Clinical/serological outcome in humans bitten by Babesia species positive Ixodes ricinus ticks in Sweden and on the Åland Islands.

The risk of contracting babesiosis after a tick bite in Sweden and on the Åland Islands, Finland, is unknown. We investigated clinical and serological outcomes in people bitten by Ixodes ricinus ticks positive for Babesia species. Ticks, blood and questionnaires were obtained from study participants in Sweden and on the Åland Islands. Sixty-five of 2098 (3.1 %) ticks were positive by real-time PCR. Three Babesia species were detected, Babesia microti (n = 33), B. venatorum (n = 27) and B. capreoli (n = 5), the latter species not known to cause human infection. Half (46 %) of the Babesia PCR-positive ticks also contained Borrelia spp. Fifty-three participants bitten by a Babesia PCR-positive tick and a control group bitten by a Babesia PCR-negative tick were tested for B. microti IgG antibodies by IFA. The overall seroprevalence was 4.4 %, but there was no significant difference between the groups. None of the participants seroconverted and no participant with a Babesia PCR-positive tick sought medical care or reported symptoms suggestive of babesiosis. Given the prevalence of Babesia in I. ricinus ticks in southern Sweden and on the Åland Islands, babesiosis should be considered a possible diagnosis in symptomatic residents who seek medical care following tick exposure.

Increased abundance of proteobacteria in aggressive Crohn's disease seven years after diagnosis.

Intestinal dysbiosis in inflammatory bowel disease (IBD) patients depend on disease activity. We aimed to characterize the microbiota after 7 years of follow-up in an unselected cohort of IBD patients according to disease activity and disease severity. Fifty eight Crohn's disease (CD) and 82 ulcerative colitis (UC) patients were included. Disease activity was assessed by the Harvey-Bradshaw Index for CD and Simple Clinical Colitis Activity Index for UC. Microbiota diversity was assessed by 16S rDNA MiSeq sequencing. In UC patients with active disease and in CD patients with aggressive disease the richness (number of OTUs, p = 0.018 and p = 0.013, respectively) and diversity (Shannons index, p = 0.017 and p = 0.023, respectively) were significantly decreased. In the active UC group there was a significant decrease in abundance of the phylum Firmicutes (p = 0.018). The same was found in CD patients with aggressive disease (p = 0.05) while the abundance of Proteobacteria phylum showed a significant increase (p = 0.03) in CD patients. We found a change in the microbial abundance in UC patients with active disease and in CD patients with aggressive disease. These results suggest that dysbiosis of the gut in IBD patients is not only related to current activity but also to the course of the disease.

Kinetics of serum antibodies in response to infection with Yersinia enterocolitica.

Information on the kinetics of the serum antibody response to infection with Yersinia enterocolitica is essential to allow the estimation and comparison of seroconversion rates in a diversity of pools of cross-sectional serum antibody measurements. Data from 94 patients with acute enteritis caused by Yersinia infection were used. The follow-up period for the longitudinal study was 36 months, addressed by questionnaire. An indirect enzyme-linked immunosorbent assay method was adapted to determine the concentration of antibodies against Y. enterocolitica in human sera. A mathematical within-host model was used to describe the interaction between pathogen and immune system and the waning of immunity after clearing of the pathogen. All observed antibodies (IgG, IgM, IgA) reached peak levels shortly after infection and then decayed slowly indicating that the median levels decreased only little during the observation period. Estimated maximum peak antibody levels were highest in IgG. Seroresponse curves of all antibodies showed large individual variation between patients. There was no apparent pattern of variation with age, nor any notable difference between genders. Estimated half-times were very long for all antibodies, and their posterior distributions were highly skewed. IgA appeared to have the most persistent antibody response, compared with IgG and IgM. Median peak levels of all three antibodies were similar. There was no significance found between peak antibody levels and severity of symptoms of gastrointestinal infection and severity of joint pain. Our findings allow the use of cross-sectional serum antibody measurements as biomarkers, to estimate seroconversion rates. Such seroincidence estimates include asymptomatic seroconversions, thereby avoiding under-reporting, and allows the comparison of infection pressures among countries, independent of their healthcare and surveillance systems.

Neonates colonized with pathogenic bacteria in the airways have a low-grade systemic inflammation.

BACKGROUND AND OBJECTIVES: The development of childhood asthma is associated with neonatal colonization with pathogenic bacteria in hypopharynx. Furthermore, established asthma is associated with systemic low-grade inflammation. We here report on the association between neonatal colonization with pathogenic bacteria in hypopharynx and the development of systemic low-grade inflammation. METHODS: Bacterial colonization of the hypopharynx with Moraxella catharralis, Haemophilus influenzae, and/or Streptococcus pneumoniae was assessed in asymptomatic children from the Copenhagen Prospective Studies on Asthma in Childhood2000 (COPSAC2000 ) cohort at age 1 month by culturing technique (N = 238) and by quantitative polymerase chain reaction (qPCR) technique (N = 249) and in the COPSAC2010 cohort by culturing at age 1 month (N = 622) and again at age 3 months (N = 613). Systemic low-grade inflammation was determined in both cohorts at age 6 months by measuring plasma levels of high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (lL-6). RESULTS: In both cohorts, bacterial colonization was associated with increased levels of hs-CRP: COPSAC2000 , 1 month culturing (geometric mean ratio of colonized/noncolonized [95% CI]), 1.39 [0.97-2.01], P = .08; 1 month qPCR, 1.55 [1.14-2.10], P < .01; COPSAC2010 , 1 month, 1.52 [1.23-1.87], P < .01; and 3 month, 1.57 [1.30-1.90], P < .01. A multiparametric principal component analysis incorporating hs-CRP, TNF-α, and IL-6 confirmed a systemic inflammatory profile in children colonized with M. catharralis, H. influenzae. and/or S. pneumoniae in the hypopharynx compared to noncolonized children (P-values < .05). CONCLUSION: The composition of the upper airway microbiome in early life may cause systemic low-grade inflammation.

Staphylococcus aureus colonization in atopic eczema and its association with filaggrin gene mutations.

BACKGROUND: Atopic dermatitis (AD) is a prevalent disease with significant impact on physical health and quality of life. Staphylococcus aureus has been directly correlated to disease severity, and may also be a contributing causal factor in the pathogenesis of AD. OBJECTIVES: The primary aim was to assess differences in S. aureus colonization in patients with AD with and without filaggrin gene mutations. The secondary aim was to assess disease severity in relation to S. aureus colonization. Exploratory analyses were performed to investigate S. aureus genetic lineages in relation to filaggrin gene (FLG) mutations and disease severity. METHODS: Adult patients with AD (n = 101) were included in the study. Bacterial swabs were taken from lesional skin, nonlesional skin and the nose. Swabs positive for S. aureus were characterized by spa and the respective clonal complex (CC) type assigned. Patients were characterized with respect to disease severity (Scoring Atopic Dermatitis) and FLG mutations (n = 88). Fisher's exact test was used to analyse differences in S. aureus colonization in relation to FLG mutations. RESULTS: Of the 101 patients included, 74 (73%) were colonized with S. aureus. Of the colonized patients, 70 (95%) carried only one CC type in all three different sampling sites. In lesional skin, S. aureus was found in 24 of 31 patients with FLG mutations vs. 24 of 54 wild-type patients (P = 0·0004). Staphylococcus aureusCC1 clonal lineage was more prevalent in patients with FLG mutations (n = 10) than in wild-type patients (n = 2) (P = 0·003). No specific bacterial lineage was linked to disease severity. CONCLUSIONS: Increased S. aureus colonization in patients with AD with FLG mutations, and increased prevalence of CC1 in patients with FLG mutations, suggest that host-microbe interactions and clonal differences in S. aureus are important for colonization of AD skin.

Epidemiological and serological investigation of a waterborne Campylobacter jejuni outbreak in a Danish town.

Following an unusually heavy rainfall in June 2009, a community-wide outbreak of Campylobacter gastroenteritis occurred in a small Danish town. The outbreak investigation consisted of (1) a cohort study using an e-questionnaire of disease determinants, (2) microbiological study of stool samples, (3) serological study of blood samples from cases and asymptomatic members of case households, and (4) environmental analyses of the water distribution system. The questionnaire study identified 163 cases (respondent attack rate 16%). Results showed a significant dose-response relationship between consumption of tap water and risk of gastroenteritis. Campylobacter jejuni belonging to two related flaA types were isolated from stool samples. Serum antibody levels against Campylobacter were significantly higher in cases than in asymptomatic persons. Water samples were positive for coliform bacteria, and the likely mode of contamination was found to be surface water leaking into the drinking-water system. This geographically constrained outbreak presented an ideal opportunity to study the serological response in persons involved in a Campylobacter outbreak. The serology indicated that asymptomatic persons from the same household may have been exposed, during the outbreak period, to Campylobacter at doses that did not elicit symptoms or alternatively had been exposed to Campylobacter at a time prior to the outbreak, resulting in residual immunity and thus absence of clinical signs.

Associations between common intestinal parasites and bacteria in humans as revealed by qPCR.

Several studies have shown associations between groups of intestinal bacterial or specific ratios between bacterial groups and various disease traits. Meanwhile, little is known about interactions and associations between eukaryotic and prokaryotic microorganisms in the human gut. In this work, we set out to investigate potential associations between common single-celled parasites such as Blastocystis spp. and Dientamoeba fragilis and intestinal bacteria. Stool DNA from patients with intestinal symptoms were selected based on being Blastocystis spp.-positive (B+)/negative (B-) and D. fragilis-positive (D+)/negative (D-), and split into four groups of 21 samples (B+ D+, B+ D-, B- D+, and B- D-). Quantitative PCR targeting the six bacterial taxa Bacteroides, Prevotella, the butyrate-producing clostridial clusters IV and XIVa, the mucin-degrading Akkermansia muciniphila, and the indigenous group of Bifidobacterium was subsequently performed, and the relative abundance of these bacteria across the four groups was compared. The relative abundance of Bacteroides in B- D- samples was significantly higher compared with B+ D- and B+ D+ samples (P < 0.05 and P < 0.01, respectively), and this association was even more significant when comparing all parasite-positive samples with parasite-negative samples (P < 0.001). Additionally, our data revealed that a low abundance of Prevotella and a higher abundance of Clostridial cluster XIVa was associated with parasite-negative samples (P < 0.05 and P < 0.01, respectively). Our data support the theory that Blastocystis alone or combined with D. fragilis is associated with gut microbiota characterized by low relative abundances of Bacteroides and Clostridial cluster XIVa and high levels of Prevotella.

Seroincidence of non-typhoid Salmonella infections: convenience vs. random community-based sampling.

The incidence of reported infections of non-typhoid Salmonella is affected by biases inherent to passive laboratory surveillance, whereas analysis of blood sera may provide a less biased alternative to estimate the force of Salmonella transmission in humans. We developed a mathematical model that enabled a back-calculation of the annual seroincidence of Salmonella based on measurements of specific antibodies. The aim of the present study was to determine the seroincidence in two convenience samples from 2012 (Danish blood donors, n = 500, and pregnant women, n = 637) and a community-based sample of healthy individuals from 2006 to 2007 (n = 1780). The lowest antibody levels were measured in the samples from the community cohort and the highest in pregnant women. The annual Salmonella seroincidences were 319 infections/1000 pregnant women [90% credibility interval (CrI) 210-441], 182/1000 in blood donors (90% CrI 85-298) and 77/1000 in the community cohort (90% CrI 45-114). Although the differences between study populations decreased when accounting for different age distributions the estimates depend on the study population. It is important to be aware of this issue and define a certain population under surveillance in order to obtain consistent results in an application of serological measures for public health purposes.

Investigations into the emergence of pertactin-deficient Bordetella pertussis isolates in six European countries, 1996 to 2012.

Pathogen adaptation has been proposed to contribute to the resurgence of pertussis. A striking recent example is the emergence of isolates deficient in the vaccine component pertactin (Prn). This study explores the emergence of such Prn-deficient isolates in six European countries. During 2007 to 2009, 0/83 isolates from the Netherlands, 0/18 from the United Kingdom, 0/17 Finland, 0/23 Denmark, 4/99 Sweden and 5/20 from Norway of the isolates collected were Prn-deficient. In the Netherlands and Sweden, respectively 4/146 and 1/8 were observed in a later period (2010­12). The Prn-deficient isolates were genetically diverse and different mutations were found to inactivate the prn gene. These are indications that Prn-deficiency is subject to positive selective pressure. We hypothesise that the switch from whole cell to acellular pertussis vaccines has affected the balance between 'costs and benefits' of Prn production by Bordetella pertussis to the extent that isolates that do not produce Prn are able to expand. The absence of Prn-deficient isolates in some countries may point to ways to prevent or delay the spread of Prn-deficient strains. In order to substantiate this hypothesis, trends in the European B. pertussis population should be monitored continuously.

Antibody development to Fusobacterium necrophorum in patients with peritonsillar abscess.

A polymicrobial mixture of aerobic and anaerobic bacteria is commonly recovered from peritonsillar abscess (PTA) aspirates. Previous studies have suggested a role for Fusobacterium necrophorum (FN) in the development of PTA. The purpose of the current study was to explore whether anti-FN antibodies were produced in patients with PTA. We developed a novel immunofluorescence-based method to measure anti-FN antibody levels in acute and convalescent sera from 15 patients with PTA and 47 patients with chronic tonsillar conditions (controls) undergoing acute or elective tonsillectomy, respectively. Bacterial cultures were performed on tonsillar cores and surfaces, pus aspirates, and blood. An increase in anti-FN antibody levels (of at least doubling of the previous level) was observed in 8 of 11 (73 %) PTA patients with FN-positive pus aspirate cultures (FN-positive patients). In contrast, the four FN-negative PTA patients did not have an increase in anti-FN antibody levels (p = 0.026). The change in anti-FN antibody levels in FN-positive PTA patients was also significantly greater than that for FN-positive electively tonsillectomized patients (p = 0.0014) and all electively tonsillectomized patients (p < 0.001). Our results validate FN as a significant and prevalent pathogen in PTA. This finding has implications for the diagnostic work-up of PTA and may also have implications for the treatment of acute tonsillitis.

Seroepidemiology of pertussis in a cross-sectional study of an adult general population in Denmark.

An increase in pertussis has been observed in several countries over the last decades, especially in adult populations. The seroprevalence of pertussis was determined in a cross-sectional study of the adult population in the Copenhagen area, Denmark, conducted between 2006 and 2008. Specific IgG antibodies against pertussis toxin (PT) were measured in 3440 persons resulting in an age-standardized seroprevalence of 3.0% (95% confidence interval 1.9-4.7) using an IgG anti-PT cut-off of 75 IU/ml. By using antibody decay profiles from longitudinal data the estimated seroincidence was 143/1000 person-years. In contrast, an incidence of 0.03/1000 person-years was estimated from the official data of notified cases during the same period. Of the investigated risk factors, only age and education were significantly associated with pertussis infection. This study indicates that pertussis is highly underestimated in the adult population in Denmark, which has implications for future prevention strategies, including raising the awareness of pertussis.

Antibiotic use during pregnancy alters the commensal vaginal microbiota.

Antibiotics may induce alterations in the commensal microbiota of the birth canal in pregnant women. Therefore, we studied the effect of antibiotic administration during pregnancy on commensal vaginal bacterial colonization at gestational week 36. Six hundred and sixty-eight pregnant women from the novel unselected Copenhagen Prospective Studies on Asthma in Childhood (COPSAC2010 ) pregnancy cohort participated in this analysis. Detailed information on oral antibiotic prescriptions during pregnancy filled at the pharmacy was obtained and verified prospectively. Vaginal samples were obtained at pregnancy week 36 and cultured for bacteria. Women who received oral antibiotics during any pregnancy trimester had an increased rate of colonization by Staphylococcus species in the vaginal samples as compared with samples obtained from women without any antibiotic treatment during pregnancy (adjusted OR 1.63, 95% CI 1.06-2.52, p 0.028). Oral antibiotic administration in the third trimester were also associated with increased colonization by Staphylococcus species (adjusted OR 1.98, 95% CI 1.04-3.76, p 0.037). These bacteriological changes were associated with urinary tract infection antibiotics. Women treated in the third trimester of pregnancy were more often colonized by Escherichia coli than women without antibiotic treatment in the third trimester (adjusted OR 1.91, 95% CI 1.04-3.52, p 0.038). This change was associated with respiratory tract infection (RTI) antibiotics. We did not observe any significant changes in vaginal Streptococcus agalactiae (group B streptoccocus) or Staphylococcus aureus colonization following antibiotic treatment in pregnancy. Antibiotic administration during pregnancy leads to alterations in the vaginal microbiological ecology prior to birth, with potential morbidity, and long-term effects on the early microbial colonization of the neonate.

Deep phenotyping of the unselected COPSAC2010 birth cohort study.

BACKGROUND: We hypothesize that perinatal exposures, in particular the human microbiome and maternal nutrition during pregnancy, interact with the genetic predisposition to cause an abnormal immune modulation in early life towards a trajectory to chronic inflammatory diseases such as asthma and others. OBJECTIVE: The aim of this study is to explore these interactions by conducting a longitudinal study in an unselected cohort of pregnant women and their offspring with emphasis on deep clinical phenotyping, exposure assessment, and biobanking. Exposure assessments focus on the human microbiome. Nutritional intervention during pregnancy in randomized controlled trials are included in the study to prevent disease and to be able to establish causal relationships. METHODS: Pregnant women from eastern Denmark were invited during 2008-2010 to a novel unselected 'COPSAC2010 ' cohort. The women visited the clinic during pregnancy weeks 24 and 36. Their children were followed at the clinic with deep phenotyping and collection of biological samples at nine regular visits until the age of 3 and at acute symptoms. Randomized controlled trials of high-dose vitamin D and fish oil supplements were conducted during pregnancy, and a trial of azithromycin for acute lung symptoms was conducted in the children with recurrent wheeze. RESULTS: Seven hundred and thirty-eight mothers were recruited from week 24 of gestation, and 700 of their children were included in the birth cohort. The cohort has an over-representation of atopic parents. The participant satisfaction was high and the adherence equally high with 685 children (98%) attending the 1 year clinic visit and 667 children (95%) attending the 2 year clinic visit. CONCLUSIONS: The COPSAC2010 birth cohort study provides longitudinal clinical follow-up with highly specific end-points, exposure assessments, and biobanking. The cohort has a high adherence rate promising strong data to elucidate the interaction between genomics and the exposome in perinatal life leading to lifestyle-related chronic inflammatory disorders such as asthma.

Prevalence of Coxiella burnetii in women exposed to livestock animals, Denmark, 1996 to 2002.

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): 6.4­15.2) and the domestically exposed population (32.2% seropositive; RR: 6.7; 95% CI: 4.3­10.6) 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.

Human ß-defensin-2 as a marker for disease severity and skin barrier properties in atopic dermatitis.

BACKGROUND: Skin infections related to disrupted antimicrobial defence are a common problem in atopic dermatitis (AD). Altered levels of antimicrobial peptides, including human ß-defensin (hBD)-2, have been reported in AD skin, and a link to impaired barrier function has been suggested. OBJECTIVES: To study hBD-2 in relation to skin barrier function in patients with AD and controls, and to study hBD-2 in relation to disease severity. METHODS: Twenty-five patients with AD and 11 controls were enrolled. hBD-2 peptide concentration was determined in stratum corneum samples collected by a minimally invasive tape-stripping method. Disease severity was assessed by SCORing Atopic Dermatitis (SCORAD), and skin barrier function was evaluated by measurement of transepidermal water loss (TEWL) and skin pH. Patients with AD were characterized according to filaggrin mutations. RESULTS: hBD-2 concentrations in the stratum corneum were found to differ between lesional and nonlesional AD skin and controls, with the highest values in lesional skin (P < 0·001). SCORAD and TEWL were significantly increased in participants with measureable hBD-2 (P < 0·018 and P < 0·007, respectively). Significant correlations between hBD-2 in lesional skin, and TEWL and SCORAD were observed (R = 0·55 and R = 0·44, respectively). No correlations with skin pH were found. hBD-2 was not found to relate to filaggrin mutations. CONCLUSIONS: A significant correlation was found between hBD-2, disturbed skin barrier function and disease severity. The minimally invasive skin sample technique enables evaluation of the stratum corneum and its proteins over time and provides the possibility of relating these findings to treatment, infections and physiological variations.

Two years' performance of an in-house ELISA for diagnosis of Legionnaires' disease: detection of specific IgM and IgG antibodies against Legionella pneumophila serogroup 1, 3 and 6 in human serum.

The aim of this study was to evaluate the performance of an in-house ELISA for the diagnosis of Legionnaires' disease (LD) by detection of IgM and IgG antibodies against Legionella (L.) pneumophila serogroups (sg) 1, 3 and 6. The evaluation was done throughout a two-year period in a diagnostic routine laboratory. Furthermore, the sensitivity of four different methods, the in-house L. pneumophila antibody test (ELISA), the urinary antigen test (Binax® EIA), an in-house PCR and culture, both alone and in combination was evaluated. From 2008 to 2010, 12,158 serum samples from 10,503 patients were analysed. During the same period, 361 cases of laboratory-confirmed LD cases were recorded in Denmark, but of these only 113 had a serum sample examined. The positive predictive value of the in-house ELISA was calculated to be 12.8 and the negative predictive value was 99.6, using only the confirmed LD cases as true positives. The sensitivity of the in-house ELISA for the detection of IgM and IgG antibodies in the confirmed LD cases was 61% and 36%, respectively. By combining the two ELISA assays the sensitivity increased to 66%. The sensitivity of the Legionella urinary antigen test (Binax® EIA) was 63%, of the in-house PCR 87% and of culture 69%. When all the different methods were combined, a higher sensitivity was calculated--for in-house ELISA (IgM+IgG) and Binax® EIA 91%, in-house ELISA (IgM+IgG) and in-house PCR 93%, in-house ELISA (IgM+IgG) and culture 93%, Binax® EIA and in-house PCR 79%, Binax® EIA and culture 68% and in-house PCR and culture 94%. This study confirms that the detection of IgG and IgM antibodies by ELISA is an important diagnostic tool, also during the initial phase of the disease. Furthermore, we showed that LD in Denmark with or without serum samples collected exhibits the same age and sex distribution and epidemiology, as in the rest of Europe, i.e., mostly men are infected, infections are mostly community acquired, followed by infection from travelling abroad. Apart from patients with notified LD, the patients investigated by serology were evenly distributed in all age groups; there was only a slightly higher ratio of men tested for "atypical pneumonia" in the serology laboratory.

Campylobacter jejuni carbon starvation protein A (CstA) is involved in peptide utilization, motility and agglutination, and has a role in stimulation of dendritic cells.

Campylobacter jejuni is the most frequent cause of severe gastroenteritis in the developed world. The major symptom of campylobacteriosis is inflammatory diarrhoea. The molecular mechanisms of this infection are poorly understood compared to those of less frequent disease-causing pathogens. In a previous study, we identified C. jejuni proteins that antibodies in human campylobacteriosis patients reacted with. One of the immunogenic proteins identified (Cj0917) displays homology to carbon starvation protein A (CstA) from Escherichia coli, where this protein is involved in the starvation response and peptide uptake. In contrast to many bacteria, C. jejuni relies on amino acids and organic acids for energy, but in vivo it is highly likely that peptides are also utilized, although their mechanisms of uptake are unknown. In this study, Biolog phenotype microarrays have been used to show that a ΔcstA mutant has a reduced ability to utilize a number of di- and tri-peptides as nitrogen sources. This phenotype was restored through genetic complementation, suggesting CstA is a peptide uptake system in C. jejuni. Furthermore, the ΔcstA mutant also displayed reduced motility and reduced agglutination compared to WT bacteria; these phenotypes were also restored through complementation. Murine dendritic cells exposed to UV-killed bacteria showed a reduced IL-12 production, but the same IL-10 response when encountering C. jejuni ΔcstA compared to the WT strain. The greater Th1 stimulation elicited by the WT as compared to ΔcstA mutant cells indicates an altered antigenic presentation on the surface, and thus an altered recognition of the mutant. Thus, we conclude that C. jejuni CstA is important not only for peptide utilization, but also it may influence host-pathogen interactions.

Evaluation of PCR methods for the diagnosis of pertussis by the European surveillance network for vaccine-preventable diseases (EUVAC.NET).

This study aimed to evaluate the performance of polymerase chain reaction (PCR) methods used for the diagnosis of pertussis in laboratories within Europe in 2011. National reference laboratories in 25 European countries were contacted and a total of 24 laboratories from 19 countries agreed to participate in the study. A panel of seven samples of DNA from Bordetella pertussis, Bordetella parapertussis and Bordetella holmesii plus a negative control were distributed and analysed according to the routine PCR methods in each laboratory. The study took place in 2011. Nineteen laboratories used a real-time PCR approach, four laboratories used block-based PCR and one laboratory used a combination of methods. Six different combinations of amplification targets were used, and ten laboratories tested only for the presence of B. pertussis DNA. All laboratories (24/24) correctly identified a sample with high concentration of B. pertussis DNA, while three misidentified the B. parapertussis DNA as B. pertussis and 15 misidentified the B. holmesii DNA as either B. pertussis or B. parapertussis. There was a wide variation in the methods used for PCR-based diagnosis of pertussis among the European laboratories. Several laboratories were not able to discriminate between DNA samples from different Bordetella species.