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Lyme borreliosis (LB) is the most common tick-transmitted infection in the northern hemisphere and is caused by bacteria in the Borrelia burgdorferi sensu lato (Bbsl)-complex. The diagnosis is partially based on serology, and clinicians often take follow-up serum samples to look for seroconversion or an increase in IgG-antibody levels. In this registry-based study, we proposed a method for determining actual changes in IgG and examined antibody reactivity and decay. Serological data from the departments of clinical microbiology at Karlstad Hospital, Sweden, and Slagelse Hospital, Denmark, were used to calculate a seroreactivity cut-off (SCOFF), above which changes between two samples from the patient cannot be explained by random variation. Increases in IgG reactivity as well as IgG and IgM decay were illustrated using time-to-event analysis and the SCOFF. A total of 44,861 serum samples from 34,157 patients were tested for Bbsl -antibodies. Of the 4301 patients with follow-up samples taken within 100 days, 201 (4.67%) were above the SCOFF of 1.42 with a median time to follow-up sample of 36 days (interquartile range: 21). IgG demonstrated longer median time for all antibody levels (indeterminate: 4.6 years, low: 7.0 years, moderate-high: 8.8 years) than IgM antibodies (indeterminate: 2.1 years, low: 3.9 years, moderate-high: 6.8 years) and higher initial antibody levels persisted significantly longer for both IgG and IgM antibodies (p < 0.001). Of the 7868 patients with follow-up samples, isolated IgM reactivity preceded an increase in IgG reactivity in 18 patients (0.23%). The SCOFF indicated little biological and random variation for Bbsl -specific IgG antibodies on the platforms used during the study. In most follow-up samples, both IgG and IgM antibodies persisted for years, with longer seropositivity associated with high initial antibody levels and IgG-type antibodies. The diagnostic value of isolated IgM reactivity was limited. [ABSTRACT FROM AUTHOR]

We investigated if diarrhoea‐causing bacteria, including Yersinia species, could mimic the symptoms of appendicitis and lead to surgery. This prospective observational cohort study (NCT03349814) included adult patients undergoing surgery for suspected appendicitis. Rectal swabs were analysed with polymerase chain reaction (PCR) for Yersinia, Campylobacter, Salmonella, Shigella and Aeromonas spp. Blood samples were analysed routinely and with an in‐house ELISA serological test for Yersinia enterocolitica antibodies. We compared patients without appendicitis and patients with appendicitis confirmed by histopathology. The outcomes included PCR‐confirmed infection with Yersinia spp., serologic‐confirmed infection with Y. enterocolitica, PCR‐confirmed infection with other diarrhoea‐causing bacteria and Enterobius vermicularis confirmed by histopathology. A total of 224 patients were included, 51 without and 173 with appendicitis, and followed for 10 days. PCR‐confirmed infection with Yersinia spp. was found in one patient (2%) without appendicitis and no patients (0%) with appendicitis (p = 0.23). Serology was positive for Y. enterocolitica for the same patient without appendicitis and two patients with appendicitis (p = 0.54). Campylobacter spp. were detected in 4% vs 1% (p = 0.13) of patients without and with appendicitis, respectively. Infection with Yersinia spp. and other diarrhoea‐causing microorganisms in adult patients undergoing surgery for suspected appendicitis was rare. [ABSTRACT FROM AUTHOR]

Background: Q fever caused by Coxiella burnetii is transmitted to humans by inhalation of aerosols from animal birth products. Q fever in pregnancy is suspected to be a potential cause of fetal and maternal morbidity and fetal mortality but the pathogenesis is poorly understood, and even in Q fever endemic areas, the magnitude of a potential association is not established. We aimed to examine if presence of antibodies to C. burnetii during pregnancy or seroconversion were associated with adverse pregnancy outcomes. Methods: The Danish National Birth Cohort collected blood samples and interview data from 100,418 pregnant women (1996-2002). We sampled 397 pregnant women with occupational or domestic exposure to cattle or sheep and a random sample of 459 women with no animal exposure. Outcome measures were spontaneous abortion, preterm birth, birth weight and Small for Gestational Age (SGA). Blood samples collected in pregnancy were screened for antibodies against C. burnetii by enzyme-linked immunosorbent assay (ELISA). Samples positive for IgG or IgM antibodies in the ELISA were confirmed by immunofluorescence antibody test (IFA). Results: Among the 856 women, 169 (19.7%) women were IFA positive; 147 (87%) of these had occupational or domestic contact with livestock (IFA cutoff > =1:128). Two abortions were IFA positive vs. 6 IFA negative (OR: 1.5; 95%CI: 0.3-7.6). Three preterm births were IFA positive vs. 38 IFA negative (OR: 0.4; 95% CI: 0.1-1.1). There was a significant difference in birth weight of 168 g (95% CI: 70- 267 g) with IFA positive being heavier, and the risk of being SGA was not increased in the newborns of IFA positive women (OR: 0.4; 95%CI: 0.8-1.0). Most seropositive women were IgG positive indicating previous exposure. Seroconversion during pregnancy was found in 10 women; they all delivered live babies at term, but two were SGA. Conclusion: We found no increased risk of adverse pregnancy outcome in women with verified exposure to C. burnetii. To our knowledge, this is the first population-based seroepidemiologic study evaluating pregnancy outcome in women with serologically verified exposure to C. burnetii against a comparable reference group of seronegative women. [ABSTRACT FROM AUTHOR]

Background: Q fever is a zoonosis caused by Coxiella burnetii. The disease is emerging in many parts of the world, likely in part due to increased awareness and the availability of better diagnostic tests. The clinical diagnosis of Q fever is difficult, and most confirmed cases rely on serology. Methods: This study compared the sensitivity, specificity, and performance of 2 commercial enzyme-linked immunosorbent assay (ELISA) kits, with a commercial microimmunofluorescence antibody test (IFA) used as reference. Results: One of the ELISA kits showed a higher sensitivity and a lower cross-reactivity than the other kit. Likewise, the same kit was superior when comparing the area under the receiver operating characteristic curves. Conclusions: The results support the continued use of IFA as a primary serological test for Q fever; for large numbers of samples, an ELISA kit can be used as a screening tool, if followed by a confirmatory IFA test. [ABSTRACT FROM AUTHOR]

Background. Several serologic tests, including anti-outer membrane porin C antibody (Omp C), are used for screening and as marker of disease course in inflammatory bowel diseases (IBD). Our aim was to investigate possible differences in Omp C level in patients with active and inactive IBD compared to controls. Methods. All blood samples were tested for Omp C. Disease activity was evaluated by Harvey Bradshaw Index, Simple Clinical Activity Index and Modified Pouchitis Disease Activity Index. Results. Blood samples were collected from 113 patients and 60 controls. Patients with active IBD did not have a higher level of Omp C than patients in remission. Surprisingly, in patients with active Crohn's disease a significantly lower level of Omp C was found compared with patients with inactive Crohn's disease ( p < 0.05). All other groups among patients with IBD did have a significantly higher level of Omp C, compared with controls, including patients with acute gastroenteritis ( p < 0.05). Although IBD patients with phylogroup B2 E. coli cultured from their fecal samples, were more likely to have a positive Omp C test ( p < 0.05), this could not explain the low Omp C level in the subgroup of patients with active Crohn's disease. Conclusions. Omp C titer was not raised in patients with active IBD compared with patients in remission. In addition, there was no difference in Omp C level in patients with active Crohn's disease compared with controls. These observations do not support the use of Omp C serology testing, either in disease activity assessment, or in screening for active Crohn's disease. [ABSTRACT FROM AUTHOR]

Background: Leptospirosis is a neglected zoonosis of ubiquitous distribution. Symptoms are often non-specific and may range from flu-like symptoms to multi-organ failure. Diagnosis can only be made by specific diagnostic tests like serology and PCR. In non-endemic countries, leptospirosis is often not suspected before antibiotic treatment has been initiated and consequently, relevant samples for diagnostic PCR are difficult to obtain. Blood cultures are obtained from most hospitalized patients before antibiotic therapy and incubated for at least five days, thus providing an important source of blood for PCR diagnosis. However, blood cultures contain inhibitors of PCR that are not readily removed by most DNAextraction methods, primarily sodium polyanetholesulfonate (SPS). Methodology/Principal Findings: In this study, two improved DNA extraction methods for use with blood cultures are presented and found to be superior in recovering DNA of Leptospira interrogans when compared with three previously described methods. The improved methods were easy and robust in use with all tested brands of blood culture media. Applied to 96 blood cultures obtained from 36 patients suspected of leptospirosis, all seven patients with positive convalescence serology were found positive by PCR if at least one anaerobic and one aerobic blood culture, sampled before antibiotic therapy were tested. Conclusions/Significance: This study suggests that a specific and early diagnosis can be obtained in most cases of severe leptospirosis for up to five days after initiation of antimicrobial therapy, if PCR is applied to blood cultures already sampled as a routine procedure in most septic patients. [ABSTRACT FROM AUTHOR]

Abstract: Q fever is a ubiquitous zoonosis caused by Coxiella burnetii. The disease is emerging in many parts of the world, likely because of increased awareness and availability of better diagnostics. The diagnosis is primarily based on serology. Because the prevalence of the disease varies worldwide, the establishment of local cutoff values is needed. A baseline for antibodies against C. burnetii in Denmark was defined by testing sera from healthy Danish volunteers using a commercially available immunofluorescence antibody test. Cross-reactivity was studied on sera obtained from patients experiencing clinically related diseases. The cutoff titers suggested by the manufacturer were found to result in very low specificity of the test. The specificity was, however, effectively increased by using cutoff titers based on the local baseline and equal to immunoglobulin M (IgM) phase I ≥128, IgM phase II ≥256, IgG phase I ≥512, and IgG phase II ≥1024. [Copyright &y& Elsevier]

Abstract: Enzyme-linked immunosorbent assay (ELISA) for measurement of antibodies to pertussis toxin (PT) is a widely used method for diagnosis of whooping cough and is also frequently used for seroprevalence studies and for assessment of antibodies after vaccinations against whooping cough. The recommended ELISA procedure for assessment of PT antibodies in human serum does, however, have a serious problem with false-positive results when heat-treated sera are analyzed. Historic sera might have been exposed to routine heat treatment, and diagnostic sera from warm geographic regions are at risk of unintentional exposure to heat. A modified version of the PT ELISA, incorporating a blocking step with 1% milk and addition of 0.1% milk to the dilution buffer, eliminates the false-positive phenomenon occurring with heat-treated sera. Results for serum antibody concentrations correlate well with the currently recommended method. This ELISA modification is straightforward and cheap, and it should be recommended at all analyses incorporating sera with unknown history of heat exposure. [Copyright &y& Elsevier]