Carmen Muñoz

Early Detection of Toxoplasma Infection by Molecular Monitoring of Toxoplasma gondii in Peripheral Blood Samples after Allogeneic Stem Cell Transplantation

BACKGROUND Isolated case reports have shown that recipients of allogeneic hematopoietic stem cell transplants (HSCTs) who develop toxoplasmosis may have circulating Toxoplasma gondii DNA in peripheral blood before the onset of clinical symptoms. METHODS We prospectively studied 106 T. gondii-seropositive adult recipients of HSCTs for the incidence of reactivation of toxoplasmosis in the first 6 months after transplantation. Toxoplasmosis infection (TI) was defined by a positive result of polymerase chain reaction (PCR) of peripheral blood specimens, whereas toxoplasmosis disease (TD) was defined as an invasive infection. RESULTS The incidence of TI was 16% (95% confidence interval [CI], 8%-21%), whereas the incidence of TD was 6% (95% CI, 1%-10%). In the 16 patients with TI, the incidence of disease was 38%, whereas it was 0% in patients without TI (P<.0001). In most patients, the onset of TD or treatment for TI was preceded by an increase in the parasite load in peripheral blood samples, as determined by quantitative PCR. CONCLUSIONS Toxoplasmosis occurs more commonly after HSCT than has previously been suggested, and routine PCR testing of peripheral blood specimens may be an appropriate tool for guiding preemptive therapy in patients at very high risk of developing invasive disease.

Antibiotic resistance trends in enteropathogenic bacteria isolated in 1985-1987 and 1995-1998 in Barcelona.

ABSTRACT Trends in resistance to antimicrobial agents used for therapy have been evaluated with 3,797 enteropathogenic bacteria,Campylobacter, Salmonella,Shigella, and Yersinia, between 1985–1987 and 1995–1998. The greater increase in the rate of resistance was observed in Campylobacter jejuni for quinolones (from 1 to 82%) and tetracycline (from 23 to 72%) and in gastroenteric salmonellae for ampicillin (from 8 to 44%), chloramphenicol (from 1.7 to 26%), and trimethoprim-sulfamethoxazole and nalidixic acid (from less than 0.5 to 11%). Multidrug resistance was detected in several Salmonella serotypes. In the 1995–1998 period, 76% of Shigella strains were resistant to trimethoprim-sulfamethoxazole, 43% were resistant to ampicillin, and 39% were resistant to chloramphenicol. Seventy-two percent ofYersinia enterocolitica O3 strains were resistant to streptomycin, 45% were resistant to sulfonamides, 28% were resistant to trimethoprim-sulfamethoxazole, and 20% were resistant to chloramphenicol.

Immunochemical localization of major hydatid fluid antigens in protoscoleces and cysts of Echinococcus granulosus from human origin

Summary Monospecitic rabbit an user a obtained through experimental immunization with previously purified proteins were used in the structural localization of two hydatid fluid antigens, antigen 5 and antigen B, in cyst membranes and protoscoleces of E. granulosus from human origin. The antigen‐antibody reaction was revealed by an avidin‐biotin‐peroxidase technique. Antigen 5 was not evident in the laminated membrane of the cyst wall, but it was associated with the germinal membrane of the cyst wall and brood capsules. The parenchyma of invaginated and evaginated protoscoleces was heavily labelled. The tegument, the calcareous corpuscles, the suckers and the hooks did not contain antigen 5. Degenerated protoscoleces were also labelled. Antigen B localization was essentially identical to antigen 5. but degenerated protoscoleces were not recognized by anti‐antigen B anliserum. Technical aspects and differences with previously published work arc discussed.

Quality control for the diagnosis of Toxoplasma gondii reactivation in SCT patients using PCR assays.

Quality control for the diagnosis of Toxoplasma gondii reactivation in SCT patients using PCR assays

Serological Diagnosis of Chronic Chagas Disease: Is It Time for a Change?

ABSTRACT Chagas disease has spread to areas that are nonendemic for the disease with human migration. Since no single reference standard test is available, serological diagnosis of chronic Chagas disease requires at least two tests. New-generation techniques have significantly improved the accuracy of Chagas disease diagnosis by the use of a large mixture of recombinant antigens with different detection systems, such as chemiluminescence. The aim of the present study was to assess the overall accuracy of a new-generation kit, the Architect Chagas (cutoff, ≥1 sample relative light units/cutoff value [S/CO]), as a single technique for the diagnosis of chronic Chagas disease. The Architect Chagas showed a sensitivity of 100% (95% confidence interval [CI], 99.5 to 100%) and a specificity of 97.6% (95% CI, 95.2 to 99.9%). Five out of six false-positive serum samples were a consequence of cross-reactivity with Leishmania spp., and all of them achieved results of <5 S/CO. We propose the Architect Chagas as a single technique for screening in blood banks and for routine diagnosis in clinical laboratories. Only gray-zone and positive sera with a result of ≤6 S/CO would need to be confirmed by a second serological assay, thus avoiding false-positive sera and the problem of cross-reactivity with Leishmania species. The application of this proposal would result in important savings in the cost of Chagas disease diagnosis and therefore in the management and control of the disease.

Infecciones por Helicobacter pylori: detección de antígeno en muestras fecales

Fundamento El objetivo del estudio es evaluar la tecnica de deteccion del antigeno de Helicobacter pylori en heces (HpSA), y comparar los resultados con los de las tecnicas standard (prueba del aliento con 13C-urea, serologia, cultivo y estudio histologico), en una poblacion de pacientes pediatricos con sintomatologia gastrointestinal sugestiva de infeccion por H.pylori. Pacientes y metodos Se estudiaron 60 pacientes pediatricos atendidos en el Servicio de Gastroenterologia por manifestar sintomas de dispepsia. Ninguno referia haber tomado antibioticos, inhibidores de la bomba de protones, ni compuestos con sales de bismuto. A todos ellos se les realizo la prueba del aliento con 13C-urea, una determinacion de IgG anti-H.pylori, se les practico una endoscopia gastrointestinal con la finalidad de obtener muestras para estudio histologico, prueba de la urea inmediata y cultivo microbiologico, y se les recogio una muestra fecal para estudiar la presencia de antigeno de H.pylori. Resultados Cuarenta y siete de los 60 pacientes estudiados mostraron estar infectados por H.pylori. En todos se aislo el microorganismo del cultivo y la prueba del aliento fue positiva. En 45 de ellos se positivizo la prueba HpSA (95,7%). No hubo ningun falso positivo de esta tecnica. Conclusiones La prueba HpSA ademas de la buena sensibilidad (95%) y especificidad (100%) que ha manifestado en este estudio, aporta ventajas sobre las otras tecnicas no invasoras, por su simplicidad en la obtencion de la muestra, realizacion de la tecnica, rapidez en la obtencion de los resultados y bajo coste economico, al compararlo con el elevado coste de la prueba del aliento.

Recommendation for Prenatal Screening for Congenital Toxoplasmosis

No general agreement currently exists about the use of serologic prenatal screening and protocols governing the diagnosis, prophylaxis and treatment of toxoplasmosis in pregnant women, because the criteria differ according to the seroprevalence of the infection [1–5]. In our hospital, the following protocol was implemented for prenatal screening and the treatment of congenital toxoplasma infection. All nonimmune pregnant women were tested every 3 months throughout the term of the pregnancy to detect seroconversion to toxoplasma infection. If specific immunoglobulin (Ig) M antibodies were detected with the first serological test, a second maternal serum sample was collected and tested 21–30 days later. If the IgG or IgM titre in the second sample was significantly higher, primary toxoplasmosis was diagnosed.

Resistance of Salmonella and Campylobacter species to antimicrobial agents.

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Towards a New Strategy for Diagnosis of Congenital Trypanosoma cruzi Infection

ABSTRACT The immigration of Latin American women of childbearing age has spread the congenital transmission of Chagas disease to areas of nonendemicity, and the disease is now a worldwide problem. Some European health authorities have implemented screening programs to prevent vertical transmission, but the lack of a uniform protocol calls for the urgent establishment of a new strategy common to all laboratories. Our aims were to (i) analyze the trend of passive IgG antibodies in the newborn by means of five serological tests for the diagnosis and follow-up of congenital Trypanosoma cruzi infection, (ii) assess the utility of these techniques for diagnosing a congenital transmission, and (iii) propose a strategy for a prompt, efficient, and cost-effective diagnosis of T. cruzi infection. In noninfected newborns, a continuous decreasing trend of passive IgG antibodies was observed, but none of the serological assays seroreverted in any the infants before 12 months. From 12 months onwards, serological tests achieved negative results in all the samples analyzed, with the exception of the highly sensitive chemiluminescent microparticle immunoassay (CMIA). In contrast, in congenitally infected infants, the antibody decline was detected only after treatment initiation. In order to improve the diagnosis of congenital T. cruzi infection, we propose a new strategy involving fewer tests that allows significant cost savings. The protocol could start 1 month after birth with a parasitological test and/or a PCR. If negative, a serological test would be carried out at 9 months, which if positive, would be followed by another at around 12 months for confirmation.

Risk of underdiagnosing amebic dysentery due to false-negative Entamoeba histolytica antigen detection.

Entamoeba histolytica antigen assays on stool are widely used to diagnose amebiasis. We report a case of confirmed amebic colitis with a false-negative antigen detection that became positive after treatment. Our results indicate that these assays may underdiagnose acute amebic infection when used alone and should be used cautiously.