ABSTRACT
PURPOSE: To compare the adherence of Acanthamoeba trophozoites and cysts to two types of unworn conventional and disposable contact lenses included in groups 1 and 4 of the Food and Drug Administration and to assess the adherence to the center and edge of the lenses. METHODS: We used 10 conventional and 10 disposable contact lenses belonging to groups 1 and 4 of the Food and Drug Administration. Each lens was divided into four segments. A human corneal isolate of Acanthamoeba suspended in saline (1x 105 amoebae/mL) was used. Lens segments were exposed to Acanthamoeba cysts and trophozoites for 2 hours. After removal, the count was made with an optical microscope at 100x magnification. Three fields at the center and three fields at the edge were read on each segment. RESULTS: Acanthamoeba adhered to both types of contact lenses, with a proportion of trophozoites to cysts between 6:4 and 7:3. There was a significantly higher adherence to disposable (8.14 +/- 3.57 organisms/mm(2)) than to conventional (4.94 +/- 2.33 organisms/mm(2)) (p < 0.0001) contact lenses. We also found that the greatest adherence was to the edge of the conventional (12.05 +/- 4.03 organisms/mm(2)) and disposable (26.10 +/- 7.84 organisms/mm(2) (p < 0.0001) contact lenses. CONCLUSIONS: This study shows that Acanthamoeba has varying adherence affinity for different new hydrogel contact lenses. The affinity for disposable lenses (etafilcon A) is significantly higher than that for conventional lenses (polymacon). This adherence is greater for ionic material and high water content. The use of low water content, nonionic contact lenses may reduce the adherence of Acanthamoeba. Finally, the edge may play an important role as an Acanthamoeba vector.
Subject(s)
Acanthamoeba/physiology , Contact Lenses, Hydrophilic/parasitology , Disposable Equipment/parasitology , Acanthamoeba/cytology , AnimalsABSTRACT
BACKGROUND: The aim of this study was to evaluate four commercial tests for the serologic diagnosis of infection by Helicobacter pylori based on the detection of IgG class antibodies versus this microorganism. METHODS: Four commercial kits were analyzed based on the ELISA method in serum samples of 48 patients admitted for digestive endoscopy. The data of the serologic tests were compared with those provided by the culture, the histologic observation and the urease test of gastric biopsy specimens. The calculation of seroprevalence of anti-H. pylori antibodies in serum of 60 asymptomatic subjects was carried out. RESULTS: The seroprevalence of infection by H. pylori in an asymptomatic population of between 18 to 78 years of age was 58.33%. A sensitivity of 94.3% and a specificity of 88.9% were observed with the Pyloriset EIA-G test. The positive predictive value (PPV) was 92.2% and the negative predictive value (NPV) 91.5%. With the Chemifarma commercial kit the sensitivity was 78.8% and the specificity 100% with a PPV of 100% and NPV of 76.7%. Plate showed a sensitivity of 85.3% and a specificity of 87.5% with a PPV of 90% and a NPV of 80.76%. Milenia had a sensitivity of 80% and a specificity of 66.7% and a PPV of 77% and a NPV of 70.7%. CONCLUSIONS: The usefulness of the serologic tests for the diagnosis of Helicobacter pylori infection is herein confirmed with the test evaluated showing a high sensitivity and specificity as well as high predictive values.
