Correlation of serum antibody titres with invasive methods for rapid detection of Helicobacter pylori infections in symptomatic children

Helicobacter pylori (H. pylori) is causally associated with peptic ulcer disease and gastric carcinoma. Typically, children get infected during the first decade of life, but diseases associated with H. pylori are seen mainly in adults. Multiple diagnostic methods are available for the detection of H. pylori infection. The aim of this study was to evaluate the correlation and diagnostic accuracy of three invasive methods [rapid urease test (RUT), histology and bacterial culture] and one non-invasive method (IgG serology) for diagnosis of H. pylori infection in a prospective cohort study conducted on 50 symptomatic children between two and eighteen years of age. Endoscopies with gastric biopsies were performed for RUT, culture and histopathological examination, respectively. IgG antibodies were measured in patient sera using a commercially available enzyme-linked immunosorbent assay (ELISA). RUT and positive H. pylori IgG antibodies were concordant in 88% (44/50) of patients. Both tests were negative in 32% (16/50), and both were positive in 56% (28/50). Disagreement occurred in 12% (6/50) of the patients: three of them (6%) had positive RUT and negative H. pylori IgG, and another three (6%) had negative RUT and positive H. pylori IgG. A combination of RUT with non-invasive serology constituted the optimum approach to the diagnosis of H. pylori infection in symptomatic children. The non-invasive serological test (ELISA) could not be used alone as the gold standard because it cannot distinguish between active and recently treated infection; and bacterial culture could not be used alone because of its low sensitivity.     

Diagnosis of Helicobacter pylori infection in adults with intellectual disability

Helicobacter pylori infection is common among adults with intellectual disability. The acceptabilities and accuracies of different diagnostic tests in this population are unknown. We aimed to determine (i) patient acceptability and (ii) performance characteristics of serology, fecal-antigen, and urea breath tests among adults with intellectual disability. One hundred sixty-eight such adults underwent H. pylori testing with serology and fecal-antigen tests, and a portion underwent treatment. One year later, the participants were retested with fecal-antigen, serology, and urea breath tests. The numbers of specimens obtained and difficulties in collection reported by caregivers were noted. Test performance characteristics were assessed among participants and 65 of their caregivers, using serology as the reference. All participants provided at least one specimen, despite reported collection difficulties for 23% of fecal and 27% of blood specimens. Only 25% of the participants provided breath specimens; failure to perform this test was associated with lower intellectual ability and higher maladaptive behavior. The sensitivity, specificity, and positive and negative predictive values of the fecal test (baseline and 12 months versus caregivers) were 70 and 63 versus 81, 93 and 95 versus 98, 96 and 92 versus 93, and 53 and 74 versus 93%, respectively; those of the urea breath test (12 months versus caregivers) were 86 versus 100, 88 versus 95, 75 versus 89, and 94 versus 100%, respectively. With assistance, fecal or blood specimens for H. pylori assessment can be provided by most patients with intellectual disability regardless of their level of function or behavior. Only those with greater ability can perform the urea breath test. Using serology as the reference test, the limitations of performance characteristics of the fecal-antigen and urea breath tests are similar to those among a control group of caregivers.     

Non-invasive techniques for the diagnosis of Helicobacter pylori infection

Helicobacter pylori infection can be diagnosed by invasive techniques requiring endoscopy and biopsy (histologic examination, culture, polymerase chain reaction), and non-invasive techniques (serology, urea breath test, urine or blood, detection of H. pylori antigen in stool specimen). However, recent studies have demonstrated that a strategy of 'testing and treating' for H. pylori in uninvestigated, young (<50 years), dyspeptic patients in primary care is safe and reduces the need for endoscopy. Indeed, a number of clinical guidelines recommend non-invasive testing in dyspeptic patients followed by treatment of H. pylori in primary care based on clinical and economic analyses. Several non-invasive tests are currently available on the market. The choice depends on the clinical circumstances, the likelihood ratio of positive and negative tests, the cost-effectiveness of the testing strategy, and, finally, the availability of the tests. Nevertheless, two non-invasive tests are commonly used: the urea breath test, and the stool antigen test.     

Diagnostic utility of PCR-enzyme immunoassay, culture, and serology for detection of Chlamydia pneumoniae in symptomatic and asymptomatic patients.

To assess the utility of PCR-enzyme immunoassay (EIA) for diagnosis of acute infection with Chlamydia pneumoniae, we compared tissue culture, PCR-EIA, direct fluorescent-antibody (DFA) stain, and serology in studies with 56 patients with respiratory symptoms and 80 asymptomatic persons. Thirty-five patients were positive by either culture or PCR-EIA, and 101 were negative by both assays. Thirty specimens from symptomatic patients and one from an asymptomatic patient were culture positive; 23 of these were also PCR-EIA positive. Of the eight culture-positive, PCR-EIA-negative specimens, five were DFA negative and three were DFA positive. Four additional specimens were culture negative and PCR-EIA positive; of these, three were DFA positive and one was DFA negative. When we used culture- and/or DFA-positive results as a reference or "gold standard," the sensitivity and specificity of PCR were 76.5 and 99.0%, respectively. When we used PCR- and/or DFA-positive results as the reference, the sensitivity of culture was 87.5%. On the basis of single acute serum specimens, only 8 of these 35 patients had diagnostic antibody titers. Of the asymptomatic patients, 75% had immunoglobulin G or immunoglobulin M antibody to C. pneumoniae; 15 (18.8%) of these had antibody levels considered to be diagnostic of acute infection. This multicenter study indicates that culture and/or PCR-EIA is more reliable for prompt diagnosis of C. pneumoniae infection than single-point serology alone.     

Unsuitability of exhaled breath condensate for the detection of herpesviruses DNA in the respiratory tract

Exhaled breath condensate is a non-invasive method for detecting a wide number of molecules as well as genomic DNA in the airways. No study investigated the detection of viral DNA in exhaled breath condensate, while only one study excluded its usefulness for detection of influenza virus RNA. In this study, the suitability of exhaled breath condensate for detecting herpesviruses infection or reactivation in the respiratory tract of lung transplant recipients was evaluated.Twenty-four matched samples (exhaled breath condensate, bronchoalveolar lavage, whole blood, transbronchial biopsy) were evaluated for the detection of human cytomegalovirus (HCMV), human herpesvirus (HHV-6 and -7), Epstein-Barr virus (EBV) DNA by real-time PCR.Eighteen bronchoalveolar lavages (75%), six whole blood samples (25%), and two transbronchial biopsies (8.3%) were positive for at least one herpesvirus. Only one exhaled breath condensate specimen was positive for HCMV DNA (and positive also in the bronchoalveolar lavage, with low viral load in both specimens); while no other patient, irrespective of the viral load in any specimen or the presence of clinical symptoms and signs, had a positive exhaled breath condensate.These findings seem to exclude the suitability of exhaled breath condensate for non-invasive detection of viral DNA in the respiratory tract of lung transplant recipients.     

Positive Result by Serology Indicates Active Helicobacter pylori Infection in Patients with Atrophic Gastritis

Patients with atrophic corpus gastritis and elevated Helicobacter pylori antibody titers but ¹³C-urea breath test (¹³C-UBT) and histology results negative for H. pylori were randomized into eradication therapy or follow-up only. Antibody levels decreased significantly in six out of seven patients in the eradication group, while in the follow-up group, the titers declined in only one out of eight patients. In patients with atrophic corpus gastritis, positive serology results may indicate an ongoing infection in spite of negative ¹³C-UBT and histology results.     

Evaluation of the Helicobacter pylori stool antigen (HpSA) test in routine clinical practice--is it patient-friendly?

A new immunoassay has been developed to detect the presence of Helicobacter pylori antigens in stool specimens. The aim of our study was to assess the accuracy and utility of the H. pylori stool antigen (HpSA) test in routine clinical practice. Dyspeptic patients undergoing endoscopy were studied. H. pylori status was defined before treatment by CLOtest and histology, and by 13C urea breath test (UBT) after eradication therapy. A standard universal container was provided for stool collection and the HpSA test was performed by an investigator blind to the results of the other diagnostic tests. Patients also provided a venous blood sample prior to endoscopy for H. pylori serology. Sixty patients (30 M : 30 F: mean age 47 yr) were enrolled in the study. The pretreatment sensitivity, specificity, positive and negative predictive value of the HpSA test were respectively, 93%, 94%, 96%, and 90%. Twenty five patients returned for post treatment 13CUBT, but only 14 (56%) provided a stool sample for analysis. The post treatment sensitivity, specificity, positive and negative predictive value of the HpSA test were respectively, 67%, 100%, 67%, and 92%. The HpSA test was negative in 19% of the patients found positive for anti-H. pylori antibodies on serology testing. All H. pylori antibody-negative patients had a negative HpSA test. Our results suggest that the HpSA test provides accurate pretreatment diagnosis of H. pylori infection but the reliability of the test after treatment is uncertain. A potential problem with the HpSA test appears to be patient reluctance about stool handling and this could prove a significant obstacle to patient compliance and the acceptability of the test in everyday clinical practice.     

Detection of transfusion transmitted virus (TTV) DNA in sera among three different population groups in Abidjan, Côte d'Ivoire in 2001

The aim of this study was to determine the transfusion transmitted Virus (TTV) prevalence in three groups of population from Abidjan, C?te d'Ivoire. The A group contained 39 multitransfused patients, the B group contained 10 blood donors supposed to be healthy persons which have never been transfused and the group C contained 43 patients with chronic liver pathology. In this last group, 33 patients had HBV positive serology and the 10 others, HCV positive serology. We used PCR to investigate TTV in patients serum. Detection rates were comprised between 67% and 82%. This is the first study to provide information about the high portage of TTV in ivorian population.     

Clinical Specificity of the Enzyme Immunoassay Test for Coccidioidomycosis Varies According to the Reason for Its Performance

The diagnosis of coccidioidomycosis relies heavily on serologic test results in addition to clinical history, physical examination, and radiographic findings. Use of the enzyme immunoassay (EIA) has increased because it is rapidly performed and does not require referral to a reference laboratory, as do complement fixation and immunodiffusion tests. However, interpretation of immunoglobulin M (IgM) reactivity by EIA in the absence of immunoglobulin G (IgG) reactivity has been problematic. We conducted a retrospective medical record review of all patients with such IgM reactivity at our institution to identify situations where the finding was more likely to be clinically specific for coccidioidal infection. From 1 January 2004 through 31 December 2008, a total of 1,117 patients had positive EIA coccidioidal serology or EIA IgM-only reactivity; of these, 102 patients (9%) had EIA IgM-only reactivity. Among the 102 patients with EIA IgM-only reactivity, 60 were tested to evaluate symptomatic illness, 13 for follow-up of previously abnormal serology, and 29 for screening purposes. Of the 102 patients, 80 (78%) had positive serologic findings by other methods or had positive culture or histology. Fifty-four (90%) of the 60 patients whose serology was performed to evaluate symptomatic illness had coccidioidal infection, whereas 13 (45%) of 29 patients whose serology was performed for screening purposes had coccidioidal infection. Of the 102 patients with isolated IgM reactivity by EIA, 12 later seroconverted to IgG and IgM reactivity. The use of EIA for screening in 29 asymptomatic persons was associated with unconfirmable results in 13 (45%). Although the majority of patients in our study with isolated IgM reactivity by EIA had probable or confirmed coccidioidomycosis, this result must be interpreted with caution for asymptomatic patients.     

Double-blind study to evaluate flow cytometry analysis of anti-live trypomastigote antibodies for monitoring treatment efficacy in cases of human Chagas' disease

The validation of flow cytometry analysis of anti-live trypomastigote antibodies (FC-ALTA) to monitor cure after treatment of Chagas' disease was evaluated with serum samples from treated and nontreated chagasic patients. After optimization of the original technique, toward better sensitivity and applicability to field surveys, we design a double blind study of 94 coded samples classified into the following categories: patients not treated (NT) and patients treated but not cured (TNC), both presenting positive conventional serology and xenodiagnosis; patients treated and cured (TC), showing negative serology and xenodiagnosis; and patients treated under evaluation (TUE), who presented positive or oscillating conventional serology (CSA) but negative xenodiagnosis. Coded samples, diluted 1:256, were assayed by incubation with live cell culture trypomastigotes, which were subsequently stained with fluorescein isothiocyanate-conjugated anti-human immunoglobulin G, with prior fixation and analysis by flow cytometry. The results were expressed as the percentages of positive fluorescent parasites (PPFP) for each individual sample, establishing 20% PPFP as the cutoff between negative and positive results. Our data demonstrated that all NT and TNC presented positive results while all but one TC had a PPFP lower than 20%. Analysis of TUE demonstrated a wide degree of reactivity, with PPFP values that were negative (PPFP 50%). As TUE with negative PPFP presented negative xenodiagnosis and positive or oscillating CSA, they were classified as dissociated according to the criteria of Krettli and Brener (J. Immunol. 128:2009-2012, 1982) and could indeed be considered cured after chemotherapy. This study demonstrates and validates the use of FC-ALTA to easily identify anti-live trypomastigote membrane-bound antibodies, offering another approach for investigating and monitoring the efficacy of specific chemotherapy in cases of human Chagas' disease.     

Rapid diagnosis of varicella-zoster virus infection with a monoclonal antibody based direct immunofluorescence technique

Diagnosis of varicella-zoster virus (VZV) infection in immunocompromised patients is difficult because of the frequent atypical appearance. Accurate and early diagnosis is important to allow rapid commencement of antiviral chemotherapy, with consequent improvement in antiviral efficacy. A monoclonal based direct immunofluorescence antibody technique (VZV IFA) was assessed in parallel with viral culture in 56 patients with suspected VZV infection. A subgroup of 17 patients from this group with classical dermatomal herpes zoster all had positive VZV IFA tests. Only 6 patients (35%) were positive on viral culture. None of the 15 patients with proven herpes simplex virus infection had a positive VZV IFA, nor did any patient with positive VZV viral culture have a negative VZV IFA. The VZV IFA test is a rapid and sensitive technique for detecting infection with VZV.     

16S rRNA based polymerase chain reaction compared with culture and serological methods for diagnosis ofMycoplasma pneumoniae infection

The use of a 16S rRNA based polymerase chain reaction (PCR) for the detection ofMycoplasma pneumoniae infection was investigated. Sputum samples from 34 patients with respiratory illness and evidence of pneumonia as judged by chest X-ray were analyzed by PCR and microbiological culture. Throat swabs from 14 healthy individuals were used as controls. For serology, an enzyme immunoassay for the detection of immunoglobulin M antibodies and a complement fixation assay were performed. Evidence ofMycoplasma pneumoniae infection was obtained in ten patients (29 %), eight of whom were found positive by both PCR and serology. Two of the sputum samples from these eight patients were negative by culture. Of the remaining two patients positive forMycoplasma pneumoniae, one was positive by PCR and culture but negative by serology, and one was found positive by serology but negative by PCR and culture. Thirteen of the 14 controls were negative by both PCR and serology. One control, however, was negative by serology but positive by PCR, which was probably due to asymptomatic carriage ofMycoplasma pneumoniae. The results of this study indicate the suitability of the PCR for the detection ofMycoplasma pneumoniae in clinical samples as well as its potential value as an additional tool for the diagnosis of infection.     

Histological identification of Helicobacter pylori: comparison of staining methods

AIM: To determine whether two recently described staining methods (the modified McMullen's and the Helicobacter pylori silver stain HpSS methods) used for the histological identification of H pylori organisms are superior to two established techniques (the modified Giemsa and anti-H pylori antibody immunostain) in terms of availability, reproducibility, rapidity, sensitivity, and cost. METHODS: Histological sections from 63 paired gastric biopsies from adult patients previously investigated for dyspepsia were stained with the four methods and these were assessed blindly and independently by two observers. Of the 63 patients, 30 were originally negative in all tests for H pylori infection, 30 were positive, and the remaining three cases had discordant results using a combination of five tests (rapid biopsy urease test, urea breath test, culture, serology, and histology). RESULTS: Interobserver agreement was best with the antibody method (98%), followed by the McMullen's (90%), Giemsa (87%), and HpSS (85%). Of the 60 "gold standard" positive and negative cases, 30 were positive by the modified Giemsa stain, 29 by the McMullen's method, 29 by HpSS, and 30 by the antibody stain. However, there were two false positives with the HpSS method. The modified Giemsa is the cheapest and easiest to perform technically. CONCLUSIONS: When H pylori are present, careful examination will almost always reveal them, whichever of these stains is used. However, the modified Giemsa stain is the method of choice because it is sensitive, cheap, easy to perform, and reproducible.     

Evaluation of a novel rapid one-step immunochromatographic assay for detection of monoclonal Helicobacter pylori antigen in stool samples from children

A new rapid one-step immunochromatographic test using monoclonal antibodies for detection of Helicobacter pylori antigen in stool in children was evaluated on coded stool samples from 159 children (mean age, 9.7 +/- 5.0 years; 118 from Munich, 41 from Vienna): 86 children were H. pylori infected defined by positive culture and/or > or =2 other positive tests ([13C]urea breath test, histology, rapid urease test), and 73 children showed concordant negative results. Seventy-nine patients (12.1 +/- 3.8 years; 42 from Munich; 37 from Vienna) were tested 6 to 8 weeks after anti-Helicobacter pylori therapy with urea breath test and stool test. In Munich, all 160 tests (118 pre- and 42 posttreatment) were independently read by two observers. Equivocal results were excluded for calculation of sensitivity and specificity but were considered as false to assess accuracy. The two observers in Munich agreed in 63 out of 65 positive and 89 out of 95 negative results, while eight times (5.0%) they judged the test as equivocal. Pretreatment and posttreatment results for sensitivity were 88.1% (79.2 to 94.1) and 88.9% (51.8 to 99.7), specificity 88.1% (77.8 to 94.1) and 93.9% (85.2 to 98.3), and accuracy 83.5% and 81.5%, respectively. We conclude that the new monoclonal immunochromatographic quick test shows a good interobserver agreement, but equivocal results occur in 5%. Performance is comparable before and after therapy. The test may become a good alternative in children in settings where a [13C]urea breath test or a reliable enzyme immunoassay stool test are not available.     

The diagnosis of cat-scratch-disease-associated adenitis: diagnostic value of serology and polymerase chain reaction

The diagnosis of cat scratch disease (CSD) associated adenitis relies classically on the association of clinical, epidemiological and bacteriological criteria. The polymerase chain reaction (PCR) looks like a more competitive diagnostic trial than serology. We evaluated the sensitivity, specificity and predictive positive and negative values of serology in routine diagnosis of CSD. A retrospective study over five years was led among patients presenting a suspicion of CSD and having a serology and/or a PCR. The Gold standard for diagnosis was PCR. The serological tests of Bartonella henselae was performed once in 482 patients, of which 2% (11 out of 482) were positive, and twice in only 39 patients (8%). The PCR diagnosis method for B. henselae was performed in biopsy of specimen lymph nodes in 28 patients and 14 out of 28 were positive. In nine patients, the diagnosis was exclusively made by PCR. Among the 14 patients whose PCR was negative, two had a positive serology and in three others patients, the serology was not performed. The sensitivity of serology was 35%, this confirms the low sensitivity of the serology in the CSD diagnosis. The diagnosis was confirmed in 56% of cases where PCR was performed. This led us to propose to perform systematically the PCR test for B. henselae in case of adenitis possibly associated with CSD.     

Prospective evaluation of a whole-blood test using Mycobacterium tuberculosis-specific antigens ESAT-6 and CFP-10 for diagnosis of active tuberculosis

A new immunodiagnostic test based on the Mycobacterium tuberculosis-specific antigens CFP-10/ESAT-6(QFT-RD1) has been launched as an aid in the diagnosis of latent tuberculosis (TB) infection (LTBI). The aim of this study was to evaluate this test for the diagnosis of active TB. Eighty-two patients with suspicion of TB and 39 healthy BCG-vaccinated persons were enrolled. Forty-eight had active TB, 25 did not, and 9 were excluded. Sensitivity and specificity of the test for active TB were evaluated in a prospective blinded manner in patients suspected of TB. The sensitivity of the QFT-RD1 was 85% (40/48; confidence interval [CI], 75 to 96), and it was higher than the sensitivity of microscopy, 42% (20/48; CI, 27 to 56; P = 0.001), and culture, 59% (27/46; CI, 44 to 73; P = 0.009). Of patients with extrapulmonary TB, 92% (12/13) were QFT-RD1 positive, whereas only 31% (4/13) were positive by microscopy and 42% (5/12) by culture (P < 0.05), and 87% (13/15) of those who were negative by both microscopy and culture were QFT-RD1 positive. By combining microscopy and culture with the QFT-RD1 test, sensitivity increased to 96% (CI, 90 to 102). Ten of 25 (40%) non-TB patients were QFT-RD1 positive, resulting in a specificity of 60%. However, 80% (8/10) of these had risk-factors for TB, indicating latent infection in this group. In healthy controls, only 3% (1/39) were QFT-RD1 positive. In conclusion, the QFT-RD1 test is sensitive for diagnosis of TB, especially in patients with negative microscopy and culture. The accuracy of the QFT-RD1 test will vary with the prevalence of LTBI. We suggest that the QFT-RD1 test could be a very useful supplementary tool for the diagnosis of TB.     

Small intestinal bacterial overgrowth in patients with chronic lymphocytic leukaemia.

As part of a study to assess the possible contribution of lymphoid infiltration of the gastrointestinal mucosa to occult blood loss or malabsorption 20 patients with chronic lymphocytic leukaemia (CLL) had a lactulose hydrogen breath test. In 10 cases (50%) a small intestinal peak was detected, suggesting small bowel bacterial overgrowth, and this was confirmed in seven patients by the positive culture of jejunal aspirate. Of the patients with a positive hydrogen breath test, radiological examination showed a duodenal diverticulum in two but no anatomical abnormalities in the other cases. There was no evidence of achlorhydria and transit times were normal. There was no difference in the incidence of hypogammaglobulinaemia among those patients with evidence of small intestinal bacterial overgrowth and those without. Seven patients with a positive hydrogen breath test, however, had undetectable secretory piece in their jejunal aspirates whereas this was present in all patients with a normal breath test who had local immunoglobulin concentrations measured (p less than 0.05), indicating that the small intestinal bacterial overgrowth may be due to impaired local immunity.     

Study of dynamic of chicken infectious anaemia virus infection: which sample is more reliable for viral detection?

Chicken infectious anaemia virus (CIAV) is a widely distributed immunosuppressive agent. SPF flocks and eggs used for vaccine production and diagnostics must be CIAV-free. Detection of CIAV infection in SPF flocks involves primarily serology or other invasive methods. In order to evaluate different types of samples for rapid detection of CIAV infection, a trial was conducted in serologically negative broiler breeder pullets vaccinated with a commercial live-attenuated CIAV vaccine. Controls and vaccinated groups were sampled before and after vaccination. Invasive and non-invasive samples were used for CIAV DNA detection by real-time PCR. Seroconversion occurred at 14 days post-inoculation (DPI) in the vaccinated group, whereas CIAV genome was detected by qPCR at 7 DPI in both invasive and non-invasive samples. Only invasive samples remained qPCR positive for CIAV DNA by 21 DPI despite seroconversion of the chickens.     

Immunoglobulin E antileishmanial antibody response in cutaneous leishmaniasis.

High levels of antileishmanial immunoglobulin E (IgE) antibodies are associated with disease activity in visceral leishmaniasis. Herein, we report our observations about the relationship between antileishmanial IgE antibodies and clinical aspects of cutaneous leishmaniasis. This study was carried out with 45 patients (29 male and 16 female), with ages ranging from 11 to 48 years. All subjects were from an area to which leishmaniasis is endemic, Corte de Pedra (Bahia, Brazil), and the duration of the illness was 相似文献