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Q fever is a zoonotic infection which can pose a danger to pregnant women. To our knowledge, Denmark has never experienced a clinically verified Q fever outbreak. We aimed to quantify risk of infection in pregnant women occupationally and environmentally exposed to Coxiella burnetii. The Danish National Birth Cohort collected blood samples from 100,418 pregnant women in the period 1996 to 2002. We sampled 195 women with occupational exposure to livestock (veterinarians and female farmers), 202 women with domestic exposure (dairy cattle and/or sheep) and a random sample of 459 unexposed women. Samples were screened for antibodies against C. burnetii by commercial enzyme-linked immunosorbent assay. Positive samples were confirmed by immunofluorescence (cut-off titre ≥1:128). The proportion of seropositive women was higher in the occupationally exposed (47.2% seropositive; relative risk (RR): 9.8; 95% confidence interval (CI): 6.4–15.2) and the domestically exposed population (32.2% seropositive; RR: 6.7; 95% CI: 4.3–10.6) than in unexposed women (4.8% seropositive). We found a high prevalence of antibodies to C. burnetii among pregnant women with occupational or domestic exposure to cattle and/or sheep compared with unexposed pregnant women. Our findings suggest that contact to livestock is a risk factor for C. burnetii infection in Denmark.

In our paper (1), we analyzed isolates from the Escherichia coli O104:H4 outbreaks in Germany and France in May to July 2011. We concluded that, although the German outbreak was larger, the German isolates represent a clade within the greater diversity of the French outbreak. We proposed several hypotheses to explain these findings, including that the lineage leading to the German outbreak went through a narrow bottleneck that purged diversity. Guy et al. (2) report the genomes of eight additional E. coli O104:H4 isolates sampled from the German outbreak. By focusing on the numbers of SNPs in their samples, they suggest that the German outbreak is more diverse than we reported and is similar to the French outbreak. In fact, Guy et al.’s data (2) strongly support our conclusion that the German outbreak represents a clade within the diversity …

During December 2008 to January 2009, two persons contracted Legionnaires' disease in a newly built block of flats in a suburb of Copenhagen in Denmark. Polymerase chain reaction and culture was used to diagnose Legionnaires' disease in this cluster. Isolates from both patients tested positive for Legionella pneumophila serogroup 1 subgroup Philadelphia sequence type 1 and the same strain was detected in hot water samples taken from the residential area indicating that the hot water supply system was the most likely source of infection. Legionella was not detected in the cold water. Two interventions were conducted to limit the Legionella colonisation of the piping and storage tanks and the effect was monitored by investigating water samples from various sites in the block of flats. Only the second intervention had a sufficient effect on the Legionella colonisation. The cluster described here points to several risk factors regarding growth of Legionella in hot water systems: (i) stagnancy of water from when the building is constructed and piping installed and until residents move in, (ii) stagnancy and low temperature (from room temperature to approximately 38 degrees C) of water in shower hoses and (iii) failure in operation of and control measures for the hot water system.

Udgivelsesdato: 2010-Feb, Maggot debridement therapy (MDT) is widely used for debridement of chronic infected wounds; however, for wounds harbouring specific bacteria limited effect or failure of the treatment has been described. Here we studied the survival of Lucilia sericata maggots encountering Pseudomonas aeruginosa PAO1 in a simple assay with emphasis on the quorum-sensing (QS)-regulated virulence. The maggots were challenged with GFP-tagged P. aeruginosa wild-type (WT) PAO1 and a GFP-tagged P. aeruginosa DeltalasR rhlR (DeltaRR) QS-deficient mutant in different concentrations. Maggots were killed in the presence of WT PAO1 whereas the challenge with the QS mutant showed a survival reduction of approximately 25 % compared to negative controls. Furthermore, bacterial intake by the maggots was lower in the presence of WT PAO1 compared to the PAO1 DeltaRR mutant. Maggot excretions/secretions (ES) were assayed for the presence of QS inhibitors; only high doses of ES showed inhibition of QS in P. aeruginosa. Thus P. aeruginosa was shown to be toxic to L. sericata maggots. This, coupled to the preferential feeding by the maggots and reduced ingestion of P. aeruginosa, could explain MDT failure in wounds colonized by P. aeruginosa. Wounds heavily colonized with P. aeruginosa should be a counterindication for MDT unless used in combination with a pre-treatment with other topical therapeutics targeting P. aeruginosa.

Udgivelsesdato: 2009-Jun, Owing to under-ascertainment it is difficult if not impossible to determine the incidence of a given disease based on cases notified to routine public health surveillance. This is especially true for diseases that are often present in mild forms as for example diarrhoea caused by foodborne bacterial infections. This study presents a Bayesian approach for obtaining incidence estimates by use of measurements of serum antibodies against Salmonella from a cross-sectional study. By comparing these measurements with antibody measurements from a follow-up study of infected individuals it was possible to estimate the time since last infection for each individual in the cross-sectional study. These time estimates were then converted into incidence estimates. Information about the incidence of Salmonella infections in Denmark was obtained by using blood samples from 1780 persons. The estimated incidence was about 0.094 infections per person year. This number corresponds to 325 infections per culture-confirmed case captured in the Danish national surveillance system. We present a novel approach, termed as seroincidence, that has potentials to compare the sensitivity of public health surveillance between different populations, countries and over time.

This study describes the prevalence, clinical manifestations and microbiological characteristics of attaching and effacing Escherichia coli isolates, i.e., enteropathogenic E. coli (EPEC) belonging to the classical EPEC serotypes, non-EPEC attaching and effacing E. coli (A/EEC) and verocytotoxin-producing E. coli (VTEC), isolated in a case-control study of Danish children aged <5 years. Among 424 children with diarrhoea and 866 healthy controls, EPEC and VTEC were more prevalent in cases (2.4% and 2.6%, respectively) than in controls (0.7% and 0.7%, respectively). There was a high frequency of A/EEC isolates (n = 121), but these were equally prevalent in cases (11.3%) and controls (12.5%), and comprised a heterogeneous distribution of O:H serotypes. The intimin (eae) subtypes in A/EEC isolates showed an even distribution; the eae-gamma subtype predominated in classical EPEC cases. The virulence genes encoding the bundle-forming pilus (bfpA) and enteroaggregative heat-stable enterotoxin (astA) were rare among all isolates, and seemed to be of limited pathogenic importance in this population. Virulence characterisation of A/EEC isolates did not reveal any significant differences between cases and controls. Colonisation of children with A/EEC was associated with contact with sheep or goats (OR 2.2). The role of A/EEC, not being VTEC or belonging to the classical EPEC serotypes, requires further clarification, but serotyping is useful in discriminating between EPEC and A/EEC strains. Udgivelsesdato: 2007-Sep, This study describes the prevalence, clinical manifestations and microbiological characteristics of attaching and effacing Escherichia coli isolates, i.e., enteropathogenic E. coli (EPEC) belonging to the classical EPEC serotypes, non-EPEC attaching and effacing E. coli (A/EEC) and verocytotoxin-producing E. coli (VTEC), isolated in a case-control study of Danish children aged <5 years. Among 424 children with diarrhoea and 866 healthy controls, EPEC and VTEC were more prevalent in cases (2.4% and 2.6%, respectively) than in controls (0.7% and 0.7%, respectively). There was a high frequency of A/EEC isolates (n = 121), but these were equally prevalent in cases (11.3%) and controls (12.5%), and comprised a heterogeneous distribution of O:H serotypes. The intimin (eae) subtypes in A/EEC isolates showed an even distribution; the eae-gamma subtype predominated in classical EPEC cases. The virulence genes encoding the bundle-forming pilus (bfpA) and enteroaggregative heat-stable enterotoxin (astA) were rare among all isolates, and seemed to be of limited pathogenic importance in this population. Virulence characterisation of A/EEC isolates did not reveal any significant differences between cases and controls. Colonisation of children with A/EEC was associated with contact with sheep or goats (OR 2.2). The role of A/EEC, not being VTEC or belonging to the classical EPEC serotypes, requires further clarification, but serotyping is useful in discriminating between EPEC and A/EEC strains.

Leptospira fainei serovar Hurstbridge is a recently discovered Leptospira species and so far it has only been cultured from animal sources. Based on positive serology and positive PCR for L. fainei among patients suspected of having leptospirosis, a role in human disease seems likely. This study describes two patients with Weil's disease from whom L. fainei was cultured. A local source of the infections was suspected, as these two patients resided in the same area of Denmark, were hospitalised approximately at the same time and had not been travelling recently. The Leptospira species was determined by serology, PCR and sequencing of bacterial DNA. One patient developed autoimmune hepatitis in the course of the L. fainei infection and was treated with both antibiotics and immunosuppression with good effect. The other patient had a self-limiting disease and did not receive any treatment.

In a human gastric biopsy specimen, 30% of adhering Helicobacter pylori strain AF4 (cagA and VacA positive) was associated with adhesion pedestals. In an AGS cell assay, only a few percent of this type I strain was found to be associated with adhesion pedestals. Nevertheless, a larger proportion of the type I strain was found to invade AGS cells (P < 0.03) and to attach with depressions in the AGS cell membrane (P < 0.03) than a type II strain (cagA and VacA negative). Incubation of AGS cells and H. pylori without adding fetal calf serum (FCS) to the culture medium increased actin accumulations (FITC-phalloidin stained) beneath adhering H. pylori, and decreased H. pylori invasion of AGS cells significantly (P < 0.01). However, no increase in the number of adhesion pedestals was observed by electron microscopy. Proteinase K treatment of FCS eliminated the H. pylori invasion promoting effect (P < 0.01). Our results suggest differences in the ability of H. pylori to induce adhesion pedestals in human gastric epithelial cells and in AGS cells, but a correlation between adhesion pedestal formation in vivo and H. pylori invasion in vitro can be speculated. In addition, H. pylori invasion into AGS cells was found to be mediated by proteins in FCS. (C) 2000 Federation of European Microbiological Societies.

Udgivelsesdato: 2000-Apr, BACKGROUND: Helicobacter pylori plays an important role in peptic ulcer disease, although not all H. pylori-infected persons will develop a peptic ulcer. Currently, H. pylori strains cannot be divided into commensals and pathogens. METHODS: Fifty H. pylori strains were cultured from patients divided into five groups on the basis of upper endoscopic findings: gastric ulcer, duodenal ulcer, gastritis, esophagitis, or normal. The ultrastructural adherence pattern in vivo, autoagglutination, hemagglutination, adhesion to human gastric adenocarcinoma (AGS) cells, and the lipopolysaccharide (LPS) profile of H. pylori strains were recorded; randomly amplified polymorphic DNA (RAPD) and urease gene typing were performed and correlated with diagnostic groups. RESULTS: Electron micrographs showed that H. pylori strains from patients with gastric ulcers adhered more frequently through filamentous strands and were less frequently found free in mucus than any other diagnostic group (P < 0.0001). Neither median hemagglutination titer nor median adhesion capacity to a human gastric adenocarcinoma cell line was related to endoscopic findings. Nevertheless, H. pylori strains from patients with gastric ulcers were more prone to autoagglutinate than were strains from the other diagnostic groups (P = 0.03). H. pylori strains from gastric ulcer patients were found to be more homogeneous, as determined by RAPD and urease gene typing, than strains from the other diagnostic groups (P < 0.01). In addition, a positive correlation was found between a patient's age and the adhesion to AGS cells of the patient's H. pylori strain (P = 0.006). CONCLUSION: A combination of an H. pylori autoagglutination test, RAPD, and urease gene typing may be useful in separating gastric ulcer-related strains from duodenal ulcer-related and non-ulcer dyspepsia-related strains.

Udgivelsesdato: 1999-Jun, Microbial typing is a useful tool in clinical epidemiology for defining the source and route of infection, for studying the persistence and reinfection rates, clonal selection in the host and bacterial evolution. Phenotypic methods such as biotyping, serotyping and hemagglutinin typing have little discriminatory power compared to genotypic methods concerning the typing of Helicobacter pylori. Therefore great efforts have been made to establish useful molecular typing methods. In this context, the most frequently used genotypic methods are described based on our own experience and the literature: (1) restriction endonuclease analysis, (2) endonuclease analysis using pulsed-field gel electrophoresis, (3) ribotyping, (4) polymerase chain reaction (using either random primers or repetitive DNA sequence primers), and (5) polymerase chain reaction-restriction fragment length polymorphism analysis of e.g. the urease genes. Furthermore, reproducibility, discriminatory power, ease of performance and interpretation, cost and toxic procedures of each method are assessed. To date no direct comparison of all the molecular typing methods described has been performed in the same study with the same H. pylori strains. However, PCR analysis of the urease gene directly on suspensions of H. pylori or gastric biopsy material seems to be useful for routine use and applicable in specific epidemiological situations.