Amparo García

Association of quantitative cytomegalovirus antigenemia with symptomatic infection in solid organ transplant patients

A prospective virologic follow-up of solid organ transplant patients was designed to determine the usefulness of antigenemia and viremia as virologic markers for the diagnosis of cytomegalovirus (CMV) infections, and also for monitoring CMV disease and therapy control. A total of 629 blood samples from 127 patients (60 liver, 47 kidney, and 20 heart transplant recipients) were studied by tube and shell vial cultures, and by antigenemia assay. This later was carried out by an indirect immunofluorescent assay method for formalin-fixed cytospin slides containing 2 x 10(5) leukocytes, using a monoclonal antibody directed against the CMV pp65 antigen. CMV was detected by at least one of the three methods in 238 specimens (37.8%) from a total of 63 patients. The antigenemia assay was positive in 215 (90.3% of positive samples). A total of 94 samples were detected only by this marker, which occurred either in samples with low positive counts (70.2% with antigenemia counts < 10 positive cells/10(5) leukocytes) or in specimens from treated patients. There were 30 episodes of CMV disease in 23 patients. Antigenemia was positive in all these episodes, 27 of them with counts > 20 positive cells/10(5) leukocytes. With this cut-off, positive and negative predictive values for symptomatic CMV infection were 100% and 97.2%, respectively. The antigenemia assay is a rapid, sensitive, specific, and early marker of CMV infection in transplantees. Cultures became negative with antiviral therapy while remaining antigenemia detectable. There was an association between highest quantitative antigenemia test results and clinical symptoms in our patients. In its quantitative version, the assay is useful to detect symptomatic infection and appears to be a helpful tool in managing patients at risk and in guiding antiviral therapy.

pp65 antigenemia as a marker of future CMV disease and mortality in HIV-infected patients.

We retrospectively evaluated the role of pp65 antigenemia (AGM) as a marker of cytomegalovirus (CMV) disease and mortality in 241 HIV-infected patients with fever. Of 225 patients in whom CD4 count was available, 189 (84%) had counts below 100/microL and 209 (92.8%) below 200/microL, 149 patients had negative AGM (AGM-) and 92 had positive AGM (AGM+), AGM+ patients were at a more advanced stage of HIV disease, as evaluated by CD4 count (p < 0.001) and prior AIDS diagnosis (p < 0.001). Overall, 29 patients (12%) presented concomitant CMV disease (18 retinitis): 24 (26%) in the AGM+ group and 5 (3.3%) in the AGM- group (p < 0.001). AGM had a negative predictive value of 96.6% but a positive predictive value of 26% which increased to 65% if a cut-off of > 10 CMV-positive cells/10(5) leukocytes was considered. The cumulative rate of future CMV disease at 3 months was 0% in AGM patients, 3% in patients with AGM 1-10/10(5) and 36% in patients with AGM > 10/10(5). In a multivariate analysis, no antiretroviral therapy, AGM+ and CMV disease were independently associated with mortality. The role of AGM as a marker of present CMV disease is limited. However, quantitative AGM may select patients at a high risk of future CMV disease. In addition, AGM may be a marker of shorter survival in severely immunosuppressed HIV-infected patients.

Comparison of three commercially available monoclonal antibodies directed against pp65 antigen for cytomegalovirus antigenemia assay.

A total of 102 blood samples were used in a prospective parallel and blind study to evaluate three commercially available anti-pp65 monoclonal antibodies for cytomegalovirus antigenemia assay, at the dilutions recommended by their manufacturers. Cytomegalovirus was detected in 42 samples (41.2%), by either culture (32 samples; 76.2% of positive samples) or antigenemia (38 samples; 90.6%). Of the antigenemia-positive samples, 37 were detected by Monofluo kit CMV, which showed statistically significant differences when compared with the other reagents (Biosoft 1C3 and Clonab C10/C11), in either positivity rates (P < 0.004) or positive cell counts (P < 0.001). This reagent also gave better results in fluorescence quality than 1C3 and C10/C11. However, technical differences were not reflected in the clinical relevance of the antigenemia results.

Antimicrobial resistance of Streptococcus pneumoniae: comparison of the in vitro activity of 16 antibiotics

Abstract A selected sample of 492 strains of Streptococcus pneumoniae (175 susceptible, 142 intermediately resistant, and 175 highly resistant to penicillin) isolated from adult patients in Bellvitge Hospital, Barcelona, Spain, was tested for susceptibility to 16 antibiotics using a microdilution broth method. Imipenen, rifampin, vancomycin, cefpirome, cefotaxime, and amoxicillin were the most active antibiotics against penicillin-resistant pneumococci. The strains with intermediate or high resistance to penicillin exhibited a significantly greater percentage of resistance ( P ⩽ 0.05) to erythromycin, clindamycin, tetracycline, chloramphenicol, and cotrimoxazole than penicillin-susceptible pneumococci. No resistance to third-generation cephalosporins was detected among penicillin-susceptible strains, whereas 1.4% of intermediately resistant strains and 13.2% of penicillin-resistant strains showed minimal inhibitory concentrations of cefotaxime ⩾ 2 μg/mL.

Influence of wire-coil inserts on the thermo-hydraulic performance of a flat-plate solar collector

Enhancement techniques can be applied to flat-plate liquid solar collectors towards more compact and efficient designs. For the typical operating mass flow rates in flat-plate solar collectors, the most suitable technique is inserted devices. Based on previous studies from the authors, wire coils were selected for enhancing heat transfer. This type of inserted device provides better results in laminar, transitional and low turbulence fluid flow regimes. To test the enhanced solar collector and compare with a standard one, an experimental side-by-side solar collector test bed was designed and constructed. The testing set up was fully designed following the requirements of EN12975-2 and allow us to accomplish performance tests under the same operating conditions (mass flow rate, inlet fluid temperature and weather conditions). This work presents the thermal efficiency curves of a commercial and an enhanced solar collector, for the standardized mass flow rate per unit of absorber area of 0.02 kg/sm2 (in useful engineering units 144 kg/h for water as working fluid and 2 m2 flat-plate solar collector of absorber area). The enhanced collector was modified inserting spiral wire coils of dimensionless pitch p/D = 1 and wire-diameter e/D = 0.0717. The friction factor per tube has been computed from the overall pressure drop tests across the solar collectors. The thermal efficiency curves of both solar collectors, a standard and an enhanced collector, are presented. The enhanced solar collector increases the thermal efficiency by 15%. To account for the overall enhancement a modified performance evaluation criterion (R3m) is proposed. The maximum value encountered reaches 1.105 which represents an increase in useful power of 10.5% for the same pumping power consumption.