Isabel Sanfeliu

Accuracy of Diagnostic Tests for Helicobacter pylori: A Reappraisal

BACKGROUNDnDespite many changes, no large studies comparing the different diagnostic tests for Helicobacter pylori have been performed in the past 10 years. In this time, monoclonal stool antigen immunoassays and in-office 13C-urea breath tests (UBTs) have appeared. The aim of this study was to evaluate the accuracy of invasive and noninvasive tests in a large series of dyspeptic patients.nnnMETHODSnA total of 199 dyspeptic patients who had not previously been treated for H. pylori infection were prospectively enrolled. Noninvasive analyses included a commercial infrared-based UBT and a commercially available stool test. Biopsy-based tests included histological examination and a rapid urease test. A patient was considered to be infected when at least 2 test results were positive. Sensitivity, specificity, positive and negative predictive values, and 95% confidence intervals were calculated. The test results were compared using the McNemar test.nnnRESULTSnRates of positive test results were similar (54%) for the rapid urease test, histopathological examination, and the stool test. By contrast, 75% of UBT results were positive, and the UBT was associated with a very low specificity (60%). For this reason, the delta cutoff value for the UBT was recalculated as 8.5%. Sensitivities and specificities with this new cutoff value were 95% and 100%, respectively, for the rapid urease test; 94% and 99%, respectively, for histopathological examination; 90% and 93%, respectively, for the stool test; and 90% and 90%, respectively, for the UBT.nnnCONCLUSIONSnHistological examination and rapid urease testing showed excellent diagnostic reliability. The stool test seems to be a good, noninvasive alternative to endoscopy-based tests. By contrast, the infrared-based UBT evaluated in our study showed a lower than expected performance, which was partially corrected when the cutoff value for the test was recalculated.

Seroprevalence and epidemiology of Helicobacter pylori infection in patients with cirrhosis

BACKGROUNDnHelicobacter pylori infection is the major pathogenic factor for peptic ulcer disease. Its epidemiology is not fully known; few data are available in patients with chronic liver disease.nnnAIMSnTo investigate the seroprevalence and factors associated with Helicobacter pylori infection in a series of liver cirrhosis patients.nnnMETHODSnTwo hundred and twenty consecutive patients were prospectively included in a study aimed to evaluate the effect of dietary intervention on cirrhosis complications and survival. At inclusion, an epidemiological and clinical questionnaire was completed. Sera were obtained and stored at -70 degrees C until analyzed. They were tested for Helicobacter pylori antibodies using a commercial ELISA kit.nnnRESULTSnEleven out of 220 patients had borderline anti-Helicobacter pylori IgG titers. Of the remaining 209 patients, 105 (50.2%) showed positive titers of Helicobacter pylori IgG. Univariate analysis showed that Helicobacter pylori infection was more frequent in older patients, those born outside Catalonia, and in patients with a low educational level. Past ethanol consumption and current smoking correlated negatively with Helicobacter pylori infection. Multivariate analysis selected age (OR 3.1. 95% CI 1.46-6.45), educational level (OR 2.2. 95% CI 1.18-4.2) and alcohol consumption (OR 0.7. 95% CI 0.45-0.99) as the variables independently related to Helicobacter pylori infection.nnnCONCLUSIONSnHelicobacter pylori infection in cirrhosis has the same epidemiological pattern as in the general population. Suggestions that the etiology or the severity of the liver disease could be related to Helicobacter pylori infection were not confirmed by our study.

Real-Time PCR Improves Helicobacter pylori Detection in Patients with Peptic Ulcer Bleeding

Background and Aims Histological and rapid urease tests to detect H. pylori in biopsy specimens obtained during peptic ulcer bleeding episodes (PUB) often produce false-negative results. We aimed to examine whether immunohistochemistry and real-time PCR can improve the sensitivity of these biopsies. Patients and Methods We selected 52 histology-negative formalin-fixed paraffin-embedded biopsy specimens obtained during PUB episodes. Additional tests showed 10 were true negatives and 42 were false negatives. We also selected 17 histology-positive biopsy specimens obtained during PUB to use as controls. We performed immunohistochemistry staining and real-time PCR for 16S rRNA, ureA, and 23S rRNA for H. pylori genes on all specimens. Results All controls were positive for H. pylori on all PCR assays and immunohistochemical staining. Regarding the 52 initially negative biopsies, all PCR tests were significantly more sensitive than immunohistochemical staining (p<0.01). Sensitivity and specificity were 55% and 80% for 16S rRNA PCR, 43% and 90% for ureA PCR, 41% and 80% for 23S rRNA PCR, and 7% and 100% for immunohistochemical staining, respectively. Combined analysis of PCR assays for two genes were significantly more sensitive than ureA or 23S rRNA PCR tests alone (p<0.05) and marginally better than 16S rRNA PCR alone. The best combination was 16S rRNA+ureA, with a sensitivity of 64% and a specificity of 80%. Conclusions Real-time PCR improves the detection of H. pylori infection in histology-negative formalin-fixed paraffin-embedded biopsy samples obtained during PUB episodes. The low reported prevalence of H. pylori in PUB may be due to the failure of conventional tests to detect infection.

Accuracy of Monoclonal Stool Tests for Determining Cure of Helicobacter pylori Infection After Treatment

Background:u2002 Studies comparing new monoclonal fecal tests for evaluating cure of Helicobacter pylori infection after treatment are scarce. The objective was to compare the diagnostic accuracy of three monoclonal stool tests: two rapid in‐office tools –RAPID Hp StAR and ImmunoCard STAT! HpSA – and an EIA test – Amplified IDEIA Hp StAR.

Evaluación de un test rápido (ImmunoCard STAT! HpSA) para la detección de Helicobacter pylori en heces

Introduccion La utilizacion de una tecnica diagnostica rapida puede ser extremadamente util para el tratamiento de las enfermedades relacionadas con la infeccion por Helicobacter pylori. Recientemente se ha comercializado una prueba rapida inmunocromatografica en heces (ImmunoCard STAT! HpSA, Meridian Diagnosis Inc., Cincinnati, Ohio, EE.UU.) para la deteccion de H. pylori. El objetivo del estudio fue evaluar la fiabilidad diagnostica y reproducibilidad de ImmunoCard STAT! HpSA en pacientes dispepticos. Pacientes y metodos Se incluyo a 63 pacientes sometidos a endoscopia para estudio de sintomas dispepticos en los que se practicaron biopsias para CLO-test e histologia antral. Se consideraron infectados por H. pylori los pacientes que presentaban ambos tests positivos, y no infectados, los que dieron negativo en los dos. En heces se realizaron dos determinaciones seriadas de antigeno de H. pylori mediante ImmunoCard STAT! HpSA. Se calcularon la sensibilidad, la especificidad y los valores predictivos positivo y negativo de la tecnica. La concordancia entre las dos determinaciones se evaluo mediante el estadistico Kappa. Resultados De los 63 pacientes, 46 presentaron infeccion por H. pylori , 12 fueron negativos y tres se consideraron indeterminados. La sensibilidad, la especificidad y los valores predictivos positivo y negativo de las distintas determinaciones de ImmunoCard STAT! HpSA fueron del 89-91, el 86-93, el 96-98 y el 72-75%, respectivamente. El indice de concordancia entre determinaciones fue de 0,845. Conclusion ImmunoCard STAT! HpSA muestra una buena sensibilidad y reproducibilidad; por tanto, puede ser de gran utilidad en el tratamiento de las afecciones relacionadas con la infeccion por H. pylori.

Serosurvey of Rickettsia typhi and Rickettsia felis in HIV‐infected patients

Consistent with the effects of HIV on cell‐mediated immunity, an increased susceptibility to intracellular microorganisms has been observed. Rickettsiae are obligate intracellular microorganisms. The aim of this study was to examine Rickettsia typhi and Rickettsia felis infections in HIV+ population. Sera of 341 HIV+ patients were evaluated by indirect immunofluorescent assay. Age, sex, residential locality, risk behavior, stage according to criteria of the Center for Disease Control and Prevention, CD4+/CD8+ T cells, Hepatitis B antigen, and Hepatitis C serology were surveyed. Seroprevalences of R. typhi and R. felis infection were 7.6% and 4.4%, respectively. No associations were found between seropositivities and the assessed variables. Findings were similar to those obtained in healthy subjects from the same region.

Evaluación de la susceptibilidad de Helicobacter pylori a la rifaximina

Introduccion La infeccion por Helicobacter pylori afecta a mas de la mitad de la poblacion mundial y esta asociada al desarrollo de la gastritis cronica, ulceras pepticas y adenocarcinoma gastrico. La rifaximina es un nuevo antibiotico no absorbible de amplio espectro del grupo de la rifamicina que alcanza altas concentraciones en el tracto gastrointestinal. Objetivo Determinar in vitro la susceptibilidad de H. pylori frente a la rifaximina. Metodos Se estudiaron 31 cepas de H. pylori por el metodo de dilucion en agar. Como antibiotico control se utilizo la claritromicina. Como cepas control se utilizaron Staphylococcus aureus y Streptococcus pneumoniae . Las placas se leyeron a los 4 y a los 7 dias de incubacion. Se determinaron las CMI50 y las CMI90 para cada antibiotico. Se consideraron resistentes a la claritromicina las cepas con CMI > 1 μg/ml. Resultados Las CMI50 de la claritromicina a los 4 y 7 dias fueron de 0,125 μg/ml y las CMI90 a los 4 y 7 dias fueron de 8 y 16 μg/ml, respectivamente. Las CMI50 de la rifaximina a los 4 y 7 dias fueron de 1 y 2 μg/ml, respectivamente, y las CMI90 a los 4 y 7 dias fueron de 4 μg/ml. El 20% de las cepas de H. pylori fueron resistentes a la claritromicina. En estas cepas, el crecimiento de H. pylori fue inhibido a una concentracion maxima de rifaximina de 4 μg/ml. Conclusion Estos resultados indican que la rifaximina puede ser util en la erradicacion de la infeccion. Este nuevo antibiotico podria tener una mayor actividad en las cepas resistentes a la claritromicina y asi ser util en las combinaciones con este farmaco o en el tratamiento de los fracasos.

Shell-vial culture, coupled with real-time PCR, applied to Rickettsia conorii and Rickettsia massiliae-Bar29 detection, improving the diagnosis of the Mediterranean spotted fever.

Rickettsia conorii and Rickettsia massiliae-Bar29 are related to Mediterranean spotted fever (MSF). They are intracellular microorganisms. The Shell-vial culture assay (SV) improved Rickettsia culture but it still has some limitations: blood usually contains low amount of microorganisms and the samples that contain the highest amount of them are non-sterile. The objectives of this study were to optimize SV culture conditions and monitoring methods and to establish antibiotic concentrations useful for non-sterile samples. 12 SVs were inoculated with each microorganism, incubated at different temperatures and monitored by classical methods and real-time PCR. R. conorii was detected by all methods at all temperatures since 7th day of incubation. R. massiliae-Bar29 was firstly observed at 28°C. Real-time PCR allowed to detected it 2-7 days earlier (depend on temperature) than classical methods. Antibiotics concentration needed for the isolation of these Rickettsia species from non-sterile samples was determined inoculating SV with R. conorii, R. massiliae-Bar29, biopsy or tick, incubating them with different dilutions of antibiotics and monitoring them weekly. To sum up, if a MSF diagnosis is suspected, SV should be incubated at both 28°C and 32°C for 1-3 weeks and monitored by a sensitive real-time PCR. If the sample is non-sterile the panel of antibiotics tested can be added.

Direct identification of Ruminococcus gnavus by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) on a positive anaerobic blood culture bottle

We report a case of bloodstream infection with the anaerobic bacterium Ruminococcus gnavus (R.xa0gnavus), associated with intestinal perforation in a patient undergoing chemotherapy for multiple myeloma and cancer of the sigmoid colon. Gram staining of positive anaerobic blood cultures revealed both diplococci and short chains of gram-positive cocci. MALDI-TOF MS done directly on the blood culture bottle identified the bacterium as R.xa0gnavus, and 16S rRNA gene sequencing confirmed the identification.