Evaluation of chlamydial tests in early trachoma

Abstract

An enzyme linked immunosorbent assay (ELISA) and an immunofluorescence (IF) test were compared with culture for their value in the diagnosis of chlamydial infection in early trachoma. Conjunctival swabs and scrapings from 81 school children with active trachoma from Khartoum, Sudan, were tested. Fourteen (17.3%) of the children with signs of active trachoma were positive by isolation. The sensitivities of the ELISA and IF tests, compared to cultures, were 85.0% and 68.2%, while the specificities for the ELISA and IF tests were 99.2% and 99.3%, respectively. Chlamydial IgM and IgG antibodies reactive with serotypes A‐C and D‐K of Chlamydia trachomatis were detected in sera of 28 (71.2%) of the 39 children from whom serum was obtained. Only eight of the 14 isolation‐positive children were tested for chlamydial antibodies, and all of them had IgM and IgG antibodies at a titer of ≥ 1:16. An IgG antibody titer of 1:16 or greater was detected in 20 (65.0%) of the 31 isolation‐negative patients tested for chlamydial antibodies. The geometric mean titers of IgG antibodies to the antigen pools A‐C and D‐K were 132 and 42, respectively. Our study suggests that trachoma is prevalent in the child population studied. Clinical signs of active trachoma were found in 47.0% of the altogether 172 children investigated. ELISA can be recommended as a diagnostic tool in trachoma field surveys.

Detection of infections of the eye withChlamydia trachomatis by the polymerase chain reaction

“…In later stages, the etiological agent is not detected any longer, conjunctival scarring often occurs without detectable C. trachomatis [20,21 ].…”

The prognostic value of epidermal growth factor receptors, determined by both immunohistochemistry and ligand binding assays, in primary epithelial ovarian cancer: a pilot study

“…Not all samples contain the micro-organism, which is known from the trachoma pathology. In later stages, the etiological agent is not detected any longer, conjunctival scarring often occurs without detectable C. trachomatis [20,21 ].…”

Análise de exames de imunofluorescência direta para o diagnóstico de tracoma

“…Esse longo tempo para um único exame inviabiliza seu emprego em trabalhos de campo, onde geralmente existe número elevado de casos 20 . A cultura de Chlamydia trachomatis é o método padrão para o diagnóstico laboratorial, com alta sensibilidade, porém exige condições adequadas de realização, de estocagem de material, além de equipamentos sofisticados de alto custo que inviabilizam seu emprego no trabalho de campo 3,9 . A imunofluorescência direta é realizada com a utilização de anticorpos monoclonais marcados, que se dirigem contra uma proteína comum aos 15 sorotipos da Chlamydia trachomatis, identificando os corpúsculos elementares extracelulares (EB) ao microscópio de fluorescência 16 .…”

“…Não há concordância entre diversos autores quanto ao critério de positividade do exame. Alguns consideram o exame positivo com presença de pelo menos um EB 7 ,outros com cinco 8,10,19,20,21 e com dez 3,12,14,20 . A Secretaria de Estado de Saúde de São Paulo (SES/SP) preconiza a realização de exames laboratoriais para confirmação de área com foco de tracoma, em locais onde não existiam casos previamente 15 , pelo fato da doença ter sido considerada erradicada do Estado no final da década de 70 5 .…”