x MIC for linezolid, but not for tigecycline, up to a concentration of 128x MIC.

Conclusions

In the present study on viridans streptococci isolated from patients with endocarditis, tigecycline and linezolid reduced the density of the biofilms as effectively as vancomycin. However, linezolid and vancomycin were bactericidal at higher concentrations. Linezolid and vancomycin at very high doses may be useful in the treatment of biofilm-associated diseases caused by VGS infections.

House dust mites as potential carriers for IgE sensitization to bacterial antigens

Background

IgE reactivity to antigens from Gram‐positive and Gram‐negative bacteria is common in patients suffering from respiratory and skin manifestations of allergy, but the routes and mechanisms of sensitization are not fully understood. The analysis of the genome, transcriptome and microbiome of house dust mites (HDM) has shown that Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) species are abundant bacteria within the HDM microbiome. Therefore, our aim was to investigate whether HDM are carriers of bacterial antigens leading to IgE sensitization in patients suffering from atopic dermatitis.

Methods

Plasma samples from patients with AD (n = 179) were analysed for IgE reactivity to a comprehensive panel of microarrayed HDM allergen molecules and to S. aureus and E. coli by IgE immunoblotting. Antibodies specific for S. aureus and E. coli antigens were tested for reactivity to nitrocellulose‐blotted extract from purified HDM bodies, and the IgE‐reactive antigens were detected by IgE immunoblot inhibition experiments. IgE antibodies directed to bacterial antigens in HDM were quantified by IgE ImmunoCAP™ inhibition experiments.

Results

IgE reactivity to bacterial antigens was significantly more frequent in patients with AD sensitized to HDM than in AD patients without HDM sensitization. S. aureus and E. coli antigens were detected in immune‐blotted HDM extract, and the presence of IgE‐reactive antigens in HDM was demonstrated by qualitative and quantitative IgE inhibition experiments.

Conclusion

House dust mites (HDM) may serve as carriers of bacteria responsible for the induction of IgE sensitization to microbial antigens.

Prospective multicentre clinical study on inter- and intrapatient genetic variability for antimicrobial resistance of Helicobacter pylori

OBJECTIVES

We report on a large prospective, multicentre clinical investigation on inter- and intrapatient genetic variability for antimicrobial resistance of Helicobacter pylori.

METHODS

Therapy-naive patients (n = 2004) who had undergone routine diagnostic gastroscopy were prospectively included from all geographic regions of Austria. Gastric biopsy samples were collected separately from antrum and corpus. Samples were analysed by histopathology and real-time PCR for genotypic resistance to clarithromycin and quinolones. Clinical and demographic information was analysed in relation to resistance patterns.

RESULTS

H. pylori infection was detected in 514 (26%) of 2004 patients by histopathology and confirmed in 465 (90%) of 514 patients by real-time PCR. PCR results were discordant for antrum and corpus in 27 (5%) of 514 patients, indicating inhomogeneous infections. Clarithromycin resistance rates were 17% (77/448) and 19% (84/455), and quinolone resistance rates were 12% (37/310) and 10% (32/334) in antrum and corpus samples, respectively. Combination of test results per patient yielded resistance rates of 21% (98/465) and 13% (50/383) for clarithromycin and quinolones, respectively. Overall, infection with both sensitive and resistant H. pylori was detected in 65 (14%) of 465 patients.

CONCLUSIONS

Anatomically inhomogeneous infection with different, multiple H. pylori strains is common. Prospective clinical study design, collection of samples from multiple sites and microbiologic methods that allow the detection of coinfections are mandatory for collection of reliable data on antimicrobial resistance patterns in representative patient populations. (ClinicalTrials.gov identifier: NCT02925091).

Comprehensive evaluation of chemiluminescent immunoassays for the laboratory diagnosis of Clostridium difficile infection

For the microbiological diagnosis of a Clostridium (C.) difficile infection (CDI), a two-test algorithm consisting of a C. difficile glutamate dehydrogenase (GDH)-immunoassay followed by a toxin-immunoassay in positive cases is widely used. In this study, two chemiluminescent immunoassays (CLIAs), one for GDH and the other for the toxins A and B, have been evaluated systematically using appropriate reference methods. Three-hundred diarrhoeal stool specimens submitted for CDI diagnosis were analysed by the LIAISON CLIAs (DiaSorin). Toxigenic culture (TC) and cell cytotoxicity assay (CCTA) were used as "gold standard" reference methods. In addition, GDH and toxin A and B enzyme immunoassays (EIAs), C. diff Chek-60 and toxin A/B II (TechLab), and the Cepheid Xpert C. difficile polymerase chain reaction (PCR) were performed. C. difficile was grown in 42 (14%), TC was positive in 35 (11.7%) and CCTA in 25 (8.3%) cases. CLIAs were more sensitive but less specific than the respective EIAs. Using culture as reference, the sensitivity of the GDH CLIA was 100%. In comparison to CCTA sensitivity, specificity, positive predictive value and negative predictive value of the two-test algorithm were 88, 99.3, 91.7 and 98.9% by CLIAs and 72, 99.6, 94.7 and 97.5% by EIAs. Discrepant results by CLIAs were more frequent than that by EIAs (9% vs. 6.3%); in those cases, PCR allowed for the accurate detection of toxigenic strains. Due to performance characteristics and testing comfort, CLIAs in combination with PCR represent a favourable option for the rapid laboratory C. difficile diagnostics.

Efficient phagocytosis of periodontopathogens by neutrophils requires plasma factors, platelets and TLR2

BACKGROUND

Periodontitis represents a chronic infection of supportive dental tissues by distinct gram-negative bacteria. It is characterized by chronic and local inflammation as well as transient bacteremia with frequently occurring infections at distant sites.

OBJECTIVES

The present work aimed to clarify the role of platelets and plasma factors in neutrophil interactions with the periodontopathogens A. actinomycetemcomitans and P. gingivalis.

METHODS

Phagocytosis, cell-cell interactions and activation of platelets and neutrophils in response to periodontopathogens were analyzed by flow cytometry, confocal microscopy and bacteria survival assay. Plasma factors, platelet signaling pathways and receptors involved in platelet-neutrophil-bacteria interactions were determined. The role of platelet and neutrophil TLR2 in phagocytosis was further evaluated in a murine TLR2 knockout model.

RESULTS

In the presence of plasma neutrophil-mediated clearance of periodontopathogens is doubled due to opsonisation of bacteria. Platelets, which become activated by periodontopathogens, further enhance clearance of bacteria by 20%, via direct interaction with neutrophils. Plasma factors (e.g. CD14) are required for platelet activation, which is mainly TLR2 dependent and results in PI3K/Akt activation. In a murine TLR2 knockout model we prove that platelet TLR2 is important for formation of platelet-neutrophil aggregates and enhanced phagocytosis of periodontopathogens. In contrast, neutrophil TLR2 is not involved in platelet-neutrophil aggregate formation but is required for efficient phagocytosis.

CONCLUSIONS

These data indicate that efficient elimination of periodontopathogens by neutrophils involves a complex interplay of plasma factors as well as platelets and requires functional TLR2. By enhancing neutrophil activation platelets contribute to immune defense but may also foster inflammation.

Immunoglobulin E antibody reactivity to bacterial antigens in atopic dermatitis patients

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease affecting up to 20% children and 9% adults world-wide. AD patients are often sensitized against a broad variety of allergens and more than 90% of them suffer from skin superinfections with Staphylococcus aureus.

OBJECTIVE

In this study, we searched for the presence of specific IgE antibodies against S. aureus and Escherichia coli antigens in AD patients.

METHODS

Sera from AD patients (n=79), patients suffering only from allergic rhinoconjunctivitis (n=41) or allergic asthma (n=37) were tested for IgE reactivity to nitrocellulose-blotted S. aureus, E. coli and gut bacterial antigens. IgE-reactive bacterial antigens were affinity purified and identified by mass spectrometry.

RESULTS

More than 30% of AD patients but not patients suffering only from allergic rhinoconjunctivitis and asthma or non-allergic persons exhibited IgE binding to several protein antigens among them DNA-binding and ribosomal proteins and flagellin. Patients with severe skin manifestations showed more frequently IgE reactivity to S. aureus compared with AD patients with mild symptoms. Positive immediate and late skin test reactions could be induced in sensitized AD patients with S. aureus extract.

CONCLUSION AND CLINICAL RELEVANCE

Specific IgE reactivities against a variety of bacterial antigens were observed in a subgroup comprising a third of AD patients and may contribute to allergic inflammation.

In vitro activity of fosfomycin alone and in combination with amoxicillin, clarithromycin and metronidazole against Helicobacter pylori compared with combined clarithromycin and metronidazole

In order to evaluate the suitability of fosfomycin in combination with other agents for the treatment of Helicobacter pylori infections, the susceptibility profiles of 65 H. pylori strains were determined against multiple antimicrobial agents and combinations thereof using the agar dilution method. For fosfomycin alone, the range of minimum inhibitory concentration (MIC) results and the MICs at which 50% and 90% of strains were inhibited were 0.5-32 microg/ml and 2 and 4 microg/ml, respectively. For the combination of fosfomycin with amoxicillin, clarithromycin or metronidazole, the means calculated for the minimum and maximum fractional inhibitory concentration index were 0.70-1.17 and 1.15-2.03, respectively, suggesting partial synergy or indifference in the majority of strains. The combination of clarithromycin and metronidazole showed synergistic activity against 14 of 28 H. pylori strains tested. The in vitro activity results suggest the combination of fosfomycin with either amoxicillin or clarithromycin may be a promising alternative for the treatment of H. pylori infection. However, the clinical efficacy of these regimens remains to be investigated.

Viridans streptococci in endocarditis and neutropenic sepsis: biofilm formation and effects of antibiotics

OBJECTIVES

Viridans group streptococci (VGS) are a frequent cause of bacterial endocarditis or sepsis in patients with neutropenia. Endocarditis in particular, is associated with plaque formation on the endocardium and valve leaflets whereas VGS septicaemia in neutropenic patients is caused by the influx of oral flora bacteria through mucositic lesions. This study examined the in vitro potency for biofilm formation of clinical VGS bloodstream isolates, and the effects of antibiotics on these biofilms.

METHODS

During the years 1998-2000, 40 VGS bloodstream isolates from 18 patients with endocarditis and 22 patients with severe sepsis and neutropenia were collected. The MICs of penicillin, teicoplanin and moxifloxacin were determined using the microdilution broth method according to NCCLS criteria. Biofilms were grown in microtitre plates, dyed with Crystal Violet, and the mean optical density (OD) was used for quantification. Biofilms were incubated with penicillin, teicoplanin and moxifloxacin at various concentrations starting with the MICs for the respective isolates tested.

RESULTS

Isolates from eight out of 18 patients with endocarditis and six out of 22 patients with neutropenia formed biofilms (not significant). For the 14 isolates, the MIC(90)s (range) of penicillin, teicoplanin and moxifloxacin were 0.5 mg/L (0.001-0.5), 0.125 mg/L (0.025-0.125) and 0.5 mg/L (0.05-0.5), respectively. Generally, biofilms persisted although incubated with the antibiotics up to concentrations of 128 x MIC. However, the ODs of biofilms after incubation with an antibiotic were significantly lower than the ODs of biofilms without antibiotic (P<0.05). A significant decrease in the biofilms with increasing antibiotic concentrations was observed for teicoplanin and moxifloxacin, but not for penicillin G.

CONCLUSIONS

VGS isolated from patients with endocarditis and patients with sepsis and neutropenia form biofilms. Biofilms persist even when exposed to antibiotics at concentrations up to 128 x MIC. Nevertheless, teicoplanin and moxifloxacin reduced the density of the biofilms at concentrations >/=16 x MIC. Thus, testing the effects of antibiotics on biofilms may supply useful information in addition to standard in vitro testing, particularly in diseases where biofilm formation is involved in the pathogenesis.

Helicobacter pylori in children and adolescents: increase of primary clarithromycin resistance, 1997-2000

BACKGROUND

The authors evaluate the prevalence of Helicobacter pylori resistance in 117 children and demonstrate the changes over a 4-year period.

METHODS

In 117 children and adolescents, H. pylori-positive gastritis was revealed by diagnostic upper endoscopy. Biopsies from the antrum and body of the stomach were tested by histology, urease test, and culture. H. pylori was isolated using standard culture techniques, and susceptibility to amoxicillin, clarithromycin, and metronidazole was tested using the E-test (AB-Biodisk, Sweden).

RESULTS

Endoscopy revealed gastric ulcers in 2 of 117 subjects, duodenal ulcers in 6 of 117, and erosive gastritis or duodenitis in 23 of 117. Almost all patients showed antral nodularity. Histology always showed chronic gastritis with different degrees of activity. During the 4-year study period, the authors noticed an increase of primary clarithromycin-resistant H. pylori strains, from 14.3% to 27.6% (mean, 20.3%). Metronidazole resistance varied between 5% and 25%. No resistance to amoxicillin was found.

CONCLUSION

Eradication of H. pylori should take place only after testing of susceptibility. The general use of clarithromycin in children should be restricted to better-defined indications. Resistance to clarithromycin of H. pylori may also become a future problem for the treatment of adults.

Antimicrobial susceptibility profiles of clinically relevant blood culture isolates from nine surgical intensive care units, 1996-2000

In order to elucidate trends in the incidence and susceptibility profiles of causative agents of bacteremia/fungemia in nine surgical intensive care units, a total of 744 isolates obtained during a 5-year period (1996-2000) were studied. The isolates included 698 bacteria and 46 fungi obtained from 523 positive blood cultures, representing 317 episodes of bacteremia/fungemia. Methicillin-resistant Staphylococcus aureus accounted for 2.3 episodes per 1000 surgical ICU admissions in 1996, 1.6 in 1997, 0.3 in 1998, 0.6 in 1999, and 1.7 in 2000. One Enterococcus faecalis (VanA) isolate resistant to both vancomycin and teicoplanin was recovered in 1996. Ciprofloxacin resistance in Pseudomonas aeruginosa decreased from 36% in 1996 to 20% in 2000, and resistance to third-generation cephalosporins decreased from 40% in 1996 to 9% in 2000. In light of differences between these results and those found elsewhere, these findings might prove useful for making infection control policy decisions in intensive care units.

[Helicobacter pylori: virulence factors, resistance and diagnosis]

Helicobacter pylori disposes of various virulence factors such as urease, vacuolating cytotoxin and the cag-pathogenicity island which--though not alone, but possibly in conjunction with host-specific factors--may explain the varying course of the infection (asymptomatic, dyspepsia, ulcer, distal gastric carcinoma). Increasing resistance to macrolide antibiotics and the lack of new therapeutic approaches makes treatment of the infection increasingly difficult. The resultant call for a strict indication for treatment is in obvious contrast to the finding that Helicobacter pylori represents the major risk factor for gastric carcinoma and eradication would therefore be absolutely desirable. Increased use of culture and susceptibility testing would be desirable for the purpose of therapy optimization but also for reasons of resistance epidemiology. The indication for diagnostic screening should be guided by the treatment indications as proposed by the guidelines of the Maastricht Consensus Conference 2-2000. In addition--and regardless of clinical picture--therapeutic follow-up primarily relying on non-invasive tests (13C urea breath test, stool antigen test) should be a matter of course.

Dysregulation of monocyte oxidative burst in streptococcal endocarditis

BACKGROUND

Streptococcal subacute endocarditis is characterized by low-grade systemic inflammation. Although structural cardiac defects are pivotal, phagocytic cells, i.e. monocytes and neutrophils, are involved in the induction and the course of bacterial endocarditis. Decreased production of reactive oxygen metabolites was described in long-lasting infections. We hypothesized that the oxidative burst of phagocytes induced by the infecting organism is defective in patients with streptococcal endocarditis.

PATIENTS AND METHODS

The monocytes and neutrophils of 11 patients with streptococcal native valve endocarditis were challenged with the respective pathogens and two control streptococcal strains, and the oxidative burst was determined by fluorescence-activated cell sorter analysis. These experiments were done before any antibiotic therapy was administered, and repeated at least 12 months after recovery. Eight volunteers served as healthy controls.

RESULTS

The monocyte response to the respective pathogens was decreased in the patient groups compared to the response to the control streptococci. After cure the monocyte response to the pathogens was not different to the response to the control strains. The monocyte response of the healthy volunteers did not show any differences between the patients' pathogens and the control strains. The neutrophil oxidative burst to the pathogens was similar to that to the control streptococci in both patient and the volunteer group.

CONCLUSION

The decreased response of patient monocytes to the pathogens may contribute to the low-grade inflammatory response and to the course of streptococcal endocarditis.

Impact of bacteria in dairy products and of the intestinal microflora on the genotoxic and carcinogenic effects of heterocyclic aromatic amines

This article gives a short overview on the present state of knowledge of the effects of the intestinal microflora on the health hazards of heterocyclic aromatic amines (HAs). Results of single cell gel electrophoresis assays with conventional, germ free and human flora associated rats indicate that the presence of intestinal microorganisms strongly enhances the induction of DNA-damage in colon and liver cells by IQ. Furthermore, it was found that supplementation of the feed with Lactobacilli attenuates the induction of colon cancer by this same amine. These recent findings suggest that the intestinal microflora and lactic acid bacilli in dairy products strongly affect the health risks of HAs. Nevertheless, most previous experiments with HAs focused on the involvement of mammalian enzymes in the biotransformation of these compounds and only a few articles are available which concern interactions of bacteria with HAs. Some of these studies suggested that the formation of directly mutagenic hydroxy-metabolites of the amines by fecal bacteria might be an important activation pathway but it turned out that the hydroxy-derivative of IQ is not genotoxic in mammalian cells and does not cause colon cancer in laboratory rodents. There is some evidence that hydrolysis of HA-metabolites by bacterial ss-glucuronidase might play a role in the activation of HAs but experimental data are scarce and no firm conclusions can be drawn at present. The most important detoxification mechanism appears to be the direct binding of the HAs to the cell walls of certain bacterial strains contained in fermented foods. It was shown that these effects do also take place under physiologically relevant conditions. Overall, it seems that intestinal bacteria play a key role in the activation and detoxification of HAs which has been an area of research long ignored. The elucidation of these mechanisms may enable the development of biomarkers for colon cancer risk and nutritional strategies of protection.

Urease prevents adherence of Helicobacter pylori to Kato III gastric epithelial cells

The role of urease in Helicobacter pylori adherence to and internalization by Kato III cells was investigated. Kato III cells were incubated with wild-type strains (N6 or P1), with isogenic mutants lacking urease (N6ureB::TnKm or P1ureA::TnMax5) or producing the inactive apoprotein (N6ureG::TnKm), and with urease-positive clones recovered after complementation of N6ureB::TnKm with ureAB. Bacteria were stained with the green fluorescent dye PKH2, and the bacteria load of cells was analyzed by flow cytometry. With mutants lacking urease, the bacteria load was considerably increased, in comparison with the corresponding parental strains (P<.001). With clone K2(3), producing larger amounts of urease than N6, a significant reduction of bacteria load was observed, in comparison with the wild type (P<.001). N6ureG::TnKm showed adherence characteristics similar to those of N6. The role of urease in internalization was not clear. Thus, urease significantly inhibits H. pylori adherence to Kato III cells by a mechanism largely independent of enzymatic activity.

Application of blood-based polymerase chain reaction for detection of Chlamydia pneumoniae in acute respiratory tract infections

The aim of this study was to investigate whether blood-based polymerase chain reaction could serve as a diagnostic tool to identify individuals with acute respiratory Chlamydia pneumoniae infection. Respiratory specimens and peripheral blood mononuclear cells of 58 patients were analyzed using nested polymerase chain reaction and cell culture. Fifteen patients were polymerase chain reaction-positive for Chlamydia pneumoniae. Nine patients were positive in only the respiratory specimen; two in both the respiratory and blood sample (time intervals between onset of symptoms and sample collection, 3-10 days and 3-4 weeks, respectively); and four in only the blood sample. Detection of Chlamydia pneumoniae DNA in peripheral blood mononuclear cells does not seem to be a suitable marker for acute respiratory Chlamydia pneumoniae infection.

Multicenter comparison trial of DNA extraction methods and PCR assays for detection of Chlamydia pneumoniae in endarterectomy specimens

The reported rate of detection of Chlamydia pneumoniae DNA within atherosclerotic lesions by PCR varies between 0 and 100%. In this study, identical sets of coded experimental atheroma samples (n = 15) and spiked controls (n = 5) were analyzed by 16 test methods in nine centers by means of PCR. The positive controls were correctly identified to levels of 1, 0.1, and 0.01 inclusion bodies of C. pneumoniae/ml of tissue homogenate by 16 (100%), 11 (69%), and 3 (19%) of the test methods, respectively. Three out of 16 negative controls (19%) were rated positive. Positivity rates for atheroma samples varied between 0 and 60% for the different test methods, with the maximum concordant result for positivity being only 25% for one carotid artery sample. There was no consistent pattern of positive results among the various laboratories, and there was no correlation between the detection rates and the sensitivity of the assay used.

[Diagnosis of Helicobacter pylori infections]

Hardly any other bacterial infection can be diagnosed with a similar variety of non-invasive and invasive tests as infection with H. pylori. Efficacy and specificity of well-proven tests such as urease test in biopsy specimens, histology, culture, and 13C breath test have been uniformly evidenced in numerous studies. Novel tests include molecular microbiological procedures, providing new opportunities for rapid detection of virulence factors and resistance genes, as well as antigen detection in feces. Though some open questions still need to be clarified, the latter test will gain major importance in the future. With the availability of the breath test and antigen detection in stool the need for the use of serological tests has been reduced, all the more so as the majority of the available quick tests have been shown to be of inadequate reliability. Well defined indications for the treatment of H. pylori infections are a major prerequisite for a reasonable use of this diagnostic armory.

Two enzyme immunoassays and PCR for detection of Helicobacter pylori in stool specimens from pediatric patients before and after eradication therapy

This study of pediatric patients was intended to determine the suitability of stool PCR and two antigen enzyme immunoassays (EIAs; Premier Platinum HpSA and the novel FemtoLab H. pylori), which detect Helicobacter pylori antigens in feces, as pretreatment diagnostic tools and especially as posttreatment control. Forty-nine H. pylori-infected children with dyspepsia received eradication therapy. Successful treatment was determined by a negative [(13)C]urea breath test 4 and 12 weeks after discontinuation of therapy. Fecal specimens were collected prior to eradication therapy as well as 4 weeks after the end of treatment. Successfully treated children delivered stool samples at 6, 8, and 12 weeks posttreatment also. Specimens were examined by seminested PCR and Premier Platinum HpSA and were reexamined by both EIAs as soon as FemtoLab H. pylori was available. In the first test series, the overall sensitivities of PCR and Premier Platinum HpSA were 93.0 and 91.1%, respectively. With specimens collected at 4 weeks after treatment, the respective specificities were 68.8 and 79.3%. After longer follow-up periods, however, they gradually increased to 100 and 96.9%, respectively. In the new test series, Premier Platinum HpSA delivered a considerably lower number of false-positive results (4 versus 18), indicating intertest variations. The overall test sensitivity was 94.6%, and the overall specificity was 97.5%. FemtoLab H. pylori showed an excellent performance with an overall sensitivity and specificity of 98.2 and 98.1%, respectively. Thus, in contrast to PCR, both EIAs were shown to be suitable for early posttreatment control.

Susceptibility testing of Candida species: comparison of NCCLS microdilution method with Fungitest

Fungitest is a new commercially available and easy-to-perform breakpoint test system using six antifungal agents. We compared this test with a modified standard method described by the National Committee for Clinical Laboratory Standards (NCCLS). One hundred isolates of Candida species were tested with both methods. Based on the same breakpoints, the correlation of qualitative results between the reference method and Fungitest was high. Best results were obtained after incubation of Fungitest for 48 h. Overall agreement was high, an excellent correlation was given with amphotericin B and flucytosine (100% and 99%, respectively), whereas itraconazole showed only 86% concordance. When Fungitest was read after 24 h the agreement was lower ranging from 100% to 75%. Some of the breakpoints used with Fungitest differ from the breakpoints recommended by NCCLS, whereas others have not been elaborated by the NCCLS. The adaptation of Fungitest breakpoints to NCCLS and determination of further breakpoints have to be discussed before Fungitest can be recommended for routine use.

In vitro activities of linezolid alone and in combination with amoxicillin, clarithromycin, and metronidazole against Helicobacter pylori

Linezolid was tested against 70 strains of Helicobacter pylori by the agar dilution method. The MIC range and MICs at which 50 and 90% of strains were inhibited were 8 to 64, 16, and 32 microgram/ml, respectively. With minimum and maximum fractional inhibitory concentration summation values of 0.31 and 2.50, respectively, the combination of linezolid with amoxicillin, clarithromycin, or metronidazole showed either partial synergy or indifference for the majority of strains.

Isolation and continuous growth of Chlamydia pneumoniae from arterectomy specimens

For the purpose of collecting Chlamydia pneumoniae strains of vascular origin that could be grown continuously in vitro, a cell culture system has been established. Using different types of vascular specimens obtained from 38 patients, Chlamydia pneumoniae could be isolated in three (7.9%) cases. The strains were obtained from specimens of the carotid artery, the femoral artery and an infrarenal aneurysm of the abdominal aorta of three male atherosclerosis patients. Thus, viable Chlamydia pneumoniae strains are also present in vascular regions other than those hitherto described.

Purification of surface-associated urease from Helicobacter pylori

Helicobacter pylori colonizes the human gastric mucosa and produces large amounts of urease. The enzyme was extracted from the bacteria by distilled water and purified by gel-permeation (Sephacryl S-300), anion-exchange chromatography (Mono Q) and a second gel-permeation (Superdex 200). Urease enzyme activity was detected with a spectrophotometic assay based on phenol red. The optimal pH for anion-exchange was 6.9. The recovery of urease was 55-75%, purity 93-98% and the overall protein recovery 0.8-1.4%. The urease in the final extract still had enzymatic activity and showed the typical subunits of Mr 66000 and Mr 30000 when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Helicobacter pylori type I strains among Austrian and Portuguese patients with gastritis, peptic ulcer or gastric cancer

The frequency of occurrence of Helicobacter pylori type I strains in isolates from Austria and Portugal and different polymerase chain reaction-based approaches to detect the cag pathogenicity island were assessed. Of the 41 Austrian strains, eight of 14 (57.2%) isolated from patients with gastritis, 14 of 19 (73.7%) from patients with peptic ulcer and eight of eight (100%) from patients with gastric cancer were type I strains. Among the Portuguese strains, eight of 14 (57.2%) isolated from patients with gastritis, ten of 12 (83.3%) from patients with peptic ulcer and five of 13 (38.5%) from patients with gastric cancer were classified as type I. Thus, Helicobacter pylori type I strains occur frequently in both populations but show no significant correlation with peptic ulcer disease. The prevalence of the type Igenotype in Austrian cancer patients, however, was significantly higher (P=0.007). The cagE-specific polymerase chain reaction was found to be a reliable and efficient method for detection of the cag pathogenicity island.

Influence of Helicobacter pylori infection on the phenotype of Crohn's disease

OBJECTIVE

Very little is known about the impact of Helicobacter pylori (H. pylori) infection on Crohn's disease. In this study we investigated a possible influence of H. pylori on the phenotype of Crohn's disease.

METHODS

Patients with Crohn's disease who had gastric biopsy between 1990 and 1994 and a clinical follow-up in our outpatient clinic for at least 2 yr were included in the study. The mean number of flare-ups per year of follow-up, the mean numbers of intestinal resections per year of disease duration, and primary disease location were compared in H. pylori-positive and -negative patients. Various regression models were calculated to test the influence of H. pylori status on these parameters, correcting for smoking habits and disease duration.

RESULTS

Of 131 patients, 50 (38.2%) were H. pylori positive and 62 (47.3%) were smokers. Due to a significant interaction between smoking habits and H. pylori infection, regression models were calculated separately for smokers and nonsmokers. Nonsmokers without H. pylori infection had more flare-ups than nonsmokers with H. pylori infection (0.77 [0.57-0.97] vs 0.29 [0.16-0.42]; p < 0.01; mean [95% confidence interval]). In contrast, nonsmokers without H. pylori infection had less intestinal resections than nonsmokers infected with H. pylori (0.08 [0.04-0.12] vs 0.11 [0.07-0.15]; p < 0.05). These differences were not significant for smokers (p < 0.41 and p < 0.07). There was a predominance of small bowel disease in H. pylori-positive patients, which did not reach statistical significance.

CONCLUSIONS

Our data indicate that H. pylori influences the phenotype of Crohn's disease, especially in nonsmokers.

Famotidine versus omeprazole in combination with clarithromycin and metronidazole for eradication of Helicobacter pylori--a randomized, controlled trial

BACKGROUND

One-week low-dose triple therapy is currently considered the gold standard regimen for treatment of Helicobacter pylori infection. However, the mechanisms involved in the synergy between antibiotics and proton pump inhibitors are controversial.

AIMS

To test the hypothesis that acid suppression represents the crucial mechanism by which the antibacterial activity of antibiotics can be enhanced, and to assess the impact of primary resistance on treatment outcome.

METHODS

One hundred and twenty patients with H. pylori infection and duodenal ulcer, gastric ulcer or non-ulcer dyspepsia were randomly assigned to a 1 week course of either famotidine 80 mg b.d., clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. (FCM group; n = 60) or omeprazole 20 mg o.d., clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. (OCM group; n = 60). Gastroscopy was performed at baseline and 5 weeks after completion of treatment. H. pylori status was assessed by biopsy urease test, histology and culture.

RESULTS

In the intention-to-treat analysis, eradication of H. pylori was achieved in 47 of 60 patients (78%; 95% CI: 66-88%) in the FCM group, compared to 44 of 60 patients (73%; 95% CI: 60-84%) in the OCM group (N.S.). Using per protocol analysis, eradication therapy was successful in 47 of 52 patients (90%; 95% CI: 79-97%) treated with FCM and 44 of 57 patients (77%; 95% CI: 64-87%) treated with OCM (N.S.). Primary metronidazole resistance was present in 27% and primary clarithromycin resistance in 8% of strains. Overall per protocol eradication rates in strains susceptible to both antibiotics and strains with isolated metronidazole resistance were 93% and 84%, respectively. No patient with clarithromycin resistance responded to treatment.

CONCLUSIONS

High-dose famotidine and omeprazole, combined with clarithromycin and metronidazole, are equally effective for eradication of H. pylori. In 1-week low-dose triple therapy, metronidazole resistance has no major impact on eradication rates whereas clarithromycin resistance is associated with a poor treatment outcome.

Diagnosis of Helicobacter pylori infection with a new non-invasive antigen-based assay. HpSA European study group

BACKGROUND

Helicobacter pylori is a common human pathogen implicated in certain gastrointestinal diseases. In the search for new non-invasive techniques to diagnose H. pylori infection, we evaluated an EIA for H. pylori antigen in stool (HpSA).

METHODS

In a prospective multicentre study, stool specimens from 501 patients (276 men, 225 women; age range 17-88 years, mean 52) undergoing gastroscopy in 11 centres throughout Europe were tested with HpSA and the carbon-13-urea breath test. At endoscopy, four biopsy samples were taken for histology (haematoxylin and eosin) and H. pylori detection (giemsa in both antrum and corpus, culture and rapid urease test). Patients were defined as positive for H. pylori if histology (antrum, corpus, or both) and urease test were positive, or if culture was positive. Patients classified as having H. pylori infection received an eradication regimen; 107 were reassessed 4 weeks after therapy.

FINDINGS

Of 272 patients with H. pylori infection by the predefined criteria, 256 were positive by HpSA (sensitivity 94.1% [95% CI 90.6-96.6]). Of 219 patients without infection, 201 were negative by HpSA (specificity 91.8% [87.3-95.1]).

INTERPRETATION

The stool assay was a reliable and easy-to-use tool for diagnosis of H. pylori infection. The test was accurate even shortly after treatment.

Effect of omeprazole and amoxicillin plus metronidazole on the eradication of Helicobacter pylori and the healing of duodenal ulcer: comparison with a historical control

BACKGROUND/AIMS

To test the hypothesis of equivalence of an omeprazole 7-day triple therapy without subsequent acid suppression and a historical ranitidine 12-day triple therapy (recruiting phase 1989-91) with subsequent acid suppression in their effect on the eradication of Helicobacter pylori (H. pylori) and the healing of duodenal ulcer.

METHODOLOGY

Seventy-seven patients with H. pylori-positive duodenal ulcers received a 7-day treatment with amoxicillin 750 mg tid and metronidazole 500 mg tid. Additional omeprazole 20 mg or 40 mg once daily was given to 39 and 38 of the patients, respectively. Endoscopy was performed before treatment and four weeks after cessation of therapy.

RESULTS

The cumulative intention-to-treat (ITT) H. pylori-eradication rate was 66% (51/77) as compared to 89% (46/52) for the historical control (p < 0.05). The corresponding ulcer healing rates were 90% (69/77) and 92% (48/52). Primary metronidazole resistance (PMR) had escalated from 10% to 27% within 6 years resulting in eradication rates of 84% for sensitive and 19% for resistant strains (p < 0.001). PMR could be demonstrated in 45% of all female, but only in 17% of the male patients (p < 0.05). In the patients with H. pylori eradication, the ulcers healed in 98% (50/51) as compared to 73% (19/26) in those with persistent infection (p < 0.005). Analysis based on the presence of PMR showed ulcer healing rates of 95% (53/56) for sensitive and 76% (16/21) for resistant strains (p < 0.05). Improvement of pain also showed a significant correlation with successful eradication. H. pylori-eradication, healing and symptom relief were similar in the omeprazole 20 mg and 40 mg groups.

CONCLUSIONS

The effect of amoxicillin plus metronidazole plus antisecretory agent on the eradication of H. pylori has decreased markedly during the past 6 years due to the escalation of PMR. Doubling of the omeprazole dose does not affect outcome. Cure of the infection as well as metronidazole susceptibility enhance duodenal ulcer healing and symptom relief. Acid suppression following a successful 1-week anti-HP therapy is not required for duodenal ulcer treatment.

Enteroaggregative and enterotoxigenic Escherichia coli among isolates from patients with diarrhea in Austria

In a 3-month prospective study among 203 Austrian outpatients with diarrhea, the role of pathogenic Escherichia coli and the use of the polymerase chain reaction in screening Escherichia coli isolates from clinical stool specimens were evaluated. Enteroaggregative Escherichia coli and enterotoxigenic Escherichia coli combined were identified as the second most frequent cause of diarrhea. Of a total of 85 bacterial pathogens isolated from 80 patients, 15 were pathogenic Escherichia coli, 13 enteroaggregative Escherichia coli and two enterotoxigenic Escherichia coli. Enteropathogenic, enteroinvasive, and enterohemorrhagic Escherichia coli isolates were not detected.

Detection of Chlamydia pneumoniae DNA in atheromatous tissues by polymerase chain reaction

Chlamydia pneumoniae is an important human respiratory pathogen. Recently, seroepidemiological data and the demonstration of chlamydial DNA or antigen within parts of atherosclerotic lesions have suggested a causal association between chlamydial infections and atherosclerosis. As the results obtained by different groups show considerable variations, we provide further data based on a highly specific and sensitive nested PCR method. Positivity was confirmed by nonradioactive hybridization with a specific probe, and sensitivity was determined by titration experiments. C. pneumoniae DNA was detected in 8/29 (28%) of carotid artery samples and 3/14 (21%) of aortic aneurysms.

IgG subclass reactivity to human cardiac myosin in cardiomyopathy patients is indicative of a Th1-like autoimmune disease

Studies performed in mice together with the demonstration of increased levels of heart-specific autoantibodies, cytokines and cytokine receptors in sera from cardiomyopathy (CMP) patients argued for a pathogenic role of autoimmune mechanisms in CMP. This study was designed to analyse the presence of IgG anti-heart antibodies in sera from patients suffering from hypertrophic and dilatative forms of CMP as well as from patients with ischaemic heart disease and healthy individuals. Patients' sera were analysed for IgG reactivity to Western-blotted extracts prepared from human epithelial and endothelial cells, heart and skeletal muscle specimens as well as from Streptococcus pyogenes. The IgG subclass (IgG1-4) reactivity to purified human cardiac myosin was analysed by ELISA. While sera from CMP patients and healthy individuals displayed comparable IgG reactivity to a variety of human proteins, cardiac myosin represented the prominent antigen detected strongly and preferentially by sera from CMP patients. Pronounced IgG anti-cardiac myosin reactivity was frequently found in sera from patients with dilatative CMP and reduced ventricular function. ELISA analyses revealed a prominent IgG2/IgG3 anti-cardiac myosin reactivity in CMP sera, indicating a preferential Th1-like immune response. Elevated anti-cytomegalovirus, anti-enterovirus IgG titres as well as IgG reactivity to nitrocellulose-blotted S. pyogenes proteins were also frequently observed in the group of CMP patients. If further work can support the hypothesis that autoreactivity to cardiac myosin represents a pathogenic factor in CMP, specific immunomodulation of this Th1- towards a Th2-like immune response may represent a promising therapeutic strategy for CMP.

Isolation of cDNA clones coding for IgE autoantigens with serum IgE from atopic dermatitis patients

Recently we demonstrated that a high percentage of atopic dermatitis (AD) patients displayed specific immunoglobulin E reactivity to human proteins. Here we show that IgE autoreactivity is found predominantly in AD patients with severe skin manifestations and reveal the molecular nature of four IgE autoantigens. An expression cDNA library constructed from a human epithelial cell line (A 431) was screened with serum IgE from two AD patients. DNA sequence analysis of three IgE-reactive clones identified the alpha-chain of the nascent polypeptide-associated complex, cytokeratin type II, and the BCL7B oncogen as atopy-related IgE autoantigens (ara). The fourth cDNA coded for an IgE autoantigen containing a typical calcium binding motif that occurred in histogenetically different cells and tissues (keratinocytes, muscle, brain). Recombinant Escherichia coli-expressed IgE autoantigens bound IgE from AD but not from patients with other immunologically mediated disorders (graft vs. host disease, systemic lupus erythematosus) and elicited immediate type skin reactions in AD patients. In serum samples collected from an AD patient over a period of 5 years, IgE anti-ara NAC antibody levels peaked during disease exacerbation. Our finding that ara BCL7B was detected in serum bound to IgE antibodies suggests that intracellular IgE autoantigens can become released after tissue damage and may occur as IgE immune complexes. Via binding to antigen presenting cells as well as to effector cells, IgE autoantigen immune complexes may contribute to exacerbation and/or perpetuation of severe atopic diseases even in the absence of exogenous allergens.

Helicobacter pylori urease significantly reduces opsonization by human complement

The role of Helicobacter pylori urease in opsonization by human complement was investigated. H. pylori wild type strain N6 and isogenic mutants lacking either the large urease subunit (UreB) or an accessory urease protein (UreG) were incubated with different sera. C3b bound to the bacteria was measured by specific staining and flow cytometry. As compared with opsonization of N6 and the UreG-lacking mutant, opsonization of the UreB-lacking mutant was significantly increased after incubation with sera from both H. pylori uninfected (P<.001) or infected (P<.05) persons. However, when sera from uninfected persons were used, effective opsonization of this mutant proved to be dependent mainly on the classical pathway of complement activation. Irrespective of the serum used, opsonization values were very low after selective inactivation of the classical or the alternative pathway. Reduced opsonization of the urease-expressing strains could, to some extent, result from degradation of bound C3b.

Detection of Helicobacter pylori in stool specimens by PCR and antigen enzyme immunoassay

A highly sensitive seminested PCR assay to detect Helicobacter pylori DNA in feces was developed. PCR with stool specimens and a novel antigen enzyme immunoassay (EIA) for H. pylori detection in feces were evaluated as diagnostic tools and in follow-up with samples from 63 infected and 37 noninfected persons. Infected individuals received eradication therapy followed by endoscopic follow-up 35 days after the start of treatment. At that time, a second stool specimen was obtained from 55 of these patients. Before eradication, the sensitivity of PCR was 93.7% and that of EIA 88.9%. Specificities were 100 and 94.6%, respectively. Of the 55 follow-up specimens, 41 originated from patients from whom H. pylori had been eradicated. Of these, 21 were still positive by PCR and 13 were positive by EIA, indicating that 1 month may be too short a period for follow-up evaluation of stool specimens by these tests.

[Incidence of increased serum Helicobacter pylori IgG antibodies in children with and without chronic abdominal pain]

The prevalence of Helicobacter pylori (HP) IgG antibodies was analysed in a group of 142 asymptomatic children (group A) and in 31 pediatric patients (group B) with recurrent abdominal pain. HP IgG antibodies were measured by a commercially available fluorescence-enzyme immuno-assay test (Heloritest IgG, Fa Eurospital). In asymptomatic children the prevalence of HP IgG antibodies increased significantly with age from 17% with 6 years to more then 40% with 14 years. A higher prevalence of HP IgG antibodies was found in children living in more crowded housing conditions. Comparing the number of HP IgG positive children in group B (58%) to a matched population from group A (35%) no statistically different prevalence rates were found. Thus HP IgG antibodies are found in similar frequencies, in both, symptomatic and asymptomatic children. Therefore the presence of HP-IgG antibodies does not necessarily indicate that the HP infection is the cause for the recurrent abdominal pain in these children.

Hyperemesis gravidarum associated with Helicobacter pylori seropositivity

OBJECTIVE

To test the hypothesis that infection with Helicobacter pylori is associated with hyperemesis gravidarum.

METHODS

From January 1995 to November 1996 we enrolled 105 patients with hyperemesis gravidarum in a prospective study. The Helicobacter serum Immunoglobulin (Ig) G concentrations in these patients were compared with those in asymptomatic gravidas matched for week of gestation.

RESULTS

Positive serum IgG concentrations were found in 95 of the 105 hyperemesis patients (90.5%) compared with 60 of 129 controls (46.5%). A chi2 test showed statistical significance (P < .001). The mean (+/-standard deviation) index percentages of the IgG titers were 74.2+/-23.6% in the hyperemesis group and 24.3+/-4.4% in the control group (P < .01, Student t test).

CONCLUSION

Infection with H pylori may cause hyperemesis gravidarum.

Highly significant role of Helicobacter pylori urease in phagocytosis and production of oxygen metabolites by human granulocytes

The contribution of Helicobacter pylori urease, the vacuolating cytotoxin VacA, and the 128-kDa protein CagA to the stimulation of human granulocytes in terms of phagocytosis and oxidative burst was evaluated. Blood was incubated with H. pylori strains and corresponding isogenic mutants lacking either the large urease subunit (UreB) or an accessory urease protein (UreG) or VacA or CagA. Phagocytosis and oxidative burst were monitored by flow cytometry. The UreB-lacking mutant was phagocytosed more efficiently (P < .001) and induced significantly less oxidative burst (P < .001) than its parental strain or the UreG-lacking mutant, which produces an enzymatically inactive urease. Values of the other mutants did not differ greatly from those of their parental strain. These data indicate inflammatory effects of H. pylori urease causing inhibition of phagocytosis and stimulation of oxidative burst by a pathway being largely independent of ammonia production.

Infant tuberculosis in Austria--trend reversal since 1990?

Since 1990 a relatively high number of cases of childhood tuberculosis has been observed in Austria, mainly occurring in the age-group of 0-4 years. Within this group most cases were registered in 1995. Since the beginning of 1995 the establishment of a lab-supported nationwide data collection system enables a more detailed recording of the cases diagnosed. Out of the 85 cases with infant tuberculosis registered in 1995 and 1996, 66 were diagnosed with pulmonary manifestation. In 45 cases tuberculosis was proven by culture. In nine (20%) of these cases the most likely route of infection has appeared to be direct transmission from an adult in the same household suffering from culture proven tuberculosis in the same year. For three of the cases the DNA of the isolated Mycobacterium tuberculosis strains from the adult and the infant was typed using RFLP analysis. In each case identical strains could be demonstrated.

Cytokine and prostaglandin production by amnion cells in response to the addition of different bacteria

OBJECTIVE

Our goal was to evaluate the effect of Escherichia coli, Bacteroides fragilis, Mycoplasma hominis, and Staphylococcus aureus on cytokine and prostaglandin production by amnion cells in vitro.

STUDY DESIGN

Amnion cells were obtained from women undergoing elective cesarean section before the onset of labor and cultured in a primary cell culture. Confluent amnion cells were incubated with heat-inactivated bacteria in different concentrations (10(1) to 10(6) colony-forming units/ml) for 48 hours. Samples for quantification of interleukin-1 beta, interleukin-6, interleukin-8, tumor necrosis factor-alpha, and prostaglandin E2 were collected at 6, 12, 24, and 48 hours.

RESULTS

Under basal conditions, minor amounts of interleukin-6 and interleukin-8 were detectable. Incubation of amnion cells with E. coli enhanced the secretion of interleukin-8 and also induced an transient increase of prostaglandin E2 in a dose-dependent manner. B. fragilis produced an increase in the secretion of interleukin-6 and interleukin-8. M. hominis and S. aureus did not cause an increase in either interleukin-6, interleukin-8, or prostaglandin E2.

CONCLUSION

The gram-negative bacteria E. coli and B. fragilis stimulated interleukin-6 and interleukin-8 to a greater degree than the other bacteria investigated in this study. This finding may be of clinical interest in the onset of preterm birth.

Molecular typing of Acinetobacter baumannii from ten different intensive care units of a university hospital

Thirty-one isolates of Acinetobacter baumannii were collected from ten intensive care units of an Austrian university hospital. All isolates were typed by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR). Two strains colonizing 13 infants in the neonatal intensive care unit were identified by ERIC-PCR. All other Acinetobacter baumannii isolates had highly divergent ERIC-PCR patterns, despite having the same antibiogram. Thus, a hospital-wide clonal distribution, as suggested by identical antibiogram patterns, was excluded by ERIC-PCR.

[Vancomycin resistant enterococci in Austria]

This study reports pheno- and genotypical analysis of 9 isolates of vancomycin-resistant enterococci (VRE) and 5 vancomycin-sensitive enterococci (VSE) in Austria: 5 E, faecium isolates of 4 patients (the sole patients demonstrating VRE at the University Hospital of Innsbruck in 1994 and 1995), 3 glycopeptide-sensitive isolates collected in Innsbruck in February 1996 for epidemiological analysis, and 6 enterococcus isolates from the University Hospitals of Vienna and Graz. The pheno- and genotypical analyses of all glycopeptide highly resistant E. faecium and E. faecalis isolates indicated the presence of VanA type resistance. One E. casseliflavus strain with intrinsic VanC-1 resistance showed a characteristic constitutive low-level resistance to vancomycin and susceptibility to teicoplanin. Genotyping with macro-restriction analysis demonstrated that 3 VRE isolates of the 5 E. faecium specimens were identical; the same applied to 2 VSE isolates. The two patients with VRE had been cared for at the same time in a surgical ICU and likewise, the two patients with VSE were simultaneously treated at a neurological ICU. The genotyping of E. faecalis strains showed that two strains of the three VRE isolates exhibited identical patterns. Epidemiological investigation did not reveal a mode of transmission for this cluster. Two of the 8 patients with VRE died within 60 days after isolation of the bacteria; the doctors in charge did not consider that the enterococci had been the cause of death. The results of our study indicate that oral vancomycin administration to humans is a primary cause of VRE in Austrian hospitals. In Austria approximately 66 kg vancomycin, 20% of it given orally, are administered to patients per year. Approx. 18-20 tons Avotan (active ingredient Avoparcin-10%)/year were used in Austria; as of April 1, 1997 the use of this animal foodstuff supplement is prohibited by the European Commission.

Amoxicillin for the treatment of Helicobacter pylori infection

Amoxicillin is one of the most active antimicrobials against Helicobacter pylori in vitro, with a minimum inhibitory concentration (MIC) of < or = 0.01-0.1 mg/l. Thus far, neither primary nor secondary resistant strains have been found. Amoxicillin, which has a bactericidal effect on H. pylori, but is less inhibitory in the stationary growth phase and against cell-adherent or slowly growing H. pylori, probably has both topical and systemic activity. It is fairly acid stable and is less affected by gastric acidity than macrolides. Nevertheless, its activity in vivo is considerably enhanced when it is given concomitantly with proton pump inhibitors. Several amoxicillin-containing treatment regimes have yielded H. pylori eradication rates of > or = 90%. Of particular interest are 1-week treatment regimens containing amoxicillin + clarithromycin + omeprazole, or amoxicillin + metronidazole + omeprazole, as well as a 1-h topical therapy developed in Japan.

Serological tests for monitoring Helicobacter pylori eradication treatment

Serological tests for the detection of Helicobacter pylori-specific antibodies are useful in epidemiological studies, as a pre-endoscopic screening procedure, and as therapeutic follow-up. For the latter application, they represent an alternative to invasive and expensive diagnostic methods such as endoscopy and breath test, respectively. However, serological tests are suitable only for long-term treatment monitoring in adults. As the significant reduction of specific antibodies, and not seronegativity by itself, is regarded as a criterion of therapeutic success, it is always necessary to establish the antibody kinetics. Enzyme-linked immunosorbent assay (ELISA) based tests are best suited for this. The most relevant antibody class to be detected is H. pylori-specific IgG. The main indication for employing serology is the therapeutic follow-up of patients who, on the whole, are free of complaints.

Influence of zinc oxide on Aspergillus species: a possible cause of local, non-invasive aspergillosis of the maxillary sinus

Recently the appearance of radiopaque 'concrements' in the maxillary sinus was reported. These radiodense objects could be identified as root-filling material for teeth of the upper jaw containing zinc oxide. This suggested that excess root-filling material containing zinc oxide in the maxillary sinus could favour the formation of a local, non-invasive aspergillosis. To verify this hypothesis in vitro, we tested the influence of zinc oxide on Aspergillus fumigatus, A. flavus, A. terreus, A. nidulans, A. niger and A. niveus. A geometric series of zinc oxide diluted in 0.1 N H2SO4 was used. Czapek-Dox agar was inoculated with the six Aspergillus species. Circular cavities stamped into the centre of each agar plate were filled with an equal amount of the dilutions and all plates were then incubated for 7 days at 37 degrees C. Readings were taken on days 3, 5 and 7. Soluble zinc oxide promoted the growth of all the tested Aspergillus species, the effect diminishing with decreasing concentration. This effect could be observed on all days of measurement. Only with A. niger was stimulation of growth minimal, probably because this species already exhibits a high growth rate on Czapek-Dox agar. Therefore, overfilling of maxillary teeth with a zinc oxide-containing root-filling material may favour the formation of local aspergillosis.

Comparison of vancomycin, teicoplanin, metronidazole, and fusidic acid for the treatment of Clostridium difficile-associated diarrhea

We conducted a prospective, randomized study to compare the efficacy of oral fusidic acid, oral metronidazole, oral vancomycin, and oral teicoplanin for the treatment of Clostridium difficile-associated diarrhea. Treatment resulted in clinical cure for 94% of the patients who were treated with vancomycin, 96% of those treated with teicoplanin, 93% of those treated with fusidic acid, and 94% of those treated with metronidazole. Clinical symptoms recurred in 16% of patients treated with vancomycin, 7% of those treated with teicoplanin, 28% of those treated with fusidic acid, and 16% of those treated with metronidazole. There was asymptomatic carriage of C. difficile toxin in 13% of patients treated with vancomycin, 4% of those treated with teicoplanin, 24% of those treated with fusidic acid, and 16% of those treated with metronidazole. No adverse effects related to therapy with vancomycin or teicoplanin were observed. Considering the costs of treatment, our findings suggest that metronidazole is the drug of choice for C. difficile-associated diarrhea and that glycopeptides should be reserved for patients who cannot tolerate metronidazole or who do not respond to treatment with this drug.

[Effect of zinc oxide on Aspergillus species: a possible cause of local noninvasive aspergillosis of the maxillary sinus]

During the last years the appearance of radiopaque concrements in the maxillary sinus was reported. These could be identified as root-filling material for teeth of the upper jaw containing zinc oxide. This suggested that excess root-filling material containing zinc oxide in the maxillary sinus could favour the development of a local, non-invasive aspergillosis. Therefore, we tested Aspergillus fumigatus, A. flavus, A. terreus, A. nidulans and A. niveus for the influence of zinc oxide. Cza-pek-Dox agar was inoculated with the six different Aspergillus strains. Circular cavities stamped into the agar's center of each plate were filled with aliquots of the dilutions of a geometric series of zinc oxide dissolved in 0,1n H2SO4. All plates were then incubated for seven days at 37 degrees C. Readings were taken on the 3rd, the 5th and the 7th day. It became obvious that solved zinc oxide promotes the growth of all the tested Aspergillus species. This influence diminished with decreasing concentration. This effect could be observed on all days of measurement. Only A. niger showed an attenuated dependence, probably due to the a priori high growth rate of this species on Czapek-Dox agar. It is concluded that overfilling of maxillary teeth with a zinc oxide containing root filling material favours the development of local aspergillosis.

Clarithromycin or amoxycillin plus high-dose ranitidine in the treatment of Helicobacter pylori-positive functional dyspepsia

OBJECTIVE

This study was intended to investigate the effect of ranitidine in dual anti-Helicobacter pylori therapy. Simultaneously, it was to evaluate the potential effect of H. pylori eradication on the symptomatology of H. pylori-positive dyspepsia.

PATIENTS AND METHODS

Fifty-four patients with H. pylori infection and symptoms of non-ulcer dyspepsia were randomly assigned to treatment with either amoxycillin 500 mg four times daily plus ranitidine 300 mg four times daily, clarithromycin 500 mg twice daily plus ranitidine 300 mg twice daily, clarithromycin 500 mg four times daily plus ranitidine 300 mg twice daily or clarithromycin 500 mg four times daily plus ranitidine 300 mg four times daily for a period of 12 days. In addition, ranitidine 150 mg twice daily was given for a further 16 days.

RESULTS

Eradication of H. pylori using the assigned treatments was achieved in 47% (seven out of 15), 50% (five out of 10), 70% (seven out of 10) and 77% (10 out of 13) of patients, respectively. Failure of therapy with clarithromycin was associated with primary or acquired resistance after treatment in 91% (10 out of 11). Symptom improvement was significant (P = 0.0001) and similar in all of the four treatment groups up to week 8. As regards H. pylori status, no differences in the mean symptom score improvement could be found between patients with eradication and those with persistent infection (12.3-7.0, P = 0.0001, n = 29 compared with 13.0-6.5, P = 0.004, n = 19). After 1 year the symptom score had increased both in patients with persistent H. pylori (9.1) and in those remaining free of infection (10.0). No reinfection could be found.

CONCLUSION

These results suggest that clarithromycin plus high-dose ranitidine is a combination which achieves reasonably high H. pylori eradication rates. However, treatment failure inevitably leads to clarithromycin resistance. The improvement of non-ulcer dyspepsia symptoms during acute therapy is independent of H. pylori eradication. Long-term benefit of H. pylori eradication with respect to the symptoms of functional dyspepsia was not observed.

Helicobacter pylori reinfection with identical organisms: transmission by the patients' spouses

Reinfection with Helicobacter pylori after eradication is responsible for the recurrence of duodenal ulcer disease. The mode of transmission has not yet been established. In this study, 18 patients with chronic duodenal ulcers in whom H pylori had been eradicated with amoxicillin and metronidazole were entered into a prospective follow up study. Control endoscopies were performed 4, 8, 14, 27, and 43 months after starting treatment and the results of direct tests were compared with the kinetics of H pylori specific IgG titres. After eradication there was a noticeable and consistent fall in anti-H pylori IgG, while reinfections were characterised by a significant increase in specific titres. Reinfection was detected in two patients after 14 and 43 months, respectively. The H pylori strains responsible for these reinfections, the corresponding pretreatment isolates, and the strains isolated from the spouses of these patients were examined by polymerase chain reaction based DNA fingerprinting. Analysis showed that reinfection had been caused by the same H pylori strain and identified the spouses of these patients as carriers of the identical strain. Considering the genomic diversity and the interpatient heterogeneity of H pylori these results suggest a person to person transmission of H pylori reinfection. By the end of the observation period reflux oesophagitis had developed in 10 of the 16 patients who had not been reinfected. This surprising finding may be explained by the changed eating habits of patients after healing of duodenal ulcer disease.