Читать книгу Practical Guide to Diagnostic Parasitology - Lynne Shore Garcia - Страница 88

1. Most of the commercially available kits have a “fill to” line on the vial label to indicate how much fecal material to add to ensure adequate preservation of the fecal material. However, patients often overfill the vials; remember to open the vials with the vials turned away from your face. There may be excess gas in the vials that may create aerosols once the vial lids are opened.

2. Although the two-vial system (one vial of 5 or 10% buffered formalin [concentration] and one vial of PVA [permanent stained smear]) has always been the “gold standard,” laboratories are beginning to use other options such as the single-vial collection systems. Changes in the selection of fixatives are based on the following considerations.

a. Problems with disposal of mercury-based fixatives and the lack of multilaboratory contracts for disposal of such products

b. The cost of a two-vial system compared with the cost of a single collection vial

c. Selection of specific stains (trichrome, iron hematoxylin) to use with specific fixatives

d. Whether the newer immunoassay kits (EIA, FA, rapid cartridges [Giardia, Cryptosporidium, E. histolytica]) can be used with stool specimens preserved with that particular fixative