Abstract
Microscropic examination of faeces is a standard laboratory method for diagnosing gastrointestinal parasite infections. In North America, the ova and parasite (O&P) examination is typically performed using stool that is chemically fixed in polyvinyl alcohol (PVA) and formalin, after which the stool is concentrated by filtration to enhance sensitivity. Mini Parasep® SF tubes allow for collection and concentration within a single collection vial. The goal of the study was to determine whether consolidated processing and concentration with the Parasep® tubes using an alcohol-based fixative (Alcorfix®) provides equivalent or better O&P examinations than processing of PVA/formalin-fixed stool using SpinCon® concentration. Parasep® tubes revealed equivalent filtration performance versus SpinCon® using PVA/formalin-fixed stool containing protozoa. Specimens co-collected in PVA/formalin and Alcorfix® in Parasep® tubes revealed comparable morphology and staining for various protozoa.
Alcorfix® was effectively fixed live Cryptosporidium and Microsporidia such that morphology and staining was conserved for modified acid-fast and modified trichrome stains. A workflow analysis revealed significant time savings for batches of 10 or 30 O&P specimens compared to the same number of specimens in PVA/formalin tubes. Direct hands-on time savings with mini Parasep® tubes were 17:41 and 32:01 minutes for batches of 10 or 30 respectively. Parasep® tubes containing Alcorfix® provide significant workflow advantages to laboratories that process medium to high volumes of O&P specimens by streamlining processing and converting to a single tube. These improvements in workflow, reduction of formalin in the laboratory, and equivalent microscopy results are attractive advancements in O&P testing for North American diagnostic parasitology laboratories.