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Objectives: To investigate whether antibody response patterns against Klebsiella pneumoniae capsular serotypes can discriminate patients with axial spondyloarthritis (axSpA) from patients with non-specific low back pain (LBP).Method: Immunoglobulin (Ig)G and IgA antibodies against K. pneumoniae capsular serotypes K2, K26, K36, and K50 were measured, and antibody seropositivity compared between groups and analysed for patient correlation in five different groups: (a) 96 patients fulfilling the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axSpA; (b) 38 patients with either a positive magnetic resonance imaging (MRI) scan as defined by ASAS or a positive human leucocyte antigen (HLA)-B27 status plus one clinical SpA feature, characterized as 'non-axSpA'; (c) 82 non-specific LBP patients; (d) 40 healthy blood donors and (e) 43 patients with diagnosed ankylosing spondylitis (AS) served as the negative and positive control groups.Results: There was no difference in IgG and IgA seropositivity against all serotypes between the axSpA, non-axSpA, and LBP groups. No significant correlations were found between anti-Klebsiella antibodies and age, gender, HLA-B27, or high-sensitivity C-reactive protein (hsCRP). IgG seropositivity against K50 was more frequent in AS (25.6%) than in axSpA (13.5%, p < 0.05). axSpA patients with radiographic sacroiliitis and AS controls concordantly had the highest frequency of seropositivity for ≥ 2 serotypes (21%).Conclusions: The antibody patterns against K. pneumoniae serotypes K2, K26, K36, and K50 did not discriminate between early axSpA and non-specific LBP. [ABSTRACT FROM AUTHOR]

The efficacy, the ability to confer protection against a target disease and the safety of a vaccine are assessed in great detail before licensure. However, inherent limitations in the prelicensure assessment necessitate continued epidemiological evaluations of efficacy and safety issues after the introduction of vaccines into use. In Denmark, the opportunities available for epidemiological research are unique. In 2001, an initiative was undertaken to take advantage of these opportunities to study the postlicensure epidemiology of childhood vaccination with respect to effectiveness and safety. First, we describe the unique opportunities for postlicensure research in Denmark with respect to the data sources available and the epidemiological and statistical methods used. We then describe a number of recent postlicensure studies of effectiveness and safety that took advantage of these opportunities. Specifically, studies on the effectiveness of Haemophilus influenzae type b vaccination, the effectiveness of pertussis vaccination, the impact of a preschool pertussis booster on infant pertussis, measles-mumps-rubella vaccine and autism, thimerosal-containing vaccine and autism, measles-mumps-rubella vaccine and febrile seizures, childhood vaccination and Type 1 diabetes, and childhood vaccination and nontargeted infectious disease are discussed.

Surveillance performed after the introduction of general Haemophilus influenzae serotype b (Hib) vaccination in Denmark identified 13 cases of invasive bacteraemic H. influenzae serotype f (Hif) disease in adults over a period of 7 years. Bacteraemic respiratory tract infections accounted for 61 % of cases, but meningitis, epiglottitis and osteoarthritis were also seen. Recent Danish isolates were compared to recent American isolates, historical Hif strains and non-Hif invasive strains. Results of conventional serotyping were confirmed by PCR detection of the serotype-f-specific cap and bexA gene sequences. Multilocus enzyme electrophoresis typing revealed that recent Danish and American isolates belonged to a single Hif clone, which may be undergoing expansion. The need for accurate serotyping of H. influenzae to enable reliable monitoring for Hib replacement by other capsular types is emphasized.

In order to determine antibody levels against Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae type b (Hib) in a population of splenectomized subjects, 561 persons in a Danish county, splenectomized between 1984 and 1993 were identified. Two hundred and thirty-five were alive and 149 participated in the study. Each person donated a blood sample for antibody determination by ELISA. Though vaccine coverage among the 149 persons was 91% only 52% had 'protective' levels of pneumococcal antibodies. Despite recommendations for regular follow-up on pneumococcal antibody levels this had only been carried out in 4% of the subjects. Splenectomized subjects who needed pneumococcal revaccination were significantly more likely to have received their initial vaccination less than 14 days before or after splenectomy, as recommended, than those not requiring revaccination. Therefore, the timing of initial pneumococcal vaccination in relation to splenectomy seems to be important. All persons had Hib antibody levels higher than 0.15 microgram/ml and 60% had levels higher than 1 microgram/ml, which are the levels thought to provide short term and long term protection, respectively. In total, 37% of the 149 persons tested had pneumococcal and Hib antibody levels thought to correlate with protection from serious infections.

In order to improve the surveillance of serogroup B and C meningococcal diseases, enzyme-linked immunosorbent assays (ELISAs) specific for anti-B immunoglobulin M (IgM) and anti-C IgM and IgG antibodies were developed. The tests were evaluated by using paired sera from 122 patients with and 101 patients without laboratory evidence of meningococcal disease. Fifty-three of 67 patients (79%) with culture-confirmed serogroup B disease had an anti-B IgM antibody response; anti-B IgM levels waned rapidly in children < or = 4 years of age. Twenty-four of 25 patients (96%) with culture-confirmed serogroup C disease had an anti-C IgM and/or IgG antibody response (IgM, 92%; IgG, 68%). In patients without evidence of meningococcal disease, 19% of children < or = 4 years of age and 69% of those > 4 years of age had intermediate anti-B IgM titers. In contrast, only 1 and 5% of these patients had intermediate titers of anti-C IgM and anti-C IgG, respectively. The ELISAs were shown to be powerful tools for discriminating between serogroup B and C diseases in 96 to 100% of culture-confirmed cases. For 90% of patients with culture-negative meningococcal disease, a serogroup-specific diagnosis could be established by examination of paired sera in the ELISAs. As serogroup B and C meningococci account for practically all cases of meningococcal disease in industrialized countries, the availability of these tests may improve surveillance and prevention.

The aim of this study was to examine the immunogenicity of a Haemophilus influenzae type b (Hib) vaccine (PRP-D) in Danish children younger than 18 months of age, given at the same time as a diphtheria-, tetanus- and polio-vaccine at the age of five, six and 15 months. The study was carried out as a multicentre study, where 21 children were vaccinated by their general practitioners. Blood samples were drawn just before and four weeks after each of the three vaccinations and the concentration of Hib-antibodies were determined using an ELISA-technique. Before the first vaccination none of the 21 children had antibody levels above 1 microgram/ml, which is believed to be the level which provides long-lasting protection, whereas after the first, second and third vaccination respectively 24, 48 and 100% of the children had antibody levels above 1 microgram/ml. There were only mild and short-lived side effects. The PRP-D vaccine given at the same time as Di-Te-Pol is safe, without serious side-effects and immunogenic in Danish children.

A retrospective epidemiological study of invasive Haemophilus influenzae type b infections among children in Denmark 1985 and 1986 was carried out and 226 cases were identified. Of these 93% occurred in patients younger than five, corresponding to an annual incidence of 40 cases per 100,000 children aged 0-4 years, 68% occurred in patients younger than two years of age, and 6% in patients younger than six months. The annual incidences of meningitis and epiglottis were 27 and 8 cases, respectively, per 100,000 children aged 0-4 years. Of the 156 cases with meningitis four patients died and seven had severe neurological sequelae. Only 67% of the cases of meningitis had been notified.