Diagnóstico de Strongyloides stercoralis a partir da análise de sedimento obtido com dez ou mais gramas de fezes : proposta de um método com uso de microscópio invertido

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

18/03/2011

RESUMO

The methods of Baermann-Moraes and Koga agar, are the most sensitive to identify Strongyloides stercoralis larvaes in stool, but they require a fresh stool. We present a simple sedimentation method, which allows to evaluate a large sample of feces, using an inverted microscope to observe the sediment obtained. Objectives. To develop and evaluate a modified methodology to identify larvae of S. stercoralis from the sedimentation of feces, by examining all the sediment using an inverted microscope and to compare the proposed method with the Hoffman, Pons and Janer method (HPJ) and the Baermann-Moraes, considered highly sensitive for diagnosis of larvae of S. stercoralis. Material and Methods. To evaluate the effectiveness of the technique, there were two things to consider: (a) test the technique in the laboratory that performs the routine fecal examinations using the Hoffman, Pons &Janer method; (b) use the same sample, simultaneously, performing the method proposed and the Baermann-Moraes, for comparison. For the first observation, we used the routine laboratory of the Hospital Cassiano Antonio de Moraes - HUCAM and the Hopital Fundação Concordia in Santa Maria de Jetibá. We examined 221 faecal samples from patients treated in ambulatory or hospitalized in HUCAM, without any choice, they were also routinely examined by sedimentation method (HPJ). At the Hospital Fundação Concórdia in Santa Maria de Jetibá we evaluated 102 consecutive samples from patients treated in ambulatory. For the second point, 112 samples were analyzed using the inverted microscope method and the Baermann-Moraes technique. The samples were weighed and mixed with water using a glass rod in the same small container and then strained through gauze into a glass sedimentation measuring 250 ml. After an hour, the samples were washed with water and then allowed to stand for one more hour. The sediment (about 15 ml), plus two to three drops of Lugol was placed in a glass chamber measuring 12x8x0,5 cm, covered with a glass slide with the same surface and examined using an inverted microscope with 4X and 10X objective . The entire chamber was analyzed, and the number of larvae, was counted. Results. Of the 221 samples analyzed at the HUCAM laboratory, larvae of S. stercoralis were identified in 20 (9.05%) cases, in which the HPJ identified only nine (4.07%). The 102 samples from Hospital Fundação Concórdia, where the identification of larvae in the previous six months did not exceed 1.5%, 10 samples were positive using the inverted microscope (9.9%). The 112 samples used simultaneously to compare with the Baermann-Moraes technique, 11 samples were positive using the inverted microscope and all were also positive in the Baermann-Moraes method. Conclusion. The method is simple, with the following advantages: (a) the sediment obtained is examined at once, allowing the identification of all larvae existed there; (b) as the amount of stool examined is large (more than 8 to 10g used in Baermann-Moraes and 2 to 4 g used to perform the Koga agar), the probability of finding larvae increases, even in cases with low parasite load; and (c) allows the identification of dead larvae, unlike both the Baermann-Moraes and the Koga agar and could also be applied in faeces preserved with buffered formalin as fixatives or MIF

ASSUNTO(S)

strongyloides stercoralis exame coproparasitológico. strongyloidiasis strongyloides stercoralis coproparasitologic exam doencas infecciosas e parasitarias estrongiloidíase

ACESSO AO ARTIGO

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